Trek issues massive quick-release skewer recall

[reohn2]

That's not actually a good solution.
A normal front disc brake will try to push the wheel out of the dropouts with a force that's not far removed from the clamping force that a QR will give. If the QR slips down a little when braking, the road will push it back again when you stop braking, and if the adjuster nut is at that end of the axle the back and forth slippage will loosen it, enough that the brake will push the wheel right out in the end and you'll crash.

That was the whole idea of 'lawyer's lips' or socketed dropouts,and forks with forward facing dropouts the problem is all but eliminated.
Whichever side qr lever is on makes no difference at all with or without these better dropouts.
But a qr lever on the leftside in the open position,that folds back far enough to engage with the spokes of either disc rotor or wheel spokes would be in a trailing position with the bike moving forward and would be brushed out of harms way.
The same open qr on the right/offside would be trapped and forced into the wheel spokes causing an OTT or collapse the wheel.

[Mark1978]

Do thru axles help with this?

[reohn2]

Do thru axles help with this?

Allen key skewers eliminate any possibility:- http://www.ebay.co.uk/itm/like/36026035 ... 108&ff19=0

In fact qr skewers are only any use for their intended purpose no tool quick change wheels ie; racing,for almost any other purpose they're of little use.

[merseymouth]

Hi There, So why do bicycles keep falling over? Because they're "Too Tired" . TTFN MM

[andrew_s]

That was the whole idea of 'lawyer's lips'

The QR nut will loosen enough to come over lawyers lips if you don't notice the looseness first.

[reohn2]

That was the whole idea of 'lawyer's lips'

The QR nut will loosen enough to come over lawyers lips if you don't notice the looseness first.

So will anything if it isn't check periodically

[fastpedaller]

Do thru axles help with this?

Allen key skewers eliminate any possibility:- http://www.ebay.co.uk/itm/like/36026035 ... 108&ff19=0

But unless a very long allen key (or extreme force) is used then they won't clamp as well as a (correctly used) QR

[andrewjoseph]

One simple solution, as we demonstrate in our video, is to simply clamp up your QR from the opposite side of your wheel, away from the disc and calliper.

That's not actually a good solution.
A normal front disc brake will try to push the wheel out of the dropouts with a force that's not far removed from the clamping force that a QR will give. If the QR slips down a little when braking, the road will push it back again when you stop braking, and if the adjuster nut is at that end of the axle the back and forth slippage will loosen it, enough that the brake will push the wheel right out in the end and you'll crash.

How does the QR, the brake or the dropout, know which side the QR is on? as far as i am aware the clamping forces are equal on both sides.

I have the head of my allen key skewers on the opposite side of the rotor as it's easier to work on without the rotor getting in the way.

[reohn2]

But unless a very long allen key (or extreme force) is used then they won't clamp as well as a (correctly used) QR

They will.
I don't over tighten mine with a standard allen key(two middle fingers),they've never budged and I've done a good few thousand miles on them.
Similarly so Pitlocks etc,etc,plenty people use them all the time,no worries.

EDIT:- Halo recommend their hex key skewers be tightened to 7Nm

[edocaster]

What do we think of this?

http://grit.cx/video/2015/04/qr-recall- ... e-industry

Mostly that anyone who can't ensure this doesn't cause a problem on their bike probaly needs help with most activities of daily living.

I highly doubt the people who have experienced accidents, some life-threatening, can be fairly characterised this way.

The QR skewer is a solution to one problem (speed of wheel change) and a compromise for everything else. A cam lever is not infallible, and with cyclic changes in tension (perhaps caused by flex in the skewer and the hub body) they can loosen. There are enough anecdotal reports of self-loosening QR skewers to show that such a problem can occur.

And then the lawyer lips save the day, or at least lessen the worst possible accident scenarios. Whatever you think about them, short of a snapped quick release (also something which is not unknown - after all, what happens when something is overtightened and flexes?), lawyer lips aren't an awful idea. However, they don't prevent the accident this current recall concerns. I think Trek are entirely sensible to pursue this recall.

At the end of the day, if you had a car where you couldn't rely on the wheels staying in without checking frequently, you'd be quite entitled to say something was a bit off.

[Brucey]

re. self-loosening QR skewers; if you have cup and cone hub bearings and you adjust them 'au point' i.e. so that they are slightly loose with the QR half tight, then the free play in the bearings will disappear when the QR is fully tightened.

I have observed that after a few weeks or months, sometimes it seems as if my hub bearings are worn. However when I check the QR, it is clearly not as tight as it was when I installed the thing. There are no signs of either the lever or the nut having moved (I.e. rotated; the lever couldn't, and the nut has road film on it from only one direction).

Now it seems to me that this only ever happens with external cam type QR levers. When they are adjusted slightly, normal service is resumed, for a few months anyway....

My theory is that the plastic seating commonly found in these external levers will creep slightly under the applied load. I therefore think that they are only suitable for frames with VDOs at the rear and lawyer's lips on the forks, since eventually wheel slippage is sure to be possible if the QR is not occasionally adjusted to compensate for this.

[edit;

EDIT:- Halo recommend their hex key skewers be tightened to 7Nm

FWIW I don't think this is as tight -i.e. produces as much clamping force- as a decent QR manages....]

cheers

[reohn2]

[edit;

EDIT:- Halo recommend their hex key skewers be tightened to 7Nm

FWIW I don't think this is as tight -i.e. produces as much clamping force- as a decent QR manages....]

cheers

I can only repeat what I posted before.
Two middle fingers on a Halo Hex Key skewer is all I've ever used to tighten them,I've never had problems.
Furthermore I haven't read or heard of any catastrophes with them or other similar systems and have had a pair of cheaper Raleigh branded ones I've been using for donkey's on various bikes without issue.
BTW these skewers are all used on disc brake wheels.

[Brucey]

actually measuring clamping force is tricky, and the grip that a wheel has will vary with the serrations on the locknuts and how they bite into the frame, too.

Nonetheless I think that 7Nm isn't enough to compete with a decent internal cam QR, and in fact I would expect that any similarly dimensioned screw-tightened device will not be able to clamp as hard as a good QR.

The reason for this is that a QR skewer sees uniaxial tension, whereas a screw being tightened also sees a torsion loading component. This significantly increases the chances of yielding at any given tension value (which you can see easily if you apply Von Mises), thus assuming the dimensions and material are similar, a screw will be expected to fail before a QR skewer will.

I may carry out some trials which will at least allow some comparison to be made, even if they don't actually give clamping force values.

cheers

[maxcherry]

What are 'Lawyers Lips'?

[Brucey]

What are 'Lawyers Lips'?

not as exciting as you might think....



cheers