Disc brakes with QRs

Something I’ve heard mentioned, and I’d like some actual facts one way or another, but is there any proof as to which side of the fork the QR lever should sit? As in some form of diagram that shows the forces and if one particular side or the other is more liable to make the skewer unscrew?

I know this is tricky, but I’m after facts, not opinions….! 🙂

IMO, the lever always goes on the nondrive side! 😉

Did the Fox V Pinder thing not shed any light on this?

I think Magura had an opinion on it.

The clamping force of a qr should be equal on both sides.
I think that the issue may have come from some qr levers having the ability to jam in the rotor should they come undone when riding.
My front is lever-drive side so it protects the rebound knob on the forks, while the rear is on the non drive side.
As yet, I have not died.

the jamming issue was a recent Trek thing which caused a recall, but it is not the thing the OP means.

It was due to vibration from the disc brake, see here under disk brake issues:

http://www.sheldonbrown.com/skewers.html

“James Annan has created something of a storm in the industry by pointing out a serious safety risk to users of front disc brakes with traditional forks. He has identified a mechanism whereby the forces generated by the disc brake can cause the skewer to loosen up in use!

and the article here :

https://web.archive.org/web/20121005235921/http://www.ne.jp/asahi/julesandjames/home/disk_and_quick_release/

This failure mode is possible even with the better skewer designs, but it’s more likely with the external-cam type.”

My hopes used to undo – I changed to a 9mm thru bolt to stop it. If you do that RWS is the way to go…

Here’s Ben Cooper’s take on it…

Disc Brake Safety Issues

The theory I’ve heard is that the QR lever should be on the brake caliper side – on the basis that if there is any small movement in the axle from braking, it would be concentrated in that dropout and could slowly back the tension off the nut.

As always, theory is not the same as “likely to happen”, but I think Ben from Kinetics did some basic tests that backed the theory up.

The jamming issue that cdoc refers to is the Trek recall isn’t it, which would be a different thing altogether.

(Edit, beaten to the punch)

I’m after facts, not opinions

There’s also the guidance from Shimano saying put the lever on the non-disc side (not possible on the back) to avoid burning your hand on the hot disc.

Magura 2007 Marta workshop manual states:

Close the quick release of your wheel which you should mount on the opposite side of the brake caliper and tighten it sufficiently.

Their choice of bold print, not mine. Doesn’t state their rationale though.

I thought there was an issue with the qr coming undone and jamming in the disc rotor.
I use bolt through on everything but i would put the lever on the non brake side on the front

I thought there was an issue with the qr coming undone and jamming in the disc rotor.

yer there was a recall recently but with really cheap shit quick releases, a decent skewer shouldn’t get into the position where it could such an issue

I wouldn’t call Shimanos “cheap shit quick releases” http://sheldonbrown.com/qr-disk-brake.html

Shouldn’t matter on which side you have the lever, as long as you tighten it correctly. That being said, the best QR is a bolt-through…

Why don’t you look at what fork manufacturers do with larger axles…surely that’ll clear it up 😀

I wouldn’t call Shimanos “cheap shit quick releases”

shock horror, company makes equipment of varying quality 🙄

Some interesting reading there chaps. Thanks for that.

the quick release of your wheel which you should mount on the opposite side of the brake caliper and tighten it sufficiently.

Also very interesting. And useful too, thanks.