Problem with Ultegra gear shift

[yvs24]

Hi guys. I have a problem and wonders if any of you with more experience can offer any advice.

I have fitted a new Ultegra group set to a bike and have an issue, it's hopefully pretty simple to explain.

The front shifter seems fine. The back shifter does not in that I have aligned the pulleys on the derailleur with the smallest rear cog and tightened the cable. When I sweep the shifter inward the first time nothing happens, the rear mech does not move at all that I can perceive. Subsequent sweeps of the shifter do result in the mech moving and it appears to be perfectly in line with each rear sprocket but of course does not make it to the largest rear due to the first "missed" shift.

Does anyone recognise this ? All the kit is brand new Ultegra 6700 10 speed. The derailleur hanger is not bent. The cable runs appear to be fine with no blockage or snags etc. The cable seems pretty taut and by forcing it to be incredibly taut by adjusting the barrel adjusters I can force it to change first time, problem is I can then get up to the large sprocket but when changing back down it will never reach he small sprocket unless I ease the tension a bit with the barrel adjuster whereupon I'm back to the first shift not working again.

Any help much appreciated !

Cheers, Neil.

 

[the_mikey]

Double check the indexing, ensure the shifter is set to it's top gear before setting up indexing. Shift up one gear and adjust cable tension until the chain is on the 2nd smallest sprocket. If that works the rest should work. Check the H and L limits allow the derailleur to access the full range of sprockets.

 

[Roadrider48]

Also, just a thought. Check the cable is in the shifter housing properly. If it isn't the derailleur won't move.

 

[yvs24]

Double check the indexing, ensure the shifter is set to it's top gear before setting up indexing. Shift up one gear and adjust cable tension until the chain is on the 2nd smallest sprocket. If that works the rest should work. Check the H and L limits allow the derailleur to access the full range of sprockets.

Thanks but that's just the issue. When I force it to jump up to the second sprocket by increasing the cable tension (via barrel adjusters) every subsequent shift up to larger sprockets is fine but it will never drop back again to the smallest sprocket. Thats what I don't get.

 

[yvs24]

It's in properly. As I said every shift after the first attempt works fine. A thought from me. If I were to remove the chain and drop the shifter down to the smallest sprocket position and tighten the cable should I see the mech move when I subsequently sweep the shifter in for the first change ? In my case there is no movement whatsoever until my second shift. I'm just wondering if I've missed something really obvious like should I seat the cable sweep it once (so it's out of sight when looking into the shifter mechanics) and have this as my default start position ? I've not used these Ultegra before so have no prior experience.

 

[Peteaud]

again just a thought but i presume your old system was 10 speed and that any spacers on the cassette have been taken into account.

This would affect the hi lo screws and the initial setup.

 

[Roadrider48]

When you put a new derailleur the chain automatically drops to the smallest cog. Without any cable attached. With the derailleur on the smallest cog, pull the cable as tight as you can then tighten the retaining bolt. Also make sure the shifter is in the highest gear aswell. If all this is done properly, the derailleur should move when operating the downshift. Then when it does move, you set the high and low limits with the two small screws on the derailleur, and adjust the tension with the barrel adjuster on the derailleur. Even if you're not familiar with indexing, make it basically move then check on YouTube for the final fine tuning.

 

[Roadrider48]

again just a thought but i presume your old system was 10 speed and that any spacers on the cassette have been taken into account.

This would affect the hi lo screws and the initial setup.

Good point!

 

[yvs24]

There was no old system. This is a brand new frame, wheels, group set etc. There was one cassette spacer which went on the rear xxxxx (whatever the cassette fits on to, for some reason the word escapes me) first prior to three "fused" large sprockets then a couple of other spacers between individual sprockets in the middle of the cassette range. I think these must be right for indexing as when the thing starts shifting on the second sweep all is perfect up to the penultimate larger sprocket which is as far as it gets.

 

[boydj]

Sounds like you need to move the limit screw a touch because the mech may be moving slightly too far onto the small cog, so that the first pull is not moving the mech far enough to get it off the small cog. Either that or something is impairing the movement of the cable, since the lever does give you 10 shifts ok.

 

[yvs24]

Thank you all. I'll check that lower limit screw tomorrow as it sounds like a real possibility. Being too low on the smallest cog isn't something I'd thought of as I'd expect it to overchange and drop off and jam between cassette and seat stay.

 

[solidthegreat]

It's been said already, take out cable, remove chain, check out casing to make sure cable is smooth through it, check limiter screws, instal chain and cable, adjust cable tension then index gears. Just out of interest are you using mavic wheels? Reason I ask is that I remember someone telling me that there were spacers behind the cassette and if the cassette has been removed and the spacers not put back it could alter alignment. Just a thought and probably not linked but I thought I would ask.

 

[yvs24]

Thank you all. I'll check that lower limit screw tomorrow as it sounds like a real possibility. Being too low on the smallest cog isn't something I'd thought of as I'd expect it to overchange and drop off and jam between cassette and seat stay.

Thanks guys, it certainly looks like the limit screw is the issue as once I had adjusted it slightly I noticed movement in the mech on my attempted first shift and by further tensioning the cable using the barrel adjusters it looks to me like there is now sufficient movement to make the first shift and afterwards all subsequent shifts are indexed so should also be OK. I'm waiting for a new chain t be delivered at the moment so will check it all out when that comes. Cheers, Neil.

 

[ianrauk]

This video has been posted many times on the forum. But is a great help in demystifying rear dérailleur and gear indexing. So may be of help to you.


View: http://www.youtube.com/watch?v=SkzvfCaIbyQ

 

[yvs24]

This video has been posted many times on the forum. But is a great help in demystifying rear dérailleur and gear indexing. So may be of help to you.


View: http://www.youtube.com/watch?v=SkzvfCaIbyQ

New chain arrived this morning, I have fitted it and with some fine tuning of the limiter screws all is now working perfectly. Thank you all for your help. Cheers, Neil.