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Can a 5 speed with 121mm drop out spacing be converted to a 6 speed?

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Can a 5 speed with 121mm drop out spacing be converted to a 6 speed?

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Old 11-25-09, 02:27 PM
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Can a 5 speed with 121mm drop out spacing be converted to a 6 speed?

I do not want to spead the frame to 126mm.

If it can be done, what hubs and freewheels are best?

Michael
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Old 11-25-09, 02:40 PM
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Originally Posted by Barrettscv View Post
I do not want to spead the frame to 126mm.

If it can be done, what hubs and freewheels are best?

Michael
You want a Suntour Ultra-6 freewheel. Hub doesn't make a difference as long as the threading is compatible with the freewheel's.
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Old 11-25-09, 02:49 PM
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and you'll want to use a "narrow" chain with the ultra 6, but that's pretty much any new chain you'll find that's 7 or 8 speed compatible. Just can't use an antique chain from the original 5 speed drivetrain, which is probably long gone by now, anyway.
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Old 11-25-09, 06:14 PM
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I have shifting troubles on an ultra-6 fw with both the original 5-speed chain, and a replacement SRAM 8-speed chain. I hava double-shifting when downshifting. Someone suggested I try a Campy CP9 chain, which is narrower, and has flat side-plates, as original Suntour ultra-6 chains had. Ultra-6 fw's have straight, not twisted, teeth, which (if the tip I got is right) doesn't work so well with chains meant for Shimano-style twisted teeth. That's the theory, anyway. Once I receive the chain and mount it and test it, I'll re-post.

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Old 11-25-09, 06:23 PM
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I ran an Ultra6 14-21 on my Gitane TdF with a (IIRC) SRAM 7/8s chain. Campy NR derailleurs.
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Old 11-25-09, 07:16 PM
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As far as I know, there isn't any "best", the SunTour Ultra-6s are THE only way to accomplish this. Well, I could be lying, I had a Helicomatic that seemed to be narrow-spaced. The Ultra-6s are reputed not to shift very well with wide size differences between adjacent cogs, so this could affect your desire for wide-range gearing on that Paramount. You'd have a wide-range system that is more useful and better-shifting with a 7-speed Shimano or Sachs-Maillard freewheel, regardless of whether you go triple. With a carefully chosen 5-speed rear and a triple you can get a pretty useful 15-speed. One of the most useful setups is a half-step plus granny, because all of the 10 large/middle gear positions are useful, and at least three granny positions can be used. It won't work out so well with any other 15-speed design, that is, you won't get so many usable gears.
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Old 11-25-09, 07:50 PM
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Hi Everyone,

I have the strange combination of 52 & 49 chainrings with a 14-16-18-23-26 cogs. This produces a big gap from 16 to 20 mph, where I just happen to spend most of my cycling time when traveling on the flat roads of Illinois.

I like the idea of a triple and have a road triple on my modern bike. But I'm reluctant to alter this bike too far from original since this bike is more for show than go. Having a selection of gears from a 2x5 or a 2x6 drivetrain is my plan at this point.

Installing 48 & 45t chainrings will give me 6 close gear combinations from 18 to 27 mph using the original cogs. The gap in the gearing should be less of an annoyance with the smaller chainrings.

A 13-23 6 speed with 13-14-16-18-21-23 cogs would also provide a good set of gear combinations with the 48 & 45t chainrings.

Michael

Last edited by Barrettscv; 11-25-09 at 07:56 PM.
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