This post compares the advantages and disadvantages of U-brakes and cantilever brakes in regards to one another.
Definitions
Before comparing the two types of brakes, it’s necessary to describe them.
U-brakes
U-brakes are rim brakes with brake arms shaped like the letter “U” upside down. U-brakes mount to brake bosses welded or brazed to the frame and fork. When the rider squeezes the lever, the brake cable pulls a straddle cable which in return moves the brake arms towards the rim.
U-brakes are losing popularity. In the past, they were found on all sorts of bikes (e.g., road, commuters…etc.) but currently, they’re used mostly on freestyle BMX bikes.
Cantilever brakes
Just like U-brakes, cantilevers are also a center-pull brake. Or in other words, a straddle cable centered in the middle of the brake pulls both arms. However, the brake arms of cantilever brakes are smaller and have a different geometry even though the principle of operation is fundamentally the same.
The Advantages of U-Brakes
- Slim Profile
One of U-brakes main advantages is their compactness. The slimmer profile of U-brakes is why we see them on freestyle BMX bikes.
In most cases, the rear U-brake is installed on the underside of the bike’s chainstays so that the brake and its cables are less likely to come in contact with the rider during stunts.
Also, BMX bikes have small frames that can’t accept larger brakes at the same location.
- Elegant Look
Retro U-brake models complement the vintage appearance of old-school bicycles.
- Simpler Adjustments
Some people consider U-brakes easier to set properly than cantilever brakes due to the limited number of settings.
- Better Compatibility with a BMX Gyro
U-brakes are the most convenient brake model to use with a gyro system (read more).
The Downsides of U-brakes
- Poor Tire Clearance
The major downside of U-brakes is that they encompass the tire and thus limit the tire size that the user can run. If full fenders are to be installed, the tire will have to shrink even more.
In addition, U-brakes are prone to mud accumulation. Hence why we don’t see them on bicycles designed for off-road terrain.
- Limited Choice
As already mentioned, modern U-brakes are seen primarily on freestyle BMX bikes. However, the demand isn’t all that great because many BMXers ride brakeless.
The low demand results in limited production and a subsequent restricted choice.
The Advantages of Cantilever Brakes
- Extra Clearance
Cantilever brakes are the rim brake offering the greatest tire clearance and thus allow the rider to use the biggest tires that the frame and fork can support.
Another benefit is the reduced mud accumulation near the brakes. Those are some of the reasons why cyclocross bikes with rim brakes rely exclusively on cantilevers.
- Lots of Adjustments
Cantilever brakes are adjustable on many levels. This property is both a positive and a negative. An experienced mechanic will be able to adjust the brake as needed for optimal performance, but a beginner may get frustrated.
The difficult setup of cantilever brakes is one of the reasons why V-brakes (the successor) were simplified so that the user doesn’t have to play with as many variables.
The Disadvantages of Cantilever Brakes
- Fork Shuddering
Cantilever brakes are known to cause vibrations of the fork during braking. The problem is known as fork shuddering and manifests when the brake cable hanger is part of the headset.
Here’s what happens:
During braking, the wheel is partially or fully locked by the brake. However, the inertia keeps pushing the bike forward. Since the wheel is prevented from spinning freely, it “bites” the ground. Then, the ground pushes the fork backward, and the fork has no choice but to bend.
When the fork bends, it stretches the brake cable. As a result, the brakes grab the rim even harder and the fork flexes again. The cycle continues until the bike slows down or the ride stops pressing the brake.
The common way to resolve this issue is to mount a cable stopper on the fork (image below) and run the brake cable through it rather than the headset.
A cable hanger will reduce the bow effect by bringing the two anchor points closer together.
Having said that, brake juddering may steel appear but to a small degree.
Conversely, U-brakes do not create this issue because the front brake can be used without a straddle cable. On BMX bikes, the cable of the front U-brake connects to the brake arms from the side. As a result, there’s no fork shuddering.
- Large Profile
Cantilever brakes are fairly wide and bulky. Their size increases the chance of hitting the brake when performing stunts. Hence why you’ll never see cantilever brakes on a BMX or another freestyle bike.
FAQ: Are U-brakes and cantilever brakes short pull?
Both U-brakes and cantilever brakes have a lower mechanical advantage than V-brakes due to the shorter arms and the less advantageous pulling angle.
Consequently, U-brakes and cantilever brakes are compatible only with short pull levers. If the brakes are combined with a long pull lever such as those of V-brakes or MTB mechanical disc brakes, the brakes would lock the wheel before the brake lever has reached its maximal travel. The outcome will be poor braking modulation (control over the braking force). (read more)
FAQ: Which brake offers more stopping power – U-brakes or Cantilever Brakes?
It depends on the model of the brake and the setup. A low quality and poorly adjusted brake will offer non-satisfactory braking performance regardless of the type.
In general, U-brakes and cantilever brakes have similar braking power. If the brakes are adjusted properly and the pads are decent, the braking force will be comparable to that of a decent set of V-brakes.
That said, cantilever brakes are expected to perform better in off-road conditions thanks to the extra clearance and smaller brake arms.
Who Are U-brakes For?
There are two prime candidates for U-brakes – BMX riders and owners of vintage bicycles. For the rest of the riders, there are better solutions such as V-brakes and disc brakes.
Who Are Cantilever Brakes For?
The main users of cantilever brakes are cyclocross riders and touring cyclists.
The reasons are as follows:
- Cantilever brakes offer lots of clearance allowing the use of wide tires and full fenders.
- Cantilever brakes are short pull and are therefore compatible with drop bar brake-shifters – the type used on cyclocross and American touring bikes.
Having said that, disc brakes outperform even the best cantilever brakes and find their place on many of the new cyclocross and touring rigs.
