carl wrote:
This brings another question to mind 2x10 or 3x10?Ii have yet to be convinced the 2x10 route is the way to go. Questions i have been asking myself... Is the small granny ring worth having, how often is it used? You have a limited range of gears when in the granny ring due to chain angle. Maybe someone can throw more light on the subject?
Next question.....Long or medium cage? According to the formula running a 3x10 set up would require a long cage i.e 42-32-24 x 36-11. Shimano quote Long = 45T Medium = 33T, Sram quote Long = 43T Medium = 37T short = 30T Doing the formula.. Subtracting the lower ring from the top ring 42-24 = 18 and the same with the cassette 36-11 = 25 then adding the 2 together 25+18 = 43T This falls into the long cage range of both makes.
But if you went 2x10 with a medium cage its a slightly different out come if you use a 11-36 cassette. Doing the same formula but using a double ring of 22-36T i.e 36-22=14, 36-11=25, 25+14=39T (out of range, prob need long cage?) using an 11-34 cassette brings the range to 37T (on the nose for sram-out of range for Shimano?) 11-32 cassette = 35T (inbetween both makes of medium cage) Is the difference in range this criticle? I think not.
Also it is possible to use a medium cage on a triple ring set up but does the loss of some gears due to the lack of range a medium cage has against a long cage warrent the advantages of crisper gear change and less chain slap? Although some loss of gears is not too much of a disadvantage as you wouldnt run big ring and big cog like wise with the granny ring and small cog anyway due to the angle of the chain. Or am i talking testicles?
Not testicles no, but the SRAM 2x10 is a little different only having front chainring options of 27T-39Tand 28T-42T so the calculations are either 39T-27T=12T cassette 36T-11T=25T so 12+25=37T in range for medium cage SRAM mech or 42T-28T=16T cassette as above 16T+25T=41T which shows you need a Long Cage.
I have no problem in making rear shifts in the set-up I have with the Med cage on a 11-36 cassette, was a doddle to index as well.
In relation to using a shorter cage than recommended I don't think it's a major problem, but you do risk operating the mech outside of its recommended range possibly altering the spring tension and causing shifting issues in all gears as it may become too stressed IMHO.