Changing rotor size

silverpigeon

It's been 10 years since I had my disc brakes fitted. Didn't even notice until today, when I was fitting my new wheels, that the rear rotor is smaller than the front.

Anyway, I currently use hope minis mounted on a IS rear disc tab. Just want to check that this is the adaptor I need.

http://www.chainreactioncycles.com/Models.aspx?ModelID=13736

The Rookie

Are the Hopes IS or PM mount, do you currently have an adaptor, if they are IS then that is the right adaptor.

Most bikes run smaller rear discs, under nearly all normal riding circumstances the rear wheel will only take about 1/2 the brake force of the front before locking, so why add more braking at the expence of progression?

silverpigeon

Thanks Beginner. Rear mount is IS and no adaptor fitted at present.

Current set up is Hope Mini's 160/140.

New wheels came with 160/160 rotors which is when I noticed the difference for the first time.

I plan to but some new XTR 985 disc brakes in the next few weeks and they are supplied with 160/160mm rotors so might wait until then or shall I have to buy the adaptor anyway?

The Rookie

For a few weeks I wouldn't bother, can you lock the rear wheel with the 140mm disc, if so leave it like that, the bike won't stop any faster with it locked on harder!

mrmonkfinger

can you move your old rotor over to the new wheels for a while?

silverpigeon

Unfortunately no. New wheels are Shimano XT's which came with centre lock discs. Old rotors are 6 bolt. I'll wait until I get the XTR's and see how that works out.