Originally Posted by
aharong
Cool.
Is there a way to know/guestimate the length of chain I'll need? Should I just add the difference in teeth to the length of the current chain (34T - 26T = 8 links longer than current)? Is the new MTB derailluer likely to require a couple more or fewer links?
Don't guesstimate.
Wrap your new chain around the biggest front chainring and biggest rear cog bypassing the rear derailleur entirely. Figure out where the shortest place you could join the chain. Add 1" of chain (2 links) to that. Believe it or not, the type of rear derailleur doesn't have to be figured into chain length calculations.