Disc Brakes: List of Pros and Cons
Disc Brakes: List of Pros and Cons
When it comes to bike brakes, you have two styles to choose from. This guide outlines the pros and cons of disc brakes to help you decide on your next bike choice. I will also outline the different types of disc brakes available.
What is the difference between disc brakes and rim brakes?
Rim brakes stop the bike by applying braking force directly to the flat side of the bike’s rim through the brake calipers. The front caliper is mounted on the front fork of the bike and the rear caliper is mounted on the seatstay. The arms of the caliper extend to the sides of the rim. The brake pads are mounted on the ends of the caliper arms. When you hit the brakes, the brake pads squeeze the rim. This creates friction that slows the bike down. Rim brakes are activated by cables from the brake levers to the calipers.
Disc brakes stop the bike with calipers that apply braking force to the rotor (disc). The rotor is mounted on the hub of the bicycle and rotates with the wheel. The calipers are mounted on the fork and seat or chainstays close to the axle. The brake pads are mounted in the caliper, on either side of the rotor. When you squeeze the brake lever, the brake pads push against the rotor creating friction that slows the bike down. These brakes are the same type of brakes you find on motorcycles.
Disc brakes are usually actuated hydraulically rather than by cables. When you squeeze the brake lever, the hydraulic oil in the brake line is pressurized in the system. This pressure causes the pistons in the calipers to push the pads against the rotors. Some disc brakes are mechanical. They use cables to activate the calipers, just like rim brakes.
Disc Brake advantages
Disc brakes provide more stopping power than rim brakes – Disc brakes provide more mechanical advantages than rim brakes. Especially if they are hydraulic. This allows the calipers to apply more force to the braking surface, which helps decelerate the bike faster. Disc brakes also have a larger surface area for the pads to grip. This increases friction and makes you slow down faster. Imagine the amount of force it takes to stop a 300-pound fully loaded touring bike and rider from sprinting down a mountain pass at 40 miles per hour. In this case, you need as much braking power as possible.
Heat build-up in disc brakes is not a problem—your brakes generate a lot of heat when going down a long pass. If you use rim brakes, overheating can cause the rim, tire or tube to fail. The most common problem with overheating is a flat tire. The heat can increase the air pressure inside the tire, causing the tube to explode or blow the tire off the rim. With disc brakes, your rims stay cool no matter how hard you brake. Disc rotors can also overheat, but due to their slim design, they dissipate heat better than rims. You can ride harder and brake longer without having to stop and wait for the brakes to cool.
Disc brakes perform better in wet weather – When your rims are wet or muddy, disc brakes still stop the bike reliably. Water does reduce your braking power slightly, but not as much as rim brakes.
You can ride faster with disc brakes – because the brakes stop you faster, you can wait longer before you start braking. For example, you can start braking 20 feet before the turn instead of 50 feet before the turn. This saves time.
Reduced hand pressure – Due to the mechanical advantage, there is no need to put too much pressure on the brake levers when using disc brakes. This reduces hand fatigue and cramping, especially on long descents where you brake for a long time.
You can ride with curved or unreal wheels – the discs stay the same and stop you even if your wheels are unreal. This comes in handy if you want to go to the nearest bike shop after an accident. If your wheels aren’t quite right, the rim brakes will rub or not work properly.
Disc brakes are safer – because disc brakes provide more stopping power, they shorten your stopping distance. This allows you to slow down or stop faster in an emergency.
You can run multiple wheel sizes with disc brakes – if you want to use one bike for road, touring and mountain use, you can build wheelsets with different rim sizes and then just swap them out with disc brakes. This is great for someone who has the budget or space for just one bike. You can install a set of 700c wheels and varnish for road riding. When you want to go off-road, you can install a pair of 650b wheels with knobs.
Disc brake pads last longer – because brake pads are made of harder materials, they take longer to wear out. This means less frequent maintenance.
Longer rim life when using disc brakes – Because disc brakes don’t rub against the rim, the rim doesn’t wear out from braking. The rims also don’t get hot. Rim brakes, on the other hand, remove some material from the rim every time you stop. Friction also heats the rims, causing them to weaken over time. When using disc brakes, you may get thousands of extra miles off the rim.
You don’t have to clean the discs as often as the rims – because the discs are higher off the ground, they don’t collect as much dirt or sand as the rims do. When using rim brakes, you must clean the rims regularly. If you don’t, you risk damaging the pads if hard contaminants like sand or small stones get caught on them. They rub against the rim and cause a lot of wear quickly. I had a hard time learning this after riding on the beach while on tour. I scraped the rims pretty badly before I started cleaning my pads and rims.
Disc brakes are more precise – thanks to the design, you have more control over the braking force you apply. Wheels are less likely to lock up. This gives you more confidence when riding in hairy conditions. For example, during winter riding in snowy and icy conditions, you may need to hit the brakes to prevent yourself from losing traction. It’s easier to use disc brakes.
You can use wider tires – disc brakes won’t limit your tire width. The only limitation is your frame clearance. When you use rim brakes, your tires must be narrower than the brake arms because the brake arms must reach around the tire to catch the rim. In some cases, you may have to depressurize the tires so they can clear the brake arms. Wider tires provide more comfort and better traction.
Disc brakes have a better feel – this is more applicable to hydraulic disc brakes. For whatever reason, grabbing and pulling on the lever just feels more secure and satisfying. Of course, this is personal preference. The high-end rim brakes also feel solid.
Disc brakes are now allowed in racing cars – After years of bans, temporary authorizations and re-bans, the UCI has finally authorized the use of disc brakes in road racing.
Disc brakes are more technologically advanced – over the past few years, professional road racers have started using disc brakes. Mountain bikers have been using them for years. Bicycle companies spend a lot of money developing better, safer and more reliable brake rotors, calipers and pads that give racers an edge. The same technique works for average riders like you and me.
Disc brakes are the current trend – almost every high-end bike these days is equipped with disc brakes. This is where the industry is headed. If you want to have the latest and greatest equipment, disc brakes are the way to go.
Disk Brake Disadvantages
Disc brakes are more expensive – because disc brake components are more complex, they cost more. Calipers and pads are more expensive than rim brake calipers and pads. You also need to buy rotors that rim brakes don’t need because the rim acts as a rotor. Bicycle frames that are compatible with disc brakes also cost more than frames designed for rim brakes. The reason is that more braking force is applied to the non-drive side of a disc brake bike. More engineering is required to design and build the frame. This increases the cost. If you’re on a tight budget, it’s best to stay away from disc brakes. You can buy a sturdy second-hand pair for almost free, and they’ll last forever.
Disc brake parts are harder to find when traveling – if you need new brake pads or replacement parts while traveling in developing or remote areas, you may have a hard time finding them. Small bike shops in developing countries simply don’t stock disc pads, rotors or calipers. You may have spare parts to ship. Most department stores also don’t sell disc brake parts. If the nearest place to sell bike parts is Walmart, you’re out of luck if you need disc brake pads.
Wheels can get out of real more easily – disc brakes put extra stress on the spokes. This is because braking force is transmitted through the spokes rather than the rim. The spokes on the disc side of the wheel take the most force. Weak or poorly built wheels can easily fail when using disc brakes. When this happens, you may experience a broken spoke. You may need to trim your wheels more often. To fix this, you may need to change the spoke patterns so that they are offset.
Disc brakes put pressure on the fork legs – the disc brake calipers are mounted on the bottom of the fork. When you come to a stop, all the braking force goes through the thinnest part of the fork, the fork legs. So you need a stronger fork to use disc brakes safely. Thin forks will fatigue over time and eventually fail. Another problem is that the thick disc brake forks also don’t absorb shock, which makes for a less comfortable ride. Rim brakes transmit braking force through the top of the fork near the stem. This is the more powerful part of the bike. You can use a thinner fork to absorb some of the shock and vibration.
Disc brake pads rub against rotors – this is a common problem. Because the pads are only a few millimeters from the rotor, they can easily rub if something is only slightly adjusted or the rotor is warped a little. Listening to the pad rubbing against the disc every turn can quickly get annoying. Fortunately, this usually doesn’t affect performance.
Disc brakes are harder to maintain and adjust – disc brakes can be a little moody. You have to adjust them so that the pads don’t rub against the disc. They need to be adjusted more precisely than rim brakes. If you have a mechanical problem with your disc brakes, it can be more difficult to diagnose because the disc brake calipers are sealed in the housing. You can’t see what’s going on. If you use hydraulic disc brakes, you must bleed the brake lines and change the brake fluid every year or so. This can be a little tricky if you’ve never done it before. The most common job you have to do is to replace the pads as they wear out. The difficulty of the job is about the same as changing rim brake pads.
Disc brakes are heavier than rim brakes – disc calipers are heavier than rim calipers. You also need rotors, which add weight to the wheel. If you want to keep your bike as light as possible, stick with rim brakes. One way you can save a little weight when using disc brakes is to use disc-specific rims. These are thinner and lighter because the rim wall is not used as a braking surface. Even then, the disc brake setup would be heavier.
Disc brakes are less aerodynamic – the calipers and discs protrude to the sides and widen the profile of the bike, creating more wind resistance. The faster you ride, the more important aerodynamics becomes. At speeds above 10 mph or so, wind resistance becomes the main force against you.
The disc can cut or burn you – do not touch the disc after prolonged descents. I’ve seen people pour water on their hot plate and let it boil and turn into steam. In the event of a collision, the disc can severely cut your leg. This is part of the reason road racers are slow to switch to disc brakes. For more, check out this article from Bicycling.com that explains how off-road racer Katie Compton got her knee cut by a disc brake.
Mechanical disc brakes lack power – cheap disc brakes probably won’t stop better than rim brakes. If you’re upgrading, make sure you’re actually getting performance, not just newer stuff. Hydraulic disc brakes provide the best stopping power available on a bike.
Hydraulic disc brakes require extra tools and fluid to maintain – while they are very reliable, you don’t want to be stuck in the middle of nowhere after all the brake fluid has leaked from the brake line. For this reason, most cyclists stay away from hydraulic disc brakes.
Mixing disc and rim brake bikes can be dangerous when racing or riding with friends—some riders have complained that the difference in stopping and cornering speeds between the two brakes makes riding together even more dangerous. For example, maybe on a rainy day uphill, a disc-brake rider will slow down quickly. The rim brake rider followed, couldn’t slow down quickly and hit his back.
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