Over the past decade, electronic shifting has quickly grown in popularity. Most high-end road, gravel, and mountain bikes come equipped with an electronic groupset. Almost all professionals use them. These days all of the major manufacturers including Shimano, Sram, Campagnolo, and FSA all offer electronic groupsets. Of course, there are still many hold-outs who prefer the more familiar mechanical shifting. If you’re on the fence, this guide is for you. I’ll outline the pros and cons of electronic vs mechanical shifting to help you decide which type of drivetrain is best for your style of riding.
In this guide, we’ll cover efficiency, cost, ease of use, reliability, performance, maintenance, and more. I’ll also outline a few of the more popular electronic shifting systems including Shimano Dura Ace Di2 and Ultegra Di2,Sram Force eTap AXS and eTap RED AXS, and Campagnolo EPS systems.
What is Electronic Shifting?
Electronic shifting allows the rider to shift gears with electronic switches instead of mechanical levers and cables. Electronic groupsets use electric servo motors to move the derailleurs and shift gears. The electric motors are housed in the derailleurs and are powered by a battery. The rider change gears by pressing electric switches or buttons that are integrated into the brake levers. The shift buttons send electronic signals to the derailleurs to tell them when to shift. This way, the rider doesn’t physically move the derailleurs. The electric motor does the work. There is a central junction box or small computer that regulates the system.
Electronic shifters and derailleurs are connected either by wires or wirelessly. Wireless systems like, Sram’s eTap, require separate batteries on all of the shifters and derailleurs. Wired systems, like Shimano’s Di2 and Campagnolo’s EPS, use a single central battery that is wired into the system.
What is Mechanical Shifting?
Mechanical shifting systems move the derailleurs with levers and steel Bowden cables. The cable runs between the shifters and derailleurs. When the rider manipulates the shift lever, the tension on the cable changes. This moves the derailleur from side to side to push the chain onto the next gear. When the rider reduces the tension of the cable, a spring in the derailleur pushes the chain onto the smaller cogs. When the rider increases tension on the cable, the derailleur pulls the chain onto the larger cogs. With a mechanical shifting system, the rider physically moves the derailleurs with levers and cables.
Electronic Shifting Pros
Less Effort is Required to Shift Gears
Electronic groupsets are easier to shift than mechanical groupsets. To shift gears, all you need to do is press a button. This requires very little effort. You barely have to move your finger or apply any force at all to change gears because the electric motor does all of the work for you. When you press the shift button, you’ll hear a quick ‘bzzzt’ sound of the electric motor doing its thing and you’ll be in another gear almost instantly.
You can also set your electronic groupset to shift through multiple gears when you hold the shift button. This allows you to shift through your gear range with less hand movement. In addition, you can install satellite shifters on your electronic drivetrain. These are secondary shift locations. They can mount anywhere on the bars including in the drops, on aero bars, on the tops of your bars. These allow you to shift without moving your hands to the brake hoods.
All of these features save you a small amount of energy. You don’t have to move your hands as much or press as hard to change gears. Mechanical drivetrains, on the other hand, require more force and a larger hand movement to actuate a shift.
This may not sound like a big deal. After all, it doesn’t take that much effort to shift a modern mechanical derailleur. When you try electronic shifting yourself, the ease of shifting is the first thing you notice. It’s game-changing. You don’t have to position your hands so you have enough leverage to push a lever. Your wrists don’t tire out as quickly. This allows you to spend more energy pedaling. These energy savings may allow you to make it over a hill that you would otherwise have to walk up or ride a little bit faster.
Electronic Shifting is Intuitive and Easy to Use
Electronic shifting takes less thought to use than mechanical shifting. There are several reasons for this. First is the shifting logic. Sram’s eTap electronic shifting system has just two shift buttons. The right button shifts up. The left button shifts down. When you push both at once, the front derailleur shifts. This shift logic is incredibly simple and intuitive. You don’t have to think as hard about which shifter to use.
Another benefit is that you don’t have to think about how hard or far you need to push the shift button to actuate a shift. You either push a button or you don’t. You can’t miss a shift or over shift an electronic drivetrain.
Electronic drivetrains also offer a setting that allows you to ride without worrying about shifting the front derailleur. For example, Shimano offers ‘Synchronized Shift’ or Synchro mode and Sram offers ‘Sequential’ mode. Recently, Campagnolo introduced their own sequential mode to their EPS drivetrains.
These high-tech systems allow the system to shift the front derailleur for you as you shift through the gear range Simultaneously, the system shifts the rear derailleur a few gears to compensate. When this mode is enabled, the right shift button moves you into a harder gear and the left button moves you into an easier gear. You don’t have to worry about which chainring to use. This system gives you the efficiency and gear range of a 2x drivetrain with the ease of use of a 1x drivetrain. I’ll talk more in-depth about this system in the following section.
The benefit of simpler and more intuitive shifting is that you can focus your mind on more important things like maintaining your cadence, producing pedaling power, choosing a line, cornering, and simply enjoying the view. There are fewer decisions to make so you can focus on riding your bike. You’re less likely to make a mistake when you’re completely exhausted. Simpler shifting is also helpful for beginners who sometimes forget which shifter to use.
You Can Customize Electronic Shifting
Because electronic groupsets are controlled by a computer and software instead of mechanical parts, they offer a great deal of customization. Shimano, Sram, and Campagnolo all offer smartphone and computer apps that allow you to make the customizations to your electronic shifting. Shimano’s app is called E-Tube, Sram’s is called AXS, and Campagnolo’s is called My Campy.
With these apps, you can control the number of gears that the drivetrain shifts when you hold the shift button. For example, you can set your shifter to shift one gear at a time, burst through several gears, or shift through your entire gear range. You can also control the speed that the system shifts through the gears. These settings allow you to find the correct gear more quickly and easily.
Shimano Di2 electronic groupsets allow you to map different shifter functions to any button you choose. For example, you can choose which hand controls which derailleur. Maybe you’re left-handed so you want to control the rear derailleur with your left hand. You can do that. You can swap upshift and downshift buttons. Newer Sram eTap AXS and Campagnolo EPS systems also allow you to customize button functions as well, though not as much as Shimano.
Sram eTap, Shimano Di2, and Campagnolo EPS electronic drivetrains with multiple chainrings offer a mode that partially automates your shifting. When this mode is enabled, the groupset automatically shifts the front derailleur for you at predetermined points in the gear range. When the front derailleur shifts, the rear derailleur simultaneously shifts a gear or two to compensate so you can better maintain your cadence. As mentioned above, Shimano calls this Synchronized shifting and Sram calls it Sequential shifting.
These automated shifting modes offer several benefits. The main one being ease of use. You get to enjoy the simplicity of a 1x drivetrain with the gear range and jumps of a 2x drivetrain. When using this mode, one button shifts up and one button shifts down. That’s all you have to remember. You never need to think about which chainring you’re using because the drivetrain chooses the best one for you. You don’t have to think about where you are in the gear range. This mode also helps you maintain a straighter chainline because you can’t cross-chain. The system also skips duplicate gears. In addition, chainring shifts feel smoother because the rear derailleur performs a compensation shift. This helps you maintain your cadence.
You can also fine-tune Synchronized or Sequential mode using your groupset’s app. You can select exactly at which gear your front derailleur shifts. In addition, you can set different shift points while upshifting and downshifting. If you like to ride at a high cadence, you may prefer to stay in the small chainring longer. If you want more torque, you may want to spend more time riding on the big chainring. You can also select the number of gears that the rear derailleur shifts to compensate. You can customize the exact shift pattern if you wish.
There is also a Semi Synchro (Shimano) or Compensating (Sram) mode. This mode lets you control the front derailleur. When you shift from one chainring to the other, the rear derailleur shifts one, two, or three cogs for you simultaneously to compensate. This helps you smoothly transition between chainrings so you can better maintain your cadence.
Shimano offers a bar end junction box with a button. You can use this button to switch between manual, synchronized, and semi-synchronized modes as you ride. The system allows you to set up to 5 custom gearing presets. You can press the button to switch through them as you ride. This way, you can test different gearing customization to find the most efficient and comfortable one. Sram allows you to switch between shift modes on their app.
Electronic shifting software is also constantly improving. You can update your system’s firmware to the newest version to take advantage of new features and customizations as they are released. With improved software, your electronic shifting system can become faster, more efficient, and more precise over time.
Electronic Shifting Requires Less Maintenance
After the initial setup, electronic drivetrains require pretty much no maintenance. They just work. You don’t need to worry about adjusting derailleur limits and indexing. You don’t have to adjust or replace cables. Everything stays adjusted. As long as the derailleurs, shifters, and wires don’t get damaged in an accident, you can ride 10s of thousands of miles without having to adjust your electronic drivetrain. The only unique maintenance you have to do is keeping the battery charged. You may also want to update the firmware when a new version is released, though this isn’t required to use the system.
Of course, you still need to take care of regular maintenance like keeping your chain and gears clean and well lubricated. You must also keep an eye on your chain, cassette, and chainring wear and replace them when necessary. These jobs are the same regardless of which type of drivetrain you use. It is easier to keep an electronic drivetrain clean because you don’t need to worry about removing debris from cable housings, mechanical linkages, or shifters.
Because electronic derailleurs never need to be adjusted, it is easy to ignore or forget to perform regular maintenance. The bike may still shift fine, even though your chain is worn out. If you ride too far with a worn-out chain, you can cause your cassette and chainring to wear out prematurely. Your bike will become less efficient as well if you don’t clean your drivetrain often enough. With a mechanical drivetrain, you know it’s time to do maintenance when your shifting performance starts to decline. When using an electronic drivetrain, remember to keep on top of regular maintenance even though your shifting still works perfectly.
Electronic Drivetrains Shift Faster
Electronic shifting is faster than mechanical shifting. For example, Campagnolo claims that “shift times are now 25% faster that than the mechanical rear derailleur (taking just 0.352 seconds to swap sprockets)”. Campagnolo EPS offers the fastest shifting followed by Shimano DI2. Sram’s eTap system shifts the slowest. Wired electronic drivetrains shift slightly faster than wireless.
Electronic drivetrains also allow you to shift from one side of the cassette to the other much faster than mechanical drivetrains. You can press and hold the shift button and the derailleur will shift from one end of the gear range to the other. Campagnolo’s EPS electronic groupsets can shift up or down up to 12 cogs at a time. With a mechanical drivetrain, you would need to continuously push the shift lever to move through that many gears at once.
The benefit of faster shifting is that it allows you to more easily and quickly find the gear that you need. This helps you maintain your cadence. Every time you shift up, your cadence slows down because pedaling becomes harder. A faster shift allows you to get back into your optimal cadence just a little bit faster. It’s less of an interruption. This improves efficiency and helps you maintain a slightly faster average speed.
Electronic Groupsets can have Multiple Shift Locations
Both Di2 and Etap electronic shift systems allow you to install additional shift buttons. These are often called accessory or satellite shifters. You can install satellite shifters anywhere on the handlebars. For example, if you’re a sprinter, you could install a second set of shift buttons in the drops. If you climb hills often, you can install a second set of shift buttons at the top of the bars near the stem. If you use aero bars, you can install shift buttons on the ends of the bars. This way, you can shift without having to re-position your hands or body. Of course, you can also always shift with the familiar shift paddles that are integrated with the brakes.
A number of satellite shifter styles are available. Shimano offers a Climbing Switch’that is designed to mount anywhere on the handlebars. In addition, Shimano offers Sprint Shifters’ that can be mounted anywhere on the drops. Sram also offers a couple of styles of satellite shifters. Blips and MultiClicks can mount anywhere on the bars. Blips can even mount under the bar tape. Satellite shifters plug into the integrated brakes/shifter levers with a wire so the whole system can communicate.
Mechanical shifting makes it impossible to have multiple shift locations because a cable must run from the shifter to the derailleur. You can’t have two cables controlling one derailleur because they would work against each other. With electronic shifting, the whole system can communicate so one shifter doesn’t interfere with another.
Electronic Drivetrains Can Collect Data
Cycling nerds love collecting data about their ride. Some use a GPS head unit to track their distance, speed, and elevation change. Some use a power meter to track their power output. Others track their heart rate.
Electronic drivetrains allows you to collect even more data about your ride. For example, you can track how much time you spend riding in each cog, when you shift, and how many shifts you make. This data can help you select the ideal tooth counts for your cassette and gear ratios for your drivetrain. You can also track this data over time to to see how your fitness improves. You can’t collect this kind of data with a mechanical groupset.
The Sram eTap AXS system can use Bluetooth, a compatible head unit, and ANT+ to save your drivetrain data to a FIT file. This file includes a shift profile. You can then use a number of applications to analyze that data.
Shimano’s Di2 system can connect with some compatible GPS devices. This allows you to track some data during your ride. For example, you can view your gear ratios and gear selection as well as check your battery life on the GPS screen. You can control your GPS with buttons on top of the brake hoods. You can program different screens to show different data.
Electronic Shifting is More Consistent
Electronic drivetrains shift exactly the same way every time you push the shift button. Shifting is much more consistent. This is possible for three main reasons.
First, electronic drivetrains are controlled by electric motors and software. These are much more precise and consistent than your fingers. The system can time each shift so it occurs when the ramps and pins on the chainrings are in the correct positions. This way, you always get a smooth shift. With a mechanical drivetrain, you can shift at the wrong time and grind gears or drop your chain.
Next, user error is much less likely with an electronic drivetrain. For example, you can’t accidentally move the shift lever too far and skip a gear or not push the lever far enough and miss a shift. An electronic shifter is just a button. You either push it or you don’t. If properly adjusted, it can’t push your chain too far or not far enough. Chain drops are less likely for this reason.
Because electronic shifters operate with a wire or wirelessly, you don’t have to worry about your shifting being affected by excess friction in the system. There are fewer moving parts. Shifter cables on mechanical groupsets can get rusty, crimped, contaminated with dirt and debris, or bent due to poor cable routing. Mechanical shifters can also get contaminated with debris. This creates friction which makes the shift rough, slow, and less predictable.
Electronic derailleurs also do not require adjustment after they are set up because there is no cable to stretch or wear. All of your gears always work as they are supposed to. With mechanical drivetrains, sometimes one gear doesn’t want to work. Maybe the cable tension or derailleur position isn’t adjusted just right. Maybe the indexing is off. This can make your shifting finicky or rough.
Electronic Groupsets Perform Better in Dirty Conditions
When using an electronic drivetrain, you don’t have to worry as much about mud, sand, dust, water, snow, or other contaminants affecting your shifting. The shifting doesn’t degrade when your bike gets a bit dirty. The reason is that electronic drivetrains have fewer moving parts. Solid-state electronic parts aren’t affected by dirt.
For example, electronic shifters are simple electrical switches. There are no moving parts that can get contaminated or gummed up. You also don’t have to worry about friction between cables and housings due to debris because the system operates electronically either with wires or wirelessly. In addition, electronic derailleurs are less affected by contaminants than mechanical models. The reason is that there are no mechanical linkages, cable linkages, or ratchet mechanisms that can get compromised by dirt. Electronic derailleur units are mostly sealed so debris stays out. For these reasons, electronic groupsets are preferable for riding in dirty, dusty, wet, or sandy conditions.
Electric Drivetrains Offer Better, More Precise Shifting
Electronic drivetrains use software and electric motors to control precisely how the derailleurs move when you shift. This helps you shift quickly and accurately every time. You’re not relying on mechanical parts and your fingers controlling the shift.
Electronic drivetrains improve shifting by allowing the front and rear derailleurs to communicate. The system can adjust the placement of the front derailleur depending on the rear cog you’re using. For example, Sram’s eTap system overshifts the front derailleur slightly when shifting from the small to the large chainring. This ensures that the chain makes the jump quickly. Immediately after the chain moves, the derailleur moves back into its regular position. When shifting from the large to the small chainring, Sram eTap derailleurs move just enough to push the chain down. Immediately after the shift, the derailleur moves back a bit. This prevents the chain from dropping between the chainring and frame.
Exactly how the derailleurs move depends on which gears you’re using. The electronic groupset makes the adjustment for you. For example, if you want to shift from the small to the large chainring while you’re using a large cassette cog, the rear derailleur tells the system which gear it’s in. This way, the front derailleur will know that it needs to overshift more so the chain will make the jump. If you’re using a small cassette cog, the front derailleur might not need to overshift at all. These minor adjustments result in faster and smoother shifting.
Shimano has a slightly different system for their Dura Ace and Ultegra Di2 groupsets. The front and rear derailleurs are programmed to move the chain exactly where it needs to be for every possible combination of gears. This way, the derailleurs are always in the ideal position every time you shift.
When you shift a mechanical drivetrain from one chainring to the other, the front derailleur always behaves the same way, regardless of which cog you’re using. Usually, it works fine. When you’re riding in the extreme high and low ends of your cassette, the front derailleur can be a bit finicky. You also have to make sure that your derailleurs are properly adjusted for shifting to be accurate and smooth.
Electric Drivetrains are Reliable and Durable
Electronic drivetrains have fewer moving parts than mechanical drivetrains. This means there are fewer parts that can wear out or fail. This makes electronic drivetrains incredibly reliable and durable.
For example, electronic shifters are simple electric switches. There are no moving parts inside. Mechanical shifters, on the other hand, have multiple moving parts that can wear out, get clogged with debris, and eventually fail. There are fewer moving parts in electronic derailleurs and linkages as well. The wires which connect the shifters to the derailleurs can last indefinitely as long as they aren’t damaged in an accident. There are no levers or ratchets on the derailleurs. just a simple electric servo motor.
Some cyclists instinctively worry about causing damage to their electronic drivetrain by getting it wet. After all, water and electronics don’t mix well. Luckily, this isn’t something you really need to worry about. Manufacturers know that you’ll be riding in the rain, through puddles, in the mud, and in the snow. They design the electronic components accordingly. Electric drivetrains are designed to be completely weatherproof. For example, Campagnolo EPS shifters, derailleurs, batteries, and connections all have an IP 67 waterproof rating. They are reliable in all weather conditions.
Having said that, you probably shouldn’t power wash or submerge your bike if you have an electronic drivetrain installed. Chances are it will survive, but it’s not worth the risk. You can safely hose it down without worry.
Electronic Shifting is Smoother
Electronic drivetrains can time the shift to take place at the ideal point in the rotation of the chainring or cassette cog. This is possible thanks to the central computer that controls the system. This allows electronic drivetrains to shift more smoothly and quickly than mechanical drivetrains.
To assist with shifting, chainrings have ramps, pins, and cutouts located at specific shift points on the rings. These features make it easier for the chain to jump from one ring to the next when you shift. By timing the shift, electronic drivetrains can easily make the transition from one gear to the next. Mechanical shifters, on the other hand, can’t always take advantage of these features. Sometimes you make a rough shift and grind your chain on a gear.
With a smoother shift, you can maintain your cadence better so you don’t lose as much momentum after a shift. This way, you spend more time cycling at your ideal cadence, which is more efficient. It’s also easier on your knees and hips. In addition, smoother shifting is easier on your drivetrain components. You won’t hear any grinding noises or loud clunks when shifting. Your components may last slightly longer as well.
Better and Easier Cable Routing
These days, many road bike manufactures have begun integrating the cables into the bike’s frame. The goal of hiding the cables in the frame is to improve aerodynamics by reducing wind resistance. Aerodynamics play a major role in your speed and efficiency while cycling.
Electronic drivetrains allow for better and easier cable routing. This is possible because the path of the wires that send signals between the shifters and derailleurs doesn’t matter. You don’t have to worry about sharp curves because there is no moving cable inside. You don’t have to worry about the length of the wire because the electrical signal travels at the speed of light.
Sram eliminated the cable problem altogether by introducing a completely wireless groupset. Sram eTap groupsets send shift signals to the derailleurs with Sram’s proprietary protocol called AIREA. There are no wires or cables at all.
No Chain Rub
Shimano Di2 and Campagnolo EPS electronic shifting systems automatically adjust the front derailleur when you shift the rear derailleur. This way, the chain never rubs on the side plates. When you shift the rear derailleur, you’ll sometimes hear the front derailleur moving slightly to accommodate for the new chain angle.
Sram designs their eTap electronic drivetrains in a way that makes it impossible for the chain to rub on the front derailleur plates no matter what combination of chainring and rear sprocket you’re using.
Eliminating chain rub improves efficiency by reducing the friction in your drivetrain. It also reduces wear and tear on your chain.
Electronic Shifting is Easier for People with Disabilities to Use
Electronic shifting makes it possible for people with physical disabilities to ride a bicycle. There are two reasons for this. First, the shift buttons can be mounted anywhere on the handlebars. For example, a person who is missing an arm may need both shift buttons positioned next to their remaining hand. This is possible with satellite shifters. Some Wounded Warriors ride recumbent bikes that are outfitted with electronic shifting systems for this reason.
Electronic shift buttons are also easier to operate than mechanical shifters. This is nice for those with dexterity issues. They can more easily press a button than operate a mechanical shifter because pressing a button requires less precise hand movement. You can’t half push a button or push it too hard. This is also nice if you’re riding in gloves or with cold hands. You can still push the shit buttons if you can’t feel them.
Electronic Shifting is More Efficient
Electronic shifters save you energy in several ways. First, it takes less energy to shift because electric buttons are easier to push than mechanical levers. You don’t have to move your hands as far in order to shift thanks to satellite shifters. You can also perform multiple shifts in one hand motion. Synchronized or semi-synchronized shifting allows you to maintain a better cadence by selecting the ideal chainring for you and compensating by shifting the rear derailleur. This makes the steps between gears feel smaller. It also helps you maintain a better chainline by eliminating the chance of cross-chaining. Electronic drivetrains make shifts faster and smoother as well. This also helps you maintain your cadence. In addition, electronic drivetrains reduce chain rub. All of these features help you save energy.
Admittedly, many of these efficiency advantages only offer marginal gains. During a long ride, these small gains add up. If you ride competitively, every little bit of energy savings matters. Electronic drivetrains allow you to ride further using less energy. The increased efficiency also allows you to maintain a slightly higher average speed.
Electronic drivetrains allow for a cleaner looking bike. The main reason is that the wires can be easily hidden in the bike’s frame. Sram eTap groupsets operate completely wirelessly so there are no wires at all. This makes for a sleeker looking bike.
At this time, all electronic groupsets are high-end. They are flagship products that are made from high-end materials with premium finishes. Shimano Di2 and Campagnolo EPS groupsets, in particular, are works of art. The finishes on the derailleurs and cranksets are beautiful.
More technologically advanced
Electronic groupsets offer the newest and most advanced technology in cycling. The reason is that most professional cyclists use electronic shifting these days. Because they are used in racing, an enormous amount of research and development goes into making the fastest, most precise, and most efficient electronic shifting system possible. For example, Shimano spent the better part of a decade testing and perfecting their Di2 groupset before releasing a commercial version.
These days, the most advanced groupsets are all electronic. Sram doesn’t even bother releasing mechanical versions of their top-of-the-line groupsets anymore. Pretty much all high-end road bikes and gravel bikes come with electronic drivetrains. If you are the kind of cyclist that likes to use the newest and most advanced cycling technology, you’ll probably enjoy using an electronic drivetrain. Generally, Sram eTap electronic drivetrains offer the most bleeding-edge technology. They offer wireless shifting as well as 12 gearing with 1x options on all of their eTap groupsets. Shimano tends to offer slightly older tech that is tried and true.
Electronic Shifting Cons
You Have to Keep the Batteries Charged
Electronic drivetrains are powered by batteries. Before your ride, you have to remember to check the battery level and charge if necessary. If you allow your batteries to run out mid-ride, your shifters and derailleurs stop working. This the biggest drawback to electronic shifting. It’s one more thing to worry about. This is something you never have to think about with a mechanical drivetrain.
The good news is that electronic drivetrain battery life is excellent. Sram claims that their eTap batteries will last for 60 hours of ride time (around 1000km). Shimano claims that their Di2 batteries will last 2,000 km between charges. If you don’t shift often, the batteries last even longer. The average cyclists who rides 3-5 times per week probably only needs to charge the derailleur batteries 4 times per year.
Because the batteries last so long, it’s easy to forget to charge them. Even professionals forget. There have been cases of cyclists running out of power during a race. To avoid running out of power during a ride, always check your battery level before leaving home. Sooner or later, you will forget to charge your bike and end up running out of power. It’s inevitable.
Transporting your bike can also drain the batteries. eTap derailleurs turn on when they sense that the bike is moving. During a flight or car journey, the derailleurs could cycle off and on and drain your batteries. It is also possible to accidentally store your bike with pressure on one of the shift buttons. This will keep the system on and drain the battery. You can solve these issues by unplugging the battery while transporting your bike.
All electronic groupsets have battery-level indicator lights that tell you when to charge. You can activate the indicator lights by actuating one of the shifters. It’s best to check your battery level before each ride.
Sram’s eTap system has an indicator light on each shifter, the front derailleur, and the rear derailleur. When the light is green, you have more than 25% battery life left. The light turns red when you have less than 25% battery life left. When the light starts flashing red, you have less than 15% battery life left. When the derailleur light turns red, you have around 15 hours of ride time left. If the light starts flashing red, you have around 5 hours left before the battery dies.
Shimano Di2 groupsets have one battery indicator located on the junction box that is mounted to the stem. It uses a similar green and red light system. When the light turns red, you have 25-50% battery power remaining. When it flashes red, you have less than 25% battery power left. To be safe, should charge your batteries when you see the light turn red.
Sram eTap groupsets have four batteries. Each derailleur has a separate removable rechargeable battery. Each shifter also has a disposable coin cell battery (CR2032). All electric components need a separate battery because the system operates wirelessly.
To charge the eTap derailleur batteries, you simply pop them out and plug them into a wall charger. They take about 45 minutes to charge. The shifter batteries are disposable. They need to be replaced about once every 1-2 years. The coin cell shifter batteries can go out unexpectedly because they last so long. It’s a good idea to carry a spare. They weigh practically nothing so it’s not a big deal.
If one of your eTap derailleur batteries dies, you can swap the live battery between derailleurs when you need to shift. Usually, the rear derailleur battery dies first because you shift the rear more often. If this happens, you can shift to your desired chainring then move the front derailleur battery to the rear derailleur and ride home. If both batteries die, you can manually place the chain on your desired cassette cog and chainring. Those who are extra catious could carry spare derailleur battery. If you keep an eye on your battery level, this isn’t necessary
Shimano Di2 and Campagnolo EPS electronic groupsets have one central battery that powers both derailleurs and shifters. This is an internal battery that mounts inside of the bike’s frame. It doesn’t come out of the bike to charge. This means you must place the bike physically near an outlet to charge the battery. You plug the battery into an adapter that plugs into the wall. The central battery takes about 3 hours to fully charge. Plugging your bike in can be a hassle if you normally store your bike in a shed or garage without electricity.
When a Shimano Di2 battery gets low, the system automatically disables the front derailleur to conserve power for the rear. You are stuck riding in whichever chainring you were using. At this point, you have 100-200 rear derailleur shifts left before the battery completely dies.
If you do happen to run out of battery power completely during your ride, the bike will still work. You just can’t change gears while you’re riding. You must manually place the chain on the gear you want then you can ride home. This would be a hassle but at least you wouldn’t be left stranded.
Another problem you can run into is battery degradation. Rechargeable battery life declines as the batteries age. After 5 years of use, you may have to charge the batteries once per month instead of once every 3 months. Eventually, you’ll have to replace the battery. Battery life is also reduced in extremely cold weather. If you regularly ride in below-freezing weather during the winter, you might want to avoid electronic shifting.
Electronic Groupsets are Expensive
Electronic groupsets are 50-100% more expensive than comparable mechanical groupsets. On average, an electronic groupset costs around $2000-$3000. This includes the shifters, derailleurs, batteries, chain, charger, junction box, crankset, and brakes. That’s more than many people spend on their complete bike. To compare, comparable mechanical groupsets cost around $800-$1000.
For example, few electronic groupsets and their prices include:
- Shimano Ultegra Di2 R8050 with hydraulic costs around $2370 with hydraulic disc brakes and around $1950 with rim brakes.
- Sram Force eTap AXS 2X costs around $2680 with hydraulic disc brakes. The 1x model with rim brakes costs around $2000.
- Campagnolo Super Record EPS 12 costs around $4600 with hydraulic disc brakes and $4200 with rim brakes.
For comparison, a Shimano Ultegra R8020 mechanical groupset costs around $1000. That’s half the price of the electronic version.
At this time, electronic drivetrains are only available in high-end and professional level options. Shimano Di2 electronic drivetrains are only available in their Dura-Ace and Ultegra range. Dura-Ace is a professional groupset and Ultegra is a high-end consumer-grade groupset. They also offer the GRX range which is a high-end gravel groupset.
Sram only offers electronic gearing in its highest end as well. The Force eTap AXS is sram’s high-end consumer level groupset and the Red eTap is a professional grade groupset. The Eagle eTap AXS is Sram’s range of high-end gravel groupsets.
There are no low-end or mid-range electronic groupsets on the market. If you’re on a tight budget, you’re only option is a mechanical groupset. Mid-range mechanical groupsets costing around $300-$800.
In addition to the standard parts, there are also some optional extras you might choose to buy for your electronic groupset that you wouldn’t need for a mechanical groupset. For example, many riders choose to buy Shimano’s inline wireless unit. This allows you to connect your phone to your electronic shifting system wirelessly to make customizations. Many cyclists also choose to upgrade to Shimano’s bar end junction box. These add-ons cost extra.
Electronic Replacement Parts are Expensive
Throughout the life of your drivetrain, chances are you’ll have to replace a shifter or derailleur after an accident. Parts can also get damaged if you travel with your bike. The cost of ownership of electronic groupsets is higher because replacement parts are more expensive.
For example, an Ultegra Di2 rear derailleur costs around $200. That’s about $100 more than a comparable mechanical Ultegra derailleur. Top-of-the-line professional-level electronic rear derailleurs like the Sram Red eTap AXS cost over $700. Electronic shifters cost $250-$350 depending on the brand. That’s around $50 more than a mechanical version. If a part breaks, you can’t downgrade to a cheaper version because all electronic components are high end and expensive. You may also need to replace the battery after 5-10 years.
If you participate in a cycling discipline where crashes and broken components are common, like downhill mountain biking, for example, you may be better off using mechanical components. If you’re regularly breaking shifters, brake levers, and derailleurs, it may not be worth it to buy electronic.
You might want to consider labor costs for repairs as well. If your electronic shifting system stops working and the issue isn’t obvious, it can be expensive to hire a professional to diagnose the problem and fix it. With a mechanical groupset, problems are generally pretty obvious and easy to repair.
Poor Parts Availability
Electronic drivetrain parts are hard to come by in some parts of the world. Particularly in the developing world and small towns. Many bike shops don’t carry them because there is too little demand for expensive high-end bikes.
Another problem is that electronic drivetrains only come in 11 and 12 speed options. Sram eTap and Campagnolo EPS systems use 12 speed components and Shimano Di2 uses 11 speed. 11 and 12 speed chains, cassettes, and derailleurs are not common in much of the world. They are a newer cycling technology that hasn’t spread everywhere yet.
For bicycle tourists and bikepackers who ride in remote regions and the developing world, parts availability is an important consideration when choosing a drivetrain. If an electronic derailleur or shifter breaks while you’re riding through Central Asia or West Africa, you probably can’t find a replacement locally. If your 12 speed chain or cassette wears out, you probably won’t be able to find another. You’d need to wait for weeks to have parts shipped in or fly to another country to buy what you need. For this reason, most bicycle tourists and bikepackers stick to 9 and 10 speed mechanical drivetrains instead. Parts are much easier to find.
Of course, globalization is making it faster and easier to get parts shipped in. If you only ride near a big city in a developed country, you won’t have any problem getting parts. Even if your local bike shop doesn’t stock what you need, you can always order parts online.
Harder to Service in the Field
Electronic drivetrains are much more complex than mechanical drivetrains. If an electronic derailleur stops working, pretty much all you can do is check your battery level and make sure all wires are connected securely. You’re out of luck if the fix isn’t simpl. If an electronic derailleur or a shifter button gets broken in an accident, you’re not going to fix it on the side of the road. It’s far too complex.
Mechanical drivetrains, on the other hand, are completely user-serviceable. With a basic multitool, you can completely disassemble a derailleur. With some basic bicycle mechanical knowledge and a bit of luck, there is a good chance that you can repair it.
This is an important point for those who ride in remote areas. If an electronic derailleur fails catastrophically while you’re in the middle of nowhere, you probably can’t fix it. With a mechanical derailleur, you may have a chance. For this reason, bicycle tourists, bikepackers, and mountain bikers are better off avoiding electronic shifting.
Electronic Groupsets are Harder to Install and Set Up
Shimano Di2 and Campagnolo EPS groupsets are quite a bit harder to install and set up than mechanical groupsets. Chances are, you’ll have to hire a professional to do it for you. The main reason is that the internal battery must be installed in the frame. Usually, it fits in the seat post or steerer tube. Sometimes it can fit in the down tube, fork, or even handlebars.
Fitting the battery can be a challenge on some bikes. Many older and low-end frames aren’t compatible with an internal battery because the tubes are too narrow or are curved. Shimano does offer an external battery if you don’t want to or can’t install your battery in your frame.
The Shimano Di2 and Campagnolo EPS installation process also involves routing wires through the frame to the shifters and derailleurs. Sometimes a hole may need to be drilled in the frame to pass the wires through. It’s best to hire a professional to do this if you don’t know what you’re doing.
Sram eTap electronic groupset are much easier to install. You simply bolt the derailleurs to the frame, install the shifters on the handlebars and mount the control unit to the stem. There are no wires to worry about because the system operates wirelessly. This makes eTap groupsets even easier to install than a mechanical drivetrain. Pretty much anyone with some basic bike mechanic knowledge can do it. Once the components are installed, you’ll have to adjust some limit screws and tension screws.
Configuring electronic shifting systems can also be a challenge. You may have to know a bit about gear ratios to take advantage of the more advanced features. You might want to take the bike to a shop to get some help optimizing the system. Sram, Shimano, and Campagnolo all offer apps that let you configure the electronic drivetrain.
Electronic Groupsets are Heavier
On average, electronic groupsets weigh 200-400 grams more than comparable mechanical groupsets. It’s difficult to compare the exact weight of the systems because there is so much variation in the weight of different crank sizes, chainring sizes, cassette sizes, brake caliper types, brake rotor sizes, chains, batteries, brake hose lengths, wire lengths, etc.
A Shimano Ultegra R8070 Di2 groupset with disc brakes weighs around 2600 grams. A Shimano Ultegra R8020 mechanical groupset with disc brakes weighs 2314 grams. In this example, the electronic shifting version weighs 286 grams more than the mechanical version.
Sram and Campagnolo electronic and mechanical groupsets have similar weight differences. For most riders, the weight difference is so small that it is insignificant.
Currently, the lightest electronic groupset is Shimano’s Dura Ace R9170 Di2, which weighs around 2400 grams. The mechanical version of this groupset, the Dura Ace R9120, weighs around 2100 grams.
One thing to keep in mind when comparing the Shimano electronic groupset weights to other models is that Shimano doesn’t include the weight of the battery, wires, and junction box. They probably do this because there are multiple battery and junction box types and every bike will use different wire lengths. A Shimano Di2 battery weighs around 52 grams. Wires weigh 30-50 grams depending on the length. The junction box weighs around 10 grams.
Electronic Groupsets are Harder to Repair
If something goes wrong with your electronic drivetrain, it can be difficult to diagnose the problem. Even for professional bike mechanics. The first step is to check the battery and wire connections. If the issue is more complex, it can take some time to fix.
For example, if a derailleur motor goes bad, you can’t just open it up and immediately see what’s going on. It’s far too complex. If the system completely stops working, you may have to check every part individually in order to find the problem. Your bike may be in the shop for a week while a professional figures out what’s wrong and fixes your bike. You might also have to wait for parts to arrive. Many bike shops don’t keep electronic parts in stock. Of course, fixing an electronic drivetrain comes with considerable parts and labor cost as well.
If something goes wrong with your mechanical drivetrain, chances are your local bike shop can get you back on the road in a couple of hours.
You May Run into Compatibility Issues
Shimano Di2 and Campagnolo EPS electronic drivetrains sometimes aren’t compatible with older or lower-end frames. This is because the battery must be installed inside of the frame. Older and lower-end bikes sometimes don’t have space to accommodate the tube-shaped battery. Shimano does offer an external battery that mounts outside of the frame. Cable routing can also be an issue. You may also have to zip tie the cables to the outside of the frame if the frame doesn’t have holes for internal cable routing.
Sram’s wireless eTap system is compatible with older frames. The batteries mount to the derailleurs so you don’t have to worry about frame tube sizing. The derailleurs operate wirelessly so you don’t have to worry about cable routing. Compatibility is excellent.
Historically, electronic drivetrains have suffered from reliability issues. In fact, several models have been removed from the market because they kept failing. Some modern electronic shifting systems are more reliable than others. While researching for this guide, I have read several complaints of electronic derailleurs failing prematurely. Mostly due to water damage. Some cyclists end up switching back to a mechanical drivetrain for this reason.
Electronic Groupsets May not Last as Long
Electronic groupsets haven’t been around long enough to really compare their longevity with mechanical groupsets. A couple of potential issues are compatibility and support. Will a 2030 electronic derailleur work with a 2021 electronic groupset? I don’t know. At some point, you may run into compatibility issues.
Also, who knows how long Shimano and Sram will support their old electronic drivetrains. One day, they could update their software, end support, and render your old components obsolete. You would still be able to ride but may not be able to install new replacement components on your old system.
You will also need to replace your batteries at some point when they stop holding a charge. If the battery design is changed in the future, you may have trouble finding a replacement.
These are all uncertainties. I’m sure I will be able to buy mechanical drivetrain components that are compatible with my current bike pretty much forever.
The good news is that the longevity of the hardware isn’t really a worry. The servos in the derailleurs are rated for hundreds of thousands of cycles. People have already put 10s of thousands of miles on electronic drivetrains without serious issues.
Electronic Groupsets Make the Bicycle Less Pure and More Complex
In my opinion, one of the most beautiful and interesting things about bicycles is the fact that they are completely mechanical pieces of equipment. They don’t require any electricity, motors, or modern tech to use. You can look at mechanical derailleurs and shifters understand exactly how they work. There is beauty in that.
Electronic drivetrains change that. They introduce electronics, software, and batteries into something that was purely mechanical. This isn’t necessarily a bad thing. Technology is amazing. It does kind of change the nature of the sport in a way. Some would even consider electronic shifting to be cheating.
Some cyclists also enjoy the tactile feel of mechanical shifting. When you move the lever, you can feel the derailleur move and the chain grab and jump to the next gear. There is something satisfying about operating an intricate mechanism like a derailleur and shifter. Simply pushing a button makes the shifting feel a bit disconnected. You aren’t physically moving the derailleur. You just push a button and the system does it for you.
Mechanical Shifting Pros
- Cheaper- Mechanical groupsets cost less than half the price of electronic groupsets. For example, you can buy a nice mid-range to high-end mechanical groupset for $600-$1000. Budget options are available starting at around $150. These prices include the derailleurs, shifters, chain, cassette, and crankset. Electronic drivetrains, on the other hand, are only available in high-end and professional level options. Prices start at around $1500 without brakes and top out around $4500. If you’re on a tight budget, mechanical is the way to go. Mechanical groupsets are cheaper to maintain as well. For example, you can buy a replacement mechanical derailleur for most drivetrains for well under $100. Shimano electronic derailleurs start at around $300. As an added benefit, you can do much of your own work if you use a mechanical groupset. You’ll spend less on labor.
- You can service mechanical parts in the field- If something goes wrong with your mechanical drivetrain while you’re out riding, there is a good chance that you can fix it. With some basic bike tools and knowledge, you can disassemble a derailleur or shifter and possibly repair it. You can also easily replace a shifter cable and adjust your derailleurs and cable tension with a simple multi-tool. With a little bit of know-how, you can repair your mechanical drivetrain on the side of the road if you have to. You’re not going to repair an electronic derailleur or shifter if it fails. It’s far too complex.
- Better parts availability- You can buy mechanical drivetrain components anywhere on earth. Even in the most remote villages. After all, people ride bicycles everywhere. If you crash and break a shifter or derailleur while touring through Central Asia, chances are you’ll be able to buy a replacement. It may not be the best quality but it will get you back on the road. You can’t find electronic components in many parts of the world. They just aren’t available. In some countries, they aren’t even imported. For this reason, mechanical drivetrains are preferable for bicycle touring and bikepacking. Having said this, you have to choose the right mechanical drivetrain if you want good parts availability. You won’t be able to find 12 speed chains, cassettes, or derailleurs in remote regions or developing countries. 9 and 10 speed components are much more common around the world.
- Easier to install and set up- With a bit of know-how and some basic bike tools, anyone can install and adjust a mechanical drivetrain. You can easily learn how to do it by watching a Youtube video. If you’re not comfortable doing it yourself, any bike shop can do the job for you. Mechanical drivetrains all work the same way, more or less. Electronic drivetrains, on the other hand, can be a bit harder to install and set up. Not every bike shop can do it. You also have to learn how to configure the system with the app. There may be a bit of a learning curve if you’re not familiar with gear ratios.
- More reliable- One major benefit of mechanical drivetrains is the fact that you never have to worry about keeping them charged. There are no batteries that can die on you in the middle of a ride. In addition, mechanical drivetrains are completely waterproof because there are no electronic parts. You can submerge them in water and power wash your bike without having to worry about causing water damage. If they get gummed up with debris, you can take them apart, clean them out, and they’re as good as new. Basically, they can take a beating and keep on going.
- Mechanical shifters offer tactile feedback- If you use friction shifters, you can feel exactly where the shift takes place when moving the shift lever. This gives you a bit more control, which can be helpful while riding on rough surfaces. Professional cyclists can use this tactile feedback to time their shifts with their pedal stroke. In this way, mechanical shifting is like driving a car with a manual transmission and electronic shifting is like driving a car with a semi-automatic transmission.
- Easier to repair- If a mechanical drivetrain starts giving you problems, it’s easy to diagnose what’s wrong. You can physically examine each moving part to determine what’s causing the problem. If a mechanical part is worn out or broken, it’s obvious. If you need to replace a mechanical part, you can easily swap it out, adjust it, and you’re back on the road. You can do all of your own maintenance if you wish. If you’d rather pay somebody to do the work, any bike shop can fix a mechanical drivetrain. Not every bike shop knows how to work on electronic drivetrains. Problems are harder to diagnose and can take longer to resolve.
- Longer lasting- A mechanical drivetrain can last decades if it’s taken care of. For example, I ride an old Schwinn High Sierra from the 80s that still has the original derailleurs. I helped my buddy restore a 30-year-old Schwinn road bike a couple of years back. We simply took the derailleurs apart, cleaned the parts, put them back together and they worked as good as new. The whole drivetrain is original except for wearable parts. If a 30-year-old derailleur dies, you can easily buy a replacement. An electronic drivetrain, on the other hand, may not last as long. Compatibility and support could become an issue down the road because the system is controlled by a computer.
- Lighter- Because they don’t require a heavy battery or a junction box, mechanical groupsets always weigh less than electronic. On average, the weight difference is around 200-400 grams. For example, the Sram Red 22 mechanical groupset weighs around 1770 grams while the Sram eTap Red electronic groupset weighs around 1970 grams.
- Excellent compatibility- Any frame that is designed to run derailleurs is compatible with a mechanical groupset. You could install a new mechanical groupset on a 50-year-old frame if you wanted to. Mechanical parts are often cross-compatible as well. You can often install shifters, derailleurs, and cranksets from different brands or product lines.
Mechanical Shifting Cons
- It takes more effort to shift a mechanical derailleur- With a mechanical drivetrain, you have to use a fair amount of force to shift gears. Particularly when shifting up into a harder gear. After all, you are physically moving the derailleur with the assistance of a lever and cable system. You may have to move your hand to get enough leverage to push the shifter with enough force. If you were riding in the drops or on top of the bars, you’ll have to move your hands to the brake hoods. The shift motion requires more hand movement as well. With a mechanical drivetrain, your hands and wrists tire out faster. You also burn a bit more energy shifting. With an electronic drivetrain, you simply push a button to shift. You barely have to move a finger.
- Mechanical shifting is more mentally demanding- There are four different controls. One upshifter and one downshifter for each derailleur. You have to think about which shift lever to use and which way to manipulate it to shift to the gear you want. Sometimes the front shift lever turns in the opposite direction from the rear. You can easily shift down when you want to shift up. You also need to remember which lever operates the front derailleur and which operates the rear. This can get confusing if you’re new to cycling. In addition, you need to move the derailleur the correct distance to make a smooth shift. You also have to push the lever with the right amount of force so you don’t move the derailleur too far or not far enough. You also have to think about which chainring and cassette cog you’re using to avoid cross-chaining. There is quite a bit of thought involved. This can pose a challenge when you’re exhausted. Electronic drivetrains, on the other hand, make shifting much simpler because buttons leave less margin for user error. You can’t push a button too hard or not hard enough. It either shifts or it doesn’t. Shimano and Sram also use software to make shifting easier and more intuitive. For example, Sram’s shift logic uses only two buttons to control both derailleurs. Both systems also allow you to partially automate your shifting.
- Mechanical drivetrains require more maintenance- As shifter cables age, they stretch. This stretching causes your derailleurs to go out of adjustment. Over time, this throws your indexing off. You may also experience ghost shifts or your drivetrain might start skipping gears. This means it’s time to adjust your derailleurs. With good quality gear, you’ll probably have to adjust your derailleurs once every year or so. You’ll also need to adjust them every time you install a new cable. You might also have to make some minor adjustments if you removed your derailleur for travel. Of course, you also need to keep the drivetrain clean and replace wearable parts as they wear out.
- Mechanical drivetrain performance tends to degrade in wet, muddy, and dirty conditions- Mechanical drivetrains rely on the cable moving through the housing to shift gears smoothly. When the housing gets contaminated with dirt, the cables no longer move smoothly due to increased friction in the system. This affects your shifting. If you ride in muddy or dirty conditions, you should clean or replace your cables frequently. Many riders don’t do this. Dirt can also clog up your mechanical derailleurs and shifters and prevent them from operating smoothly. There are lots of moving parts inside. For example, rear derailleurs have a ratchet mechanism inside as well as moving linkages. If your derailleur gets too dirty, you may not be able to shift into some gears. If you ride in the winter, your mechanical drivetrain can freeze up. Electronic drivetrains have far fewer moving parts so they don’t get clogged up as easily.
- Less consistent shifting- The rider directly controls the movement of the derailleur. For this reason, user error is possible. For example, with a mechanical drivetrain, you can easily push the shift lever too far and over shift or not far enough and miss a shift. You can grind your gears or drop a chain if you don’t operate the lever correctly. Electronic drivetrains eliminate user error because the software controls the movement of the derailleur. Sometimes your mechanical drivetrain may not behave the way it should. For example, maybe you can’t shift into a particular gear. This could be caused by a number of factors. Maybe the drivetrain went out of adjustment because of cable wear. Maybe some debris made its way into your cable housing, causing friction. Sometimes shifting is just a bit rough because the drivetrain is dirty. Electronic drivetrains shift the same way every time.
- Slower shifting- If you want to shift from one side of the cassette to the other with a mechanical drivetrain, you’ll have to actuate the shifter multiple times. You can only shift one or sometimes two gears at a time. With an electronic drivetrain, you can configure your shifters to move you across your entire gear range much faster. Mechanical drivetrains also take about 25% longer to shift between gears than electronic drivetrains. The slower shifting is more disruptive to your cadence.
- There is only one shift location- Mechanical groupsets can only have one shifter for each derailleur. This means you often have to move your hands to shift. For example, when you’re riding in the drops, on aero bars, or on the tops of the bars, you’ll have to move your hands to the brake hood. With electronic derailleurs, you can install satellite shifters that allow you to shift in whatever hand position you choose.
- Less efficient- Mechanical shifting has a number of small inefficiencies that cause you to use more energy while riding. For example, in order to shift a mechanical drivetrain, you must use move your hands further and use more force. You can’t perform multiple shifts in one motion. This takes more energy. It is also easier to make a bad shift. You could shift at the wrong time or push the lever too far. This can throw off your cadence, which slows you down. There is no automation which makes chain rub more likely. It’s also easier to cross-chain. While all of these inefficiencies are minor, they do cost you energy. During a long ride, you’ll tire out faster when using a mechanical groupset.
- Less precise shifting- Because mechanical drivetrains are controlled by a human, the shifting just isn’t quite as precise as computer-controlled electronic drivetrains. Sometimes you can make a sloppy shift if you’re not paying attention. This can throw off your cadence and slow you down. Also, mechanical drivetrain front and rear derailleurs operate independently. When riding in extreme high and low cogs of your cassette, it can be difficult to shift your front derailleur because the chain is running at an angle. The chain can also rub on the front derailleur plates. With electronic shifting, the front and rear derailleurs can communicate and adjust themselves slightly depending on where you are in the gear range to make shifting a bit smoother and more precise.
- Complicated cable routing- Shifter cables can cause a bit of drag when they are exposed. To solve this, many manufactures have begun hiding the cables in the frame on higher-end bikes. This often results in a complicated cable routing that is difficult to access and work on. Extra-long or tightly bent cables also have more friction, making it harder to shift. Sram eTap offers electronic drivetrains that are wireless. This completely eliminates the cable problem.
- Chain rub can be a problem- When riding in the smallest and largest cassette cogs, your chain runs at an angle. In some cases, it can rub on the front derailleur plates. This is particularly common when cross-chaining. Chain rub reduces efficiency and speeds up chain wear. Electronic derailleurs self-adjust so the chain never rubs.
- No customization- Mechanical groupsets work the way they work. You can’s adjust shift speed or the number of gears that shift when you press the lever. You can’t swap shift buttons. There are no automation options. If you’re not happy with some aspect of the shifting, you’ll just have to live with it.
- Can’t be used by some people with disabilities- Some people suffer from physical disabilities that make it difficult to use mechanical shifters. For example, a person who is missing an arm or a person with arthritis in the fingers may have trouble operating mechanical shifters. Electronic shifters are easier to actuate and can be placed anywhere on the handlebars.
- Less technologically advanced- Mechanical drivetrains are a bit more limited in what they can do. They can’t provide you with any data about your ride. They can’t be customized. There is no software to assist your shifting. You must control everything. In addition, there is less innovation in mechanical drivetrains because they are no longer used in racing, for the most part. Most professionals use electronic drivetrains.
- The industry is moving away from mechanical drivetrains- These days, most top-of-the-line road and gravel bikes come with electronic shifting. In some cases, mechanical options aren’t even available. For example, Sram hasn’t released a high-end 12 speed mechanical road groupset. I imagine we’ll start seeing mid-range electronic groupsets within the next few years.
Shimano Di2 Vs Sram eTap VS Campagnolo EPS Electronic Shifting Systems
The two most popular electronic shifting systems are Shimano’s Di2 and Sram’s eTap. The third most popular is Campagnolo’s EPS. Shimano Di2 was the first to the market in 2009, followed by Campagnolo EPS in 2011. Sram released their first eTap groupset in 2016.
The three systems have a lot of similarities. They all use similar technology and operate in a similar manner. They all offer most of the same features and customizations. Each system has a version of synchronized shifting. They all have their own smartphone app that can be used to make customizations. They are all available with disc or rim brakes.
Of course, there are a few major differences to take into consideration. For example, gearing options and battery management vary widely. This section outlines the main benefits and drawbacks of Shimano vs Sram vs Campagnolo electronic groupsets.
Shimano offers three electronic groupset options:
- Dura Ace Di2- This is Shimano’s professional level groupset. It is also the lightest.
- Ultegra Di2- This is Shimano’s high-end consumer level groupset.
- GRX Di2- This is Shimano’s gravel-specific electronic groupset.
All Shimano Di2 systems are use 11 speed gearing. Dura Ace and Ultegra models are available only in 2x. GRX Di2 groupsets are available in 1x and 2x versions.
Shimano’s Di2 is a wired system. The derailleurs, junction box, and shifters wire to a central battery housed in the frame. The benefit of a wired system is that it allows for faster and more reliable shifting. Those who ride competitively or those who want the best performance out of their drivetrain will prefer Shimano electronic groupsets. The drawback to a wired system that the system looks a bit less clean. You have to either route the wires through the frame or attach them to the outside with zip ties.
Di2 shifters work almost the same as standard mechanical shifters. There are two buttons near each brake lever. One for shifting up and one for shifting down. This makes the transition from mechanical to electronic shifters seamless because the controls are the same.
One common criticism of Di2 shifters is that the upshift and downshift buttons sit too close together. This makes them difficult to differentiate. Particularly while you’re wearing gloves. You can accidentally push the wrong button. Over time, most riders grow used to the button placement. If you don’t, one solution is to map the brake hood button to perform downshifts. You could also utilize satellite shifters.
Shimano Di2 electronic groupsets use one large battery to power the entire system including both derailleurs, the junction box, and the shifters. The advantage of this is that there is only one battery to worry about keeping charged. You won’t run out of power for one of your components. This also allows Di2 groupsets to be integrated with e-Bikes. The drawback is that the battery is not removable. You need to plug your bike in to charge it up.
Shimano Di2 electronic groupsets also weigh around 300-400g less than comparable Sram models. Some riders prefer Shimano’s gearing options and ergonomics as well. Another difference is the size and looks of the derailleurs. Shimano electronic derailleurs are smaller, sleeker, and lighter. This is possible because they don’t have a battery built-in and they don’t have a wireless receiver. Shimano electronic derailleurs also tend to feel a bit more premium and high-end. The finish is a bit better. The buttons feel a bit more satisfying to push. Shimano Di2 systems are also a couple of hundred dollars cheaper than comparable Sram eTap models.
One drawback of the Di2 system is the fact that it is more difficult to install. The reason is that the cylinder shaped battery must be installed in one of the frame tubes. It can can often fit in the frame tube, steerer tube, or even handlebars. In some cases a hole must be drilled to connect the wires to the battery. Professional installation is often required. This isn’t that big of deal because you only have to install the system once. Most cyclists will pay a professional to install and set up electronic shifting, regardless of which brand they choose.
Connectivity is a bit more complicated with the Di2 system as well. In order to make customizations to the shifting, you must connect your computer to the system with a wire. For the most functionality, you’ll need a Windows PC. There is also an iOS and Android App. In order to connect to the system wireless, you’ll need to buy a Bluetooth adapter.
Another potential drawback is the gearing. All Di2 systems currently 11 speed. Ultegra and Dura Ace Di2 groupsets are only available in 2x versions. If you want a 1x road groupset, you’ll have to use a GRX Di2 gravel crankset.
Sram offer three eTap options
- Red eTap AXS- This is Sram’s professional level groupset.
- Force eTap AXS- This is Sram’s high-end consumer-level groupset.
- Eagle AXS- This is Sram’s mountain bike groupset. There are three different Eagle AXS options: XX1 Eagle AXS, X01 Eagle AXS, and GX Eagle AXS.
Sram’s electronic derailleurs operate wirelessly. The front and rear derailleurs connect to the system’s computer with a proprietary wireless protocol called AIREA. This is the main feature differentiating Sram’s electronic shifting from their competitors.
The wireless connection makes the system easy to install. You just bolt the derailleurs, shifters, and control unit onto the bike and make some minor adjustments. It’s easier to install than a mechanical drivetrain. The system also looks a bit cleaner because there are no wires hanging off the frame.
All Sram AXS eTap groupsets have 12 speed gearing. The Force and Red AXS lines are all available in 1x or 2x options. The Eagle AXS lines are designed for 1x gearing. The Eagle cassettes offer up to 520% gear range.
Sram Force and Red eTap systems also feature modern X-Range gearing. This new approach to gearing uses two smaller chainrings with a 13 tooth difference between gears. These chainrings are paired with a wide range 12 speed cassette with a 10t small gear. X-Range cassettes offer an excellent gear range of up to 360% and small steps between cassette cogs.
The main benefit of X-Range gearing is that it allows you to use the same chainring longer without having to shift. This improves efficiency because you don’t have to make as many chainring shifts, which are less efficient than rear shifts. The shift between chainrings is also smoother because the difference is smaller at only 13 teeth. This improves efficiency because your cadence stays more constant when shifting between the similar-sized chainrings. Fewer compensation shifts are also required when shifting between chainrings thanks to the small difference between cassette cog sizes.
eTap systems use 4 batteries. One large battery attaches to each derailleur. There is also a coin cell battery in each shifter. The benefit to this is that you can remove the batteries and take them inside to charge them. You don’t have to place the bike near an outlet. The drawback is that there are two batteries to charge. Strangely, Sram’s charger only charges one battery at a time. You also have to worry about the coin cell batteries in the shifters going out. You’ll have to carry a spare.
Some cyclists find Sram’s electronic shifters to be easier and more intuitive to use. There is one paddle on each brake lever. The right paddle shifts up. The left paddle shifts down. You press both at the same time to shift the front derailleur. You can easily actuate shifts, even with thick gloves on. The shift logic is simple. On the other hand, some cyclists prefer Shimano’s more familiar shifter layout.
Sram eTap groupsets also offer better and easier connectivity. You can install the AXS app on your phone and wirelessly configure your gearing. The app is available for both iPhone and Android. This is very convenient.
One drawback is that Sram electronic groupsets are heavier than Shimano’s. The system also weighs 200-400 grams more. The derailleurs look modern but a bit bulky because of the batteries. Sram eTap systems are also a bit more expensive than Shimano Di2. The reason is that eTap requires expensive chains and cassettes. Sram derailleurs are also more expensive. In addition, some cyclists don’t like Sram’s gearing option.
Another common complaint is compatibility. Sram’s 12 speed cassettes use the XD/XDR rear hub driver. This is a newer and less common freehub design. This limits you to using Sram cassettes. The eTap AXS line also uses a proprietary bottom bracket design called DUB (Durable Unified Bottom Bracket). This limits you to using only Sram cranksets.
Sram eTap electronic groupsets also shift slightly slower than Shimano Di2 and Campagnolo EPS. There is a delay when you press the shift lever. This is necessary for the system to determine whether you wanted to shift the front or rear derailleur. After you press one of the shift levers, the system waits for a fraction of a second to see if you are going to press the other lever or if you’re just pressing one lever. This causes a slight delay before the system actuates the shift. For most riders, this isn’t really noticeable.
Some cyclists also feel that Sram shifters feel cheaper or more plasticky. The finish on the components is a bit less premium as well.
For more in-depth info, check out my complete guide to Shimano Di2 Vs Sram eTap electronic shifting.
Campagnolo offers one electronic groupset, the Super Record EPS. It is available in hydraulic disc and rim brake versions. Both feature 2×12 speed gearing. The Super Record EPS is a professional-level road groupset. Campagnolo does not offer an off-road electronic groupset.
Possibly the biggest benefit Campagnolo electronic shifting offers over Sram and Shimano is ergonomics. The brake lever shape is comfortable. The shift buttons feel sturdy and offer a satisfying click when you press them. In fact, the buttons feel very similar to mechanical buttons.
The button placement is also very familiar. Campagnolo shifters each have two buttons. The buttons are separated, making them easy to push while wearing gloves. One button is a paddle next to the brake lever that you control with your index finger. The other button sits on the brake hood. You press it with your thumb. This setup is the same as Campagnolo’s mechanical shifter setup so there is no learning curve to deal with.
The EPS system shifts quickly and precisely. Possibly even better than Shimano’s Di2. Campagnolo’s Multishifting technology allows you to shift through up to 12 gears with a single move of the shift lever. There is also a sequential shift mode that allows the system to operate the front derailleur for you automatically. The aesthetics are beautiful as well.
There are some drawbacks. Campagnolo offers fewer customization options for their EPS systems. There are no satellite shifters available at this time. For some, this is a deal-breaker. The MyCampy app has fewer customization options than Shimano’s e-Tube. You can adjust the shift speed and pressure required to actuate a shift. You can’t swap shift button functions.
When it comes to gearing, your Campagnolo EPS options are somewhat limited. The only gearing option is 2×12. There is no gravel or 1x options. Only road gearing is available. Campagnolo also offers fewer cassette and combination options than Sram or Shimano.
Campagnolo EPS is a wired system with an internal battery, like Shimano Di2. One drawback is that Campagnolo hardwires the battery to the system. If a wire gets damaged in an accident, it’s a bit of a hassle to fix. The charging port is also incredibly fragile. It is easy to damage the prongs in the charging port if you’re not careful when plugging the charger in. The only solution is to be very careful. One nice feature is the option to unlock the derailleur and manually place the chain on your desired gear if the battery dies.
Possibly the biggest drawback is the cost. Campagnolo EPS systems cost around twice as much as similar Shimano Di2 and Sram eTap systems. For example, the Campy Super Camp EPS with disc brakes costs around $4600. That’s more than most casual cyclists are willing to spend.
Who Should Use Electronic Shifting?
At this time, electronic shifting is a premium option. All of the electronic groupsets on the market are high end or professional grade. Electric shifting has become the norm at the professional level of the sport. For example, if you watch the professional road peleton, professional cyclocross racing, or gravel racing, you’ll notice that everyone is using electronic shifting. Electronic groupsets are just a bit faster, more consistent, and easier to use than mechanical groupsets. At the top level of the sport, any edge, no matter how small, is important. For this reason, anyone who rides competitively would probably benefit from using an electronic drivetrain.
Cycling enthusiasts will also enjoy electronic shifting. These systems incorporate some of the newest and most advanced technology in the sport. Current electronic shifting systems feel incredibly refined. They are a joy to use.
Of course, the cost is a major factor for many. If money isn’t an issue for you and you want electronic shifting, you might as well spend the extra couple of thousand dollars and get it.
Beginners can also benefit from electronic shifting. For example, Sram’s eTap system cuts the number of shifting controls from 4 to 2. This system makes it much easier to learn and remember how to shift. It’s very intuitive.
Shimano’s Synchro shift and Sram’s Sequential shift also make shifting much easier for beginners by shifting the front derailleur for you. In addition, with electronic shifting, you’re less likely to miss a shift or over shift. You just don’t have to think about shifting as much with an electronic drivetrain. You can focus your mind on watching the road, traffic, maintaining your line, etc.
Finally, those with disabilities will also benefit from using electronic shifting. The buttons are easier to actuate than mechanical shifters. The shifters can also be positioned in a way that make them easier to reach.
Who Should Use Mechanical Shifting?
Mechanical shifting is still the best choice for the vast majority of cyclists including recreational riders, commuters, bicycle tourists, and anyone on a budget. For these types of cyclists, speed and efficiency don’t really matter. For example, there is no reason to spend thousands of dollars on electronic shifting to make your daily commute a couple of seconds faster. Modern mechanical drivetrains are affordable, easy to work on, reliable, and offer excellent performance.
In addition, anyone who rides in a cycling discipline where accidents are common should probably stick to mechanical derailleurs. If you crash your bike and break a mechanical derailleur or shifter, the replacement cost is much lower.
Bicycle tourists and bikepackers will probably want to stick with mechanical shifting as well for now. Mechanical drivetrain parts availability is much better across most of the world. There are also no batteries to worry about charging. It’s also much easier to fix, adjust, or replace a mechanical part if you need to. Parts compatibility is better as well. For most components, the brand doesn’t matter.
A Bit of History about Mechanical and Electronic Shifting
In 1905, a French bicycle tourist named Paul de Vivie invented a 2 speed rear derailleur to make cycling in the alps a bit easier. This early derailleur design used rods to push the chain onto the different gears.
In 1928, the Super Champion Gear was released. This system used paddles mounted on the chainstay to move the chain. The rider would reach down to manipulate a lever that moved the paddle to push the chain back and forth. The parallelogram derailleur was invented soon after.
In 1937, derailleurs were first used in the Tour de France, 34 years after they were invented. The following year, the first cable shifting derailleur was introduced by Simplex.
Suntour introduced the slant-parallelogram derailleur in 1964. This remains the current mechanical derailleur design. In the years since, the technology has been further refined but the basic design has remained the same. The shifters were moved from the downtube to the handlebars. Gear indexing was introduced.
Electronic Shifting History
The first electronic gear shifter was introduced by Mavic at the 1992 Tour de France. They called this mechanism ‘Zap.’ The system was not successful commercially but it did work as a proof of concept. It showed that an electronic shift system was possible.
During the years that followed, Mavic, Shimano, Sachs, and Campagnolo all experimented with electronic shifting. Shimano found success in 2009 when they introduced the Di2 (Digital Integrated Intelligence) system. During that year, the system was used by several professional cycling teams in the Tour of California and Tour de France. Giant also released an off-the-shelf bike equipped with Di2. The Di2 became the first commercially available and successful electronic groupset on the market.
In 2011, Campagnolo released its first electronic groupset, the EPS. Sram released its wireless RED eTap electronic groupset in 2016. Today, electronic groupsets have become the norm in the top level of the sport of cycling. Most top-of-the-line road bikes also come equipped with electronic shifting.
Final Thoughts about Electronic Vs Mechanical Shifting
As you can see, both systems have their own set of benefits and drawbacks. For most cyclists, mechanical shifting is still the best option. A quality mechanical groupset can shift accurately, quickly, and reliably. Maintenance is minimal. You may need to adjust or replace a shifter cable once or twice per year. The biggest advantage is the cost. Mechanical groupsets cost a fraction of the price of electronic to buy, maintain, and repair.
Of course, electronic groupsets have their benefits. Electronic drivetrains shift faster, smoother, and more accurately. They require much less maintenance. The technology also allows for an incredible amount of customization and performance tracking. For many, the slight improvement in performance and efficiency is worth the cost.
At the high end, electronic shifting is really the only choice. Mechanical models are being phased out. Most cyclists who make the switch from mechanical to electronic shifting also tend to stick with it. Whichever system you choose, I hope this guide has helped you make your decision.
Where do you stand on the electronic vs mechanical shifting debate? Share your tips and experience in the comments below!
More from Where The Road Forks
- How to Buy a Used Bike
- Carbon Fiber Vs Aluminum Bike Frame
- Thru Axle Vs Quick Release: Pros and Cons
- Oval Vs Round Chainrings
- Are Dynamo Hubs Worth it? Pros and Cons
- Types of Bicycle Handlebars