Shiimano post mount adaptors

Switchblade

Hi there,

This may come across as a silly question but here goes.

I want to fit a bigger rotor to the rear of my bike, the frame is post mount as is the caliper. Shimano have post - post mount adaptors BUT they seem to be listed for front usage, is this more a typo and can say a 180 or 203mm post - post Shimano adaptor be used on the rear????

Thanks in advance.

Dave.

nicklouse

for the rear use the same measurements as for a post to post front unless you have alternative mounts on the frame.

what frame?

Switchblade

It's a 2012 GT Avalanche 1.0 frame so i assumed the post mount on the rear is the same as on forks.

Dave.

cooldad

As a matter of interest, why do you want a bigger one on the back.

Switchblade

Well the rear 160mm needs replacing, it's a little buckled and i've noticed it's scored and i already have some new discs knocking around, one 180mm and two 203mm so thought i use one of those..........obviously the 203mm is probably too big for the rear lol.

Thought i could go 203mm front, 180mm rear????

I also have a couple of perfectly good condition Hayes 160mm rotors.

For general XC would it be best to stick to 160mm F & R ????? would going to a bigger front and rear set up only be useful for an aggressive rider or DH riding or would i get better modulation, last thing i'd want is to suddenly make the brakes become more grabby and lock up all over the place due to being overkill.

Thanks for any advice, new to all this.

Dave.

Chunkers1980

Xc 180f 160r

cooldad

They would be more grabby - you would get less modulation. If you actually need more braking power, then maybe 180mm on the front, I wouldn't go larger than that on a short travel XC bike.
The rear does very little braking, and the harder you brake, the less it does as all weight is transferred to the front. Chances are it will just lock up. Even DH types manage happily with 160, or even 140 on the rear.

The Rookie

For XC 160/160 or even 160/140 will be fine, bigger disc - more weight.

What brakes?

sigorman85

I have 203 on the front and 180 on rear it works fine for me

cooldad

sigorman85 wrote:

I have 203 on the front and 180 on rear it works fine for me

Right, that's good enough for me - off shopping for monster rotors.