bjorsa

I just bought a used Lynskey Backroad that needed some parts to complete. The chainset, which has to be a mountain one to fit the BB, came on nicely. The rear Ultegra derailleur and cassette works fine. However, the front XT derailleur can't seem to reach the biggest cog. Here's me pushing the derailleur as far out as it can go and it barely lets the chain stay there:



On the other end, it can retract the chain more than close enough to the frame, even passing the smallest cog. Here you can also see I've completely removed that plate with the limiting screws, just to be sure I didn't limit the reach myself:



Is this a common problem? Did I do something wrong? Never expected the XT parts to match so poorly. Seems the bike has an unusually wide BB, pushing the chainset further out from the frame than standard? Anyways, this is my firts time doing this stuff so I figured I should ask here before I start whining, screaming and buying new parts.


Also, I'm not sure it works too well with the Dura Ace brifters I got with the bike. It's the old type where the shifting cables come straight out, pointing to the middle parallell to the ground while the break cables track the bar under the tape.


Grateful for any help.

HillRider

Put the limit screws back in and adjust them properly. You will have to tighten the low limit screw to keep the fd from moving too far inward and loosen the high limit screw to let it move outward far enough. disconnect the shift cable and shift the fd by hand as you set the limit screws. Once they are set, reconnect the shift cable and refine the shifting with the cable tension.

bjorsa

I already loosened the high limit to the point of removing the screw altogether yo! Also, the shift cable is disconnected and I still can't push the thing outward enough.

striknein

It's highly unlikely that you'll be able to tune the front derailleur properly using brifters. I'd recommend finding a road triple RD such as a tiagra or the IRD Alpina.

cny-bikeman

Contrary to what you are assuming, the derailleur is not the problem. Rather the chainwheel is too far out. That derailleur is designed for a 50 mm chainline (distance from center of seat tube to middle chainring). I don't know much about external BB's but the 780 is supposed to fit both 68 and 73mm BB. If you left in a spacer that makes it work for 68 mm then your chainwheels would be out too far. If it had the OEM BB then of course it could be as JoeJack describes below.

joejack951

I dig some digging and I have an idea of what the problem might be. Assuming this bike was built by Lynskey, there's a good chance it had an SRAM crank on it before. SRAM bottom brackets are NOT compatible with Shimano cranks. That means there's a very good chance your crankset isn't positioned properly due to the bottom bracket. If the bottom bracket cups say Shimano then nevermind.

joejack951

This is true. No road brifter will shift a MTB front derailler. He could fit a downtube/bar end shifter for front shifting and still use the right side brifter for shifting the rear, assuming he likes those Dura Ace. The left side brifter could be used as a brake only item.

bjorsa

Thanks for the good advise!

cny-bikeman and joejack, I think you guys nailed it. Looking at my BB, the former owner certainly left some spacers there. No wonder the XT crank felt almost short. I know he used a Middleburn duo x-type crankset. I should have checked up on that, of course.

I like the brifters so I think I'll pick up an Ultegra triple front derailleur, currently for cheap at Wiggle. That should sort it out, combined with removing some spacers down there?

I would like to thank you for the excellent support you have given me on this. It helped a lot.

/Björn

joejack951

According to Lynskey that frame has a 68mm wide BB shell which means most if not all MTB cranksets with external bearings will have one non-drive side spacer and two driver side spacers at 2.5mm thick each. You don't want to remove these.

However, if the axle on your crankset seems short it likely is the bottom bracket itself causing the problem. As far as I know Middleburn cranks are designed to work with Shimano bottom bracket cups but that in no way means your frame has a Shimano bottom bracket. Check that first, take some pictures too, and get back to us.