Strange Shimano ultegra gear shifter intermittent failure

I am a human wrote:

I can recreate your symptom by moving the brake lever as if I'm downshifting to an easier gear, then carrying on the movement with the upshift lever - it then encounters no resistance and moves the whole length of the lever throw.  Is there something that's making the brake lever move inward at the same time as the upshift lever?

No, the brake lever isn't being moved at all. Thanks!

kenyond wrote:

My tiagra 4700's wont shift if they have been pulled back a bit as if I was using the brakes, like you say theres no click or anything, you may have a little grit stopping it going back and not engaging the ratchet for gear changes

Thanks. Hopefully giving them a good clean, as in the videos recommended by @TypeVertigo, will get things working again.

Tjuice wrote:

Like everyone above has said, I would have said

1) Is it possible that cables are not moving freely enough

2) Possibility that the grease in the shifter has got too sticky and is stopping the mechanism working properly. 

Re: the latter, do you find you have more problems when it is cold and fewer problems when it is baking hot?  Try heating up the shifter with a hairdryer for a few minutes (worth peeling back the hoods first to stop them insulating your attempts) - does that make the shifter work better?  If so, it could well be gummed up grease (heating it up can make it less viscous and sticky).

I had a problem that sounds extremely similar to yours a number of years back with some Shimano RSX shifters.  Despite the warnings that these are not user-servicable and should not be taken apart, I decided that I had nothing to lose, and I was pretty confident of my ability to put back together something mechanical that I had taken apart (I have quite a bit of experience of dismantling/repairing/re-building a variety of mechanical things).

I found that it was entirely possible to dismantle the shifter very carefully and found that there was some very, very thick old grease in there.  I thoroughly cleaned everything, and then re-greased with something much less viscous and put it all back together again.  Shifters have been faultless since then.  I just wish I could get some replacement hoods for them!

Good luck finding a solution

Hi TJuice

I don't think it's the cable. There's a new cable in there and the shifting is just like when the bike was new. The problem I have only arises occasionally - 99% of the time the shifter works great. I think if it were a cable problem I'd have it all the time.

I'm guessing gummed up grease is probably the culprit, as you suggest. I've not noticed a hot/cold difference - hadn't thought about it. If I can't fix it with cleaning I might take it apart (and take photos along the way so I can put it back together). I have to wait for some lube & grease to arrive before I try though.

Thanks again!

Duncanap wrote:

It may not be relevant but I had something similar when my hoods (the rubber covers) stretched and moved.

i seemed like the hoods were providing the return spring so you could shift once but the would just get a soft lever.

could be worth a check.

Actually, my hoods do move around a lot now (following a bike service & new bar tape being added). But the problem was happening before the hoods started to move about. I will take a look though. The difficulty is that I only occasionally have the problem - it's not easy to reproduce (hence the videos in my original posting - at my LBS I couldn't get the problem to occur, so had to film it in the wild).

Thanks!

. . wrote:

Duncanap wrote:

It may not be relevant but I had something similar when my hoods (the rubber covers) stretched and moved.

i seemed like the hoods were providing the return spring so you could shift once but the would just get a soft lever.

could be worth a check.

I had the same problem. There's a small lever that pushes against the hood, and when the hood slipped, the lever would get stuck.   The lever is just above where your thumb sits when riding on the hoods, and I found I could push it back with my thumb when it got stuck.

The problem is now solved by Gorilla-gluing the hoods in place.  Not sure if Shimano would approve, but it works.

OK, I'm going to take a close look. Thanks very much. I couldn't come up with a reason why standing up out of the seat (normally on hills) could be so well correlated with the problem occurring. But when I stand up to climb, I pull up on the handlebars with my hands wrapped around the base of the hoods, and they do get moved. Particularly the right one gets rotated quite a lot (45 degrees sometimes). It could be that my shifters have a grease problem, but that would strike more consistently or randomly (not well correlated with hill climbing), but it seems more likely now that it's the hoods.  I'm going to look right now.....

Thanks again!

TypeVertigo wrote:

terrycojones wrote:

@TypeVertigo - thanks, that sounds super helpful, and like it could be the cause. I'd never even heard of pawls. I should probably play more Scrabble Anyway, I'll go track down the Art's Cyclery video.

Allow me to help point you in the right direction.

https://www.youtube.com/watch?v=9657OoOY3oE

The video shows SRAM DoubleTap levers, and the products used are White Lightning Clean Streak for cleaning (vs WD40) and Slick Honey + Boeshield T-9 for relubrication (vs regular Shimano grease + Tri-Flow Superior Soy Lube), but it's still basically the same method.

 

There's also "RJ the Bike Guy," another YouTube channel. RJ's hobby is buying old or inoperative bikes and restoring and/or upgrading them to modern drivetrains; some of these projects he keeps while the rest he sells. He mentions the WD40 fix a lot, and he has so many videos detailing the technique - below is one of them. The fix works even with flat-handlebar MTB trigger shifters.

https://www.youtube.com/watch?v=JbgsJRt-h1A

https://www.youtube.com/watch?v=49lAdo_vUX4

I hope this helps.

Thanks TypeVertigo!  I'd found the first after your original reply, and just watched the two from RJ. I have a couple of products on order & will give it a shot as soon as they arrive...

arckuk wrote:

I've had a similar, though less severe issue with my Ultegra (6700 - 10 speed) shifters. It will sometimes be the case that shifting to a smaller cog results in no click, and a lack of the usual slight resistance that is associated with the shift. This is pretty much always solved by repeating the shift action. I've assumed it was down to poor engagement of the sprockets in the shifter and/or resistance in the cabling. 

I've also found it difficult to adjust the read derailleur position to get consistent gear indexing - twiddling on the barrel adjuster never seems to get things as perfect as they are on my 105 (5800 - 11 speed) shifters.

I changed the cable a month ago or so, mainly to try and get the indexing to improve, which it has slightly, but thinking about it I think the failed shifting hasn't occured since, so maybe this has solved it. Maybe a replacement of the cable outers (which I changed a year or so ago) and perhaps a look at the bend radius in the cables would also improve things. I find the action of both 6700 levers to be significantly stiffer than my 5800 equivalents.

Sounds like the same thing, but repeating the shift action has no effect for me (see videos). For me it's just a matter of time until it comes good again. That would be, I think, consistent with the shifter being a little gummed up - something sticks and doesn't return to its usual place, but after a minute or two it slips and reverts to normal.

Re gear indexing, I'm getting better at it. There's no stiffness at all in shifting (when it works). In your case you might have slight cable fraying - that will really cause a big increase in stiffness. I had that happen recently (on the front rings) due to rubbing where the cable entered the frame.

Thanks!

Acm wrote:

On older Shimano shifters, a similar thing would happen if you put some pressure on the brake lever (started to shift to a larger/easier sprocket) and the pushed the lever for a smaller (harder) sprocket. I've no idea if this is the case for the newer shifters but it might be

if the new shifters do work in the same way, I'd suggest that the cause is something to do with the ratchet not returning properly after shifting to a larger sprocket, which could be because the shifter is gummed up but might also be because the cables need replacing.

for what it's worth, I stripped a Shimano STI shifter down once and it was a bitch to get it all back together. It still works, but I had to leave out a return spring in the shifter so my advice would be not to try and take it apart!

Thanks for this. I think it's more likely the shifter than the cable, as this (also) happened with a cable that was brand new (was installed the same day by someone who knew what he was doing, not me!). I've also heard that you should never try to disassemble an STI shifter... thanks