shifter question

geepeetee said:

Hi

Will an 8 speed shifter work on a 7 speed bike, are the spacings
between the rear cogs the same?

Not the same spacings:

http://sheldonbrown.com/k7.html#spacing

Personally, doubt it would work reliably. However, if you've got a 7-speed
cassette, its fairly cheap to replace the cassette with an 8-speed one. If
its a 7-speed screw-on block then its effectively a new wheel to change
things.

- Nigel

--
Nigel Cliffe,
Webmaster at http://www.2mm.org.uk/

Nigel Cliffe said:

geepeetee said:

Hi

Will an 8 speed shifter work on a 7 speed bike, are the spacings
between the rear cogs the same?

Not the same spacings:

http://sheldonbrown.com/k7.html#spacing
Personally, doubt it would work reliably. However, if you've got a 7-speed
cassette, its fairly cheap to replace the cassette with an 8-speed one.

(assuming this is shimano gears)
It's the opposite - easy to fit a 7 sp cassette to 8 sp. hub, just fit a
3mm spacer behind the cassette, a 8 speed cassette will be too long to
fit onto a 7 sp. hub, though if they have removal spacers between the
cogs, then it can be done, but TBH, is it worth all that trouble, when
for not much more, you could upgrade to 8 or 9 sp anyway.
Alan.
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geepeetee said:

Hi

Will an 8 speed shifter work on a 7 speed bike, are the spacings between the
rear cogs the same?

thanks

Gary

if the system is Campag, then yes, as they are the same spacing. in
fact 7 spd campag and Shimano are the same spacing, so a Campag 8spd
([censored] & mech) will work with a Shimano or Campag 7spd wheel. Just
adjust the rear mech to limit the travel for the unused gear stop.

A Shimano 8spd shifter will sort of work (carefully adjusted), though if
it is a bar-end shifter, then they work quite well on 7spd systems.

pete whelan said:

geepeetee said:

Hi

Will an 8 speed shifter work on a 7 speed bike, are the spacings between the
rear cogs the same?

I was given some 8 spd STI's which I had to make work on a 7 spd
cassette (operation not critical as the bike in question has been chez
Sheddi ever since) I did however find that the main difference between
Shimano 7 and 8 speed cassettes was not the spacers but the thickness
of the cogs themselves. So playing around with two types of cassette
and losing the top shifter position into the limit screw area so it
does nothing will probably work.