aloysius

Could I use a short cage 105 or ultegra 9 speed derailleur with a 26 tooth cog? Would it shift well?
Thanks,
Lynn

'nother

Cage length is more a function of your crankset (double/triple). Cage length does not determine cassette cog capacity. Shimano's spec for large cog on all road-type derailers (105, Ultegra, Dura-Ace, long or short cage) is 27T. So, most likely, unless you have a triple crankset (or double with a *huge* difference between large<>small ring), yes, a short-cage 105 will work just fine.

Al1943

The size of the 26t cog is not a problem but since Shimano hasn't offered a 26 in some time I assume you are talking about running some other brand with a Shimano drivetrain and if so it may not shift as well as if it was all Shimano.

Al

TallRider

Rear derailler cage length determines how much excess chain can be wrapped. The angle at which the cage pivots (and a couple of other variables) determine the largest cog the derailler can be used with, even if you were only using a single chainring up front.

Shimano's road-grouppo rear derailllers are usually listed as taking a max cog of 27t, although in practice they nearly always work on 28t and often even 30t.

Shimano's mtb-grouppo rear deraillers usually take a max cog of 32t of 34t.

cuda2k

I'm running a SRAM cassette with a 26t with an older Shimano 105 derailleur. I have no problems.

the beef

Me too. Bike shifts great. My 105 short cage can take up a 53-26 combo.

erader

i ran a 12-26 8sp w/ DA derailleur for years. 52 x 38 in the front. in fact i could have run a 28 but didn't need it.

ed rader

aloysius

I'd be running a Sram pg-950; that's compatible with shimano road stuff, right?

'nother

Yes (as long as you're getting the 11-26 or 12-26 PG-950, and not the 11-32 or 11-34; those would require a MTB rear derailer). The hub/cassette spline pattern is the same for MTB and Road.