Rotor upgrade

f3nners

Having been on an intense trail ride recently I discovered that my 160mm rotors werent up to the job on my boardman pro (2011), I have sorted the front rotor upto 185mm using a post to post adaptor but am a bit puzzled as to what i need to get for the rear of the bike, info is a bit scarce on what adaptor i require for upgrading to 185mm on the rear as some state that the rear needs a smaller adaptor i.e a 185mm adaptor will be used for a 203mm rotor. Im confused as on the bike there is no adaptor and the brake is bolted directly to the frame. Slightly confused as currently its a 160mm rotor? Brakes are avid elixir r.

nicklouse

see the topic in the FAQs. there is 10mm difference in the specs for mount front to rear. which gives a 20mm difference for the same mounts used front or rear.

The Rookie

To clarify what nick is saying, a rear 180mount would need 200mm discs if used at the front, so you need the mount for a front 200 or a rear 180 to fit 180mm discs to the rear.

Simon

Shackster

I'm no expert but I think the previous two answers would be true, IF the frame has IS brake mounts. Can't see on the boardman website what type of mounts are on the rear.

I've had to research this today as I'm changing the elixirs on my Canyon to XTs, and need new mount adaptors as the rotor size is slightly different (avid 185, shimano 180). The Canyon has a post mount fixing at the rear and I suspect this is what the OP is referring to on his bike - apologies if not.

Anyway, from my research I believe that the SAME SIZE post to post mount adaptor works on both front and rear; this is why, I think, I couldn't find a specific rear post to post adaptor anywhere on the internet. The current adaptors on my bike certainly look identical.

Which is why I've ordered two front mounts, hoping they work!

davewalsh

IF the caliper is mounted directly to the frame it sounds like the frame has a post mount rear brake. Does the mount look the same as the one on the fork ? If that's the case you need the same adaptor as the one on your fork.

Why not swap the bits front to back and see if it fits ?

Shackster

This may be sacrilege but the FAQ topic appears to be out of date as it doesn't mention the possibility of the frame having a post type mount on the rear.

nicklouse

Shackster
good spot.

I had not realised that It was Post mount rear. Which it does look like.

Post mount is a standard and any caliper that mounts on it directly should need a 160mm disc. (God knows how the racers will manage having no 140mm disc option!). Some frames have an alternative position for mounting the caliper for a 180 disc.


so if you want to fit a 185 rotor then just use a front Post to Post 185 adapter or if a 180 rotor use a post to post 180 adapter.

f3nners

spot on lads, yes its a rr post mount not is, will swap the adaptor from frt to rear and see if that goes. thx.

S-M

After cooking my Boardman Pro (2011) brakes at Chopwell and Hamsterly a few weeks back, i fitted 203mm discs all round with adapters from Superstar Components.

It stops pretty well now to be honest, i did find the larger discs a bit more noisy though, i suppose thats to be expected.

Post mount adapters are identical front and rear on mine, i assume yours should be the same.....

HandjobDan

Make sure to check Superstar for the adapters only £5 each. Much cheaper than the rest at £11 quid upwards each.