[eaterofdog]

So with disc brakes, I gather the front mounts are one size larger than the rear mounts. So a brake adapter that fits a 180mm disc on the front will fit a 160mm on the rear. Does this mean I can use a 160mm front adapter to install a 140mm rear? Is there some kind of clearance issue or something?

I'm setting up a 24" dirt jumper and looking for a smaller rear disc with the BB7. A 140mm with organic pads will provide more than enough brakes. A smaller disc should warp/get hit less.

 

[eaterofdog]

Ok, looking at a pic of a rear adapter here and it has 160F 140R on it so that answers my question.

I am putting together a DMR Rhythm. It's going to be a sick bike. Half mountain, half bmx, 24 specific frame and fork. MMM

 

[zebrahum]

Sounds like a fun build, you're right about the adapters, but you already knew that.

 

[sanjuro]

Rotor size is up to the user.

Considering that braking is 80% in front brake, a larger rotor is advantageous there. You can also save a little weight by running a smaller rear rotor.

But for compatibility and pricing reasons, a lot of bikes have the same size front and rear rotors.

Also, I believe most 140mm rear brake mounts, the 160mm adaptor is just flipped over.