front wheel slewing under braking - thoughts?
shefbiker
Posts: 255
Hi
I've got a rigid alloy front fork with disks which, following a good crash, has a slight dent about the size of a thumb print on the inside of the left hand leg which has the disk mount on it.
Basically, under braking the wheel slews slightly to the left, and i've noticed that it's the left hand end of the QR moving slightly downwards on the drop-out surface. It doesn't matter how hard i do the QR, or which make of QR i use, it still happens. The QR remains tight throughout, but when I release it, the forks drop back onto the QR proving that the QR has slipped.
My theory is that the fork leg is actually ever so slightly bent (although you can't actually see it), and hence the drop-out surface will be slightly out of alignment. The force on the QR from the disks is massive, and hence the movement.
Does that sound feasible/probable? The only solution seems to be new forks...
Thanks
Tim
I've got a rigid alloy front fork with disks which, following a good crash, has a slight dent about the size of a thumb print on the inside of the left hand leg which has the disk mount on it.
Basically, under braking the wheel slews slightly to the left, and i've noticed that it's the left hand end of the QR moving slightly downwards on the drop-out surface. It doesn't matter how hard i do the QR, or which make of QR i use, it still happens. The QR remains tight throughout, but when I release it, the forks drop back onto the QR proving that the QR has slipped.
My theory is that the fork leg is actually ever so slightly bent (although you can't actually see it), and hence the drop-out surface will be slightly out of alignment. The force on the QR from the disks is massive, and hence the movement.
Does that sound feasible/probable? The only solution seems to be new forks...
Thanks
Tim
0
Comments
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Yes, that does sound plausible.
Also you get a downwards reaction force from the axle under breaking, which can cause some movement in some forks, as well as actually unscrewing the QR!0 -
Thanks for that.
If you do the maths, the force is astronomical trying to rip the axle out the bottom of the dropouts... so i'm quite wary of my front brake at the moment!0 -
Yes, can be over 2000N!
Most forks do tend to be ok - rigids however seem to be affected more in my expereince. Not sure why!0
