Just received my 200mm Hope floating rotor in the post. It’s HUUUUUUUGGGEEE! I needed to increase the size after changing to post-mount forks, but it looks as though I’ve strapped another wheel to the side of the bike.

To complete the picture it’s used by a Hope Mono Mini, which had plenty of power at 180mm but a slight tendency to overheat in race conditions. Oh, and that’s on a Giant Trance to complete the bodge job.

So… leave it, change the caliper, or change the brakes? Or, alternatively, can I get an IS to post mount adaptor that doesn’t add 20mm?

I’ve never needed more than 160mm but then I guess it depends how much you use your brakes and how heavy you are 🙂

what fork is it – does it have a rotor size limit on it?

Giant do an IS to Post mount with no increase in rotor size.

It’s a Fox F120 – maximum rotor size is 203mm so I’m OK there. The brakes were spot on for me at 180mm on the front. I only weight a piddly 60kg so there weren’t really any problems.

I also need a IS to PM adaptor keeping rotor size at 160mm but it seems from a quick look on the web that these aren’t readily available.

I’m terrible at the mechanical side of things but I don’t understand why these wouldn’t be pretty ubiquitous?

http://www.ashima.com.tw/products_02_14.html

Au21 or 22 I think.

60kg and overheating discs in an XC race… what you doing wrong??

I find that the light reflecting from my Hope 203’s scare the antelope away and so far ive never been mowed down by one.

Stick to 160mm.

Cooking the brakes suggests you are perhaps using them a bit much maybe…

You’re using Hope brakes – that’s where you’ve gone wrong. Try Magura or Shimano, you’ll find they have better heat isolation, better modulation, better stopping power, can get away with smaller rotors, etc etc.

In fact you’ll wonder why anyone buys Hope brakes…

Maybe you need XT Ice cooling system

Overheating? When was the last fluid change?

how were you observing overheating? the rotor getting hot, or significant brake fade/fluid boiling? I very much doubt the brake is getting too hot. I do run a 205 on my xc bike but only cos that’s what I had lying about

slight tendency to overheat in race conditions

What kind of race?

I run 160/140mm hope minis and at 15stone they just about cope with me but with a lot of brakeing they can boil the fluid so I change it for some 5.1 branded as for use in high performance/track day/motorsport applications. Just a note, DOT4 often has a higher boiling point than 5.1 when fresh, but 5.1 lasts longer due to adatives (the same addatives reduce the fresh boiling point).

The Pitch has 200/180 rotors and that feels about right.

If you are 25 stone then probably not. 180 is plenty for an xc bike, just needs to be setup right.

203 each end here…. but it’s hardly a featherweight xc bike….

big bike has 225/205…. and mono6/m4 calipers…

160/140 on FS XC with 80kg hanging on, running juicy 5’s with EBC pads and it stops like its got airbrakes, suppose it depends on how much you use your brakes.