Rear axle threads digging into dropouts! Please help.
 

Hi everyone, I've lurked for a long time, but now I really need some of your advice if I could be so bold to ask for it.

As you can see from the pictures, my rear dropouts have grooves worn into them from the threads on my rear axle. I have tried to research this before posting, but most of the threads have to do with wear on the sides of dropouts, whereas in my case, the inner surfaces of the dropouts are being affected. The grooves are about 1mm deep now.

I always tighten the QR properly, keep the dropout/axle interface clean, and always centre my wheel when putting it back in after taking it out. The dropout measures 130mm right on.

I can't figure out whats going on, and I'm worried that my frame will be junk.. I was hoping to keep this frame my whole life.

Thanks guys and girls!

torontoroadie

I see nothing there to be concerned about. Threads on a steel axle will bite into the aluminum dropout but only as deep as the root of the threads, so no worries.

+1 Although there's perhaps no such thing as a stupid question there are those that could avoided by application of some thought and logic. Aluminum is softer than steel, but what would allow the steel axle to cause any further damage? Also millions of bikes have been made of aluminum over more than 3 decades, most not cared for as well as yours, yet there has been no outcry about axles destroying dropouts.

Worry less, ride more.

Good answer.

OP, it was a valid question.

Thanks to everyone for your help and your time, it is very much appreciated.:)


happy riding!

I don't think carbon dropouts would fare any better and the OP really has no problems with his. Aluminum bikes can, and are, long lived too.

I like to see this, I don't like all the tire rub paint damage to the inside of the NDS chain stay from a slipping rear wheel I so often see, especially on a carbon chain stay.

I would check dropout alignment and whether the width of the dropouts and hub match, because those marks make it look like the dropouts are twisting as the QR closes.

It might not be, but that's what I would want to confirm.

You can get smooth lock nuts devoid of knurling. And you can find many threads in this forum discussing the problems they cause.

The issue isn't the locknuts but the 10mm axle threads.

Your bike looks like it has seen some use. All good. Dropout finish is probably the single most abused feature on any bike. Many bikes in the past had chromed dropouts simply because of this.

It is possible to abuse a dropout so much it has to be replaced or the frame retired. But that very seldom is the case (barring derailleur hanger damage - a separate issue we are not addressing here). But what I see here looks completely normal and expected. Ride it and enjoy.

Ben

You can also get smooth, unthreaded axle ends to prevent a cosmetic issue.

For hubs that use threaded axles? I don't think so.

Possible, it would require turning the thread off the end.. grinding tool while axle rotates in the lathe chuck , being tempered steel..

OCD has a cost.. do you want to spend it?

Which would result in an axle that doesn't fit the 10mm sized dropout, allowing it to cant while tightening the QR.

yea , there is that , maybe they want new wheels with a hub with aluminum axles..

Yes, that would indeed prevent the trauma of seeing thread marks when holding the frame upside down with the wheel off.

And that's all we have here, a cosmetic issue that is only visible with the wheel out and the bike upside down.

I have read all the comments and I thank everyone for their input.

I understand and gather form everyone's input that this is not a critical concern, but rather a wear and tear/cosmetic issue. I actually couldn't care less about what my bike looks like upside down with the wheel off, but I posed the question initially because I wasn't sure if this was a safety issue.


*AS A RELATED, OCD side note, for those interested:
I understand that this phenomenon is not uncommon. However, if the axle is straight, and the dropouts are straight, and the spacing is good (all of which I believe are true), then I would expect to see the markings evenly distributed across the affected surface of the dropout. However, what I observe is that the markings are not distributed evenly, but rather are on the inside half of the affected surface, toward the front of the bike (see pictures).

Maybe I'm splitting hairs at this point, but I like to learn as much as I can about these things.

I measured the spacing between the dropouts and it is 130mm. However, when I go to put the rear wheel in, sometimes I have to *ever so slightly* coerce the wheel into the dropouts. Perhaps the spacing is off? or my hubs are larger than 130mm?


Thanks my friends!

happy riding

a QR axle is well sized if it contacts less than 100% of the dropout width , 70% + is OK if steel ,, NB:

Conic QR spring needs space to compress into when QR is closed..


you can measure that, y/n ?

The one thing that I'd add is make sure you get your skewers tight.

I'm seeing knurling on the outside of the dropouts indicating that I think you are getting them fairly tight. However, you don't want the axle to be shifting and grinding in the dropouts.

Knurling on the locknut is more important than knurling on the skewer. Vintage Campagnolo skewers were smooth. Perhaps other brands too.

If you really wish to get rid of the problem, then many modern hubs come with smooth endcaps which don't have the exposed threads, and thus no wearing issues.

Unfortunately, nobody is making cone & locknut to endcap conversions, although in theory it wouldn't be too hard to make, if one could just get the spacing right (locknuts are generally thin, but on at least the rear, often have enough spacers that they could in theory be replaced by a thicker endcap).

:roflmao2:

Agreed.

If you're clamping steel onto steel of about the same hardness, a smooth face gives maximum surface area contact. If you're clamping steel onto a softer material, teeth increase both the contact surface area and provide a mechanical "bite" between the materials.
Clamping aluminum onto steel works OK on vertical dropouts, but often isn't secure enough on a horizontal dropout. Many aluminum QR caps have toothed steel faces for this reason.

OP, I agree about those marks being non relevant, but if you are concerned about QR tightness you should use internal cam ones IMO.