Roller Cam Brakes: Adjustment and Compatibility

by wheretheroadforks

A few years back, I decided to buy an old steel-framed mountain bike to convert into a touring bike. I ended up getting a Schwinn High Sierra. I believe mine is a 1986 model. It came equipped with roller-cam brakes. After buying the bike, I took the brakes apart, cleaned them up, then reinstalled them with new brake pads. I have since put a few thousand miles on the bike. This guide outlines roller-cam brakes. I’ll review them and explain what they are, how they work, compatibility, how to adjust them, and more.

front roller cam brakes

What are Roller-Cam Brakes?

Roller-cam brakes are a type of rim brake. They have two brake arms which mount to studs on the frame and fork. The studs are located just above the rims on either side of the wheel. On one end of each brake arm is a roller. These are small metal wheels that spin freely. On the other end of each brake arms is a brake pad. The brake arms pivot in the center.

Roller-cam brakes work similarly to center pull brakes. The main difference is that roller-cam brakes use a cam instead of a transverse cable. The cam is a triangular piece of metal. The brake cable attaches to the narrow end or top of the triangle. The rollers, which mount to the top of the brake arms, sit on the downward sloping sides of the triangular cam.

When you squeeze the brake lever, the cable pulls the cam away from the bike’s wheels. The rollers on the brake arms roll down the sides of the cam away from each other. The brake arms pivot in the center so the opposite ends, where the brake pads mount, squeeze the rim.

Roller-cam brakes use a standard-pull brake lever. These are the same levers cantilever brakes use. They are not compatible with long-pull brake levers that are used with direct-pull brakes (v-brakes.)

roller cam brake

Advantages and Disadvantages of Roller Cam Brakes

The main advantage roller cam brakes offer over other types of rim brakes is increased mechanical advantage. They achieve this with a rigid design. They don’t flex. The brake levers and rollers are very robust.

Roller-cam brakes also offer more precise control over how much brake you’re applying than other types of rim brakes. They achieve this by using a cam with curved sides where the rollers roll. This gives your brakes a variable pull ratio. When you first start pulling your brake lever, the pads quickly travel toward the rim. As you continue pulling, they travel more slowly.

With this design, more of your brake lever’s range is used to control the actual braking rather than moving the pads to the rim. This design also lets the pads sit further away from the rim, which reduces the likelihood of your brakes rubbing if your wheels are out of true.

Another advantage that roller-cam brakes offer is that the brake arms sit closer to the frame. They don’t protrude out like cantilever brakes. This allows you to mount them in odd locations like under the chainstays. This was popular on mountain bikes for a period in the 80s. This way, the brakes won’t interfere with the cranks.

rear roller cam brakes

The main drawback to roller-cam brakes is that they are a hassle to set up and adjust. They are touchy. The first time I tried to adjust mine after buying my Schwinn High Sierra, I spent over an hour messing around with them before I finally got them set right. If they aren’t set just right, they don’t work well. I’ll go over the adjustment process later on in this guide.

Another problem with roller-cam brakes is that the pads tend to hit the rim higher and higher up as they wear down. Eventually, the pads start to rub on the sidewall of the tire instead of the rim. If you allow this to happen, your tire will quickly be destroyed as the brakes wear out the sidewalls.

The solution is to check where your brake pads are hitting on the rim once in a while. When they start to wear and hit too close to the tire, adjust them so they hit lower toward the center of the rim.

Roller-Cam Brake Compatibility

Roller-cam brakes are not compatible with standard cantilever brake studs. The reason is that cantilever brakes pivot below the brake pad, closer to the center of the rim. Roller-cam brakes, on the other hand, pivot above the pad, further away from the rim.

If your bike uses roller cam brakes and you want to swap them for a different style of brake, you have one option. That is U brakes. U brakes use the same stud location and type as roller-cam brakes. They are interchangeable. U brake and roller cam brake mounts are called 990 mounts.

Roller-cam brakes have been out of production for quite some time. Parts are getting hard to find. Even though bike brake calipers last pretty much forever if you maintain them, it’s nice to know that you can simply replace them with U brakes if you have to.

U brakes are commonly used on BMX bikes and recumbent bikes so you won’t have any trouble finding them. For more info, check out this guide to U brakes from Sheldon Brown.

For brake pads, roller cam brakes use standard smooth stud pads. These are the same pads that cantilever brakes use. These are also sometimes called cantilever threadless brake pads or simply cantilever brake pads.

When I replaced mine, I used these Kool Stop Cantilever Thinline brake pads. They provide excellent braking performance.

How to Adjust Roller-Cam Brakes

  1. Remove the bolt on the pivot point- You can use an Allen key or you may need a wrench if they haven’t been removed in a while.
  2. Remove the brake arms and springs from the studs- The arms should slide right off with the spring inside. If they haven’t been maintained, they may be stuck. My brake arms were all gummed up when I got my bike. I sprayed them with WD-40 to loosen them up then used a rubber mallet to gently pound the arms off.
  3. Take note of how the spring and washer are installed in the arm- You don’t have to remove the spring and washer but if they fall out, you need to remember how to reinstall them properly. One end of the spring sticks in a small hole in the arm. It’s pretty simple.
  4. Clean and grease the studs- It is important that the studs don’t rust. You want to coat them liberally with some bike grease like Park Tool PolyLube 1000. If they look rusty, you might need to clean the stud off first. They need to be clean and well greased so the brakes operate smoothly.
  5. Reinstall the brake arms with the pads spread at their maximum distance from the rim- The rollers will be touching your tire when you install the brake arms. This is how you tension the springs so they hold the pads away from the rim. If you don’t do this, your brakes won’t work.
  6. Install and tighten the bolts that hold the brake arms to the frame- Don’t over tighten them. Make sure the arms can still move smoothly.
  7. Adjust the height of the cam- The cam clamps to the cable with a nut, bolt, and washer. To adjust the height, use an Allen key to loosen the bolt so you can slide the cam along the cable. You want to position it so the rollers sit at the part of the curve the provides low mechanical advantage. This is the less steep section near the top. As the rollers roll down the cam, you want them to contact the rim when they are in the higher mechanical advantage section of the curve. If you don’t get it just right, it’s fine. You can fine-tune it later.
  8. Adjust the brake pads- This part gets a bit tricky. You’ll need a wrench and an Allen key. Loosen the bolt on the back of the brake arm where the pads attach so you can move the pads around. You want to adjust your brake pads so they contact the center of the rim when you apply the brake. They should sit equidistant from the rim when they are not in use. You can adjust them in and out and up and down. It takes some trial and error to set them just right. I recommend you tighten them just enough so they stay in place then test where they hit by pulling the brake lever. Loosen them and make adjustments from there as needed.

Now your brakes are adjusted. You’ll want to periodically check where the brake pads hit the rim. As the pads wear down, they hit higher and higher up on the rim until they hit the tire. If they hit your tire, they will probably ruin it. Make sure you readjust them before that happens.

Another problem you’ll face as the pads wear down is that the point where the brakes transition from low to high mechanical advantage moves further from the rim. This happens because there is less material on the brake pads as they wear. They must travel further to reach the rim. Eventually, you’ll run out of room for your rollers to roll on the cam and your brakes won’t work. You can fix this by adjusting the pads so they sit closer to the rim as they wear.

How to Remove the Wheel With Roller-Cam Brakes

As with most rim brakes, you have to open up your roller-cam brakes to allow the tire to pass through when removing the wheel.

The easiest way I have found to do this is to start by squeezing the pads to the rim with one hand. This pulls the rollers away from the cam. You can then twist the cam a bit and remove it from between the rollers, letting it dangle from the cable.

With the cam removed, you can then push the rollers together so your wheel has enough space to pass between the brake pads. If you’re having trouble getting the cam out, you can loosen the barrel adjuster on the brake lever a bit to lower the cam so it’s easier to remove.

roller cam brake with the cam removed

Rear brake with the cam removed. Notice that the rollers are touching. The tire can clear the pads in this position.

You may have to deflate your tire a bit if the opening still isn’t wide enough. If your tires are really wide and still won’t clear the brake arms, you’ll have to remove one of the brake arms.

When you go to put the wheel back, you just repeat the process in reverse. After mounting the wheel, squeeze the brake pads against the rim and replace the cam between the rollers where it belongs. Be sure to test your brakes when you have everything back in its place. You shouldn’t have to make any adjustments when you do this.

A Bit of History

Roller-cam brakes were designed by Charlie Cunningham and licensed to Suntour in 1985. They were designed to eliminate flex and improve braking accuracy and performance. During the mid to late 80s, higher-end bikes often came with roller-cam brakes. They are a unique vintage style of brakes.

Suntour made a couple of different models of roller cam brakes including the XC and XCD models. I’m not sure what the difference is. If anyone knows, please comment below!

The earlier Suntour roller cam brakes used plastic rollers. Suntour recalled these in the early-mid 80s because they had tended to break. If this happened, you could lose braking power because the spring would pull the brake pad away from the wheel. Suntour changed the roller material to brass to solve this issue. They sent out replacement brass rollers for riders to swap out for the dangerous plastic rollers.

Notice the brass rollers

A Note About WTB Toggle Cam Brakes

WTB (Wilderness Trail Bikes) also made a version of roller cam brakes, called Toggle Cam brakes. These use a slightly different design than roller cam brakes. They allow the cable to pull from the side rather than straight from the top. This allows for greater compatibility with mountain bikes with short seatstays.

WTB brakes also allow you to quickly adjust the pads when they wear. Supposedly, these brakes are so strong that they can bend seat stays on some bikes. To solve this, WTB sold a bridge to provide extra support for the seatstays. These WTB Toggle Cam brakes are rare and are actually pretty valuable.

My Experience

Performance-wise, roller-cam brakes work well. They provide excellent stopping power. They also feel pretty robust and durable. The arms, cam, and rollers are all thick and sturdy pieces of metal. I can’t imagine them ever wearing out as long as they’re maintained and don’t corrode.

My biggest complaint with roller-cam brakes is that they are a hassle to adjust. There are too many variables between the cam height and the placement of the pads. You have to get it just right for the brakes to perform at their best. If something is slightly out of adjustment, the brakes feel weak.

In my experience, the adjustment process takes some trial and error. After adjusting the cam location, I really have to tinker around with the pad placement to get them in the optimal position. As they wear, they need to be readjusted.

One good piece of news is that roller cam brakes stay adjusted when you get them where you want them. They don’t need to be tuned frequently.

Schwinn High Sierra with roller cam brakes

My Schwinn High Sierra with roller cam brakes loaded up for a tour

Final Thoughts

If you’re looking into buying a vintage bike that comes equipped with roller-cam brakes, don’t be scared away by them. They are a functional and serviceable piece of gear.

One thing to consider is that these parts are getting pretty old. This means finding replacements is getting a bit harder. If your roller-cam brakes are getting worn out by age or if they weren’t properly maintained, you may need to replace them. Luckily, you can use modern U brakes if you can’t find the parts that you need.

For more info on bike brakes, check out my disc brake vs rim brake pros and cons list.

Do you use roller-cam brakes? Share your experience with them in the comments below!

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