Shimano Ultegra Left Shifter

dazza106

Hello,

I have just installed a new FD 105 triple (old one seized), New Cables (inners and outers). My left shifter will take up the cable slack and move the FD from the little ring to the big ring fine, but the shifter will not release the cable tension to allow the FD to move from big ring to small.

If I disconnect the cable from the FD and hold it under tension with my hand then the slack is taken up and released as normal.

I am really confused.... do I have a knackered shifter or have I made some schoolboy error somewhere along the line with the installation..?

Thanks.....

desweller

Check that the pip on the end of the cable is correctly seated in the shifter.

crankycrank

Also make sure the shifter is released all the way, i.e. pull on the cable while moving the inner shift lever until there are no more clicks before clamping the cable in the front mech.

Bordersroadie

I hope I'm wrong but you could have come across the dreaded 6703 left shifter "issue".

In short, the action of moving the lever inwards is effectively an anti-clockwise (unscrewing) motion in respect of the machine screw and special nut that holds the whole pivoting mechanism together, so eventually it falls apart. A redesign with a left hand thread would solve the problem. If you haven't lost the nut it is a fixable problem.

See this excellent thread for details.
viewtopic.php?f=40004&t=12914428&p=18237341&hilit=6703#p18237341

Also Google "CRC 6703 STI" and look at the CRC customer reviews to see a series of people with the same problem. Mine was replaced under warranty by CRC and I'm about to do the fix, bonding the allen head of the machine screw to the plastic shifter body to prevent it unscrewing.

dee4life2005

@bordersroadie, I've had my bike with ultegra groupset for about 16months now and the left ultegra 6703 shifter is rattling quite a lot, could this be the dreaded "left shifter issue" ?

Bordersroadie

dee4life2005 wrote:

@bordersroadie, I've had my bike with ultegra groupset for about 16months now and the left ultegra 6703 shifter is rattling quite a lot, could this be the dreaded "left shifter issue" ?

I'm not sure, but it may be. If you imagine that the shifter/lever has two "axles", one for each pivot direction. As far as I know there are no issues with the brake lever pivot, it's the shifter pivot that is the problem. Even if yours isn't loose I'd recommend that the fix (described in the link to the forum thread I gave above) is done as it seems to be a permanent solution that can save you well over a hundred quid for a new STI assembly if it breaks.

If you remove the left shifter (no need to move bar tape, just undo the hex headed bolt visible on top of the lever after peeling back the hood) and look at the rear face of the plastic shifter body (which normally nestles into the bar) you will see a smaller hex head machine screw. This is the "axle" of the gearchange part of the pivot. Tighten it up just enough so you feel it "bite" (ie not very tight) and then fix the head to the surrounding plastic casing to stop it rotating. Others have used superglue but I'd recommend epoxy resin, applied with something like a pin or other very small point, around the edge of the bolt head (but not in the hex bit obviously). The aim is just to stop this screw unscrewing itself from the nut located at the front end of the shifter body.

It's pretty annoying that a simple design fault (ie using a right hand threaded screw) causes it to slowly unscrew itself, until the specially shaped front nut drops out onto the road and the (expensive) lever needs replacing as none of the parts are replaceable. It can also leave you stranded on the 50 ring, not great if you're many hilly miles from home.

The good thing is that it seems easy to prevent.