Ooh, I love a nice big set of cogs...

[Bopomofo]

Yep, I'm a cog man.

I currently have a fairly standard road set-up....Ultegra 53/39 up front and a 12-25 rear. Actually the rear cassette is maybe 105, whatever MtB put on to save me some cash when he replaced my chain and I bought an Ulty 12-25 to put on my new Cosmics...

Anyway, I'm a fat old bastard and many of my friends are spinning up hills on Compacts (Jibbs?) or with a 12-27 cassette (my mate Paul, about the same standard as Jibbs)

I can't justify a compact, so I'm looking to stick a 12-27 or 13-27 on my training wheels. Race wheels can stay at 12-25 as I just avoid lumpy races.

Questions:
1) How can I work out what kind of Ultegra I have?
2) Does anybody know what the max cassette ranges are for Ulty.

I can probably work out 2) myself if I can work out 1).

Any ideas? What has worked for you? Are the gaps too big on a 12-27? Is 13-28 possible and is 13 too low?

[Kevy427]

I've got an Ultegra double with an 11-28 cassette as I'm the proud owner of two pipe-cleaners Makes hills a damn sight easier

[IanM]

I think 28 is the max usable Shimano cog without a long cage derailleur. I've got an 11-28 for very hilly stuff. There's gaps in there when dealing with less severe terrain but that's less of a concern than actually being able to get up the nastiest of hills!

Should be a product code on it that will tell you exactly what version of Ulty it is? All 10 speed variants should work though.

[Sir Jibbenstein]

Yeah I was spinning up Old Winchester on my compact with an 11-28 rear.

The rear derailleur should have a model number stamped on it on the inside piece that covers the spring, e.g RD-6700. 6700 is the series of Ultegra.

Max range will be defined by the size of the rear cage and the length of your chain. I'd hazard a guess that you have a short cage rear derailleur so the max sprocket will be a 27:

1.
Determine Maximum Chainring Difference by subracting the number of teeth in the smallest chainring from the number of teeth in the largest chainring
2.
Determine Maximum Cassette Cog Difference by subtracting the number of teeth on the smallest cassette cog from the number of teeth on the largest cassette cog
3.
Determine Total Drivetrain Capacity by adding Maximum Chainring Difference to the Maximum Cassette Cog Difference
4.
Record the Maximum Cassette Cog (the number of teeth on the largest Cassette Cog)

For Shimano:
SS - Short Cage Road Double - Maximum Cassette Cog is 27 and Total Capacity is 29
GS - Medium Cage MTB/Road Triple - Maximum Cassette Cog is 34(MTB)/27(Road) and Total Capacity is 33(MTB)/37(Road)

[Kevy427]

The model series is found engraved somewhere on the relevant part, be it the crank, RD or chain (6600, 6700 etc.). Didn't need to change the derailleur on mine with the cassette swap either, and as IanM has alluded to already, getting up the hills is more important than the rare occasion of being flat out for yard upon yard in 53x11

[Sir Jibbenstein]

Without changing your crankset the maths would suggest that 12-27 is the widest range you can have, or you can maybe just about squeeze a 13-28 on there.

[CCS]

No idea how you tell which type of ultegra you have... does is matter?
Champ runs an ultegra rear mech (pretty old, I am guessing) and I have 11-28 on both sets of wheels with no issue... nice ladylike gearing...
Slightly scared that the new bike is a standard double ... not taking it near any hills!

[Kevy427]

I have 11-28 on both sets of wheels with no issue... nice ladylike gearing...

Thanks, I feel even better now

Slightly scared that the new bike is a standard double ... not taking it near any hills!

Ah, that makes me feel better

Won't be long before Jack comes along on his Penny Farthing wondering what all these pansy legged Southernists are going on about, having to have gears on their bikes to get oop the mounds of soil that pass for hills

[Jack Hughes]

Yeah. I've put this thread through google translate at least six times and I still can't make sense of it.

[Jack Hughes]

What have you got at the front? Can you put a smaller small chain ring on?