Axle ends causing damage to dropout?
 

Hi all

Has anybody heard of axle ends (the end bits on hubs that sit in dropouts) causing damage to dropouts due to not being long enough? I may have some damaged dropouts and LBS is saying the axle ends are eating in to carbon dropouts because of this.

FYI - the ends sit just passed the half way mark of the dropout. The ends are the smooth type.

It seems like a rudimentary design flaw of a hub to me and the manufacturer is a small but very reputable and experienced US designer/builder of wheels (prefer not to name names).

So im inclined to disagree with LBS assessment and continue using wheels in other frames.

Any thoughts?

I've always wondered about wear CF dropouts.

For threaded rears, I've started to use axles for 135mm hubs on aluminum dropouts spaced for 130mm. Unfortunately for the "end caps", they are generally one size fits all, so they are made short for steel dropouts, and don't have much sticking through for wider aluminum and CF dropouts.

If the axle ends are damaging the slot, I'd uspect that the QR isn't tight enough. If you think back to the days of horizontal dropouts, the wheel was kept in place by the pressure between the axle face and QR head, or nut and washer. By the same logic the bike shouldn't be supported on the axle face, but held fast by the QR. When all is good, the wheel could be kept in place by the faces alone even of there were no axle extension.

Thanks both for the replys...
QR is definitely tight enough. when seating wheel in dropouts, if i ensure the end caps/Axle ends are pulled right up in to the drop outs the wheel is straight/aligned when the QR is tightened. Then take the bike for a spin, check the alignment again and the wheel will be several mm closer to the non driveside chainstay. it would seem a tighter QR would help the issue but thats been tried!

Unfortunately the several mm shift is enough to cause tyre rub and some shifting issues..

These are contradictory statements.
What type of QR levers are you using ?
Try a nice beefy Campy or Shimano skewer.

The wheel shifting while riding as you describe is a common symptom of a QR skewer that isn't tight enough. Or of one that's not getting enough "bite" into the dropout face, particularly if your bike has horizontal dropouts like a single-speed or track bike.

Something odd is going on. You have vertical dropouts (?), so the "home" position for the wheel is with the axle resting on the top and front of the dropout. I suspect that you're tweaking the wheel back to center the rim in the stays, then the chain is pulling the right side forward (as it will). The ideal way to mount a wheel is with the bike vertical on level ground, and let gravity position everything. When you do that the wheel should center. If not, then maybe the dish is off, or the rear triangle is.

Or, with the bike vertical, pull the wheel forward and center by grabbing the rim and seat tube in one hand and gently squeezing. (this is only necessary when the shape of the slot doesn't do the job for you, but shouldn't be necessary when all is right).

Bike has carbon vertical dropouts.

If the bike is upside down and the wheel is inserted in to dropouts the wheel naturally wants to sit closer to the non driveside chainstay. At this point, prior to tightening the Quick release, there appears to be play in the drive side dropout. by putting some pressure on the hub end caps whilst in dropouts, especially the one on the drive side with the "play", you can manually seat the wheel correctly/straight in to the drop outs. QR is then suitablly tightened, all looks good, until i start riding.
Ive only tried using the skewers i got with both wheelsets... plastic stock ones. nothing aftermarket.

Central to the theme of the thread... could the short end caps be responsible for causing the damage in dropout which has lead to the play? Not keen on writing off the wheel set.

thanks again for the replies

Yes, there's always a bit of wiggle in the dropouts. You're getting the wheel square by pulling the right side out, which is wrong, since the chain will always pull it back.

You want to square the wheel (if necesary) by pushing the left side forward instead of pulling the right side back.

If yhat isn't possible, you're back to either a wheel with incorrect dish or a rear triangle that isn't centered properly. I can't see or fix either from here, so I've helped as much as I can.

Perhaps you have flimsy external cam skewers. Can you post a pic.
Sounds like your dropouts are not perfect, but good solid skewers would make up for it by holding the wheel in place.

It's problematic to establish a solid bite on carbon dropouts without tearing them apart. (one good argument against non-metal dropouts). So, I don't think the OP will ever get enough bite to hold fast against chain tension. That's why it's critical that the top forward axle position (on both sides, but certainly on the right) provides perfect wheel centering.

If the wheel has to be canted back off the forward face of the right dropout, the chain tension will always pull it back forward, which is what the OP is reporting. As I said, it's either a wheel dish or rear triangle problem, (third time's the charm?) and needs to be properly diagnosed and fixed. I don't know which, nor how new or old the frame is, so I hesitate to advise further except to see a dealer who actually knows what he's doing.

Wheel dish and triangle checked and all good.
Sounds like a solution would be stronger skewers - only tried the stock skewers. Im surprised this wasnt a LBS suggestion.
I understand the problem itself is baffling.... and im getting a replacement frame so im over finding a solution... but as stated in my first post im unsure if i should risk using my current wheel set given that the LBS thinks the design of the hub end caps (being too short) was the cause of the dropout damage. Im questioning that thinking and would prefer to not have to write off my reasonably expensive boutique wheel set.
Thus the question.... are short hub end caps likely to cause damage to carbon dropouts?

No.
What should be holding the wheel in place - as already stated by FB - is the dropout being pinched between outside face of locknut(or corresponding item on the hub used) and the inside face of the q/r.

Things that are a lot higher on the blame list:
- poorly clamping q/r. Ti skewer, external cam etc
- poor bite on outside face of locknut (equivalent) and/or on q/r inside face. Lightweight stuff often have these in aluminium, which really isn't a clever idea.
- wheel dish and/or rear triangle alignment being off, which is what's forcing you to hand position the wheel, which is what allows it to move in the first place. Had it been positioned w/o tweaking, wear wouldn't have happened no matter what q/r you had used.

The skewer is NOT tight enough (or not clamping tight enough anyhow), the axle shouldn't move at all. Try a set of Shimano or Campagnolo skewers with an well-lubricated internal cam mechanism. They give a stronger bite with the same lever pressure. The skewer should be adjusted tight enough that it takes significant "oomph" to close and leaves a mark on the heel of your hand when closing it. If you can close it with your fingers or thumb it is not tight enough. Plastic and/or external cam skewers have too much friction and too little rigidity to get the job done.

Thanks all for your input on this. Much appreciated.

axle ends need to span at least half the thickness of the dropout.

(my hi-light in red) I haven't been keeping up with all of the latest trends in bike mfr'ing, but all carbon drop-outs!?!? Wow, that can't be a good idea, can it? Can layers of fiber strands and plastic resin really be as crush-proof as a metal alloy?