Enthusiast

I swear I'm not trolling...My situation:

I will be leaving on a long bike tour shortly and have decided that my Ultegra double crankset doesn't offer a low enough gear. My two choices for the crankset are a cheap Bontrager road triple crankset or a XT M751 crankset. I prefer the XT over the Bontrager because of reliability concerns. Unfortunately, the XT FD will not work with the early 1990's 105 downtube friction shifters I have mounted. I am left wondering what type of shifting performance I could get if I stuck with the 1973 Dura-Ace FD I'm currently using. I believe it can be adjusted to reach all three chainrings but I have no idea about the suitability of the angle of rise (what is the correct term?) and the shape of the FD cage itself. I'm not expecting smooth shifting here, but will it shift at all? I do not have the time, money, or inclination to buy new parts.

Jeff Wills

OK- I'll bite. Why won't the XT front derailleur work with your downtube shifters?

And I think the ancient Dura-Ace front derailleur should work OK, but you may not be able to use a lot of the rear cogs while on the small chainring due to the short cage. If you were very, very lucky you could track down a cage extension for this derailleur. Shimano made them, but they're rare as hen's teeth now.

Garthr

Why is the Bontrager crank less reliable?

Yes, why wouldn't the XT FD work with friction shifters? Have you tried it?

With things like this, theories and maybe are all trumped by putting them on the bike for some trial and error. If you're not prepared for the unknown outcomes, don't go changing things until you are prepared, or can pay someone to figure it out for you.

norwood

I can't think of any reason the XT FD wouldn't work with the 105 shifters. And I would guarantee you that set-up would be better than the DA FD which is for a double and not designed at all to shift to three chainrings.

LarDasse74

Friction shifters should work with any derailleur.

Do you have a bottom bracket for the crank you are planning on installing? Because whichever crank you choose to use will probably need a different spindle length than the crank currently installed.

Enthusiast

Thanks for the replies. It's not that the derailleur couldn't work with friction shifting, just downtube shifters. The XT FD didn't work because it was designed for a cable that ran down the seat tube from the top tube but the downtube shifter cables route around the bottom bracket and up to the derailleur.

I felt the bontrager crank was less reliable because it was a road crank vs a mtn crank and because the chainrings were thinner and stamped out vs the machined XT chainrings. I snapped a road crank a couple months ago so I'm a bit paranoid.

Garthr, I agree. I post here to check if there's something I'm overlooking. Shortly after I posted, I did the work and tested it out. Works great. I used the ES71 BB that came with the XT crank. I added a 2.5mm cassette spacer to the drive side to adapt the 73mm BB to the 68mm shell.

bikinfool

Well if you're going to screw around with the intended cable routing for the fd what do you expect? Best to provide all details next time. Cranks are cranks, chainrings aren't all that special. What did you "snap" on a road crank and what was it, what happened, etc.? You seem to be looking for problems that don't exist...

Tabor

Hey, lighten up. Historically mountain bike front derailers have been top pull, while road front derailers have been bottom pull. I was confused too... but that is because I don't work on mountain bikes all that much. The OP is just looking for help. I am sure he included all the details he thought were relevant.

norwood

That info would have been helpful from the start. But don't assume that all MTB F. derailleurs are top pull because they certainly are not. Shimano, at least on most of the older MTB stuff made a top-pull and a bottom-pull version of their FD. And a FD designed to shift a triple crank wil work way better on a triple than one designed for a double.

Jeff Wills

OK- so you get a bottom-pull front derailleur (as others suggested) and bolt on a plastic cable guide: https://harriscyclery.net/page.cfm?Pa...ils&sku=FS1092 .