The Chainlink

I'm looking for a modern Shimano front derailleur for a road triple set up. I recently updated my drivetrain and it seems that my trusty XT FD is not compatible with my new Dura Ace downtube shifters.

Please PM me if you have anything you'd like to sell. I'm trying to spend $25 or less. 

Thanks!

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It should work fine, what is the issue you are having?

That's what I thought too, I mean they're friction so I assumed it wouldn't matter. It worked with my old Ultegra barcons, but the DA shifters just don't put enough cable. Evidently, Shimano revised the amount of cable pull in the 7900 shifters and I'm seeing some stuff online that says 7900 is double only... 

I should also add that I had my LBS set it up after I was having trouble and they said there's most likely an incompatibility issue. 

The 8sp XT FD has a super wide cage, and a much longer pivot arm compared to modern stuff. I'm hoping something more compact will work more efficiently. 

Are you still using an 8spd drive train?

Nope. 3 x 10. 

It's not the shifter as much as it is the chain; it's just to narrow for the wider cage.

I picked up an ultegra FD. I'll report back after install.

It's not a cable pull thing, it is a cage width thing.  The 10spd chain is narrower than the 8spd so the cage is to wide to move the chain.

If there is a cable pull issue you can solve that, within reason, by taking a Dremel to the stops in it.

Jeff Schneider said:

We know the ST-7900 cable pull is different than the other ST shifters.  The SL-7900 down tube shifter also has a pretty short throw.  Mine can't pull much more than I need to shift my double.

What you say about the XT FD cage width makes sense, too.  I wonder if KM tried it with another shifter and 10 speed chain?


notoriousDUG said:

It's not a cable pull thing, it is a cage width thing.  The 10spd chain is narrower than the 8spd so the cage is to wide to move the chain.

I installed the 9sp Ultegra triple last night and it is a night-and-day improvement. There is plenty of throw from the 7900 shifters when using the Ultegra FD. I think most of the improvement is related to the shorter pivot arm on the Ultegra mech compared to the XT. The shorter arm allows it to move further with the same amount of pull from the shifter. The narrow cage certainly helped as well. 

The only downside is that the Ultegra FD is designed to work with larger chainrings compared to my 42-32-22 XT crankset. I had to mount the FD a slightly higher than I would have liked to keep the inner cage off the center ring while riding in the outer ring. 

I also noticed that my outer ring has some lateral wobble to it. I've only used the ring for about a year. Do you think the wobble is more likely related to the crank or ring? It was a budget ring, a Vuelta or something...

How much wobble?  A little is pretty normal on cheap chainrings.

Maybe 2mm max. Its mostly noticeable when I might get some chain rub on the cage while in 1st or 10th gear.

notoriousDUG said:

How much wobble?  A little is pretty normal on cheap chainrings.

That's definitely normal.

Kelvin Mulcky said:

Maybe 2mm max. Its mostly noticeable when I might get some chain rub on the cage while in 1st or 10th gear.

notoriousDUG said:

How much wobble?  A little is pretty normal on cheap chainrings.

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