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Question About Going to Larger Rotors

1221 Views 10 Replies 5 Participants Last post by XSL_WiLL, Jun 30, 2006

jdubsl2

Discussion Starter · Jun 29, 2006 (Edited)

I have a question about upgrading to larger rotors. I have a 2005 Specialized Stumpjumper FSR Pro that came with a Manitou Minute 1:00 fork (garbage). I just installed a new Fox Vanilla RLC and am very happy with it. However, to do this, I needed to purchase an adapter to mount the caliper on the Fox's IS mounts. I just installed new pads on the front and rear and noticed the front is slightly warped and dragging on the pads. I'd like to upgrade to a 185mm rotor because this would be my third rotor to correct warp. I know I need an adapter, but my question is -- can I install an adapter when I've already done so once to mount the caliper on the Fox fork? Or is there an adapter that will both change it to IS and allow a 203mm rotor to be installed? Where can I get the adapter from? The brakes are M-765s.

Thanks.

Justin

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XSL_WiLL

· #2 · Jun 29, 2006

You can do both. The first is redundant and stupid. You might as well just get the proper adapter to convert your post mount calipers to IS mounts for front 185mm rotors.

You can use any brand adapter: Avid, Hayes, Shimano, etc. They all have the same profile.

Your LBS can order you one if they don't have it in stock. About a week to get it in.

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XSL_WiLL

· #3 · Jun 29, 2006

http://www.jensonusa.com/store/product/BR407Z14-Avid+Cps+Disc+Brake+Adapter+For+Is+Forks.aspx

You can get them from Jenson USA for about 10 bucks.

The QR20 203mm adapter won't work with your fork, it's too thick. I wouldn't recommend a 203mm rotor on that fork anyways.

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jdubsl2

Discussion Starter · #4 · Jun 29, 2006

XSL_WiLL said:
You can do both. The first is redundant and stupid. You might as well just get the proper adapter to convert your post mount calipers to IS mounts for front 185mm rotors.

You can use any brand adapter: Avid, Hayes, Shimano, etc. They all have the same profile.

Your LBS can order you one if they don't have it in stock. About a week to get it in.

Yeah, the thought of having two adapters on the bike seemed kind of ridiculous. I've been looking into the various adapters available. It looks like THIS one (from a2z) would work for what I need to do. I'm going to try and find one at the LBS first though. Fox says a 203mm is the maximum allowable for the 32mm stanchion forks, but I decided I'm going to go with the 185mm. 25mm is a large step-up as it is.

Thanks. :-D

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fsrxc

· #5 · Jun 29, 2006

XSL_WiLL said:
http://www.jensonusa.com/store/product/BR407Z14-Avid+Cps+Disc+Brake+Adapter+For+Is+Forks.aspx

You can get them from Jenson USA for about 10 bucks.

The QR20 203mm adapter won't work with your fork, it's too thick. I wouldn't recommend a 203mm rotor on that fork anyways.

05+ fox forks do support 8" rotors...

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XSL_WiLL

· #6 · Jun 30, 2006

I didn't say that you can't use one. I said that I don't recommend it. I don't recommend the use of a 203mm on ANY QR fork.

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jvp108

· #7 · Jun 30, 2006

jdubsl2 said:
Yeah, the thought of having two adapters on the bike seemed kind of ridiculous. I've been looking into the various adapters available. It looks like THIS one (from a2z) would work for what I need to do. I'm going to try and find one at the LBS first though. Fox says a 203mm is the maximum allowable for the 32mm stanchion forks, but I decided I'm going to go with the 185mm. 25mm is a large step-up as it is.

Thanks. :-D

You can't use the A2Z adaptor for your Fox Fork. The one that you linked to is for Manitou Post-mount forks, to convert to 185mm rotor and IS mounts. You need it the other way around (IS for fork, Post for caliper).

I have the a2z adaptor that you referenced on my manitou nixon fork with a 185mm rotor.

EDIT: Unless you can flip it around, but i dont think it was designed for that and don't know if it would work

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monkeyfist23

· #8 · Jun 30, 2006

XSL, why don't you recomend using a 203 with a QR fork? I'm curious because I just put one on my minute03. I only have one ride with it, but I love the increase in stopping power. Is this a serious safety issue or do I just need to be a little more careful when tightening the QR and making sure it's secure before rides?
thanks

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XSL_WiLL

· #9 · Jun 30, 2006

Make sure it's real secure, use a good Shimano XT skewer if you have QR. They're a good quality cam-action QR. Not like others that just push it together. Going bolt-on is even better.. The 203mm can make the fork flex a lot more under hard braking. This can result in accelerated bushing wear.

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monkeyfist23

· #10 · Jun 30, 2006

XSL_WiLL said:
Make sure it's real secure, use a good Shimano XT skewer if you have QR. They're a good quality cam-action QR. Not like others that just push it together. Going bolt-on is even better.. The 203mm can make the fork flex a lot more under hard braking. This can result in accelerated bushing wear.

Yeah, I use XT skewers and I'm totally anal about keeping my stuff in top condition and working order. I've searched manitou's site relentlessly for info about recommended rotor sizes, and have found nothing. I do regular maintainance on the fork, so I'll keep an eye out for bushing wear. Thanks for the response man.....

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XSL_WiLL

· #11 · Jun 30, 2006

I have used 203mm rotors on my Sherman for a brief period of time. I think the Sherman is incredibly stiff, even the QR model is real stiff.

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