Another Front Derailleur thread!

calbelfield

Hi all,

Just fitted my (already used) ultegra 6800 fd on my new bike. Set the inner limit to be 0.5mm clear of the chain, added cable, shifted to big ring and set the outer stop. Add some more tension with the barrel adjuster and then shifted away. Only problem is, there's now significant chain rub in the lower 3 gears on the little ring (i.e. 39-21,23,25). If I try and reduce tension to get the derailleur to move inwards , there then all of a sudden isn't enough tension to get the chain to shift onto the big ring. This is with less than a turn of the barrel adjuster.

So basically I can't win, it's either rubbing gears or not being able to use the big ring!

Any advice would be appreciated.

Thanks

trailflow

Are you positioning the outer FD cage inline with the big ring before clamping the cable,then releasing the cage back to the inner position ? If not you need to do that to achieve the correct tension.

Try this tutorial
viewtopic.php?t=12976309

calbelfield

trailflow wrote:

Are you positioning the outer FD cage inline with the big ring before clamping the cable,then releasing the cage back to the inner position ? If not you need to do that to achieve the correct tension.

Try this tutorial
viewtopic.php?t=12976309

I hadn't been doing that but just given it a go , to the same result either the tension is fine to get onto the big ring but with chain rub in small ring/big cogs, or there's no rub but not enough tension to get onto the big ring. I can push the derailleur in by hand so the limit is set fine, but it's almost as if the derailleur is 'sticky' and so won't fall back to the inner limit.

Thanks for the help anyway

trailflow

Then it could be a cable friction issue. Check the cable for kinks or for burrs on the cable ferrules or frame stops. Try lubing the bottom bracket guide. Lubing the cable run and mechanism inside the shifter can help too even if they're new (not wd40 as that will strip the grease) try not to get any lube on the hoods otherwise they'll slip.

Also check for any tight radiuses in the outer cable. In can be a good idea to cross over the cables where they enter frame ie. The left cable enters the right side of the frame and vice versa. This will minimise the curve of the outer bend and the inner cable will move more freely. The cables will cross over in or under the downtube but it wont cause any problem.

And also try the second cable clamping tab position.

Another posible cause could be too much cable tension.

jermas

Check height compared to large chainring- leaving about 1mm clearance. Check angle that it's square in relation to the chainring. Also there's a converter pin (2mm hex) next to the cable clamp- try it in the other position and make sure the cable is routed correctly around the clamp bolt.

calbelfield

A quick update- swapped over to my 105 5800 FD and set up in exactly the same way with the same cables. Seems to have done the trick, just about! Thanks for your help though everyone, not quite sure what was going on with the ultegra one, that's the second one I've had in less than 3 years!