Originally Posted by
thook
you just have to decide which RD you're gonna use and what the gear range will be on your cassette/freewheel. then, you can figure the max chain length with some math
If....
short cage RD capacity = 28t
freewheel = 28-13t = 15
chainset = 46-30t = 16
16+15 = 31
so, that exceeds the RD capacity by 3 teeth
so, then figure what largest cog you can away with using while on the large ring to fall within the RD capacity
24-13t = 11
16+11= 27...within the RD capacity
so, set the chain length while on the 24t cog and largest ring. never shift to the 28t cog while on the largest ring you're safe
NO. We have seen this movie before. We have seen this movie before way too many times. The following is not a theoretical concern. This happens.
Shift to the large/large combination with a short chain and the derailleur is bent, twisted, sheared off. If you're lucky. Frame damage is likely as well. Crashing is not automatic but very likely. ALWAYS have enough chain for large/large. You cannot count on remembering. Recipe for failure.