Can I convert a 10 speed cassette into a 9 speed cassette?

Heres what you can do if you REALLY want to...

Remove the 10 speed cassette from the wheel, remove all the spacers, replace them with 9 speed width spacers, delete one of the MIDDLE cogs (not the 11 or 12), add an additional spacer to fill the space at the BACK (towards the wheel) of the cassette, and reinstall.

You'll then need to readjust the derailleur and remind yourself that you only have 9 gears in the back.

By the way, once you do this you have to reverse everything to put back on the 10 speed-equipped bike.

9 Speed Cassette

10 Speed Cassette

No you can't. A 10-speed cassette isn't just a 9-speed with an extra cog added to the outside. The two are the same total width, but the 10-speed fits an extra gear into that space. Taking one cog off wouldn't work at all; and installing it as a 10-speed would result in very poor shifting.

No, the 11t cog is threaded and is required.

If for some incomprehensible-divine-revelation reason you want to get ride of the 11t, you will have to buy a new cassette that is 12-28.

You could also have 12-28 with 10 speeds since you already have the 10 speed shifters. You would loose about $500 worth by doing the mod that you propose.

The spacing between cogs is different so it wont work. A 9 speed chain will also be too wide. Return the cassette or sell it and get the correct one.

The spacing between cogs is closer together with the 10 speed cassette. You have to have all the cogs for the lockring to tighten the cassette in place. Removing a cog doesn't change the spacing and the cassette will not tighten in place.

pretty sure 10 speed cogs are thinner and have different center to center spacing than 9

the shifting won;t work right

or maybe 9 and 10 are the same, but 11 is thinner

wle

Even if you took a gear off, the 9 speed shifter will not work (I am not %100 on this) because

the indexing is different.

I think if you put a 10 speed shifter, it will work.