Going from a Triple to a Double?

[Acotts]

So I just replaced my Ultegra Triple Crankset with an FSA K-Force Double Crankset and I just cant get my Shimano 105 front deraileur to work properly.

I thought that I would just be able to narrow the limits on the deraileur and it would function as a double, but that does not seem to working for me. Is this a compatibility issue? Do I need to get new Brifters and front deraileur when going from a triple to a double?

Or should it work, it was late, and I had drunk one too may beers and couldn't figure it out?

[Tobias]

Are you using a 105 triple front derailleur? Is it a 9 or 10-speed?
What are new chainring sizes?

[CaptStash]

The 105's are definitely double and triple compatible. You may need to switch to a 5501 FD though. Shimano's compatibility chart gives me a headache. If you dig through the Shimano website you should be able to find the appropriate FD installation and tuning instructions.

CaptStash....

Shimano Website

[Pete Serotta]

some of them are for triple only and have a "deeper/longer length to catch the smaller chainring. Should be able to pick one up, if that is it, cheap here on the forum unless it is 10 speed and that could be a little more.

Grant or one of the other experts would be the best source of info unless someone else has personally done it,

[Acotts]

Yeah, it seems to me that the Derailer is too long.

As for the crankset, I am not sure what the size is. Its a pretty standard compact setup. 34/50 I think.

I am using a shimano 105 10 spd on the Brifters and derailers. I am not sure what model as they came on another bike i got 3 years ago.

-A

[Richard]

Just a couple of questions to ponder:

Did you lower the derailleur to compensate for going to a compact drive from the triple?

Is there a difference in BB shaft length for Shimano triples and doubles? If so, did you replace the BB?

[Ken Robb]

I used my DA 7800 dbl. front derailer to shift an FSA 50-34 compact. I'm quite sure that 105 and Ultegra 9spd. brifters can be used as dbl or triple but the DA are one or the other. I would be worried that a triple derailer wouldn't like a 16 tooth gap between rings but I never tried it.

[RPS]

Originally Posted by Ken Robb

I would be worried that a triple derailer wouldn't like a 16 tooth gap between rings but I never tried it.

+1
Ultegra and 105 9-speed triple front derailleurs don't like more than a 10T jump from middle to large (which is what it's being ask to do). Additionally the chainrings are now probably closer to the centerline of the bike.
From above information I'm not sure if we are talking about 9 or 10 speed. I thought 105s were 9-speed three years ago (but I may be wrong). In any case I'd try a new double front derailleur.

[thwart]

No Shimano experience, but I've used Campy triple FD's on Campy (and FSA) compact cranks successfully.

Although a standard double FD seems to work just a little better...