Does Rotor Size Matter?

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Most of the myths around car parts and changing or replacing these parts lack the support of science and the manufacturers of these parts. The brake rotor is included in these myths. Rotors do not come in a single universal size. There is more than one size of rotors out there. The bigger size rotors however seem to be favored over the smaller or regular sizes. 

So, does rotor size matter? There is a manufacturer specification for all automobile parts, be it for a car or bikes, or other types of vehicles. These specifications state the recommended type, size, and other aspects for every part of the bike or car. So, size does matter when it comes to rotors.

The assumption that bigger is better may not always be true in all situations. This calls for a need to confirm that the principle applies when it comes to brake rotors. Yes, the brake is your lifeline, especially when it comes to riding a mountain bike or similar automobile.

Every effort to improve the performance of the brake is therefore encouraged, except for modifications that may compromise the brake over time.

In a mountain bike, most of the brake work is done by the lever. It is this part of the bike that grabs onto the wheel to stop its rotational movement. You cannot throw away the manufacturer’s specification for rotor size, simply out of your desire to customize the brakes or improve their performance.

It is not safe to simply ignore the manufacturer’s specifications and pick and choose whichever rotor size you fancy. The consequences of such recklessness come in the form of premature rotor fades and failure, unsettling squeal noise, smoke, and inefficient brake performance. So, complete disregard for the manufacturer’s specification is not a good idea.

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Why does rotor size matter?

The performance of your brakes depends on several brake parts and not just the rotors. the pads, lever, and other brake parts are important determinants of how the brake performs. However, for most people, changing the brake pads is the first thing they think about when the brakes become inefficient.

Yes, worn brake pads can cause inefficient braking. changing such brake pads will bring about a tremendous improvement in braking performance. However, the impact felt when the rotors are changed is far more than that of changing the brake pads.

If you are looking for a way to get the brake stopping power up by a nudge, then you consider the rotors to help you with this and not the brake pads. The size of the rotor is an important factor in how the rotor can absorb heat.

Remember, heat or thermal energy is a familiar and constant finding in the braking system, especially with the hydraulic brakes. How much of the heat is absorbed affects the stopping power of the brakes. with larger rotors, there is enough surface area for more absorption of the generated heat. The stopping power is therefore sustained longer. The reduced absorptive capacity of the rotor causes the premature onset of fading.

Size matters a lot for the brake rotors. Generally, the durability, rate of fade, braking performance, and other properties of the rotor is linked to the size. The bigger the better. So, I guess the principle applies to the brake rotors at all.

Is it okay to use the same rotor size for both front and rear rotors?

For a mountain bike or any other type of bike, the size of the front rotor should be different from that of the rear rotor. When getting a rotor for the rear side, ensure to specify this at the auto shop. The size difference between the front and rear rotors is to ensure smooth braking, especially while riding a mountain brake on rough terrain.

The size range for bike rotors is somewhere between 140 to 230 millimeters. Any rotor size between this range is okay and will give a good performance. However, ensure to stick with the manufacturer’s guide for the front and rear rotor sizes.

The rear rotors are usually bigger than the front rotors. The braking performance of the rear brakes is more crucial especially when moving down heels or in rough terrain. It is safer to apply the rear brakes forcefully in emergencies than the front brakes.

If the front brakes are larger and possess a better braking performance, when applied suddenly as in an emergency, this could lead to loss of control of the automobile and swerving off the road.

Depending on your level of professionalism and the type of ride you are practicing with your mountain bike, you may consider installing a bigger size in front as against what was explained earlier.

The reason for the initial recommendation is that when the rear brakes get locked up, you are unlikely to crash with your back. It simply causes the back wheel to skid on the road but will not affect the steering. The rider still maintains total control of the steering and can keep the bike from crashing.

However, if the lock-up happens with the front rotor, this is less tolerable and may cause you to lose control of the bike and crash. Bike crashes often cause varying degrees of injuries depending on the protective gear you are putting on and how severe the crash is.

Unlike the car, where the driver is relatively safe, especially while putting on the seat belt, a bike crash will cause your body to strike the ground. So, even without an open injury, you could suffer intense body pain for weeks or fracture a bone or two simply because you refused to install the brake rotors properly.

There are situations where it is best to install the bigger size rotor on the front wheel of your mountain bike. There are also occasions when you should give up on high-performing big-size rotors and stick with the regular, small-size rotors. 

When practicing too long descents on a steep slope, your front brakes are more important in this situation and similar to other situations that the rear brakes. So, in this case, it is okay to have the bigger rotors in front.

beginners should not move to install big-size rotors, bigger than the following come of the bike. Ensure to master riding with the stock brakes and take all the time you need to get used to them. only attempt installing a larger size when you are conversant with the stock size.

Does a big-size rotor have any benefits?

Riding with big-size rotors is not the same as the stock-size rotors. There is a clear difference which is obvious from the very first application of the brakes. 

The bigger the size of the rotor the better its braking, durability, and lowered fading. so, bigger rotors have better heat performance, higher durability, less fading, and more effective braking. These are what will change when you go higher on the size of the rotor on your bike.

Several factors are however considered before selecting a particular size of the rotor. this decision is not arbitrary or at the discretion of the rider. Rather, the rotor must be within the recommended size, and suitable for the terrain as well as the expertise of the rider.

Whatever combination you decide on has merits and demerits. Some have a bigger rotor at the rear and a stock rotor in front. Others have a bigger rotor in front and the stock rotor at the rear. For an optimal braking experience, install a front rotor bigger than the stock size and a rear rotor bigger than the front rotor. This way, the braking experience will change forever.

When on a high speed, the stock rotors may not get you to stop as quickly as you would have loved to. The final size of the stock rotors puts into account the overall weight of the bike and does not focus only on the performance of rotor brakes. So, to have a lighter bike, manufacturers do not install big-size brake rotors on the bike.

When aftermarket rotors that weigh a couple of grams more than the stock rotors are installed, the weight difference does not impact significantly on the speed of the bike, it, however, brings about a massive difference in the brake performance and how safe the brakes make the feel while riding at top speed.

The rear rotors are more deserving of a bigger size than the front rotors. Take a look at your rotors, especially if you are a rider who weighs more than 80kg, and rides on rough terrain, and see how discolored it has become. Notice how the front rotors are still able to retain their color? This tells you when an upgrade is to be done, more attention should be paid to the rear rotors.

Does Rotor Size Matter – Conclusion

For a better braking experience, stopping power, and fading, the bigger the rotor the better. However, the upgrade is not done indiscriminately. There is a guiding principle to ensure the best outcome. This has been covered here in this article.

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