Ultegra 6800 front shift problem

[Paul Drawmer]

I think the mech / cable are adjusted OK - sometimes the shifting is fine.

The problem is to do with changing from small to big ring. Sometimes it doesn't work - move lever, but no movement of mech. Sometimes this can be fixed by flipping the big to small action a couple of times, then it works, usually.

But sometimes however I fiddle with the change levers, actuating the small to big change has no effect. It feels as if the action is normal, but the front mech just doesn't move.

I assume there's some kind of ratchet system within the lever - do these wear out, and if so are they replaceable?

[itsnotarace]

If you pull the cable taught by hand, can you induce the shift?

Do you have an inline barrel adjuster that can be tightened a twist or two?

[Paul Drawmer]

itsnotarace said:

If you pull the cable taught by hand, can you induce the shift?

Do you have an inline barrel adjuster that can be tightened a twist or two?

I've tried all the normal adjustments and I'm pretty certain it's adjusted right, as when it works, it works just fine.

Re: pulling directly on the cable, can't do that whilst riding as the only available cable is the bit up from the bottom bracket.

Needless to say, this never goes wrong when it's on the work stand!

[itsnotarace]

Yeah off the bike obviously, pull the cable as hard as you can and see if the mech moves

[ShortShift811]

Could also be a frayed cable. I had this recently - couldn’t diagnose a shifting issue at the front mech - and it turned out the cable had bizarrely frayed somewhere near the point it entered the frame

[Piginapoke]

ShortShift811 said:

Could also be a frayed cable. I had this recently - couldn’t diagnose a shifting issue at the front mech - and it turned out the cable had bizarrely frayed somewhere near the point it entered the frame

It's probably this- a fraying cable in the shifter itself, where you can't see it. I had this 70k from home, and after constant messing with the lever I promptly only had 3 gears available. After a slow ride home, bike shop said it was held on with only 1 remaining strand!

[Dnlm]

Had similar issues after a service last week. New brake cables and bad rub / not shifting. All perfect on the workstand.

The barrel adjusters could never get it perfect (from nothing to 1 in 5 shifts failing). The shop ended up having to adjust front limit screws whilst out and testing under load - sounded very finicky but fixed now.

[Marcellus]

There’s a small lever inside the main gear shift lever, which if not in position properly disengages the ratchet mechanism to make the shifter work.

[moonigan]

Try disconnecting the cable from the mech altogether and check that it moves when you shift. You can pull the cable on the upshift to try and gauge if its working OK as the Ultegra front mech requires a lot of tension to work. It might be snagging somewhere.

[Paul Drawmer]

Thanks for all the suggestions....but it wasn't adjusted correctly!!!

Basically, I had wound up the barrel adjuster so much that it was operating with far too much tension in the cable and was operating only on the tightest part of it's use. The lever has a total of four clicks (including the 'trim' settings) and I was operating on the tightest three. Mostly it worked..but now it works much better.

This was causing the reluctance of the lever to reset to reverse its pull direction.