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A front mech query! (Exciting I know)
I'm going to run a tripple road chainset with a MTB 11 - 34 rear cassette and MTB long cage rear mech. I've noticed some of Shimanos road front mechs have a max capacity of 16t and some 20t.
So do I need a 20t front mech to cover the 11 - 34 range on the back without the chain rubbing against the cage? Will that do the job?
Ta in advance!
I've toured with a 30-39-53 Ultegra triple crank using an Ultegra triple front mech and a 34T XT cassette, without any trouble.
I'm running a 26/36/48 front with a 20t capacity 105 derailleur with no trouble, 11-36 at the back. The capacity of front mech is meant to refer to difference between smallest and largest chainrings on the front, but you can go over by a couple without too much trouble, though you do have to watch to not get the chain too slack with the big gear range.
Thanks all, that's helpful. Slightly odd that the Shimano website currently doesn't mention a 105 mech with a max capacity beyond 16t yet there's both a Tiagra and Ultegra one that does. Wonder if Shimano made a typo.