I am trying to convert a 6-speed Dura Ace 7200 cassette hub to single speed. Bought a conversion kit and all fits except the retaining ring (A). Note that the inner diameter of the retaining cassette gear (B) is larger than (A). QUESTION: can anyone point me to any kind of threaded nut in lieu of part A? Please don’t suggest simply screwing on part B or somehow shaving the gear teeth of part B, as I don’t view those as adequately elegant solutions.

Hmmm, no replies. Maybe a different question: what are the dimensions of part B (diameter, thread count and pitch), the sixth gear and lock ring of a Dura Ace 7200 hub? I’m thinking if I know those dimensions, maybe I can find a lock ring from a non-cycling application. As I think about this, maybe grinding down the gear teeth on part B is the easiest solution. Opinions?

you bought a kit for hyperglide freehub, bub.

bummer.

if you grind off the gear teeth, you will play hell ever removing it without cutting it off.

you should have chosen a hyperglide freehub.... a DA 7400 hub would work fine.

if you're using a tensioner for the chain, you could use that hub and cog... and have an optional high gear available...

1.37 x 24 tpi... now where have i seen that thread size... hmmmmmm... hint: it's a common bicycle assembly.. (the old styles used a Hook Spanner to remove the LOCKRINGS....;-)

I didn’t choose the freehub, it came with the project bike (early 1980s Araya Road 821), and I won’t swap out the hubs and wheels as they are very nice. Good point about grinding off the gear teeth! I’m doing a full restoration on the Araya Road 821, but thought also that it would be a good candidate for a single speed so wanted to try that out. If I can’t find a solution, I’ll just restore it to 12-speed. So, looks like I’ve got to figure out if there is any non-cycling lock ring that would work in this specific situation. Again, any suggestions greatly appreciated.

see the updated response above... your lockring will be a common BICYCLE part.
sorry about the "updates'... i'm suffering a bad tooth and on pills that are NOT pleasant... and had to look up the old uniglide thread size... once i saw that... the wheels began to spin.

"Please don’t suggest simply screwing on part B or somehow shaving the gear teeth of part B, as I don’t view those as adequately elegant solutions." xpacpal1x

Ok, I won't suggest the obvious and very functional solution. Maybe find a machine shop that can turn out a one off lock ring (would look much like a fixed cog's but RH threading). This suggested is some tongue in cheek...

I don't do hardly any web searches for question posters here but perhaps there's a single speed conversion kit that is made for the freehub body you have (a UG twist tooth version). The kit you got isn't made for what you have. Perhaps the company/people you got the wrong kit from have the right one? (Which I would be surprised if they did).

I see 3 choices and 1 hope- First is to use the thread on cog that you know works and costs nothing. Second is to get some custom part made. Third is to move on from this hub/wheel and get something that was intended to work as a single speed. The hope is that someone out there makes what you seek. Good luck finding that and I wouldn't hold my breath. Andy (who learned about square holes and round pegs quite a while ago)

Thanks. I appreciate the help. Had to ask, and I now can move forward without wondering, “what if I’d asked on Bike Forums?” Agreed, the simplest solution is use the lock ring and gear that I have. I just visited a local bicycle co-op…they have bins of old parts but I didn’t get the feeling that any manufacturer ever made a locking like the one I need. Maybe it commonly exists in some other application (automotive, lawn mowers, air conditioners, pneumatic equipment???), but agreed again that holding my breath not a good idea. And I couldn’t readily identify any kit to convert a Dura Ace 7200 6-speed hub. It’ll still be a great ride as a 2 x 6-speed!

Maddog34, your suggestion doesn’t work, part B is not 1.37 x 24T, if I understood you. Thanks for trying.

ahhhhh... i just now blew up that pic... it's an obsolete Six Speed EX freehub... Maybe someone will have one to measure... i may have seen one a couple decades ago....i figured it was a Uniglide. I think those EX hubs pre-date unis... that sprocket is your best source of any dimensions. You might post in the "Classics and Vintage" section.. someone might have some info or a retainer for you there. and the bike will be funner, and easier to sell, if it's a 2x6 anyway... single-speeders never seem to bring good money.

https://primary.jwwb.nl/public/w/c/s...IMG_1619-1.jpg

It's very easy with what you have.

If the 1st position threaded sprocket happens to be the size you need, just thread it on, and you're done. The forward thread will keep it tight.

Otherwise, use whatever sprocket you need, surrounded by spacers to give you the right chainline, and use the threaded sprocket to hold it all toghther.

Shimano 600 Uniglide lockring...

Dura Ace Uniglide Lockring Work Around?

From what I've read the regular Uniglide thread is 34 mm x 24 TPI so 1.37" will be a loose fit. And Dura-Ace is smaller, maybe 32 mm. It's a simple job for anyone with a thread cutting lathe, add some notches to allow fixing and removal, or a couple of holes for a pin spanner.