Now that we have learned more about braking, there are a number of things we can do to improve the performance of our brakes.
One of the best things we can do to get better performance from our brakes is to have larger rotors.
The reason for this is that every time we use our brakes, we are removing energy from the combined kinetic energy of ourselves, our bike and our speed.
This energy is transformed *mostly* to heat, which builds up in our rotors and pads. Too much heat and we lose performance of our brakes!
Larger rotors allow more room for this heat to dissipate, which is likely the main benefit among some others we won’t get in to!
Below are 3 Science-Based reasons you might want to consider bigger rotors:
REASON #1 TO HAVE BIGGER ROTORS
Very fast riders have greater kinetic energy than slow riders. In fact, greater speed increases your kinetic energy more than what your weight does! This means that for the fast riders to slow down as much as we do, they will need to remove more energy (and thus build more heat!).
If fast riders want to ensure the performance of their brakes, they might want to look at larger rotors. 203mm is not out of the question for enduro and DH racers.
[UPDATE: Now, companies are building bigger rotors to cope with the higher speeds! There are prototype 223mm rotors in existence, and I even got my hands on a prototype 246mm rotor! (below)].
REASON #2 TO HAVE BIGGER ROTORS
There is a sad fashion that has existed since disc brakes were invented for bikes, which stipulates that many bikes come with a larger front rotor than in the rear. However, we’ve learned that most riders brake more (and thus remove more energy and build more heat) in the rear brake.
Try having at least the same size rotors…and if you put a larger one in the rear you wouldn’t be the first person 🙂
It’s highly likely that you are braking more overall with the rear brake, so having a higher heat capacity in the rear will improve your control of the bike.
REASON #3 TO HAVE BIGGER ROTORS
A 20mm larger rotor rotor can weigh as little as 20 grams more.
My guess is that you won’t notice the additional weight, but you WILL notice the additional performance!
Time and time again when I get riders out testing with the brake power meter, one of the first things they notice is how powerful the brakes are. I am just using standard brakes, but ALWAYS use at least a 203mm rotor.
And for a pro tip: I always replace my rotors–even more often than my brake pads. The rotors wear fast, and once the etching in them is smoothed over by the pads, they are pretty much useless!
Unless you are doing a style of racing where braking performance matters less than the weight of your bike, it’s probably worth experimenting with larger rotors.
What do you have to lose?
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