NEUROSPORT

i have a 12-25 cassette ( 10 speed ) that appears to be ultegra ( says 6600 on it )

if i buy a 11 tooth cog can i turn it into a 11 - 25 cassette by dropping the 16 cog ?

https://techdocs.shimano.com/media/te...9830608752.pdf

based on the above chart i could.

question is - would it still shift properly with hyperglide and all that ?

specifically would it shift properly between 15T and 17T ?

AngrySaki

I've never had an ultegra cassette, but with all the cassettes i've ever used, the smallest cog is a special cog that's designed to work with the locking doodad. I think you'd have to buy a new "standard" 12T as well as an 11T.
(I've mixed and matched cassettes before, and it's shifted fine, I've had a cassette shift fine from 21T to 34T)

edit: looking at the pdf you linked, it looks like what i said above doesn't apply for the ultegra cassettes, and you could just get an 11T.

Ingleside

The short answer is No.
All you would be doing is switching out a 12t cog and lock ring out for an 11t cog and lock ring and the 16t will stay right where it is. The last cog on shimano cassettes (all cassettes for that manner) are designed to only be mounted on the outermost position. They are king of like a "crown cog". You will not be able to slide the 12 further on to the freehub.

NEUROSPORT

according to this:

https://techdocs.shimano.com/media/te...9830608752.pdf

the 12T on the cassette that ends in 12 is the same part as 12T on the cassette ending in 11.

?

AS2914

If you can do it, you'll have to use a lockring from a 11t cassette. The chain will skip using the lockring from a 12t cassette

Metzinger

Based on the PDF one would expect moving the 12 to 2nd position (and removing the 16t) to work.
One rider's attempt is discussed here.

AEO

you need an 11T cog and 11T lock ring to make it work.
there really is no difference in feel when changing gears between 15T and 17T.

I've done it before.

mixing cassettes is easier with 9sp since all the cogs are singles with 105/tiagra/sram cassettes, but it's easy to do on 10sp cassettes as well, as long as you're not trying to change a cog on the carrier, which is impossible.

NEUROSPORT

i examined the PDF more carefully and i think you are right. it does mention different lockring for 11T ...

so lockring + cog is about $20 vs about $60 for the cassette - seems like it's worth a shot.

yes ?

ericm979

No. The second cog is also special. So you also need a 12t second cog, and a 13t "regular" solo cog. Add the 11t first cog and 11t lockring and it'll be cheaper to get a 105 11-23. With that and your 12-25 you can make an 11-25. Jenson has 11-23 105 for $55.

Dilberto

OP....just buy a 11-25 cassette. End of discussion.

AEO

no, the 12T is built to work with 11T cog or a 12T lockring.

ericm979

You're right. All this time I thought the 12t would't slide over, but I went out and tried it and it does.

Eclectus

Miche (Italy) is really good for single-cog changeouts. I learned this from Sheldon Brown.

ac29593

I have used Miche cogs, bought them from Sheldon's shop, and they worked fine.

I would just buy a new cassette online and sell your old one on craigslist. Net cost might be the same as buying a new cog with lock rings and filler cogs without all the running around.

Hunt-man

Just buy a new one. They wear out. Good to have more than one. Much more economical than buying one cog / and a lock ring.

NEUROSPORT

ok good discussion ! i think i understand the options more or less now.