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Q for machinists/tinkerers.(6 posts)

Q for machinists/tinkerers.ohio
Dec 19, 2001 1:27 PM
I was wondering if anyone has ever tried taking the first 3/8" or so of threading (1.37 x 24tpi?) off of an old freewheel style hub and then RE-threaded that portion left thread (1.29 x 24 tpi?) to turn it into a track hub. It's basically so I don't have to abuse a decent track hub through the winter.

Since the wheel I'm thinking of is built I can't mount the hub in a lathe and do it. I'd probably just run a file over the threads while spinning the wheel in the frame, then thread it with a hand die (although the chances of my friend's machine shop having a left 1.29 x 24 is pretty slim). Since the lockring doesn't effect much it wouldn't matter if the job wasn't precision, and it seems like there's enough material underneather the freewheel threading to rethread it at the smaller diameter.

Any opinions?
wellJack S
Dec 19, 2001 1:48 PM
I have thought about this myself... if it would work, the cog would still be threaded on "too far", resulting in a bad chainline.
Interesting, butStraightblock
Dec 19, 2001 2:48 PM
why bother? Plenty of people, me included, run fixed on a standard freewheel hub with no lockring or a bottom bracket lockring. You say yourself that the lockring doesn't effect much, so it seems to me the likelyhood of butchering your hub offsets any "advantage" of having the fixed-gear correct left-hand thread. If it ain't broke, don't fix it.
Approachgrzy
Dec 19, 2001 3:28 PM
Even if you had a LH die avail. you'd be hard pressed to do a decent job of threading the hub by hand. Often time the die has a fair taper in the way the threads are developed and you may bottom out the die before you get enough threads on. The next aspect will be maintaining perpendicularity with the axis of rotation. While this may not soound like a big deal on a bike w/out shifting it could be bad enough that the chain may want to jump when stressed. You could probably cob it together and use the tapered threading like they were pipe threads. I think the best way to do it and have it come out would be indexed the hub alone in a four jaw chuck on a lathe. With a big enough lathe you could swing the whole wheel, but now we're talking about a significant sized lathe.
machinist opinionCrankist
Dec 20, 2001 10:05 AM
Pull the hub and have your friend turn and single-point your thrd. reqm't. and then re-lace. Otherwise forget it. [Note that there may be some harmless cross-threading apparent afterward if existing thrd. depth exceeds .040" ( and it probably does)].
Mike
other options.Blair
Dec 22, 2001 3:42 PM
First consider your options and reasons.
Your cheap alternative is a $30 suzue track hub, so there isn't an incredible amount of money to be saved. and time is money.

If a cassette wheel is available, welding the freehub body together is a better alternative.