Getting front derailleur to shift up smoothly

[Yellow Saddle]

Okay, so I couldn't find a chain tool so wasn't able to take the chain off unfortunately. I took a few pictures last night, although I don't know if they're any help, with the chain being on and also bad light + camera flash. Anyway, to took photos of the derailleur from the top whilst on the little ring, on the big ring, and also a side view to show the clearance between the cage and the big ring. It's hard to see from the photos, but there didn't seem to me to be a problem with alignment.

http://imgur.com/nAzbkfz
http://imgur.com/VNE5GLQ
http://imgur.com/eoCOU7w

Without knowing what gear the bike was in and hence not knowing the chain line, I think the derailer needs to be repositioned so that it is parallel with the chainrings. In the one photo it seems a bit tail-out. The two blades should be in line with the chainrings because the pushing bulge is about 1/3 from the front and it seems like yours is making contact in the tail-end of the derailer. Can you conform that? The height seems fine and the limit screw seems fine.

 

[Kestevan]

Agree with above.
Although I'd perhaps also try lowering the mech a tad.... SRAM seems to be really picky about the vertical positioning (much more so than Shimano). I found that when setting up Mrs Kes Apex system it needed to be bang on parallel, and closer to the chainring than I would have thought.

 

[danhoro]

Thanks for the replies, will investigate a bit tomorrow morning and will report back. Cheers.

 

[danhoro]

Okay, so I had a play around with it yesterday but only had the time to take it out for a cycle today on the way to work. The problem is still there. Yesterday I unclamped the FD, tried to get the alignment as perfect as possible (looking at the position of the derailleur cage relative to the big ring), and also experimented with the height a bit. I got it working as smoothly as I could in the shed (albeit with the problem still occasionally arising), and had the same issue shifting up to the big ring on the very first attempt when cycling in this morning.

Another thing I've noticed is that one of the teeth of the big ring is very slightly bent inwards more then the others. It is immediately inside the right-hand crank. My theory is that it might have happened when, a week or two ago, I pressed the left lever to shift down to the small ring as I came to a stop, but failed to pedal through so that the chain actually shifted before I became stationary. When I pulled away again, with force, I had a horrible shift/slip down to the small ring. However, I find it hard to believe this is the root of the issue, because my problems shifting up have been there since I first got the bike.

 

[Yellow Saddle]

You exasperate me... But we have to fix it. My next suggestion is to keep turning the high limit screw out by say 1/4 turn and testing between each turn. Keep on doing this until the chain is thrown off the chairning and then go back until that stops.

Also, just bend that tooth back into position using a shifting spanner or, since you probably can't get in there, a hammer. Small hammer, small blows.

Actually, before you do step one above, turn the limit screw out by two whole turns (or any small integer that wont complicate an accurate return) and then with the chain on the big ring, see if anymore pressure on the lever will make the derailer move further. We want to see if the cable is not too slack and thus if the shifter cannot take up all the slack to complete the movement at the derailer. If you are happy with that, return the screw to its original position and then go up with the aforesaid 1/4 turn and test.

 

[shouldbeinbed]

Just one thing to double check on the the bent tooth, its not the standard chain un/ship tooth is it, roughly replicated 1/4 or so round the chainring

 

[Yellow Saddle]

Just one thing to double check on the the bent tooth, its not the standard chain un/ship tooth is it, roughly replicated 1/4 or so round the chainring

Usually those appear to be worn away or shorter, not bent outwards, as I understood the OP.

 

[ColinJ]

Actually, before you do step one above, turn the limit screw out by two whole turns (or any small integer that wont complicate an accurate return) and then with the chain on the big ring, see if anymore pressure on the lever will make the derailer move further. We want to see if the cable is not too slack and thus if the shifter cannot take up all the slack to complete the movement at the derailer.

That was exactly the problem that I had on my Basso. I always had to forcibly 'overshift' (beyond the click position) with the left shifter to get the chain up onto the big ring. I didn't have any more adjustment left on the inline adjuster but tightening the cable did the trick.

 

[danhoro]

Many thanks, will try those suggestions later.

Just to confirm, the bent tooth isn't one of the deliberately shorter ones.

 

[ColinJ]

In case it isn't obvious ... If you are in my situation with an adjuster at the end of its travel, remember to put it back in the middle of its range before you pull the cable through to where you want it. That way, you will regain your ability to fine-tune using the adjuster.

 

[shouldbeinbed]

Usually those appear to be worn away or shorter, not bent outwards, as I understood the OP.

Totally agree, just making sure every eventuality is covered and its not something not clearly conveyed in words.

 

[danhoro]

You exasperate me... But we have to fix it. My next suggestion is to keep turning the high limit screw out by say 1/4 turn and testing between each turn. Keep on doing this until the chain is thrown off the chairning and then go back until that stops.

Also, just bend that tooth back into position using a shifting spanner or, since you probably can't get in there, a hammer. Small hammer, small blows.

Actually, before you do step one above, turn the limit screw out by two whole turns (or any small integer that wont complicate an accurate return) and then with the chain on the big ring, see if anymore pressure on the lever will make the derailer move further. We want to see if the cable is not too slack and thus if the shifter cannot take up all the slack to complete the movement at the derailer. If you are happy with that, return the screw to its original position and then go up with the aforesaid 1/4 turn and test.

Tried all of this, except trying to bend that tooth back. Will need to dig out a good spanner for that. But I tried making sure that the cable is taut enough to shift all the way out, and then tried adjusting the limit screw until it threw the chain off. It actually started coming off just half a turn from its original position, which I guess means it was already set fairly far out. But in any case, no luck - the dodgy shifts were still there, even at it's outermost functional position.

 

[Yellow Saddle]

Tried all of this, except trying to bend that tooth back. Will need to dig out a good spanner for that. But I tried making sure that the cable is taut enough to shift all the way out, and then tried adjusting the limit screw until it threw the chain off. It actually started coming off just half a turn from its original position, which I guess means it was already set fairly far out. But in any case, no luck - the dodgy shifts were still there, even at it's outermost functional position.

I am outta ideas. This is something that a mechanic needs to see. Remote control isn't working. I'm still not (too) convinced that there is an actual problem to start with. Have someone else ride the bike and give you a second opinion.

 

[danhoro]

Well thanks for sticking with it for this long! I'll see if I can find someone to look at it in person.

 

[danhoro]

If anyone's interested, I managed to fix this problem. I have to admit it didn't involve much in the way of technical troubleshooting - instead I invested £24 in an Ultegra FD. Works perfectly. Haven't had any issues on two fairly long rides now, and the shifts are smooth as butter, even compared to the smoothest I was getting on the Apex FD. Having had a search around on this issue I found that a lot of Sram users seemed to have issues with the FD that were hard to resolve, even on Rival/Force/Red.