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double vs. triple front derailluer?(10 posts)

double vs. triple front derailluer?outofthesaddle
Dec 4, 2003 9:44 AM
What is the difference between the Ultegra double and triple front derailluer? I'm converting from a triple to a double set up and am wondering if I have to change front derailluer. Any thoughts appreciated.
triple moves further; need to change nmDougSloan
Dec 4, 2003 10:26 AM
Thanks - was hoping to able to use current dr - oh well (nm)outofthesaddle
Dec 4, 2003 10:33 AM
You've got it.So give it a try....Rusty Coggs
Dec 4, 2003 10:47 AM
I don't undrstand the 'moves further' part. Consider the middle/big ring on a triple. the middle is a 42, but can be changed to a 39, and still work with the same derailer. The rings on a double are 39/ whatever, and spaced the same amount apart....Worst case, with the shorter double spindle, the derailer may have insufficient inward movement to shift to the small ring before contacting the seattube.
sorry, misunderstood; thought you were double to tripleDougSloan
Dec 4, 2003 11:41 AM
I got it backwards. Yes, you may be able to use the triple derailleur on a double crankset. Just dial in those limit screws. Can't hurt to try.

If you were going from double to triple, you'd not have enough range.

Doug
sorry, misunderstood; thought you were double to tripleRusty Coggs
Dec 4, 2003 12:06 PM
Some,double dreailers will shift a triple.Not sure about the ultegra tho.
quite different I would think.theBreeze
Dec 4, 2003 10:28 AM
A double der won't have the range to move the chain across all three rings. An Ultegra triple has four indexed positions, one each for the big and granny rings and two for the middle ring to allow you to trim the chain line depending on which cog you are using.
triple down to double - done it, and it worksterry b
Dec 4, 2003 11:01 AM
the biggest difference is the travel. the second biggest difference is in the size of the back plate - it's a bit larger on the triple.

I've gone from a triple down to a double while keeping the triple FD. you need to set the limit screws to prevent it from walking the chain off in both directions. not pretty, but if you're aiming to save a few bucks it can be done.
I've even used doubles to shift across triples...Ray Sachs
Dec 4, 2003 11:50 AM
... and had pretty good luck. I wouldn't try it with STI, but I had this setup on a touring bike for years with barcons (friction front shifting). The shift from the granny to the middle ring wasn't super smooth, but it worked OK for a touring bike that I was never in that much of a hurry on anyway.

-Ray
I'll probably spend the few $$ and get the double.outofthesaddle
Dec 4, 2003 11:54 AM
One of the reasons I'm bailing on the triple for my road training bike is that I haven't had great luck in keeping the shifting dialed with the triple set up. I know that others on the board have had much better better sucess than I have. I'd like to be able to use the bike for group training rides and possibly for crits.

In this case, I just finished building a 'cross pit/rain/commuter bike with a double. I realized (right after I finished it) that I could use the double set up for my road training bike and swap the triple over the the 'cross bike. An added benefit is that I can use my 'cross bike as a mountain bike with the triple ring.