Just got back from my LBS where I tried to get an adapter for an 8inch front rotor on my 2005 Vanilla 130 RLC (hayes disc system). The guy at the shop said I can't put an 8in rotor up front on that fork because it will create too much torque for the dropouts and QR axel. Is this true? I know it used to be a problem on older forks, but man, these dropouts look huge. Whats the deal?
Yes you can, here's from the manual. Disc Brakes Important - Torque calipers to brake manufacturer's specifications. Disc brakes with 160-203mm rotors can be used on FOX FORX. Do not use rotors larger than 203mm. Install disc brakes and torque all fasteners according to manufacturer’s recommendations. Install, route and check that all cables or hydraulic hoses are securely fastened to the lower leg and will not move during compression of the fork. It is recommended that new disc brake pads be installed to ensure proper alignment and to minimize drag. Test brakes for proper operation on flat land. Brakes
There is a school of thought that says that 8" rotors are not really very safe on QR forks, though. Frankly, QRs don't instill me with any kind of confidence, especially for a part that flexes as much as a fork. If you're doing the kind of riding that requires 8" disc brakes, you might want to consider switching to a bolt-on solid axle on the front.
I remember a Specialized recall of Enduros which were spec'ed with 8 inch rotors (and I believe it was Fox forks on the front).
Prior to 2004 (I believe) Fox recommended nothing larger then a 7" rotor on their Forks with QR. I know this since I have a 2003 Talas, I am currently running Magura Louise FR's. Personally I would not run that large of a rotor on a QR fork.
Yep, but those were older models. Fox has reworked the dropouts and now allows 8" rotors. Still, an 8" rotor and a QR is iffy at best. That's a lot of leverage to be putting on a very small piece of metal.
fox says that there is no problem on newer forks, but if you run an 8 inch rotor i would replace the axle with a bolt on axle if your hub will allow. it makes for a much stronger front end and it will increase the stiffness very much. qr axles are usually about 5 or 6 mm in diameter, a solid axle is 10mm. the dropouts are strong, the axle is not.