Does a rear gear know how many cogs?...

secretsam

...on a cassette??? Am about to buy some second hand wheels with 105 hubs and 9 speed cassette, and am wondering if my friction rear gear will know that there's 9 gears rather than the current 6 speed freewheel

Part 2: does a modern shifter care how many sprockets you use at the back? My Sora on bike 2 has 8 to deal with, but if I were to change to a (say) 10 speed with new shifters, would it cope? I.e. am I right in thinking that it's the shifters that determine the number of speeds it can handle, not the gear, so a Sora with a 10 speed shifter would work (assuming it's within the gears "teeth" range)

If this makes no sense, my humble apologies... :oops:

nicklouse

part 1 if the friction shifter can pull enough cable then it will be fine.
Part 2 the indexed shifter and cassette need to match. due to the differing distances between the cogs.

NB. shimano 7 and 8 spd have the same spacing allowing a mix to be used but you will only have 7 usable cogs.

redddraggon

Any shimano rear mech will do 8, 9 or 10 speed with the correct shifter chain and cassette.

satanas

NB: Older rear mechs (Shimano and others) may not have enough lateral movement to cope with 8-10 speed cassettes. This includes 6&7 speed Dura-Ace and Ultegra mechs, which will struggle with 8 speeds or more. 8-10 speed cassettes are all basically the same overall width, so more modern mechs are more adaptable.