larger brake disk at rear instead of front weirdness

[frisbee]

I'm currently building a bike from the frame but as it's integrated cables it came with the brakes and levers installed. The website states brake disks 160/140 mm for my frame size.

I built the wheels up. The back wheel went on fine. The front got stuck on the calliper.

The front calliper is fitted with a bracket that you can flip over to swap between 140 and 160mm disks. It is configured for 140mm disks.

I went to take the back wheel off and noticed the calliper was missing most of the disk. It turns out it has a spacer fitted to take 160mm disks.

I can flip the bracket at the front and remove the bracket at the rear but before I do so am I going mad? I would expect both disks to be the same size or the larger disk to go at the front.

The front could be a mistake but you would need to fit the bracket specially at the rear.

[frisbee]

Reconfigured it for 160mm front and 140mm rear. It's no longer a Raleigh Chopper wannabe.

Now I just need to fit the chain, index the gears, wait for decent weather....and lose 20lbs!

[GravelBen]

frisbee said:

I would expect both disks to be the same size or the larger disk to go at the front.

That is the common approach, though there is actually a pretty good argument for having a larger disk on the rear for downhill/enduro MTB (and some pro DH racers do) - the rear brake tends to be dragged more frequently for control while the front is used in shorter harder bursts for stopping, so the rear can actually get more heat buildup.

https://enduro-mtb.com/en/rotor-size-myth/

That's for MTB though, not sure about road which I assume is your case as you're talking about a 140mm rotor.

[frisbee]

Yes, a road bike. The Shimano design is quite clever so it was easy enough to swap them around.