Rowan

I've just finished a century that was going very well until km 98 when I felt the rear wheel slip as though the tyre had lost grip while climbing a steepish grade (exactly what I was doing, so I didn't think anything of it), then km 122 when I lost drive completely. It is a Velocity cartridge bearing track hub (probably by Formula).

I ran an inner spacer to get optimum chainline (which saved my ride because of the four or five threads still under it, and I walked up a lot of hills!) and of course the reverse-direction lockring. The hub has done only about 1800km, admittedly with some loaded touring in there (but not hugely heavy). I live in the country, and I don't do gutters and stuff, but I do a little leg-braking (but again not much because I have brakes).

Has anyone else had this happen on an alloy track hub or indeed any type of spin-on hub? Would I expect it to be less likely on an old-school steel track hub (there's a pair of Dura Ace up for auction at the moment)?


Cheers!

matthew_deaner

The inner spacer really isn't a good idea... Use a BB with a shorter spindle to adjust the chainline instead. The spacer may have contributed to your problem, but it is most likely that your cog wasn't on tight enough. A track hub should not strip during normal use.

I get my cog on really tight with a chain whip, then mash up a hill without backpedaling before tightening the lockring. The cog needs to be on TIGHT.

Also, be sure you are using a CNC milled track hub, rather than a cheap stamped cog. The stamped cogs can lead to stripping.

Hobartlemagne 

I've only stripped threads in the act of removing cogs. I think it was because I hadn't put any
grease on the threads. (I do use a lockring)

jgedwa

This is is topic #4 on the SS/FG forum. Lots of claims are made there about what causes this. Not sure if any of those claims are grounded in reality.

I will save you the verbal abuse of asking over there though; the answers you will get are:

-cheap, stamped cog. You really are asking a lot of those threads in this application. If those threads are not cut into a fairly precisely machined cog, the possibility is there.

-cheap hub. Maybe the threads are not cut as well on them. Or maybe the aluminum is softer. Velocity is a tested and trusted hub, so this is not the cause here.

-I can't see how the spacer would contribute, unless it moved the cog/lockring over enough that one or the other did not have its full width threaded on. You wrote that you had 4 or 5 threads under the spacer, which would make it a fairly big (2 or 3mm?) spacer, so maybe this was the cause.

My own theory is its not the threads at all, but how the shoulder of the cog sits against the shoulder of the hub. Some are squared off and some have a bit of curve to them. Usually the stamped cogs just have a bend with a pretty large radius. If so, then there really is not a positive stop when you crank it on.

The threads on that side of your hub are toast, so there may be no reason to bother exploring what went wrong, but look at that cog again and re-think what the spacer is doing to the set-up back there.

jim

reckon

why ARE they like that over there?

dobber

Do a Search



(That's the typical response to any question in there)

Rowan

Thanks guys. I think the stamped cog might be the reason. Oh well... at least the hub cost me only AUD$80 new, and I do like the cartridge bearings. Looks like a new one, a decent cog and ensuring everything is ultratight.

Thanks again!

roadfix

99% of the time, it's the quality of the cog that causes this. I mostly only use EAI cogs on all my wheels.