Replacing a 7-speed freewheel with a 9-speed?

[Deleted_user202]

Is that possible without switching out the hub, and is that possible at all? I have a base shimano groupset and I'm in the process of upgrading everything (I'm switching out the crappy tourney der for altus 9-speed, cables etc), and I would really rather switch out my freewheel for a 9-speeder also. Do you think it's achievable?

[Jesper]

(06-10-2020, 11:23 PM)Roman Fanian Wrote:  switch out my freewheel for a 9-speeder

Hi Roman,
There are a few factors determining compatibility. Most 7 speeds were freewheels, although there were some early 7 speed freehub/cassettes, but doubtful a 9 speed cassette would fit anyways). If your 7 speed is indeed a freewheel with a traditional screw-on hub and not a cassette fitted on a freehub, then you will have to replace the hub and rebuild the wheel with a freehub sized for a 9 sprocket cassette, more than likely needing new spokes due to length difference, and a narrower width chain (maybe length also). Also, the spread of the rear fork needs to be wide enough to accept a 9 speed set-up. I am not familiar with Shimano's shift compatibility concerning 7 to 9 speed indexing if you keep the 7 speed gear cluster. Hopefully, someone with experience will reply and give you more specific answers since I generally work on friction shift systems from the mid '80s and earlier. Certainly a bike shop should be able to provide to you that information. I have much newer and older parts that range decades difference in age, but most major changes came about in the very late '80s and later, much due to the evolution of mountain bikes and their designs. Really narrow chains don't work well on early freewheel (≤6 speeds) due to sprocket spacing, I can fully attest to this after trying to use them in certain instances. You may want to refer to Sheldon Brown's site concerning the changes you would like to make.

Take care,
Jesper

[Joe_W]

Measure the rear axle length. If it is 130mm you can use a road bike rear hub. The 9 speed MTB stuff fits the 9 speed road groups, so that could work.

I did that on an older Giant bike, 7 speed Shimano 200sl to 9 speed shimano... Deore (LX, I think). Rear hub is a Tiagra, circa... 2006?