Originally Posted by
ddeand
Asking to see if this is a possible solution.
I'm building up an old (1988) Miyata 312, and I'll be using a set of wheels that has a Shimano 7-speed freewheel (126mm spacing). I'll also be using an 8-speed Tiagra brifter on the bike. I understand the problems with the difference in spacing between the shifter and freewheel. That combination seems to work well for some and just so-so for others. I'm wondering if it would be possible to replace the spacers between the freewheel cogs with ones that would allow the 8-speed to smoothly match up? I know I'll have to set the limit screws to block the one extra click on the Tiagra. But can I improve shifting by swapping in different spacers?
Thanks for any advice!
The 126mm rear dropout spacing and 130mm rear dropout spacing have nothing to with it.
Cog spacing between 7 and 8 speed Shimano freewheels/cassettes are identical. You can freely use 8sp shifters with 7 speed cassettes/freewheels.
By the book there is a variance of 4.8mm c-c on 8sp cogs vs 5.0mm c-c on 7sp cogs but effectively that 0.2mm is within the range of the floating top pulley. Treat them as completely interchangeable.