warped disc brake rotor

ccf

ccf

Guru
Is it normal for them to get warped? A quick Google search turned up MTB threads about fixing warped rotors with crescent wrenches, hammers, etc.

Here's what mine look like:

This image shows the inner edge (toward the hub) of the rotor. It doesn't touch the table at any point around the circumference.
inside edge_sm.jpg

This image shows the outer edge of the rotor. It touches the table at some spots, but lifts off at others.
outside edge_sm.jpg
 
RojoRacing

RojoRacing

Donut Powered Wise-guy
warping isn't really much of an issue with quality rotors ridden in even hard mtb terrain. What can warp rotors is constantly lightly dragging them for tens of mins on a really long descent. We're talking a 3000' mountain descent or more of dragging the brake and never letting it cool. The more common reason for rotor warping is them just getting bumped from the side during transport or moving them around in the garage because they do bend quite easy. The good news is you can bent them back just as easily with them mounted in the bike. It's most precise in the wheel truing stand but faster to just grab a small adjustable crescent wrench and give it a little tweak here and there to get it strait again. Do not use a hammer, there is no reason too and I can only imagine the handful of ways you can rotor with a hammer.
 
ccf

ccf

Guru
I don't think it was the 3000' descent on New Years Day. I suspect it is this descent:

https://www.strava.com/segments/612463

which I do regularly on my hillier commutes. I'm in the habit of pulsing the brakes, but they got "spongy" recently (not using compressionless cable housing). And on the last time down that hill I had to ride them for an extended duration to make the turn at the bottom. I think I'll look into alternate routes down the hill.

I got the rotor straightened with a crescent wrench. Took a while, though.
 
RojoRacing

RojoRacing

Donut Powered Wise-guy
Well I still doubt it's heat related unless you have some seriously faulty rotors. On the V20 when I did the white mountain double it has a 6000' descent with both 50-60 mph sections broken up with 15mph hairpins. I was so hard on the brakes I started worrying about the heat causing some kind of catastrophic failure due to the heat I was generating. I know my rotors were glowing going into each of those hairpins but alas everything held strong and strait. Hard to imagine someone on the road putting rotors through a harder time unless they were purposely trying to drag them continuously on purpose. If I were you I wouldn't worry about over heating your rotors, I don't other then that one time at white mountain.
 
T

tiltmaniac

Zen MBB Master
Going "medium speed" heats the brake surface (whether rims or discs) more than going fast, as there isn't enough wind to carry the heat away fast enough.

I've encountered brake fade well before the disc rotors got hot enough to lose temper.
 
B

bladderhead

Zen MBB Master
Brakes lose their temper? What do they do, start shouting?

Flying down this bloody hill and now he wants to stop! And this heat is getting to me! Well I'm not having it! Tell you what I'm gonna do, I'm gonna fade right now and see how he likes it!
 
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