rwidman

I just totally rebuilt a tandem with upgraded components. The original was set up with a mountain bike triple crank. I changed it over to a road triple crank. In the process of changing out the front Derailleur to a road triple, I can't find one that will shift up to the big ring. I tried several. They seem like they don't have enough throw to make the shift. I was thinking that maybe the new crank is too far away from the seat post. But according to Sheldon Brown's website it measures right where it should be. Is there a special front Derailleur that is recommended?

HillRider

Have you set the high limit screws correctly? I have road triple cranks and road triple derailleurs on all four of my bikes and not one has the slightest problem shifting to the big chainring. This is particularly puzzling if, as you say, the chainline is correct.

One more thought: Is your front shifter indexed? Did you set it at the smallest chainring position before attaching the cable and has the slack been taken out of the cable before tightening the clamp?

rwidman

Yes to all that. I even took one of the new Derailleurs and filed material off the swing arm to give it more swing and still was not enough. I'm going to reinstall the old crank and measure the chain line and compare it to the new crank set up. I'm thinking that is where my problem is. I might need a narrower bb.

Bill Kapaun

You failed to install "road" compatible shifters.
They pull different cable amounts.

rwidman

Wish it was that easy. Just checked the shifter and it is pulling the derailleur as far as the derailleur will go. It is bottomed out.

rwidman

Definitely a chain line problem. There is a 1/4" difference between the new and old crank. I guess I will have to figure in new bottom brackets.