Shimano Di2 Vs Sram eTap Electronic Shifting

Over the past 12 years, electronic shifting has quickly grown in popularity. At this point, most high-end road and gravel bikes come equipped with an electronic groupset. There are a number of electronic groupsets on the market from Shimano, Sram, and Campagnolo. This guide outlines the pros and cons of Shimano Di2 Vs Sram eTap electronic shifting. In this guide, we’ll cover performance, costs, customization, ergonomics, gearing, weight, price, and much more.

This guide compares Shimano’s Ultegra Di2, Dura Ace Di2, and GRX Di2 lines with Sram’s Force eTap AXS, RED eTap, and Eagle eTap lines. I’ll also talk about a third electronic sifting option, Campagnolo EPS. Hopefully, this guide helps you choose the best electronic drivetrain for your style of riding.

For more general info, check out my electronic vs mechanical shifting guide.

Disclaimer: This post may contain affiliate links. Please see my disclosure policy for details.

Shimano Di2

Shimano began experimenting with electronic shifting in 2001. Throughout the 2000s, they continued refining the system and testing in various professional races. In 2009, Shimano introduced the first Di2 (Digital Integrated Intelligence) electronic groupset.

During that year, the new Di2 system was put to the test by several teams in the Tour of California as well as the Tour de France. This groupset went on to become the first commercially available and successful electronic gourpset on the market. In the years since, Shimano has further refined and updated the Di2 system every 3-5 years. There are three different classes of Di2 groupsets available today:

1. Dura Ace Di2- This top-of-the-line professional-level electronic groupset is Shimano’s lightest and highest-end option.
2. Ultegra Di2- This is Shimano’s consumer-level high-end electronic groupset. It lies one step below Dura Ace on Shimano’s hierarchy of components.
3. GRX Di2- This is Shimano’s first gravel bike specific electronic groupset.

All of Shimano’s Di2 groupsets are 11 speed and are available in hydraulic disc and rim brake versions. Shifting works similarly to mechanical groupsets with two buttons on each brake lever. A single rechargeable battery, which is hidden in the seat post, powers the entire system. The derailleurs, shifters, and junction box are all wired together and to the battery. The Dura Ace and Ultegra models are only available in 2x. GRX models are available in both 1x and 2x. You can mix and match road and gravel components if you want to put together a 1x road groupset. Di2 systems can connect to a PC, phone, or tablet for customization using the E-Tube app. An adapter is required to connect wirelessly with Bluetooth.

Sram eTap

Sram announced their first eTap electronic groupset, the Red eTap, in 2015. It featured 11 speed gearing with wireless shifting. Soon after, they released a hydraulic disc brake version. In 2019, Sram launched the eTap AXS system. Sram’s current line of electronic groupsets include:

• Red eTap- This professional-level electronic groupset is Sram’s highest-end option.
• Force eTap AXS- This is Sram’s consumer-grade high-end electronic drivetrain. It competes with Shimano’s Ultegra line.
• Eagle eTap AXS- This is Sram’s mountain bike specific electronic groupset. There are two slightly different Eagle AXS options: XX1 Eagle AXS and X01 Eagle AXS. Both of these are very similar except for the finish and weight.

Sram’s eTap electronic groupsets operate completely wirelessly with a proprietary wireless protocol called AIREA. This is the main feature that differentiates Sram from the competition. A removable, rechargeable battery powers each derailleur and a disposable coin cell battery powers each shifter.

Sram electronic groupsets also feature a unique shift logic. One paddle on each brake lever controls both derailleurs. Satellite shifters are available. All of Sram’s electronic groupsets are 12 speed and are available in 1x or 2x versions. The chainring and cassettes are optimized to run Sram’s 12 speed cassettes with a 10t small cog. To fit the extra small 10t cog, they use an XDR driver instead of a standard freehub. Red and Force level groupsets are available in both rim brake and hydraulic disc brake options. eTap systems can connect to a phone or tablet wirelessly for customization using the AXS app.

Shifting

Shimano and Sram use slightly different button layouts and shift logic for shifting between the cassette cogs and chainrings. The ergonomics and button feel differ as well.

Di2 Shifting

Shimano Di2 button layout is similar to their mechanical shifting systems. There are two buttons located under each brake lever. One button shifts up and the other shifts down. The buttons on the right brake lever control the rear derailleur and the buttons on the left brake lever control the front derailleur. The only difference between Shimano’s mechanical and electric shifting is that the brake lever doesn’t sweep sideways to shift. The shifters are just buttons.

The beauty of Shimano’s Di2 shifting logic and button placement is that it will feel very familiar if you’re used to using Shimano mechanical shifters. They’re almost identical. This means there is no learning curve.

The Di2 system also offers a nice tactile click to let you know that you’ve pushed the shift button hard enough. Some cyclists find that the Di2 shift buttons feel a bit more robust than those found on Sram’s eTap. In addition, Shimano Di2 drivetrains shift slightly faster than Sram. Particularly the front derailleur which is incredibly fast and smooth. Shifting is faster because there is a dedicated button for each type of shift. The system doesn’t have to wait to see if you want to shift the front or rear derailleur. More on that later.

One common criticism of Di2 shifters is the button placement. Both shift buttons sit right next to one another and feel pretty much the same when you press them. This makes it easy to accidentally press the wrong button and shift the wrong way. This is particularly easy to do when you’re wearing thick winter gloves. You will get used to the button placement over time but you may push the wrong button on accident once in a while.

eTap Shifting

Sram reinvented its shifting logic when designing its eTap system. Instead of using the familiar DoubleTap system found on their mechanical drivetrains, eTap uses a small paddle located behind the brake lever. The right paddle shifts the rear derailleur up into a harder gear. The left paddle shifts the rear derailleur down into an easier gear. When you press both paddles at the same time, the front derailleur shifts. When you hold a shift paddle, you’ll shift through multiple gears.

This system is incredibly intuitive and easy to use because there are only two shifter buttons rather than four. You’ll never press the wrong button and shift the wrong gear. Shifting also requires less thought so you can put more focus on producing power, cornering, and enjoying the view. For this reason, Sram’s shifting logic is great for beginner cyclists. Of course, beginner cyclists usually don’t use electronic groupsets due to the cost.

One minor problem with Sram’s shifting logic is that the system has a slight delay. This is necessary so the system can determine whether you want to shift the front or rear derailleur. After you press one shifter, the system waits for a fraction of a second to see if you are pressing both shift paddles at once or if you’re just pressing one. The system shifts slightly slower because of this delay. Some cyclists also feel that eTap shifters feel a bit less substantial than Di2 shifters. They feel a bit plasticky.

Advantage: Shimano for their slightly faster and more precise shifting. That said, Sram’s shifting logic is noteworthy for its ease of use.

Customization

One major benefit of electronic groupsets is that they allow you to customize and even automate some of your shifting.

Synchronized and Sequential Shifting

Both Di2 and eTap systems offer a setting that allows the groupset to shift the front derailleur for you as you shift through the gear range. Shimano calls this ‘Synchronized shifting’ or Synchro. Sram calls it ‘Sequential shifting.’

When using this setting, the front derailleur shifts occur at predetermined points in the gear range. At the same time that the front derailleur shifts, the rear derailleur automatically shifts a couple of gears to compensate. You can use your groupset’s app to customize exactly when the front derailleur shift occurs. For example, if you like to ride at a higher cadence, you might customize your settings so you stay in the small chainring longer. If you want more torque, you might want to stay in the large chainring longer. You might also want to shift chainrings at different points while upshifting and downshifting through the gear range.

This system offers a number of benefits. First, it’s easier to use. All you have to worry about is shifting up and down. You don’t have to think about which chainring you’re using or where you are in the gear range. You also can’t cross chain. The shift from one chainring to the next is also smoother because the rear derailleur shifts simultaneously to compensate. In addition, the system helps you avoid overlapping or duplicate gear ratios.

Both eTap and Di2 systems also offer a semi-automatic mode if you want more control. Shimano calls this ‘semi-synchronized’ mode and Sram calls it ‘compensation’ mode. While using this mode, you shift the front derailleur yourself and the system simultaneously shifts the rear derailleur up or down a few gears to compensate for you. This gives you a much smoother shift between chainrings, which helps you maintain your cadence. At the same time, you have more control over your shifting than you do with Synchro or Sequential mode.

Synchronized and Sequential shifting operate similarly. Neither Sram nor Shimano really has an advantage here. Shimano does offer a bar-end junction box with a small button. You can press the button to switch between manual mode, Synchro-shift, and Semi-Synchro while you ride. With Sram’s system, you have to use the app to switch between Sequential mode, semi-sequential, and manual. You’ll probably have to stop riding to do this.

Satellite Shifters

Sram and Shimano also both allow you to install additional shift points. These are sometimes called satellite or accessory shifters. These give you the ability to shift without moving your hands to the main shifters. For example, if you are a sprinter, you can install satellite shifters in the drops. If you climb hills, you can install satellite shifters on the top of the bars. You can also install satellite shifters on aero bars. With both systems, the satellite shifters attach to the control unit with a wire.

Sram calls their satellite shifters ‘Blips’. Blips are small round buttons that are designed to sit under the handlebar tape. You can also leave them exposed if you prefer. They plug into the shifters and can be installed anywhere on the handlebars.

Shimano offers a couple of different styles of satellite shifters. Their ‘Climber Shifters’ zip tie to the top of the bars. Their ‘Climbing Switch’ satellite shifters can be mounted anywhere on the handlebars, similar to Sram’s Blips.

Shift Customizations

One benefit of the Shimano Di2 system is that it also allows you to map the shift buttons to whatever shift function you want. For example, you could swap the upshift and downshift buttons. You could make your left shifter control the rear derailleur and your right shifter control the front. This might come in handy if you’re left handed and you want to control the rear derailleur with your dominant hand. You can’t make these changes with an eTap system.

Shimano shifters also feature a small hidden button on the top of each brake hood. These buttons can be programmed to control a number of devices including some Garmin GPS units, lights, and cycling computers. eTap doesn’t offer this function.

Advantage: Shimano Di2 groupsets offer more customization options. This is possible because Shimano shifters each have three buttons while Sram shifters only have one button each.

Batteries

Electronic groupsets use batteries to power the small electric motors that move the derailleurs as well as the electronics in the shifters and control unit. Both eTap and Di2 deal with the batteries a bit differently.

Di2 Batteries

Shimano Di2 groupsets have one large rechargeable battery to power the entire system including both derailleurs, both shifters, and the control unit. Shimano claims that their battery lasts 2,000km under normal use. If you don’t shift often, you might get 2,500-3,000km out of a single charge.

The Di2 battery is cylindrical and is designed to fit in the bike’s frame. Most riders mount their battery in the seat tube. It can also fit in the steerer tube or even in the handlebars on some bikes.

When the Di2 battery starts to die, the system automatically disables the front derailleur to conserve power for the rear derailleur. This means you’re stuck riding whichever chainring you were on when the power fell too low.

Some cyclists complain that it’s easy to run out of power with a Di2 groupset simply because the battery lasts so long. Most cyclists will only have to charge 2 or 3 times per year. It’s easy to forget that the battery is there when you charge it so infrequently.

Because the battery is mounted in the frame, it is not removable. This means you must physically place your bike near a power outlet to charge the battery. This could be an annoyance if you store your bike in a shed or garage without an outlet nearby. The internal battery also makes the system a bit harder to install because all wires must connect to the battery in the frame. This sometimes involves drilling holes in the frame. You may have to pay for professional installation.

eTap Batteries

Sram eTap groupsets use four batteries. Each derailleur has a removable rechargeable battery. Each shifter has a disposable coin cell battery (CR2032). Both derailleurs and shifters need a separate battery because the system operates wirelessly.

Sram claims that their derailleur batteries last for about 60 hours of ride time before they need to be recharged. This is about half the life of Shimano’s battery. Generally, the rear derailleur battery dies first because you shift it more often. Of course, the battery life depends on how often you shift.

The coin cell batteries in the shifters are supposed to last about 2 years. Because the coin cell shifter batteries last so long, it’s easy to forget to replace them. It’s a good idea to carry a spare. They weigh practically nothing.

One excellent feature of Sram derailleurs is that you can swap derailleur batteries. If one of your derailleur batteries dies while you’re riding, you can swap it for the live one. For example, if your rear battery runs out of juice, you can shift to your desired chainring then move the front battery to the rear derailleur and ride home. If both batteries die, you can shift manually by placing the chain on your desired gears. If you’re really concerned about a battery going out, you could even buy a spare to carry with you while you ride.

When it comes time to charge the batteries, you simply pop them out of the derailleurs and plug them into the wall charger. Strangely, Sram’s charger only charges one battery at a time. The batteries take about 45 minutes to charge.

One drawback is that the batteries sticking out make Sram derailleurs look a bit bulkier than Shimano’s, which doesn’t have batteries in the derailleurs.

Both Shimano and Sram electronic groupsets have battery indicator lights that tell you how much battery life you have left. The indicator lights illuminate when you actuate a shift. Sram eTap systems have battery indicator lights on the shifters, front derailleur, and rear derailleur. If the light is green, you have more than 25% battery life left. When the light turns red, you have less than 25% battery life left. When it starts flashing red, you have less than 15% battery life left.

Shimano Di2 systems have a battery indicator light on the junction box that mounts to the stem. It uses a similar green and red system. When the light is green, you have more than 75% battery life. When the light is red, you have 25-50% battery life. If the light flashes red, you have less than 25% battery life. With both systems, you should charge your batteries when the light turns red.

Advantage: Shimano because the battery last longer and there is only one battery to charge. That said, Sram batteries are easier to charge because they can be removed.

Gearing and Component Options

Sram and Shimano approach gearing a bit differently. In this section, we’ll look at gearing options and compatibility.

Sram eTap Gearing

Sram recently started taking a new approach to gearing on their eTap groupsets. This new gearing system pairs two smaller chainrings that are similar in size with a wide range 12 cog cassette. Sram calls this gearing X-Range. This setup offers more gear range and a smoother shift between chainrings. In the past, Sram groupsets used more traditional-sized double chainrings with a more narrow range 11 speed cassette.

The current 12-speed eTap cassettes all come with a 10t small cog. They come in 10-26t, 10-28t, 10-33t, and 10-36t ranges. If you want to use the smallest range 10-26t cassette, you’ll need the shorter cage 33t-max derailleur. If you want to use the larger range 10-36t cassette, you’ll need to use the longer cage 36t-max derailleur. The 10-28t and 10-33t cassettes will work with either derailleur.

You can also mix and match Sram road and mountain bike components if you want a wider gear range. The eTap AXS road and Eagle AXS MTB components are cross-compatible. That said, you’ll need an Eagle AXS mountain bike rear derailleur if you wish to run a mountain bike cassette because the range is wider. This is a longer cage derailleur. The AXS Eagle rear derailleurs can accept cassettes with a 52t max. Sram road and mountain shifters are cross-compatible.

In the eTap AXS range, front chainrings are available in 46/33t and 48/35t options. In the higher-end Red range, a 50/37t is also available. All of these options feature a 13 tooth difference between the small and large chainring. With a Force eTap AXS setup, the lowest available gear is 33/36t. The highest gear is 48/10t. If you run a Red crankset, you can achieve 50/10t top gear.

Sram’s higher-end Red chainrings are a single piece. This reduces weight and makes shifting a bit smoother. The drawback is that they are much more expensive to replace because you’re replacing both chainrings when one wears out. If you’re using a chainring integrated Quarg power meter, you’ll have to replace that too.

Sram also offers a 1x electronic groupset option. Force eTap AXS 1x cranksets are available with a single chainring that ranges from 36t to 48t. These use the same AXS rear derailleurs and cassettes outlined above.

The beauty of the eTap AXS system is that all AXS parts are cross-compatible. For example, you can pair the 10-36t cassette with any eTap AXS chainring option. You can pair the AXS 43/30t chainrings with any eTap cassette option. Shifters are all cross-compatible. The only thing to keep an eye on is the max tooth count of the rear derailleur and cassette. Several different derailleur lengths are available that are designed for different cassette sizes.

The main drawback to Sram’s eTap line is compatibility. The system uses a number of odd-sized or proprietary parts. Compatibility is good within the eTap system but if you want to use parts from other manufacturers, you’ll run into issues.

For example, the eTap AXS line uses a proprietary bottom bracket called DUB (Durable Unified Bottom bracket.) The benefit of this is that the system is compatible with pretty much all frames. The drawback is that have to use Sram’s cranksets that are compatible with the DUB bottom bracket. Next, Sram 12 speed cassettes use the XDR rear hub driver. This is a new and uncommon freehub design. Chances are, you’ll have to install a new freehub body on your wheel if you want to install an eTap system. You also have to use Sram’s 12 speed flattop chain and cassettes. Parts from other manufacturers are not compatible. In addition, Sram’s older 11 speed eTap components are not compatible with the newer 12 speed eTap parts. Overall, compatibility is pretty poor, in my opinion. I’m sure this is by design so you have to buy more Sram parts.

Shimano Di2 Gearing

Shimano uses more traditional gearing for its Di2 groupsets. The Ultegra Di2 and Dura Ace Di2 use 2×11 gearing. Shimano also offers a gravel line called GRX. This system offers both 1×11 and 2×11 options. For the most part, road and gravel components are cross-compatible but there are a few exceptions.

Cassette options for Ultegra Di2 systems include 11-25t, 11-28t, 11-30t, 12-25t, 14-28t, 11-32t, and 11-34t. There are two rear derailleur options. Which one you need depends on which cassette you choose. The short cage Ultegra rear derailleur works with the 11-25t through 11-30t cassettes. The long cage rear derailleur works on the 11-28t through 11-34t cassettes. Dura Ace cassette options are similar but a bit more limited.

Cassette options for the gravel GRX Di2 system include 11-25t, 11-28t, 11-30t, 11-32t, 11-40t, 11-42t, 11-46t, 12-25t, and 14-28t. There are two different derailleur options. One has a maximum low sprocket size of 34t and the other has a maximum low sprocket size of 42t.

DI2 chainring options include 53/39t, 52/36t, and 50/34t for the Ultegra line. These chainring options are all interchangeable. They use the same four bolt layout. There is also a 48/31t option from the GRX line which is compatible. Because GRX cranksets have a wider chainline than the road cranksets, you’ll need to use the GRX front derailleur if you wish to use GRX chainrings on your Di2 system.

Ultegra and Dura Ace Di2 groupsets are all 2×11. It is possible to put together a 1x groupset by using some GRX components. 40T and 42t GRX chainrings are available that are compatible with road Di2 rear cassettes and derailleurs.

Shimano cranksets all work with Hollowtech II bottom brackets. These have been standard for many years now and are compatible with pretty much all frames. They are affordable and commonly available as well.

One major advantage that Shimano Di2 electronic shifting systems offer over Sram is compatibility. The reason is that the system uses more standard sized parts. This allows you to use parts from other manufacturers. For example, Shimano Di2 systems use a standard freehub design. This allows you to use cassettes from other brands. You can also use 11 speed chains from other brands. This saves you money and gives you more options in terms of the components that you can use.

There are rumors of an updated Shimano electronic groupset coming out this year. It’s possible that it will include wireless shifting and a 12 speed cassette. I’ll try to update this section if and when the new model is announced.

Advantage: Sram because their 12 speed gearing is more modern. There are also more 1x drivetrain options.

Performance

Shimano Di2 groupsets shift slightly faster than eTap. There are a couple of potential reasons for this. First, the wired connection allows the system to transfer data between the shifters and derailleurs faster and more reliably. Sram’s wireless system works great but a wireless connection is never as reliable as a wired connection.

The second reason has to do with the software. Shimano has 4 dedicated shift buttons. One for each type of shift (shifting the front derailleur up, shifting the front derailleur down, shifting the rear derailleur up, and shifting the rear derailleur down.) When you press a shift button, the system shifts almost instantly.

Sram, on the other hand, only has two shift buttons. Those buttons control both derailleurs. You shift the rear derailleur down by pressing the left shift paddle. You shift the rear derailleur up by pressing the right shift paddle. To shift the front derailleur, you press both paddles at once. The problem is that the system has to wait to see if you’re pressing both shift paddles or just one. Of course, this delay is just a fraction of a second. It’s not even noticeable under most circumstances but it may bother some riders.

Shimano’s shift buttons also feel a bit more substantial than Sram’s. The click when you press the button is a bit more satisfying. This inspires confidence in your shifts. That said, some riders prefer Sram’s shifter design and shifting logic because it is easier to use.

Advantage: Shimano Di2 groupsets shifts slightly faster and more reliably than Sram.

Connectivity and Customization

Both Shimano Di2 and Sram eTap groupsets have phone and computer apps that allow you to make customizations to your shifting, collect diagnostic information, keep an eye on your battery life, as well as update the system’s firmware. There are some differences in the ways that the systems connect. The customization options are a bit different as well.

Connectivity and Apps

Sram eTap systems offer better connectivity than Shimano Di2. The reason is that you can connect your phone to your groupset wirelessly with Bluetooth. This function is built-in. All you need is a smartphone and the Sram AXS app, which is free. The app is available for both Android and iOS. Sram’s user interface is very intuitive and easy to use. You don’t need to know much about bicycle gearing to set it up and make adjustments. You don’t even need to make any customizations if you don’t want to.

Shimano Di2 doesn’t offer the same easy connectivity. You can connect your computer to the system with a wire. To do this, you need a Windows PC. There is no Mac program. You can also connect the system wirelessly to your iPhone or Android Phone with Shimano’s E-Tube app. In order to connect wirelessly, you need to buy a Shimano Di2 Inline Wireless Unit. This is basically a Bluetooth adapter for your groupset. This piece of equipment is usually not included with Di2 systems. There are rumors of a new Shimano Di2 system coming out this year. Some speculate that it will feature Bluetooth.

One unique feature of Shimano Di2 groupsets is the ability to connect to certain Garmin GPS models. When connected, the GPS can display which chainring and cassette cog you’re using. You can also use the buttons on the brake hoods to control the GPS unit. For example, you can set different screens to scroll through. Sram eTap systems can be set to control a wireless dropper seatpost with the shifter paddles.

Shift Customization

With both eTap and Di2 systems, you can customize almost every aspect of the shifting. For example, you can control how many gears the system shifts when you hold the shift button. You could set the system to burst through several gears or shift through the entire gear range. Shimano also allows you to set the speed that the system shifts.

Di2 systems allow you to map the shift buttons to perform whichever function you choose. Shimano offers more customization options in this category because each shifter has three buttons. There are upshift and downshift buttons on each shifter as well as an extra button on each brake hood. For example, with a Di2 system, you can choose which hand controls the rear derailleur or which button downshifts. If you’re left-handed, you might prefer to control the rear derailleur with your left hand. Shimano also allows you to set 5 presets for your gearing. You can easily switch through them as you ride by pressing a button on the junction box. This way, you can try out different gearing customizations while you ride to find out which one feels best.

You can also customize Synchronized shift mode (Shimano) or Sequential shift mode (Sram). As outlined earlier, these function allows the system to control the front derailleur for you. When using this mode, you just shift up and down. The system automatically shifts the front derailleur depending on which cassette cog you’re using. When the front derailleur shifts, the rear shifts simultaneously to compensate.

You can customize Synchronized or Sequential mode using your electronic groupset’s app. You can choose where in the gear range the front derailleur shifts. This might come in handy if you prefer to ride at a high cadence. You can set the system to stay in the small chainring longer. If you want more torque, you can set the system to stay in the large chainring longer. You can set the exact shift pattern. You may want to shift between the large and small chainring at different points while shifting up and shifting down through the gear range.

There is also a Semi-Synchronized or Semi-Sequential mode that allows you to shift the front derailleur manually. When you shift, the system automatically compensates by shifting the rear derailleur for you. This gives you a smoother shift between chainrings. You can also customize this mode so the rear derailleur shifts 1, 2, or 3 gears to compensate automatically.

Software Updates

Sram and Shimano are constantly improving their software. You can use your system’s app to update your groupset’s firmware to the newest version. This allows you to take advantage of new features. Also, as the software improves, your shifting can become more precise, faster, and more efficient over time.

One important note is that you don’t absolutely have to connect your electronic drivetrain to your computer or phone if you don’t want to or don’t know how. You can simply use them in the default mode or take your bike to your local bike shop for help making customizations and updates. Most Shimano Di2 systems allow you to switch between shifting modes with a button on the junction box on the bar end. This doesn’t require the use of an app. With a Sram groupset, you do need to use the app to switch between shifting modes.

Advantage: This one is a tossup. Sram makes it easier to connect to the system so you can make customizations. Shimano offers more customization options. If you like to tinker with your bike, you’ll prefer Shimano. If you prefer to set it up and forget it, you’ll prefer Sram.

Brakes

Both Sram and Shimano electronic drivetrains come in rim and hydraulic brake options. All of the brake options offer excellent stopping power and brake modulation. You can adjust the reach and bite point of the brakes with small screws on the levers. If you opt for hydraulic disc brakes, you can choose from 160mm and 140mm rotors.

Shimano brakes seem to offer a little more braking power than Sram brakes. They are also a bit easier to modulate because the brake levers also feel a bit more firm. This could be caused by a slightly stiffer brake caliper.

One benefit of Shimano brakes is that the pads sit a bit further from the braking surface when you’re not squeezing the lever. This reduces the likelihood of brake rub if the rotor or rim gets bent, the braking surface gets contaminated, or the brakes go out of adjustment. It also makes it a bit easier to adjust the brakes because there is more margin for error. Sram brakes are a bit more likely to rub. You might also hear some noise when contaminants get thrown up onto the rim or rotor. This is really just a minor annoyance that you’ll rarely have to deal with.

One difference between Sram and Shimano hydraulic disc brakes is the type of fluid they use. Sram uses DOT 5.1 brake fluid. Shimano uses a proprietary type of mineral oil for brake fluid. In theory, DOT 5.1 brake fluid performs a bit better than mineral oil. In the real world, you probably won’t notice a difference. One drawback to DOT 5.1 brake fluid is that it can damage paint if you spill it on your frame or any other painted surface. Mineral oil is completely safe.

Another difference is the aesthetics of the brake levers. Sram is known for producing hydraulic disc brakes with a large master cylinder in the brake hoods. The benefit of this is that it give you a good solid place to grip while riding over a rough or technical section. The drawback is that the brake hoods aren’t aesthetically pleasing. They are tall and bulky. Shimano does an excellent job of hiding a smaller master cylinder under the brake hoods. In fact, Shimano hydraulic disc brakes look almost the same as their mechanical disc brakes.

This choice really comes down to personal preference. Shimano and Sram’s brakes have slightly different feels because both systems work a bit differently. Both brands offer excellent braking performance. There is plenty of braking power and they are easy to modulate.

To help you decide on the best type of brakes for you bike, check out my guides:

• Disc vs Rim Brakes
• Hydraulic vs Mechanical Disc Brakes

Advantage: Shimano brakes because they offer slightly better performance, better brake pad clearance, and better looks.

Groupset Weight

On average, a Shimano Di2 groupset weighs 200-400 grams less than a comparable Sram eTap groupset. 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.

Shimano claims that their Ultegra Di2 R8070 in its standard configuration weighs 2450 grams. This weight does not include the battery, cables, and junction box. I do not know why Shimano doesn’t include the weight of the battery as it is a standard component that is required to use the system. They don’t include the weight of the cables and junction box because cable lengths vary and there are a number of different junction box options. The standard internal battery weighs 52 grams. The junction box weighs around 10 grams. All of the cables weigh around 30-50 grams. In addition, many riders will choose larger 160mm brake rotors and a wider range cassette than are found in Shimano’s standard configuration. These add a bit of weight as well. If you add these extra components, the total weight comes to around 2600 grams.

Sram, on the other hand, claims that their Force eTap AXS groupset weighs around 2810 grams. This includes a 10-28t cassette, 175mm cranks, 48/35t chainrings, the DUB bottom bracket, derailleurs, shifters, batteries, brake calipers, and 160mm rotors.

In this example, the Shimano Ultegra groupset weighs around 210 grams less than the Sram Force eTap AXS groupset. Of course, this weight difference will vary slightly depending on the exact components you choose and cable length. For example, you might also wish to install extra accessories such as satellite shifters or Shimano’s Bluetooth connector. These add weight as well.

There are also lighter options to consider if weight is important to you. Shimano offers higher end Dura Ace Di2 groupsets. These weigh around 300-400 grams less than their Ultegra Di2 groupsets. Sram offers higher end Red eTap groupsets. These weigh 200-300 grams less than their Force AXS level groupsets.

If you’re looking for the lightest possible electronic groupset, it’s Shimano Dura Ace Di2. It weighs in at around 2400 grams.

Advantage: Shimano Di2 electronic groupsets weigh 200-400 grams less than comparable Sram eTap models

Installation

Sram’s eTap system is much easier to install than Shimano’s Di2. The main reason is that all Sram electronic groupsets use wireless front and rear derailleurs. This means you don’t have to worry about cable or wire routing. In addition, the batteries mount directly to the derailleurs and shifters so you don’t have to deal with any wiring. Anyone can install and set up an eTap groupset with a few basic tools and some basic bicycle knowledge. It’s even easier to install than a mechanical groupset.

Installing a Shimano Di2 system is a bit more complex. The main reason is that the battery must be mounted somewhere in the frame. On most bikes, the best location is in the seat tube. Some people put the battery in the fork, steerer tube, or even in the handlebars. Basically, you have to put it wherever it will fit. This can take some trial and error and a bit of work to get it to fit securely.

Another problem you can run into while installing a Di2 system is cable routing. Both derailleurs and shifters as well as the junction box must connect to the battery with wires. This means running cables through at least part of the frame. Some bikes just aren’t designed for this. In some cases, you’ll need to drill holes in the frame to pass the wires through. You may also need to mount the junction box and wireless adapter unit to the frame. For these reasons, it’s usually best to hire a professional to install your Di2 system for you.

Of course, you only have to deal with installation once. It’s not really a big deal. If you don’t feel comfortable doing it yourself, you can just hire someone and not have to worry about it. If you’re buying a bike with electronic shifting already installed off the shelf, you don’t have to worry about installation at all.

Advantage: Sram eTap groupsets are easier to install.

Parts Compatibility

Sram eTap systems are compatible with pretty much any bike that is designed to run a derailleur groupset. You can just swap out your mechanical parts for electronic parts, adjust them, and you’re good to go. Everything bolts into place the same as mechanical parts and there are no cables to worry about.

Shimano Di2 systems, on the other hand, aren’t compatible with every bike. The reason is that the battery must be installed in the frame. Sometimes it just won’t fit because the tubes are too narrow or curved. This problem is most common on older bikes and lower-end bikes. Particularly bikes built before 2010. Shimano has solved this problem by offering an external battery option. The drawback to this is that you have a battery hanging off of your frame.

Cross-compatibility of components is a different story. In this category, Shimano is the clear winner. Di2 drivetrains use more common 11 speed components. The freehub uses a standard HG design. You can use whichever 11 speed chain, cassette, and chainrings you like as long as your rear derailleur has the correct cage length. This allows you to use cheaper parts or different gearing from different brands. Having said this, it is likely that Shimano moves to 12 speed on their next generation electronic drivetrains. This may limit cross-compatibility. We’ll have to wait and see.

Sram really limited cross-compatibility when they moved the system from 11 speed to 12 speed. Chains, cassettes, and chainrings are no longer interchangeable with other brands. For example, in order to fit the wider range 12 speed cassette with a 10t cog, Sram had to change the freehub body to their XD-R design. This limits you to XD-R cassettes, which are much less common. In addition, Sram requires a proprietary 12 speed flat top chain. You can’t use chains from other brands. The DUB bottom bracket design limits which cranks you can use. You’re pretty much married to Sram if you go with an eTap groupset.

Having said that, parts compatibility within the Sram eTap AXS line is pretty good. AXS Eagle mountain bike and AXS Force road bike parts are cross-compatible. This allows you more options in terms of cassette and chainring combinations. For example, if you want to run a wide range 10-50t mountain bike cassette on your road bike, you can. You will have to install an AXS Eagle rear derailleur in order to do this. AXS road and mountain shifters are also cross-compatible. You can also use the same rear derailleur for a 1x or 2x setup.

For more info on Sram eTap AXS compatibility, check out this excellent guide.

Advantage: Sram eTap groupsets are compatible with a wider range of bikes. Shimano Di2 systems offer greater parts compatibility.

Price

Electronic groupsets are expensive. Prices for a few of the more popular models include:

• Sram Force eTap AXS 2X groupset with hydraulic disc brakes- around $2680
• Sram Force eTap AXS 1X groupset with rim brakes- around $2000
• Shimano Ultegra Di2 R8050 groupset with disc brakes- around $2370
• Shimano Ultegra Di2 R8050 with rim brakes- around $1950

The prices listed above are average sale prices. Manufacturers suggested retail prices are even higher. You can almost always find these groupsets on sale online. Very few people pay MSRP.

Also, prices vary depending on the exact specifications you choose. For example, a basic Shimano Di2 groupset comes with a stem mounted junction box. Many cyclists prefer the bar end junction box. This adds to the cost. You also may have to buy some components separately. For example, maybe you want a specific chainring and cassette combination that is not available as a complete groupset. This would be necessary if you wanted to put together a 1x Shimano drivetrain. In this case, you’ll have to piece things together by buying your derailleurs, cranks, and cassette separately. This can add to the cost.

Advantage: Shimano Di2 groupsets are cheaper.

Maintenance Cost

When calculating the cost of a groupset, it’s important to factor in the cost of ownership. Throughout the life of the drivetrain, you’ll have to replace the chain, cassette, and chainrings many times. You may have to replace a derailleur or shifter after an accident if it gets damaged. The cost of replacement electronic drivetrain parts adds up quickly.

Shimano Di2 groupsets are cheaper to maintain than Sram eTap because Shimano components are significantly cheaper. For example, a Shimano Ultegra Di2 rear derailleur costs about $180. The comparable Sram Force AXS eTap rear derailleur costs around $350. A Shimano Ultegra Di2 shifter costs around $250. A Sram Force eTap shifter costs around $350. This is important because the rear derailleur and shifters are the most likely parts to break during a crash.

Consumable parts like chains, cassettes, and chainrings are also cheaper with a Shimano groupset. For example, 11 speed chains cost around $20. Sram 12 speed chains cost around $35. A Shimano Ultegra 11 speed cassette costs around $70. A Sram Force eTap 12 speed cassette costs around $185. Also remember, you can use cheaper parts from other brands with a Shimano Di2 groupset because the chain and freewheel body use standard sizes. With a Sram eTap groupset, you must use the more expensive Sram chains and cassettes.

As you can see, Shimano Di2 drivetrains are signifcantly cheaper to maintian. Over the life of the groupset, you may spend thousands of dollars less if you go with Shimano. This is important if you’re on a tight budget.

Advantage: Shimano has the clear advantage in terms of price. Shimano replacement parts are significantly cheaper, making the cost of ownership over the life of the grupset much lower.

Aesthetics

For many, looks are an important consideration when choosing a bike. At the same time, looks are subjective. Both Sram and Shimano take a bit different approach to aesthetics.

Sram eTap groupsets operate wirelessly. There are no wires running from the shifters to the derailleurs. This feature gives the bike to have an incredibly clean and modern look. It also helps with aerodynamics by eliminating the cables which can create some wind resistance.

The drawback to Sram eTap wireless components is that they look kind of bulky. The derailleurs are chunky because they each have a separate battery mounted to the side. The brake hoods are large and kind of square because they have a large master cylinder hidden inside. This makes the bike look a bit front-heavy.

Sram eTap groupsets also look a bit cheap up close. They are kind of plasticky in appearance. The textures on the cranks and derailleurs don’t look as nice as Shimano. That said, Sram’s high-end Red line does look quite a bit more premium than their Force line.

Shimano Di2 grupsets make the bike look a bit messier because everything is connected with wires. There are wires running from the shifters to the derailleurs. There are also wires running from the shifters and derailleurs to the battery, which is mounted in the frame. If your frame doesn’t have internal cable routing, you’ll have to zip tie the wires to the frame. This just looks ugly. If your frame has internal cable routing, the wires aren’t really a problem because they can be hidden inside of the frame.

Shimano Di2 components look sleek and attractive. The derailleurs are smaller than Srams because they don’t have to have a battery mounted to the side. Shimano also does an excellent job of hiding the master cylinder in the brake hoods. The shifters and brakes look pretty much the same as mechanical shifters.

The finish and textures of Shimano Di2 groupsets appear more premium than Sram eTap. Both Ultegra and Dura Ace level groupsets look high-end. One potential drawback is that it’s fairly easy to damage the finish. Rubbing your foot on the crank can rub some of the finish off over time.

Advantage: Sram because there are no messy wires. That said, Shimano Di2 groupsets look a bit more premium than Sram eTap.

Technology

Sram eTap groupsets use some of the newest and most advanced technology in cycling. Wide range 12 speed cassettes offer a phenomenal gear range. 12 speed chains are more durable and long-lasting than any other chain size. Sram’s wireless shifting is completely unique. No other brand offers it at this time. Etap groupsets are maybe the most technologically advanced available.

Shimano, on the other hand, uses a bit older technology in its Di2 systems. 11 speed chains and cassettes work great but are becoming outdated in the high-end of cycling gear. There is no wireless derailleur option at this time.

Shimano and Sram seem to have different philosophies when it comes to new technology. Traditionally, Shimano likes to perfect a new cycling technology before introducing it into their product line. This ensures that the product is reliable and long-lasting. For example, Shimano was experimenting with electronic shifting for almost a decade before releasing the first commercially available Di2 groupset. Sram, on the other hand, tends to push out the newest technology as soon as possible.

Advantage: This one comes down to personal preference. If you prefer to use tried and true technology, you’re better off with Shimano. Those who like to experiment with the newest tech bleeding edge mignt prefer Sram.

Power Meters

Both Di2 and eTap systems are compatible with power meters. Sram offers several different cranksets that are compatible with their Quarq Dzero power measurement technology. You can choose from the Eagle AXS, Red AXS, and Force AXS level cranksets. The systems measure both left and right leg power with an accuracy of +/- 1.5%. They are also water-resistant. The system is powered by a replaceable coin cell battery.

It’s important to note that the Red level power meter and crankset are fully integrated into the crankset. This means you’ll have to replace the entire unit including the power meter when your chainrings wear out. This adds to the cost. At the Force level, the power meter and cranks are separate so you can replace them separately as they wear out.

Shimano offers a Dura Ace crankset with an integrated power meter. Gauges sit in each crank arm to measure both left and right leg power. The unit is powered by a rechargeable battery. You charge the battery with a special magnetic power adapter. Shimano’s power meter crankset does not have a waterproof rating but it is tested for water resistance.

Advantage: Sram because there are more options.

Another Electronic Shifting Option: Campagnolo EPS

After Shimano and Sram, Campagnolo is the third largest manufacturer of electronic groupsets. Their EPS system offers a number of benefits over the competition.

Campagnolo EPS ergonomics are excellent. Many cyclists prefer Campagnolo’s brake lever and shift button shapes and positions. There are two buttons on each shifter. The buttons are separated, making them easier to use than the Di2 buttons. One shift button is a paddle that you control with your finger. The other is a button on the brake hood that you control with your thumb. The shift buttons feel similar to mechanical buttons when you press them. This makes the system very easy to use. There is no learning curve if you’re used to Campagnolo shifters. The system also shifts quickly and precisely, like Shimano’s Di2. The Campagnolo EPS system offers beautiful aesthetics as well. The rear derailleur, in particular, is a work of art. If you’re a loyal Campagnolo user, you’ll love EPS electronic shifting.

Of course, there are a number of drawbacks to consider as well. First, Campagnolo EPS offers fewer customization options than eTap and Di2 systems. For example, Campagnolo does not offer satellite shifters for their EPS system at this time. This is a deal-breaker for some riders who have grown used to them. The My Campy app offers some shift customization options but not nearly as many as Sram and Shimano. You can adjust the shift speed and pressure to actuate a shift. There is also no 1X or gravel drivetrain option, only road. There are also fewer cassette and chainring combinations to choose from.

Another drawback is that the battery is hard-wired into the system. If a shift wire gets damaged, it’s a bit more complicated to replace. You can’t just swap in a new cable. Probably the biggest complaint with the Campagnolo EPS system is that the charging port is very fragile. It’s easy to damage the prongs in the port if you’re not careful when plugging the charging cable in. The only solution is to be careful and make sure the prong is lined up when plugging it in. Campagnolo EPS electronic drivetrains are also incredibly expensive. They cost almost twice as much as comparable options from Shimano and Sram at over $4000 for the hydraulic disc brake option. This prices many cyclists out.

Who Should Choose Shimano Di2?

Shimano Di2 is a great choice for those who are on a tighter budget. You’ll save a few hundred dollars when buying the system and probably a few hundred more over the life of the system because replacement parts are cheaper. It’s also a good choice for those who care about weight. On average, Di2 weighs a few hundred grams less than eTap. You’ll also enjoy Shimano’s system if you want the best performance. Di2 shifts precisely and quickly every time. In addition, Shimano’s Di2 system is an excellent choice for those who like to tinker. There is an enormous amount of customization that you can do. If you care about looks, you’ll prefer Shimano’s more premium-looking groupsets.

Who Should Choose Sram eTap?

Sram eTap is a great choice for those who want to use the newest cycling technology. Sram uses the newest 12 speed chain and cassette technology. This comes with a wider gear range and smaller steps between gears. The fact that the system is wireless is also very cool. You’ll also prefer Sram eTap if you plan to do your own installation and maintenance. The parts just bolt-on. There is no wiring to deal with. Anyone can install and set up an eTap groupset. eTap is also easier for beginner cyclists to use due to the intuitive shifting logic. There are also fewer customization options to worry about. You can just set it up and use it.

Final Thoughts

This decision largely comes down to personal preference. Both systems shift quickly, smoothly, and precisely. They operate reliably and offer excellent battery life. At this point, the technology has been refined for over a decade. Sram’s eTap and Shimano’s Di2 product lines are both incredibly high quality. It’s impossible to choose a winner.

Personally, I prefer Shimano. The main reason is that the cost is lower. Shimano electronic groupsets also outperform Sram by a slim margin. Parts compatibility is a bit better as well. That said, I’m a bit biased. I’ve always been a fan of Shimano gear. I’ve used their groupsets and fishing reels since I was a kid and have always enjoyed the quality of their products.

For more info, check out my electronic vs mechanical shifting guide.

Do you use a Shimano Di2 or Sram eTap groupset? Share your experience in the comments below!

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Zachary Friedman

Zachary Friedman is an accomplished travel writer and professional blogger. Since 2011, he has traveled to 66 countries and 6 continents. He founded ‘Where The Road Forks’ in 2017 to provide readers with information and insights based on his travel and outdoor recreation experience and expertise. Zachary is also an avid cyclist and hiker. Living as a digital nomad, Zachary balances his professional life with his passions for hiking, camping, cycling, and worldwide exploration. For a deeper dive into his journey and background, visit the About page. For inquiries and collaborations, please reach out through the Contact page. You can also follow him on Facebook.

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