Bicycle Mechanics - Ultegra/DA FD compatability

I was just wondering whether it's possible to use a 9 Speed dura ace front derailleur with ultegra 9 speed STI's. The reason I ask this is because with ultegra, the STI's work both the triple and double front derailleurs implying that the amount of cable moved by each click is the same, i.e. the front derailleur moves a different amount for each click. However Dura Ace uses different STI levers for double and for triple i.e. presumeably the cable pull for each lever click might be different between the two types of levers and hence might not be the same as the ultegra lever.

Anyone know whether they're fine together? Apologies this wasn't explained well. I may have to try again.

I think it would be fine as long as you don't use a double der for triple chainrings.(Or the other way around) The big difference is in the der., the length of the lever arm where the cable is attached and the shape of the cage.

edit: Reading back my answer, I am not sure if it is to clear either :)

I was just wondering whether it's possible to use a 9 Speed dura ace front derailleur with ultegra 9 speed STI's. The reason I ask this is because with ultegra, the STI's work both the triple and double front derailleurs implying that the amount of cable moved by each click is the same, i.e. the front derailleur moves a different amount for each click. However Dura Ace uses different STI levers for double and for triple i.e. presumeably the cable pull for each lever click might be different between the two types of levers and hence might not be the same as the ultegra lever.

Anyone know whether they're fine together? Apologies this wasn't explained well. I may have to try again.
If you're asking if the Dura Ace double front dérailleur can be use with the Ultegra STI's....yes. Using that combo, you will have a few more trim positions. The high and low limit screws on the dérailleur will limit the max travel of the dérailleur.

Ok thanks, do the dura-ace double STI's just have less clicks then?

Ok thanks, do the dura-ace double STI's just have less clicks then?
Yes. If you use the Ultegra STI with the Dura Ace dérailleur you will notice a few more 'clicks' if you 'soft shift' or 'feather' the lever as if you were trying to trim. If you shift normally, up to or down from one chain ring to the other, you will barely feel them. May I ask why you're contemplating doing this? The difference in performance of the Ultegra and Dura Ace front dérailleurs is relatively small.

Well I have a dura-ace front derailleur and a 105 triple derailleur. Have been making a slow upgrade from triple to double, I got a good price on a 2nd hand DA front derailleur and presumed it would work. I never found my STI's feathered well on the front derailleur, although they do have 4 clicking positions so maybe it will be better on the double, the triple was a real pain to keep adjusted. I ran the 105 triple front derailleur as a double for a while too, that did work but not very well as if you imagine the four different positions being:

LL LH HL HH

where LL is say 42 - 25
LH is say 42-15
HL is say 53-19
HH is say 53-12

Then if you wanted to change from HL to LH, you had to shift down twice to LL, as otherwise the chain wouldn't jump on to the 42, and then shift back up to LH. The same for the way up from LH to HL involved going to HH and back to HL in order to jump the chain.

The difference between the double and triple dérailleurs is primarily in the size and shape of the inner and outer cages, and a slight difference in the length of the 'throwing' arm. A triple dérailleur has to lift the chain from 30 to 42 to 52 chainrings whilst the double only has to lift from the 39 to 53. The dérailleur really only does what the shifter tells it to do. I've installed a double dérailleur on my wife's Ultegra triple bike because I didn't have the correct dérailleur, and it worked pretty good. The triple dérailleur, of course, worked much better when I finally got one.

If your 105 dérailleur doesn't trim well, it's usually caused by improper cable tension upon installation. Generally a front dérailleur, if properly installed and 'tuned' will never get out of adjustment other than simple cable stretch.