7-speed hyperglide to 8-spd conversion???

rmdrouillard said:

🙄 I have a circa '92 touring bike with a 7-speed hyperglide cassette and 105 downtube index shifting. I've seen 8-speed downtube shifters available in catalogs... anybody know if there's an 8-speed cassette that will fit the freehub? I'm assuming the UG chain will have to be replaced with a narrower one.:o

An 8 speep casette won't fit. You can get a lower end 9 speed shiamno or a sram 9 speed, remove a cog(biggest one works best) and a spacer, which will alow it to fit the 7 speeed hub and shift it with a shimano 9 speed shfter.

boudreaux said:

An 8 speep casette won't fit. You can get a lower end 9 speed shiamno or a sram 9 speed, remove a cog(biggest one works best) and a spacer, which will alow it to fit the 7 speeed hub and shift it with a shimano 9 speed shfter.

What model chain will work with this? And when you say: 'remove a cog(biggest one works best)' what exactly do you mean?? Thanks for your insight🙂

boudreaux said:

An 8 speep casette won't fit. You can get a lower end 9 speed shiamno or a sram 9 speed, remove a cog(biggest one works best) and a spacer, which will alow it to fit the 7 speeed hub and shift it with a shimano 9 speed shfter.

In addition to the issues of the 8/9 cog carrier being longer than the 7 speed carrier, unless you have a steel frame you won't be able to spread the frame to accomodate the wider droppout requirement of an 8/9 without damaging the frame.

rmdrouillard said:

What model chain will work with this? And when you say: 'remove a cog(biggest one works best)' what exactly do you mean?? Thanks for your insight🙂

That would require 9 speed chain since the sprockets are spaced per 9 speed distance.

Personally, I generally prefer having a very low available bottom gear over smoother shifting between my two lowest cogs so would remove the second lowest cog if I was following that procedure. That would be particularly so for touring since you're apt to have steep hills somewhere.

rmdrouillard said:

What model chain will work with this? And when you say: 'remove a cog(biggest one works best)' what exactly do you mean?? Thanks for your insight🙂

you need a 9 speed chain. what can 'remove the biggest cog' mean?