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who could make a special part?

Old 06-07-14, 12:00 PM
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who could make a special part?

I have a project ive been collecting parts for . its a gitane track bike. it has a mix of mavic ,shimano ten pitch , and forged campy seat post. my need is a special made lockring .it has to be like the ten pitch ring, but in French threading . this bike has ten pitch drive train on mavic rear hub . Ive acquired the standard thead ten pitch cog to go on the mavic rear hub, but a standard French lockring wont let the chain seat properly onto the cog. any ideas who might be able to make me a lockring that could work?
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Old 06-07-14, 12:02 PM
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Old 06-07-14, 12:06 PM
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Even a simple part like this can be very expensive to have made commercially. A hobbyist could make one provided he has the ability to generate the thread, since a tap for the job would be prohibitively costly (if it can be found).

I suggest you DIY using your existing lockring. It has the right thread, so it's a fairly simple matter of turning, filing, or grinding down the OD to clear the chain, then cutting a notch so it can be tightened.
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Old 06-07-14, 12:09 PM
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could I rethread a pitch ten lockring? how expensive a job are you thinking it could be ?
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Old 06-07-14, 12:38 PM
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Originally Posted by lofter
could I rethread a pitch ten lockring? how expensive a job are you thinking it could be ?
First of all, is there enough material on the ID? If not it can't be rethreaded at all. If it is possible it won't be a cheap job, since you need to set up a screw cutting lathe with a metric lead screw to generate the thread. These days it could be done with a CNC lathe and a thread generating program, but the set up and programming time will be longer than the running time, and time is money on these machines.

If you're going to have one made, it's probably easier to start from scratch working on the end of a bar stock nub, boring the ID beyond the ring's thickness, threading that, turning the OD then parting it off. That has a complete lockring done in a single fixturing, except for the notches which can be added later.

It can be made from an air hardening grade of stainless steel, so you get a solid quality finished part. Unfortunately, it's probably cost about $100 or so.
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Old 06-07-14, 01:00 PM
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a hundred bucks or so would be nothing . I have no metal working knowledge except of listening and reading of what you just described.id pay more if I had to. nothing on this build has been cheap or easy to get for that matter . I bet not many of these bikes were sold . and either mavic , who I suspect ,or shimano had to been the ones to make the special lock ring . never seen it in a French size only the proprietary shimano size and English in a catalog. I have a shimano proprietary ring . I haven't the faintest as to who I could contact to do this .
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Old 06-07-14, 01:11 PM
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Originally Posted by lofter
a hundred bucks or so would be nothing . I have no metal working knowledge except of listening and reading of what you just described.id pay more if I had to. nothing on this build has been cheap or easy to get for that matter . I bet not many of these bikes were sold . and either mavic , who I suspect ,or shimano had to been the ones to make the special lock ring . never seen it in a French size only the proprietary shimano size and English in a catalog. I have a shimano proprietary ring . I haven't the faintest as to who I could contact to do this .
I'm still a bit unsure why you have a problem with the lockring. Just about any lockring would clear the chain on all but the smallest sprockets. I understand that you're using a 10mm pitch chain, but I'd expect a standard lockring to work on anything bigger than 14t.

If you want more help from me, please post a close up photo of the hub with the sprocket and lockring on.
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Old 06-07-14, 08:19 PM
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Old 06-07-14, 08:24 PM
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how hard would it be to mill the lockring on this down to make its OD diameter smaller and then deepen the notches a little ? the chain wont properly seat on the cog with the standard mavic lockring as shown. this is a 15 tooth cog, standard mavic 33x1 lockring.
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Old 06-07-14, 08:31 PM
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here is the size difference between a standard cogon the left and the ten pitch on the right. its a 15 tooth compared to the 14 tooth standard cog. thought I would post this so everybody checking out the thread could see the size difference between the two.
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Old 06-07-14, 08:35 PM
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Originally Posted by lofter
how hard would it be to mill the lockring on this down to make its OD diameter smaller and then deepen the notches a little ? the chain wont properly seat on the cog with the standard mavic lockring as shown. this is a 15 tooth cog, standard mavic 33x1 lockring.
That's what I suggested earlier. It's a very easy job to turn down the lockrings OD. Anybody with a lathe and 3 jaw chuck can knock it off in minutes with no special fixtures or tooling needed. Milling the notches, if they need to be deepened is a separate operation, easily done in a milling machine. But otherwise can be also done freehand with a file.

Remove the lockring, and wrap a chain around the sprocket to determine the require OD. Reduce that by another millimeter or so, for a margin of error, and call Luke Shirk, at Shirk's bike in East Earl, PA. Tell him I said hello, and ask for a quote before mailing the ring to him.

BTW- I know the sprockets are rare as it is, but if you found a 16t sprocket that would solve the problem.
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Old 06-07-14, 09:15 PM
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Originally Posted by FBinNY
BTW- I know the sprockets are rare as it is, but if you found a 16t sprocket that would solve the problem.
yeah I found this one in Australia, cost me a 100 spot. had to wait on ebay awhile = 1 1/2 years for a standard thread to come up ,then another year for a front 80mm hub to come up , got that one from Portugal. those have been the hardest parts so far to get . the mavic stem ive never seen before. the seat post is a forged sr campy . im trying to put it to catalog specs.
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Old 06-08-14, 07:53 AM
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thanks again for the advice
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