Anybody successfully done a 9 of 10 on 7? This means 9 cogs of a 10 speed cassette on a 7 speed freehub. I am building a touring wheelsets and was thinking this would be a good way to go on a 126 spaced frame that is not interested in spreading. I know 8 of 9 on 7 works, and Sheldon said the 9-10-7 would work, but I'm looking for real world trials if possible. Thank you!

Yes, it works. I have been using a 10 speed shimano cassette minus one cog on a 7 hub for years without problem.

Is this so you can save money on a hub because you already have the hub?

I would think it would depend on the size of the smallest cog and the frame/DS dropout. In other words, some frames might give you enough clearance to run the chain on that smallest cog, and others might not.

This is a way to get more sprockets onto a wheel that's 7-speed width. There are plenty of bikes made to the 7 speed width standard that can't have the rear triangle spread, and so are stuck with 7 unless the 8-of-9-on-7 or this trick are resorted to.

Well I just bought a NOS Deore MT60 hubset that's Uniglide and I have a 7 speed HG freehub, so I figured I would do the freehub swap, and keep the spacing at 126.

Also in the name of consistency, my other bikes are 10 speed cassettes, so I have lots of 10 speed shifters and cogs laying around, making transferability pretty easy.

I have been doing it for years and with no issues.

Just curious, does it have to be 9 of 10 or could it also be 9 of 9? I was under the impression cog spacing was the same and you just used a spacer when using a 9 speed cassette on a 9/10 hub.

........or could it be 7 of 9?

If you're going to use a 7-speed hub, you need to throw away something or they won't all fit.

9 of 9 won't fit into the space of a 7 speed cassette. The bike's a 7 speed, 126mm rear rather than 130mm, as I understand it, and you won't be spreading aluminum or carbon rear triangles.

So please splain...

Several guys above saying a 10 speed cassette less 1 cog will work. How is this different than all 9 cogs from a 9 speed cassette?

Maybe I'm missing the whole concept.

Because 8, 9, and 10-speed cassettes are all about the same width. Shimano achieved the extra speeds in 9- and 10-speed by making all the cogs and spacers a little thinner.

For example, a 7-speed Shimano cassette is about 32mm wide, and the hub has a little bit less than that to ensure the lockring can compress it adequately. If you were to do an 8 of 9 on 7, you'd start with a 9-speed cassette (36.5mm), remove one cog and spacer (4.34mm), and end up at 32.16mm again.

I think you must be. 9 of 10 is obviously less wide than 10 of 10 or 9 of 9. There's less available space on a 7 speed freehub body than there is on a 8-9-10 (all of which are the same width). 126 vs 130 -- it's got to come from somewhere. None of this would matter if the stays were flexible -- in fact, my 1963 Jack Taylor Sports, which was made with a 120mm wide rear triangle for a 5 speed hub will fit a 130mm hub just fine, simply spread the dropouts a tiny bit with the fingers and the 130mm wheel slips right in -- or can be cold-set and respaced. But certain frame materials can't be cold-set, and therein lies the problem.

This is effing brilliant!

I made my first foray into 10 speed and I think I spoiled myself. I've got a DX wheel set and now I'm thinking... and that's never a good thing.

To the OP, have you checked out Sheldon Browns site ? It is discussed, www.sheldonbrown.com/k7.html, see the paragraph : Upgrading From 6-/7-speed (126 mm) to 8-/9-speed (130 or 135 mm).