Originally Posted by
dynaryder
Yeah,3rd/big ring would be cross-chaining(assuming modern 2x10). And this can be bad for skinny 10spd chains. I see folks come into my clinic all the time with their bikes cross-chained,and I explain proper shifting and gear selection.
3rd largest / big ring with a tight cogset and compact crank could be like 2nd smallest / small ring which is even worse and may be too far outboard for the chain to clear the big ring.
Ex: 50-34 x 12-13-14-15-16-17-18-19-21-23. 50x19 = 34x13.
I spent 5-6 years with 50-34 x 13-14-15-16-17-18-19-21-23 with oodles of time in 34x14 or 50x21. It worked fine and my last C9 chain was just reaching 1/32" of elongation at the 5000 mile mark when I broke a discontinued right shifter spring and moved on to 10 cogs.