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Old 01-19-13, 06:47 PM   #1
tmas7
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Dura Ace RD 7200 with 52/39 and 13-28 uniglide?

I just posted in the introduction forum so here I am with the questions.

Dura Ace RD 7200 with 52/39 and 13-28 uniglide?

Has anyone tried this? I'm about to and I was wondering if anyone had any input on the idea.
I know it's speced at 26 max cog with 26 capacity but I just got a wheel that matched my front( MA40 Dura ace 7400 hub)
The wheel came with a 6speed 13-15-17-20-24-28 uniglide cassette. I can search for a 26 uniglide cog and a 23 to go with it but I prefer the 28 anyway.

I'm going to try it and I'll post here how it goes.

Thanks
Thomas
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Old 01-19-13, 06:56 PM   #2
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Hi Thomas and welcome!

You said it right - try it and see. I've made 28 tooth cogs work with various derailleur and dropout combinations and most will work. You may have to try moving your axle position further aft.

BTW, I still like UG gears for friction shift and use a Dura Ace EX (is that the same as 7200?) UG cassette and a Campy NR RD effectively at 28t.

Good Luck! - Jim
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Old 01-20-13, 07:48 PM   #3
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Well it does work. It shifts up to the 28 just fine. The chain is a bit short for 52/28 and a bit slack for 39/13 but not too much so there wouldn't be a major problem if I accidentally shifted to those gears. At least the info is here for posterity in case anyone else searches for it . BTW the frame is a 1981 Pro Miyata. And yes, Dura Ace EX is 7200.

Thomas
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Old 01-20-13, 08:35 PM   #4
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What happens if a derailer doesn't like the large cog size? How would you tell when it's at it's limits. I want to try a larger than spec max-cog size, but I don't want to damage my derailer.
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Old 01-20-13, 08:44 PM   #5
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i think the jockey pulley will be too close to the cog and the chain won't be able to move.. but i'm not sure
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Old 01-20-13, 09:09 PM   #6
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Quote:
Originally Posted by frantik View Post
i think the jockey pulley will be too close to the cog and the chain won't be able to move.. but i'm not sure
That's about it, just wont be able to shift. You can usually get away by a few teeth with a Shimano RD because they spec conservatively to keep "clueless" customers from abusing/damaging their equipment. I had a 7402 FD shifting 28t chainring up to a 50t and back down
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