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@Soul It's a 5800
Thanks guys @Greenbank it's a RD-5800 short cage with a front chainring of 36/52. I'd like to change as little as possible component wise, so if I can go with a 11/28 I can live with that.
clefty-
Thanks guys @Greenbank it's a RD-5800 short cage with a front chainring of 36/52. I'd like to change as little as possible component wise, so if I can go with a 11/28 I can live with that.
Short cage version of RD-5800 is:-
Maximum low sprocket 23-28T with double chainset Maximum front difference 16T, total capacity 33TMaximum low sprocket of 25T would work.
52-36 = 16T, so front difference is within spec.
(52-36)+(28-11) = 16+17 = 33T, so total capacity is just fine.So, yes, 52/36 and 11-28 is just within spec for the short cage version.
If it's the medium cage version:-
Maximum low sprocket 28-32T with double chainset Maximum front difference 16T, total capacity 37T(52-36)+(32-11) = 16 + 21 = 37T
So you can just squeeze in a 11-32T cassette with a medium (GS) cage version.
Greenbank
Rear mechs have various restrictions based on "capacity". For example:-
http://www.wiggle.co.uk/shimano-105-rd-5700-rear-derailleur/ gives:-
Short cage:
Medium Cage:
The "total capacity" is the maximum difference between smallest and biggest gears. i.e. for a 50-34 and 11-28 you've got (50-34)+(28-11) = 16+17 = 33T
So front difference is 16T and total capacity is 33T, within the specs for that short cage mech.
An 11-32 would have a total capacity of 36T, more than a short cage RD-5700 could handle safely.
So it'll depend on what front chainring setup you have too. Find out that, and the rear derailleur model number and then check the specs.