Shimano 6 Gear Shifter
Analisa Wisdom
The front shifter is a Shimano integrated brake-and-shift assembly. The front derailleur "groupo" is Shimano SIS. I can pull the cable to make the derailleur shift into third but the shifter doesn't have "enough throw" to do it via the shifter.
By pushing the thumb lever, I could make the chain go into 3rd. But I could not for the life in me get it to click into 3rd inside the shifter and stay there, and so the shifter would fall back to 2nd.
After trying a bunch of things, including spraying WD-40 into the shifter to try and remove old lubricant as suggested in many videos, I finally played with the tension a bit further, and only then got it to work.
The lesson is: the mechanical strengths and precisions of a cable can be really surprising. You'd think that your thumb is really strong and would be able to overcome them with the brute strength of or hands, but that may not be true.
Soon after getting it to work silky smooth as mentioned previously, and including cable changes, I went for a 4 hour ride on wet conditions, and I could clearly notice how progressively the 3rd was again getting harder and harder to get into, until it got impossible again.
Since the cable tension had been unchanged during the ride, I concluded that the main factor now was actually the front derailleur, which is close to the bottom bracket, and so that is the most likely part where water would have gotten into, as opposed to the shifter.
Part of the difficulty of this diagnosis is that the WD-40 doesn't take effect immediately it seems, you have to move the hinges around several times to let it penetrate and remove what as creating the friction.
Cable tension screw at the paddle shifter was the cause of my problem.A second-hand bike.Someone had unwound the cable tension screw at the cable exit of the paddle shifter to it's maximum tension so I couldn't get it into third. I didn't have enough movement.I wound it all the way back in, re-tensioned the cable at the FD and then re-adjusted the cable tension at the paddle shifter.Bingo.
I think there is some problem with the basic cable tension, if it is not set up properly then the 3rd gear could be a problem. Try to find a youtube video, where they explain how to set it up properly, it's not that hard, just need some practice/patience.
The shifter has two size cogs in the centre. The first activates 1st and 2nd. To activate the third gear, a spring pulls the lever bar towards the centre (smaller cog). The spring isn't very strong and will stick, not pulling it in and therefore not catching the cog. Clean the area of the spring. I just use oil.
From what it looks like, it can be the derailleur angle affecting the shifting to the third chainring or, it can be that your derailleur cage has suffered damage and is out of shape or shaved. You can rule out the limit screws if the shifter is getting to the third index, as you've said it is. The cable tension is another possibility but since the other two shifts are good, it's unlikely that's the issue.I recommend you get the bike to your LBS to get it sorted out if you have troubles diagnosing the problem. Just appraise your derailleur cage and it's angle wrt to the chainrings before that, it's likely you get to the root once you do that. And yeah, the cage should be approximately parallel to the chainrings, you know what's wrong if it's not. I hope this helps. :)
It has been suggested by an anonymous edit, from a person who had a similar problem, to double check the cable placement at the derailleur fixing bolt. For example this extract from the Shimano Tourney Dealer's manual
The tip above from Swifty made me look carefully at the cable routing. I realised that my son's bike's cable was routed UNDER the metal protrusion rather than over it. This shifted the moment of leverage closer to the axis and hence made it harder to move the derailleur.
I assume your daughter was able to operate the gears fine before the bike was serviced. In that case, the shop broke your bike and it's absolutely their responsibility to fix it. Since you've had no joy from the mechanic, I suggest you speak to the manager about it: your key contention is that your daughter could operate the bike before they worked on it, and now she can't.
Unfortunately, if they still refuse to do anything about it, you probably can't do much more than leave bad reviews, and go to another bike shop: it's unlikely to be financially viable to sue, for example. I'd also note that $100 sounds like a lot of money to replace a low-end Shimano shifter, assuming you mean US dollars. The shifter itself costs $15-20, and fitting it shouldn't be anything close to $80 worth of labour.
With the shifter in the top gear, hold the rear wheel off the ground, pedal, and manually push the derailleur cage towards 1st gear (you'll probably need someone to help you do this, and be careful not to catch you fingers in the chain). The derailleur should go all the way to first gear easily.
While this may not be the identical shifter, and the adjustment procedure describe pertains to the front, cable tension might be a factor for the rear, as well. Keep in mind that adjusting cable tension may change the indexing (where it cleanly shifts into gear), so you may need to adjust this as well.
I've been trying to deal with this for years. Finally, I've discovered something that works in most cases. I primarily work assembling new bikes, including for kids, and have found that sometimes the shifter is jammed up tight against the handlebar grips. I loosen the brake lever and shifter and move them usually no more than 1/16 inch toward the center of the handlebar. That leaves about that amount of space between the shifter and the grip. Oftentimes that's enough to allow the shifter to move more easily.
Follow the gear cable to the back of the bike until you come to the nut that holds it, pinch the cable with a set of pliers and undo slightly the nut. Let it off a tiny bit and retigten the nut to hold the cable.
All the shifting was working smoothly until my bike fell off to the ground (edit1: to my right side hitting the right side of the bike) with me couple days back. Now after about a week when I took my bike for a ride I found that the rear shifter doesn't work as intended.
The problem is when I push the lever (rear) to shift to a smaller gear (larger cog), the lever doesn't come back to the neutral position, thus I have to manually pull it back to the neutral position. When I push the lever, it sort of gets stuck there. So when I want to shift to higher gears I have to push the lever then take it back and then push it again and so on and so forth. Shifting to higher gears works perfectly and generally there's no problem with indexing or any other tunning thing, only thing is the lever getting stuck. Can't be a problem with cable either.
Front shifting working as usual. Today I opened the case just to see if I can find the reason for the issue by visual inspection but I can't identify anything to fix (have attached a pic after removing the rear shifter case).
EDIT3 (closure): First I tried losing the cable tension to see if the lever is still stiff and it was. Which made it clear that the problem is with the shifter and not with the cable. And then I removed the back cover of the shifter and voila! it started working. But it gets stuck when I fully screw the nut in with the back cover. So I just screw it in to the extent that the lever is working and left it there.
This is not easy to solve without actually having the bike to play with. It's also something I'd do fairly quickly so I'm trying to give a detailed explanation of something I've learned to do from experience rather than written instructions. I've built my own bikes, worked for a year as a mechanic, and ridden rather a lot on a variety of different bikes. I'm also regularly wrong and still learning. So...
Modern derailleur systems have a lot of things that have to be adjusted fairly accurately for them to work properly. Unfortunately some of the tests that a mechanic will do are destructive, in that they will usually cut the gear cable and replace it. Generally speaking for anything more complex than tweaking the barrel adjuster they will replace the cable and outer, because those are often the problem and they're cheap. In other words, paying $5 or $10 for a new cable+outer will often save $20 or more of mechanics time.
Leave the cover off the shifter (as it is in the photo), everything should still work. If you lost that cover in the crash, buy a new shifter (or replace the cover if you can somehow find a matching one). The missing cover isn't a problem in a nice clean shed, but on the road the shifter will fill up with water and muck and stop working fairly soon.
Look inside the shifter, jiggle the bike, trying to see whether there are any loose parts in the shifter (or random debris). Note that it's full of sticky grease so anything loose will likely be stuck in place by the grease.
Next, get slack gear cable next to the shifter. Often there will be open sections of cable and you can pop a section of outer off the bike to get this. The attachment to the frame looks like this, although they're usually welded on rather than riveted:
Now you can pull the cable to make sure it slides freely in each section of outer. If it doesn't , replace it. What you're looking for here is not "maybe a little extra friction" but "hard or impossible to move by hand".
The shifter. Look for obvious damage. Hopefully you did that already :) Specifically, if the release lever that's not returning is bent it might rub on the body of the shifter. Even plastic levers do this.
Pull gently on the cable as it leaves the shifter. You're just reproducing the pull from the derailleur spring, not ripping the shifter off the handlebars. Now click the other lever on that shifter to change back up through the gears.
It sounds as though the last step is likely to fail. If so all you can do is poke around in the shifter more aggressively, trying to dislodge anything loose, maybe put a bit more oil in there to looses the grease and see if that helps.
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