Ultegra 6870 & 10 speed backwards compatibility?

Discuss light weight issues concerning road bikes & parts.
jockster
Posts: 87
Joined: Fri Apr 13, 2012 7:25 pm

by jockster

So, if I had a 6870 Di2 rear derailleur and a rear wheelset with a 10-speed cassette, could I make it run?

I think I have heard that the 6870 Di2 levers would work with a 6770 RD & FD.

I would like to get the 6870 groupset for my main bike, but switching all my wheelsets to 11 speed would break my economy and it would make me sad getting a new 6770 group when the 6870 is out.
Last edited by jockster on Tue Oct 29, 2013 10:56 pm, edited 1 time in total.

jockster
Posts: 87
Joined: Fri Apr 13, 2012 7:25 pm

by jockster

Anyone?


dha
Posts: 163
Joined: Tue Jun 12, 2012 4:40 pm

by dha

Levers from any version of di2 (except 7900) will work with any front or rear mech. This applies to 6770, 6870 and Dura Ace 9070. You will need the latest firmware in all components for it to work.

The 6870 and a 10 speed rear might work, but I don't know of anyone who has tried it.

etownfwd
Posts: 236
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Location: Central PA

by etownfwd

D'oh! Somehow I read that too fast and missed the Di2 part. Still, what dha said...

@dha - Thank you for the backstopping!

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Tinea Pedis
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by Tinea Pedis

Are you referring to 6800 or 6870 (Di2)?

Your OP could be confusing people.

jockster
Posts: 87
Joined: Fri Apr 13, 2012 7:25 pm

by jockster

Sorry. All about 6870 here - corrected my first post for clarification

gjash
Posts: 34
Joined: Mon Dec 24, 2012 6:42 am

by gjash

I'm running 6800 shift levers with my 10 speed wheels without a problem. The throw distance is the same so it just works. Eventually I'll move all my wheels to 11sp but for now it beats having waste good hubs by replacing with 11.

RichTheRoadie
Tinker, Taylor, Tart
Posts: 2006
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Location: Sydney, Aus.

by RichTheRoadie

If you can change your freehub to Campag, do that and run Campag cassettes - I'm using 9070 Di2 on a Chorus cassette and it works perfectly.

gjash
Posts: 34
Joined: Mon Dec 24, 2012 6:42 am

by gjash

BikeTart wrote:If you can change your freehub to Campag, do that and run Campag cassettes - I'm using 9070 Di2 on a Chorus cassette and it works perfectly.



Thanks for that! very interesting. You just saved me from rebuilding wheels for the price of a cassette.

jockster
Posts: 87
Joined: Fri Apr 13, 2012 7:25 pm

by jockster

@gjash - Do you have a 6800 rear derailleur as well?

gjash
Posts: 34
Joined: Mon Dec 24, 2012 6:42 am

by gjash

jockster wrote:@gjash - Do you have a 6800 rear derailleur as well?


Yes, that's right.

jockster
Posts: 87
Joined: Fri Apr 13, 2012 7:25 pm

by jockster

dha wrote:Levers from any version of di2 (except 7900) will work with any front or rear mech. This applies to 6770, 6870 and Dura Ace 9070. You will need the latest firmware in all components for it to work.

The 6870 and a 10 speed rear might work, but I don't know of anyone who has tried it.



So one would most probably be fine running a 10sp cassette with 6870 levers and rear derailleur then?

RichTheRoadie
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Posts: 2006
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Location: Sydney, Aus.

by RichTheRoadie

It's the rear mech that determines whether the system 'thinks' it's 10 or 11spd. If you run a 6870 rear mech the system will think it is 11spd - then the only way to run it 10spd is to wind in a limit screw to stop it reaching the 11th sprocket.

BdaGhisallo
Posts: 1886
Joined: Wed Mar 17, 2004 1:38 pm

by BdaGhisallo

In that scenario the shifting will not be perfect since the 6870 RD will be shifting to 11sp cog spacing. If you want 10sp cassettes, you will need a 6770 RD and can use 6870 everywhere else.

The RD determines the the cog setup. 6770 = 10sp 6870 = 11sp. All other components are compatible, though not optimal. The 6870 FD will trim based upon 11sp chain and chainring architecture, so you may have some misalignment, though you won't know how much until you try it.

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