

Hello, I upgraded some parts on my bike and now the brakes are gonna be next.
I will get a new set of M6120 and new rotors. I know the fork can handle 203mm rotor, but I'm not sure if I can put 203mm on the back, or just 180? How can I measure what is the biggest size?
And if you were wondering, no, the customer support doesn't help me with this question, I already tried.
by Trael07
4 Comments
180mm will be large enough and looks more likely to fit than 203mm. You aren’t going to need larger than 180mm unless you weigh 200 kg.
depending on body position (and a few other things), between 70 and 80% of your braking power goes to the front wheel.
a 180 in the rear is enough for dh racers, anything more is overkill and not worth the headache.
that said, yes you can. you’ll need an adapter for the caliper bridge to shift it outwards, but i don’t see why you shouldn’t be able to.
Do not do this. If you’re not getting enough power out of a 180mm on rear, the problem is not rotor size. It’s pads or brake bleeding/setup.
Oversizing your rotor (if it fits at all) will potentially void your warranty and could even break your frame.
It will put a lot of stress on your frame and it’s way Overkill.