[Closed] Rotor sizing

Depends on your weight and how/what you ride. Im 12.5 stone go down some pretty steep hills and have never needed anymore than that.

I don't think it really matters. My bike came with 180 front and rear. I replaced the brakes from the Elixir's I had to some Formulas that were on offer at a good price and came with 203 discs. I notice no problems at all with the 203's. They modulate very well, never feel overpowered. I did cook my Elixir's up a few times on one or two fast descents on one of my local rides, and these 203's seem to handle that section without the smell of burning pad material and reduction in braking performance at the bottom of the descent - but that's just one section of one trail I ride.

Aye, all sorts of things going on with this- bigger rotors can feel less subtle and are heavier, but will tend to heat up less. Front/rear balance really depends on you- I've almost always got a bigger rotor on the front but if you use the back brake a lot, maybe going up a size makes sense.

I had some 170s custom made - just right.

To be honest I've never noticed any fade locally. There's only one descent locally that gets my rear pads smelling. That said I'm hoping I'll be going faster on a full sus. I'm light only 10 stone. I have to buy new rotors as I'm keeping my old bike so can go with any combo, kinda feel I don't know enough to make an informed decision!

There is a school of thought that says there's no point (other than aesthetics) increasing the size of the back rotor unless you're already running a 203 up front. The back brake does comparatively little work of braking as the front tyre has more grip and your weight is effectively thrown forward under braking. All you'll do by increasing the rear rotor size is reduce modulation and make it easier to lock the back wheel.

Fair enough so go 203 & 180 or is that only necessary for alpine shenanigans?

I've got 203 and 183, extra 3mm makes all the difference...
seriously though went from 160 rear to 183 and noticed the difference, 203 from 180 front and didn't. Will probably go 180 bpth ends again

For your weight I think 180 F - 160 B would be plenty.

I have 180 front and 160 rear on my Bandit. Seems to be perfect on the local Stanes trails.
I would probably go 203 / 180 if I was doing longer, steeper downhills. That's what I have on my Covert - to be honest it's overkill for regular trail riding but the Covert encourages speeds beyond my comfort zone so it's good to be able to reign it in a bit!

200fr and 160 rr for me. Pretty much irrespective of bike.

Thanks everyone, think I'll stick with 180/160!

Cheers!

Ooh while I'm at it, how do I work out which post mount adapters I need?

Sticking with the same size rotors also makes it easier for swapping wheels over should the need arise - depending on your axles and hubs