bellweatherman

I have some old 8 speed stuff collecting dust in the garage and was thinking putting together a cross bike. Anybody know if 10 speed Dura-Ace bar end shifters are compatible with 8 speed rear deraillers?

HillRider

If the rear derailleur is NOT a Dura Ace, it will work fine with the 10-speed shifters.

I believe there is a cable re-routing technique that will even let you use pre-9-speed Dura Ace derailleurs but any non Dura Ace derailleur will work with no alterations.

bellweatherman

DA10 barcons are compatible with other Shimano 8sp deraillers, but not with DA8 deraillers?! That's really weird. You'd think that DA10 shifters, if they are compatible with all other Shimano 8sp stuff,,, well - you'd think it'd be compatible with DA8 deraillers too. Why is this?

grolby

https://sheldonbrown.com/dura-ace.html

bellweatherman

What I don't get is how to use a 10 speed shifter with an 8 speed cassette. Basically, from Sheldon's site the derailler has nothing to do with how many cogs can be shifted. That is the sole duty of the shifter and cassette.

Sheldon's site is cool. It shows that with alternative derailler cable routing you can use an older shifter with a newer derailler. However, I'm trying to do the opposite. I want to use a newer shifter (10 speed) with an older derailler (8 speed or a 9 speed). There is no such alternative cable routing for such a scenario. Yet, on Sheldon's chart it indicates that a 10 speed shifter is compatible with a 9 speed derailler and 9 speed cassette. How? Is the 10th shift going to go straight into the spokes?

HillRider

There is no way to get a 10-speed indexing shifter to index with an 8-speed cassette. The cog spacing is all wrong. If you want to use the 10-speed barcons with an 8-speed cassette, you are going to have to use it in friction mode.

As to a 10-speed shifter with a 9-speed cassette, you set the derailleur's inner limit stop to prevent it from traveling too far and effectively block out the 10th click.

Gonzo Bob

If the rear derailer is not Dura-ace, just get a 10s cassette and chain. Or I spose you could get 9s cassette and chain and use the alternate cable attachment. You won't be able to run 8s.

The Dura-ace 8s rear derailer travels more per shift than other Shimano. If that's what you have, you have two choices that will work with 10s shifters. 1) Get a 9s cassette and chain. 2) Use the alternate cable attachment and use an 8s cassette and chain. You can't run 10s with this (unless you run friction) because the derailer already travels too far per shift and the alternate cable attachment makes it travel even farther per shift.