Oh dear, oh dear oh dear oh dear.

[Kenny]

Hello,

A couple of days ago i tried some different crank lengths, and of course managed to **** ** the threads on the hub. My almost new UDC Max Traction.. *sob* ..
Well, if i was an optimist i could always think that this is a great oppertunity to learn to ride long-distance one-footed, or wheel-walk and some gliding. But i'm not...

According to my bank account my options are:
A. Weld crank to hub and rebuild wheel when my wallet is big enough for new hub and cranks.
B. Fix the threads. (No idea how).
C. Become an optimist..

Any tips or suggestions? I can't be the only one who have messed up this?

/Kenny

[onewheeldave]

I'm afraid I've got no experience with fixing threads, but I was wondering what you did to damage them as it may help others to avoid doing the same thing.

[phil]

Originally posted by Kenny
Any tips or suggestions? I can't be the only one who have messed up this?

Definitely not; I think I've actually heard of more people destroying / damaging hubs this way than bending them. I did it to my Max Traction, by forgetting to remove the nuts before trying to remove the crank with the crank remover. Overtightening of the nut will probably do the same thing.

If you get the crank(s) welded on, sooner or later you will have to replace the lot for one reason or another, including the price of a new set of cranks. I'd definitely try to find some way of getting hold of a new hub, even if it's a cheaper one rather than a suzue; if you're not doing big drops I don't think there's any difference.

Phil

[Kenny]

Either i tried to tighten it to hard, and/or the bolt wasn't properly in place when i tightened it.


Never underestimate the damage a hungry and tired Kenny can do..

[andrew_carter]

Take it in to your local bike shop and see if they can help you out. In my early days working at the bike here I stripped the thread on a crank arm and Gary fixed it for me.

Good luck,
Andrew

[JoeRowing]

you've had it

welding will knacker the heat-treatment.

Either buy a new hub or possibly get an engineering company to braise-up the threads with some high-strength nickel-bronze rods and re-cut the thread.

[cjd]

Originally posted by phil
Definitely not; I think I've actually heard of more people destroying / damaging hubs this way than bending them. I did it to my Max Traction, by forgetting to remove the nuts before trying to remove the crank with the crank remover. Overtightening of the nut will probably do the same thing.
...

Yep, that's how I did mine. I was getting a click on one side. I thought it was the crank, so I torqued it. Must have been the pedal or a spoke.

I stripped some of the threads on the hub and most of the threads on the nut. The hub will still hold a (replacement) nut, but now I'm nervous about changing cranks, since that would put the remaining threads to the test.

I never managed to strip b*cycle cranks/bottom brackets, but I guess the materials are different.

[john_childs]

Originally posted by cjd
I never managed to strip b*cycle cranks/bottom brackets, but I guess the materials are different.

Most bike crank spindles have internal threads and a retaining bolt. While most unicycle hubs have external threads and a retaining nut. A unicycle hub with internal threads (like the QU-AX hub) would be less likely to have the threads strip.

I'll attach a picture (that I stole from Jagur) of the QU-AX hub with internal threads to show what I'm talking about.

[jagur]

if there is still a couple of threads left at the bottom that are still there,you may be able to beat or press the crank arm on with a wooden mallet/clamp just far enough to catch the last of the threads with the nut.

before i learned to beat them on every time then tighen the nut,i did just what you did.the threads on uni hubs seem weak and the chroming process makes them brittle.

[Adrian]

While most unicycle hubs have external threads and a retaining nut.

Is there a good reason for this? The bike system of having internal threads seems more logical to me, maybe it's just because it's what I'm used to.

Edit: Of course, one of the advantages of internal threads is that you can't leave the nut attached whilst using a crank extracter

[john_childs]

Originally posted by Adrian


Is there a good reason for this? The bike system of having internal threads seems more logical to me, maybe it's just because it's what I'm used to.

Edit: Of course, one of the advantages of internal threads is that you can't leave the nut attached whilst using a crank extracter

Bike crank spindles used to be made with the external threads. It's an older design. Then the bikes switched over to the internal threads. My guess is that the unicycle hubs just haven't bothered to make the redesign yet. It may also be cheaper and easier to make unicycle hubs with the external threads. Since companies like Suzue already have the machining and tooling set up to make the external threads, why change?

I do hope that companies like Suzue change over to the internal threads for their unicycle hubs. It's a better design. Maybe one day...

[foolish]

I do hope that companies like Suzue change over to the internal threads for their unicycle hubs. It's a better design. Maybe one day...

That one day is today! Cokers have internal threads. Yet another reason for its superiority over a 29er

[nb]

Originally posted by Adrian


...

Edit: Of course, one of the advantages of internal threads is that you can't leave the nut attached whilst using a crank extracter

But you can leave the washer in place once you have removed the bolt... I would have thought

nick

[jagur]

Originally posted by foolish
That one day is today! Cokers have internal threads. Yet another reason for its superiority over a 29er

only some of them,another reason for better resale value when selling it for a 29errrrrrrrrrr.

[harper]

I made the uni.5 axles with internal threads because I could tap them MUCH deeper than the external threads on an axle extend. This gives alot of pulling strength to that connection and, since the threads are internal, if the bolt is kept clean for installation it's likely to stay clean. I have three times the thread length contact with the internal threads as opposed to the unicycle standard external threads. Removing material from the end of the axle and replacing it with a bolt weakens that area somewhat.

I (probably erroneously) thought that it was a cheaper way to go also. Steve Howard told me that for production purposes it would be easier and cheaper to make the axles with external threads. I think bicycles went to internal threads to keep them from being constantly exposed even though the production process may be more costly.