8 speed with 11 speed

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webber
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Joined: 2 May 2012, 3:48pm

8 speed with 11 speed

Postby webber » 7 Feb 2019, 9:19am

Will shimano 8 speed drive train work with 11 speed rear mech??

Samuel D
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Location: Paris

Re: 8 speed with 11 speed

Postby Samuel D » 7 Feb 2019, 9:19am

No, for almost all understandings of your question.

webber
Posts: 243
Joined: 2 May 2012, 3:48pm

Re: 8 speed with 11 speed

Postby webber » 7 Feb 2019, 9:40am

Sorry not the very clear lol i have a bike running 8 speed dura ace and a friend has an 11 speed rear mech will the 11 speed mech index ok as 8 speed or is the cable pull different

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Audax67
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Re: 8 speed with 11 speed

Postby Audax67 » 7 Feb 2019, 9:47am

Wellllllll... It's not the mech that does the indexing or the cable pull but the shifter, so if the chain will run through it without sticking it just might work. But why bother? A mech made specifically for 8v isn't exactly pricey.
Have we got time for another cuppa?

Samuel D
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Re: 8 speed with 11 speed

Postby Samuel D » 7 Feb 2019, 9:50am

Dura-Ace 8-speed is another animal from the other 8-speed systems, but none of them work with an 11-speed shift ratio. The 11-speed derailleur expects more cable pull per shift, that is, it won’t move enough each time a shift is commanded. You can use a friction shifter (as opposed to an indexed one) to get around this problem, but even then you may need a shifter that pulls a lot of cable (has a large barrel) and you may have to use narrower than 8-speed chain to get it through the pulley cage.

Other 8-, 9-, and 10-speed road derailleurs won’t work with 8-speed Dura-Ace shifters either. You specifically need a Dura-Ace derailleur or one with a similar shift ratio (some old SunTour, etc.).

Is the Dura-Ace derailleur not working in some way?

Samuel D
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Joined: 8 Mar 2015, 11:05pm
Location: Paris

Re: 8 speed with 11 speed

Postby Samuel D » 7 Feb 2019, 9:52am

Audax67 wrote:Wellllllll... It's not the mech that does the indexing or the cable pull but the shifter, so if the chain will run through it without sticking it just might work. But why bother? A mech made specifically for 8v isn't exactly pricey.

Well, 8-speed Dura-Ace was an anomaly in the Shimano line-up in that it used a different shift ratio with low cable travel per shift. To get a modern 8-speed derailleur to work will require new shifters too. There may be a hack involving changing the cable attachment point on the derailleur, but that sort of thing is for dedicated experts.

Brucey
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Re: 8 speed with 11 speed

Postby Brucey » 7 Feb 2019, 10:18am

webber wrote:Sorry not the very clear lol i have a bike running 8 speed dura ace and a friend has an 11 speed rear mech will the 11 speed mech index ok as 8 speed or is the cable pull different


Dura-Ace 8s shifters pull 2.5mm per click and a dura-ace 11s mech requires 2.7mm/click to shift on 11s. There's basically nothing useful you can do with these parts attached to one another unless you use a shiftmate or something.

cheers
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webber
Posts: 243
Joined: 2 May 2012, 3:48pm

Re: 8 speed with 11 speed

Postby webber » 7 Feb 2019, 11:42am

Looks like its an ebay job then theres lots on there lol