[Mai]

I am considering larger rotors for my 575 and need to know what size fits and also the adaptor that I need to buy. I have a Float 36 fork with Shimano XT brakes. I am thinking about at least 180mm rotors. Finding the right adapter is driving me nuts.

 

[hurf de durf]

If your caliper (XT765, XT775) is post mount, you'll need Shimano item # ISMMAF180PPA, which is a post-mount to post-mount adapter from a 160mm std post mount. If you have XT 755s, which are IS mount, you'll need a PM to IS adapter, which Shimano makes as well but for only certain size rotors.

 

[Mai]

This is the front. It is a post mount 74mm I think

 

[Mai]

This is the rear. IS 51/74mm correct?

 

[crisillo]

you are correct Mai!

the fork is postmount/74mm (so you need a postmount-postmount adapter there), and the frame is IS/51mm (so you need a IS-postmount adapter)

unless you are having overheating issues, I'd recommend to go mostly with the front rotor upgrade. In the rear, a smaller rotor usually gets the job done. Actually now I am downgrading the rear rotor from 180mm to 160mm on my Terremoto, because I don't really need it and saves some weight (I still run a 203mm in the front though )