RD-M910 GS Rear Mech Question...

[Tallpaul]

I have a short cage M910 rear mech, an M900 12 - 28 Cassette and an M900 Chainset with 26/36/46 chainrings; will the mech run a useable spread of ratios on the 46t chainring or is it too short?

 

[one-eyed_jim]

Did you mean GS? SGS is long cage.

 

[Tallpaul]

It's short cage, if it were long cage i wouldn't be asking.

 

[one-eyed_jim]

It's short cage, if it were long cage i wouldn't be asking.

Figures, but I thought it didn't hurt to check before wasting time writing a reply to the wrong question.

A GS 910 mech should wrap a 33t difference. Set it up with the minimum chain length to wrap big-big, and if there's any slack in small-small it won't be a problem.

 

[Tallpaul]

Ta very much

 

[Carsten]

the GS is the medium cage and the most common one (SGS only for tandems and pretty rare). 12-28 and 26-46 is what it was meant for and it works just fine.

Carsten

 

[Tallpaul]

Right, just to clairfy (albeit without a clear picture) this is a picture of the mech from the auction:

It is what people commonly refer to as (at least in MTB terms) short-cage. I'm aware this is not the correct name, but for mountain bikes mechs are usually referred to as long or short, irrespective of what Shimano calls them.

 

[one-eyed_jim]

http://bernd.sluka.de/Fahrrad/Shimano/T ... 0_1995.gif

The specs for the GS and SGS versions are noted on the diagram: 32t Max and 33t wrap for the GS, 38t wrap for the SGS.

Carsten's right on the money. The GS mech was standard issue for the 910 triple group.

The short-medium-long thing is a pain, because you do occasionally see genuine short (SS) cage mtb mechs around, and of course what we normally call short in mtb terms (GS) is long in road terms.