What if you want to go lower than 27T with Shimano Ultegra?



sergen said:
My bike has full ultegra components - brakes, FD, RD, triple hollowtech chainring and a 12-15 CS6600 cassette.

I know that Shimano's official line is to not go any lower than a 27 but recent forum users have suggested that this is just Shimano being conservative and that the rear derailleur could probably handle a 29T sprocket. Indeed, given that I never cross-chain I wouldn't have to worry about getting a new chain to cope with 52x29. I simply wouldn't use that ratio.

But since Shimano don't manufacture a sprocket any lower than 27T, what cassettes are available on the market that would allow me to get a 30x29 gear? I'm obviously looking for something that would not cause shifting problems with Ultegra components.

Many thanks


I regularly use a 30 - 28 set up for the mountains here and I can´t see that going to 29 would help much - now the difference between 25 and 28 is noticable but you do start to get into stability issues riding slower than the 28 ( mtb with slicks and 22 inner ring ) and it´s just easier to walk than wobble like that ; you seem to spend more time steering than pedeling .
 
Scram makes an 11-28 10 speed cassette but don't know if the ultegra rear derailler will handle the 28?????
 
Have you considered running a "mountain" rear derailleur and and a 12-32 or 12-34 cassette? That's what I run on my climbing bike, along with a 52-39-30 triple. All gear combinations are accessible. Shifts fine. (Yes, I'm a wuss, but I'm overweight and over 60 and needed the 30-34 combo to finish the Battenkill...)
 
Problem s I have a 10 speed set up. Tnhere are no 10 speed mountain bike deraillers or cassettes. Otherwise I would have already done that. I normally don't need it as I'm a fairly strong Cat II but I live in the Blue Ridge Mountains and now and then do rides where something lower would be nice.
 
You can get an aftermarket 10 speed Shimano compatible cassette that will give you a 12-32 or 12-34, or even 11-34, gear range in the back.

10-Speed Elite Shimano-Wide Range

"Must use mountain rear derailleur such as Shimano LX or XT ('07 XTR not recommended because it lacks a barrel adjuster and the body flexes too much for good shifting performance)."

This should shift 10 speeds fine, as indexing is built into the shifter, not the rear derailleur.
 
sergen said:
My bike has full ultegra components - brakes, FD, RD, triple hollowtech chainring and a 12-15 CS6600 cassette.

I know that Shimano's official line is to not go any lower than a 27 but recent forum users have suggested that this is just Shimano being conservative and that the rear derailleur could probably handle a 29T sprocket. Indeed, given that I never cross-chain I wouldn't have to worry about getting a new chain to cope with 52x29. I simply wouldn't use that ratio.

But since Shimano don't manufacture a sprocket any lower than 27T, what cassettes are available on the market that would allow me to get a 30x29 gear? I'm obviously looking for something that would not cause shifting problems with Ultegra components.

Many thanks

I've used a SRAM 11/28 10 speed on my ultegra compact (50/34) drivetrain for 1 year. Great combo; no problems. If you put the new cassette in, I suggest putting a new chain also...
 
Ozark Bicycle said:
I prefer to read upright! :)

Anyway, I know what you were saying in your prevoius post and, IME, this is not wholly correct. So long as the chain will clear the bottom rear cross bar of the cage(clear enough?) on the 2 or 3 largest rear cogs, all is well. Those are your climbing gears. Why stay on the inner ring when the same gear is available on the middle ring?

The true limitations in the minimum usable size of the inner ring are 1)FD capacity, which can usually be slightly exceeded 2) the shape of the inner cage. Shimano will usually spec a min chainring size which, again can usually be slightly exceeded. In this case, we are exceeding FD capacity and recommended min chainring size by 2T.

Bottom line on using a 28T inner on an Ultegra Triple: it works. A 26T would be a bit dodgy on an STI road triple with a 52T outer and a 24T will probably be impossible.

I've done the same(28t) as well as a 26. 24 will not work. Pretty limited for big cogsets for 10s and shimano. 11-28 is new for shimano but expensive and the 52(3) 11 is a HUGE gear, not needed by most. A smaller small ring is cheap, easy to install and any decent LBS can make it work.
 
sergen said:
My bike has full ultegra components - brakes, FD, RD, triple hollowtech chainring and a 12-15 CS6600 cassette.

I know that Shimano's official line is to not go any lower than a 27 but recent forum users have suggested that this is just Shimano being conservative and that the rear derailleur could probably handle a 29T sprocket. Indeed, given that I never cross-chain I wouldn't have to worry about getting a new chain to cope with 52x29. I simply wouldn't use that ratio.

But since Shimano don't manufacture a sprocket any lower than 27T, what cassettes are available on the market that would allow me to get a 30x29 gear? I'm obviously looking for something that would not cause shifting problems with Ultegra components.

Many thanks

10 speed: SRAM 11/28. works great on shimano drivetrains
Also if you want a 30 tooth: (only with long cage RD) add a 30 tooth cog from SRAM MTB; 9 speed cassette (they are single cogs; must unscrew hex retaining bolt to remove each cog) to the 11/28 by taking one of the middle cogs off (off the 11/28). You can then use one of the middle cog spacers (from the 11/28) when you add the 30 tooth at the end. In essence, you end up with a custom 30/11; 10 speed