Using a 8-speed Shifter with a 7-speed Sprocket

[gerardpaule]

I recently upgraded my old SIS rapid-fire shifter to a Shimano Alivio Shifter with 8-speed option. But, my bike has only 7-sprockets. I know this would work, but I need to know on how to fine tune it by myself. Thanks.

[DaveM]

I'm somewhat sure that 7 and 8 speed systems have the same spacing between the sprockets. So this "should" work fine. You would adjust the shifter * rear derailleur as normal except that the shift will have an extra click that will not do anything as the derail will already be on the innermost cog. Be extra careful to set the inner limit screw properly to make sure that the shifter can't push the derail over in to the spokes.