bent disc rotors

[wherd]

hey yall,

so here's my story i just got a pair of avid discs and can't believe how well my bike stops!!!!

the problem is in the 2-3 months i have used em i already put a noticable warp in the back rotor, and just noticed a slight wobble in the front.

i have never (that i noticed) bounced the rotors off of anything or abused them in any way i thought could have bent em....

so i got a few questions.

anyone got any good ideas for getting slightly bent rotors reasonably straight or just a little straighter?

what about replacement rotors are thare any good cheap durable options??

do you guys carry a spare rotor in your camelback?? i think i might start...


finally, if you own a machine shop let me plant an idea in your head. these things should be able to be produced pretty cheaply and, if everyone is bending em like me were gonna need lots of replacements soon. if you could make a better stronger cheaper rotor......

thanks for any help you might have on the subject.

here's a picture of my lastest work in progress
http://quantifactus.wcupa.edu/students/trailweb_page/my-new-ride.JPG

[jimilton80401]

Someone's going to have to solve this dilemma before I invest in discs, despite their advantages.
Anyways, I believe that with a dial run-out gauge and the appropriate clamping mechanism, along with delicate use of an adjustable wrench, you should be able to get your discs back within spec. I don't imagine that you'll be able to do much better than one ten-thousand of an inch, but then again, I've never tried it.
You can probably find the run-out guage on line or at a local industrial supplier. I think that they run from 50.00 or so on up. A used one would do fine. If you know a machinist, he or she should be able to get you one and/or help you get the set up right.
I also just read that someone is marketing one of these, including a special clamp, for this application.
good luck!

[mbrider1974]

From my experience with motorbikes the rotors are warped by heat, I didnt realise so much heat could be produced through mountain bike use too warp them.

What materials are used for rotors on mtb's, just plain steel?

[carlvoss]

I have found that just using my hands I can get a rotor close enough to true that it doesn't rub on the pads. If it's really bad, use a big channel lock wrench and some rubber to protect the rotor surface and get it close. Then put it on the bike and use the caliper as a guide, fine tuning by hand. Make sure your hands are clean so you don't contaminate the rotor surface.

[Divscotty]

I too had that problem.

I taped a sharpie pen to a bench. Put my disk so it just touched, spun the wheel - the pen left a mark so I knew where the wammy was.

Then I took a hammer turned it over so the rubber handle part was on the bent part of the rotor then ever so softly (believe me softly) tapped the hammer head with my palm.

Presto fixed both front and back. I am not much of a mechanic but I figured what did I have to loose.

[wherd]

i found my slacker solution:

if they aren't to badly warped (like mine were) just riding em seemed to straighten em pretty good again.....

perfect example of the "if you ignore it long enough it will go away" idea.

they squeek a little now but i'm not one to care much about a squeek, so long as it is not slowing me down and i know it won't eventually lead to a gruesome crash.