Wear in fork dropouts

[Chris S]

There's an issue with one of the regularly used bikes in our stable - it's quite hard getting the wheel to secure, and a few times I've found it decidedly loosey goosey. As it's a front wheel, I don't think this is a Good Thing.

The dropouts definitely show signs of wear:

20170813_135931 by Chris Smith, on Flickr

20170813_135822 by Chris Smith, on Flickr

and even if you cinch the QR down tight (too tight for the regular rider to undo, which in itself is not good) it seems to come loose again.

Is the fork fubar'd?

[LittleWheelsandBig]

Looks fine to me. I'd replace the (probable) external cam QR with an internal cam QR. That would take care of lots of possible problems.

[Asterix, the former Gaul.]

Loose front dropouts are exceedingly dangerous.

[Chris N]

Disc or rim brake? If rim, new QR - Shimano style enclosed cam like LWaB says - and carry on riding it. If disc, new fork and a decent QR.

[Chris S]

Disc.

[ACyclingRooster]

Hi to you all out there. I must confess in all of the years that I have been riding alloy bikes/alloy forks I have never ever seen this kind of wear/damage to any of my bikes and I have had many many bikes over the years.
This type of wear/damage looks very much as it is possibly a combination of insufficient tightening of the QR and possibly a spindle that is not a snug fit into the drop-out.
It could possibly be combined with the grips on the QR interfaces not being sufficiently grippy on the dropouts.
 The images that are showing the surface that is gripped is showning signs of QR's with two different diameters of contact,that over a period of time could easily create instabilty/insecurity at the QR interfaces.
It could also be that the droppouts are pourous/softer than they should be.

How old are the forks and what make/brand is the bike/forks ?

[Chris S]

It's on a Giant Liv - two or three years old - used for commuting.

We've found an internal cam QR, and it certainly cinches up tighter, but I'm still concerned that the dropouts are compromised - to my mind, the wheel doesn't line up right if it sits all the way in the dropouts.

ETA: It's done 9500km apparently.

[Sergeant Pluck]

The wear looks as if it is now at the point where you might be partly cinching the skewer onto the narrow ends of the hollow axle that slot into the dropouts,  rather than compressing the dropouts themselves. Sometimes that narrow section of the axle ends only a mm or so below the dropout surface.

Another thought: is you hub one of those in which tightening the skewer provides the load required to fully take the play out of the hub bearings? Could it be that at some stage, the hub set up has not allowed for the additional pressure on the bearings that occurs when the skewer is done up? So the bearing would have felt fine with the wheel off the bike, but the bearings were not running freely with the skewer done up? The reason that occurs to me is that the wear in one photo looks almost as if at some stage the whole hub / axle / skewer / nut was rotating together. 

[mrcharly-YHT]

Is it a dropout that is flared (fatter at the open end)? If so I wonder if that has enabled the skewer to 'work' in the dropout?

Part of me thinks that it would be a good idea to file the faces flat again.

[fruitcake]

So the wear to the aluminium is a result of a loose wheel spindle, caused by a weak skewer, and you believe you've addressed that by chaging to a skewer with internal cam.

Only question now is can the fork be used as it is, do the fork ends need dressing with a file to remove (most of) the deformed aluminium from the surface, or does it need replacing.

Incidentally, Sheldon Brown advocated filing fork ends. That was in instances where a new spindle was sligtly too fat for a vintage fork.

I guess the question is this: after filing, would there still be enough material for the fork end to resist the forces on the spindle, and to retain the wheel, and to be a sufficiently tight fit. That depends how good a fit the spindle is at the moment.

[Paul]

The wear looks as if it is now at the point where you might be partly cinching the skewer onto the narrow ends of the hollow axle that slot into the dropouts,  rather than compressing the dropouts themselves. 

That's what I wondered. Have you replaced the wheel/hub/axle, or done some work to it/them?

[andrew_s]

The forces on the wheel axle from using a disc brake can be over double your body weight*, and if the QR isn't clamping tightly enough, the axle will slip until the nut meets the lawyer lips. After you stop braking, your weight (or the next pothole) pushes the axle back to the top. This back and forth motion will tend to loosen the adjuster nut, especially if it's at the slipping (disc) side, and as it gets looser the less hard you have to brake to cause slip.

If you rarely take the wheel out, and don't notice the looseness or the top of the wheel moving sideways under braking, the QR can eventually get loose enough to allow the wheel to come out of the forks despite the lawyer lips. This generally hurts.

As stated, use a strong QR skewer (Shimano type enclosed cam, or an allen key skewer), and keep it properly tight. It's also best to have the adjuster nut at the other side of the hub from the disc.


* You can brake at about 0.5g before the back wheel lifts, a 160 mm disc is about 1/4 the size of the wheel, giving double bodyweight. The direction of the wheel ejection force is downwards and backwards, perpendicular to a line between the axle and the disc pads.

[jsabine]

I'd probably dress that dropout with file to remove the marks from the axle thread, in case they're making it sit a bit funny, then dress either or both dropouts to ensure the wheel sits square when fully seated in them.

My natural caution about QRs, discs and ejection force is probably addressed by the new QR, lawyer's lips, and checking it after every couple of rides.

(I think the witness marks from the axle thread show that the QR isn't bearing on the end of the axle, so wouldn't worry about that.)