karlt wrote:I define crosschaining as when the chain rubs in the derailleur on an indexed system. On a friction system it's whatever I've noticed looks a bit odd on the stand. So on the better bike (50/39/30 x 8sp 12-26) it's bottom two cogs on the big ring, top two cogs on the middle ring and top four cogs on the little ring - so that's a total of 8 out of the 24 theoretical I never use. On the commute bike (52/40 x 8sp 12-30 (was 11-30 but I swapped the 11 cog for a 12 I had lying around)) it's top two cogs on the little ring and lowest two cogs on the big ring - big/big is actually unattainable and I can't be buttocked to lengthen the chain for a combination I never use. So that's 4 out of the 16 I never use.
My unused ratios are:-
Outer ring,biggest cog, though I have enough chain should I forget.
Middle ring I use all cogs but rarely use top,
Inner ring top two cogs but more usually top three.
Plus one duplicate ratio largest 4th on the inner ring.
That makes a 19/20sp system but with more chain wrap and less extreme x/chaining than a 2x8/9/10sp system