Shifting problem

[Catrin]

I do not know what to think. Last Sunday my LBS adjusted both front and rear derailleurs because they were shifting very roughly, chain making lots of noise, and my chain was falling off the front.

Took it for a short ride twice since then - those were fine. Today went for a 55 mile ride and the problems started up again. This time, however. I noticed that the problem was only in the middle ring (I have a triple). Lots of noise and long after shifting the chain "catches" and so forth. This has been known to cause my foot to come off the pedal!

I wound up spending as much time as I could in the big or granny gears - and things were as smooth as silk.

Any ideas what might cause this? I am going to ride to my LBS tomorrow afternoon - and thankfully they do not charge for that. I am starting to get concerned that something else might be going on. I only have 750 miles on the bike - 710 miles since my LHT conversion.

Is this sort of thing normal sometimes, that it needs adjustment so often? If so - then I need them to teach me how to do it myself....

[Catrin]

I do this. The rear cog is somewhere in the middle when I shift the front - but I am not talking about what happens when I shift the front (that is fine) the problem is when I shift the rear cog. Pretty much ANY shifting of the rear cog when I am in the middle chain causes all kinds of noises and catching and not-fun things to happen. Other two chains are fine when I shift the rear cog.

Sorry for any confusion.

[Catrin]

I see

In that case hopefully the earlier post might pertain to someone else. Because I've no idea what would cause that.

Oh it certainly pertained to me in the not so distant past

Last weekend it was happening with any shifting, regardless of what chain I was in. They adjusted both derailleurs - actually they worked with it for quite a bit. They probably just need to tweak that adjustment.

It was the only thing that kept me from having a perfect ride today - and I did figure out how to get around it - by avoiding the middle chain entirely

[OakLeaf]

If they did a big adjustment - i.e., had to re-position the cable in its clamp rather than just using the barrel adjusters - then the cable and housings will re-seat a bit just as they did when everything was brand new. So, probably normal.

You should learn to do this yourself. It's very simple. Most LBS will be happy to show you.

[Catrin]

If they did a big adjustment - i.e., had to re-position the cable in its clamp rather than just using the barrel adjusters - then the cable and housings will re-seat a bit just as they did when everything was brand new. So, probably normal.

You should learn to do this yourself. It's very simple. Most LBS will be happy to show you.

He appeared to do a fair amount to both front and back - he did more than adjust the barrel adjusters. He also adjusted the stops(?) on the FD to help prevent the chain from falling off.

[KnottedYet]

I'm trying to remember what kind of shifters you have on your flat bars, so I may be completely off here.

Has anyone explained "trimming" the derailleur to you?

Indexed brifters have pretty much one click or two half clicks and BOOM the front der is where it is gonna be. Some of the bar shifters have lots and lots of clicks, and your front der has several choices of where it can be. They act almost like friction shifters.

For sake of illustration, assume here I'm talking about a bar shifter with infinite clicks, or friction shifters:

Whaling the shifter to one extreme or the other pops the chain onto the big or small ring, and the derailleur cage (if the limiter screws are set just so) is pretty much out of the way of the chain as you merrily zip through the rear cassette. (assuming here you are not cross-chaining, which I know you know about)

The middle ring can get kind of exciting, because the cage can be centered on the ring, or more toward the big ring, or more toward the small ring. The chain can be merrily whipping through the cage in the middle ring and rub against the cage sides if it is too far one way or the other. If it is a bit too far one way or the other, the chain will rub as you shift the rear der and the line of the chain changes.

There is nothing wrong with the shifter or the der. This is just how it works. It has an arc of travel. At each end of the arc there is a ring ready and waiting. Somewhere in the middle of the arc is the middle ring. You get the chain onto the middle ring, and if you hear chain hitting der cage, you finesse the cage away from the running chain by moving the der a smidgen. (on my twist shifts, it was a couple tiny clicks, on my trigger shifts it was one click, on my friction shifts it is a smidgen) That trims the derailleur.

Here's your experiment for the day:
Take the bike out, ride around, shift into the middle ring. Get off the bike. Look at the chain, see where it sits relative to the two sides of the der cage. Now, move your left shifter a smidgen. See how the cage moves but the chain is still on the middle ring? Move that cage until the inside plate is touching the chain. Now move it until the outside plate is touching the chain. Now move it until it is centered. Get on the bike again. Ride a few yards. Does it make noise? Shift up and down the cassette. If it makes noise, move the left der a smidgen. If that causes MORE noise, move the left der the other way TWO smidgens. Voila! You've trimmed your front derailleur!

Of course, if you can't move the front der a smidgen and eliminate the noise you get from changing rear cogs.... then what I've just told you is useless and your shop needs to give you a hand.

But maybe it would be useful for someone else.

[Catrin]

I'm trying to remember what kind of shifters you have on your flat bars, so I may be completely off here.

Has anyone explained "trimming" the derailleur to you?.....

Of course, if you can't move the front der a smidgen and eliminate the noise you get from changing rear cogs.... then what I've just told you is useless and your shop needs to give you a hand.

But maybe it would be useful for someone else.

I have trigger shifters - and someone has explained how to trim it - though it is only available to me if I have shifted up from the granny chain (per my LBS). I will try your experiment this afternoon. I tried to trim yesterday with the smidgen click on the shifter - but little seemed to help when I was in the middle chain. That does not mean that I was trimming it correctly...

[KnottedYet]

I have trigger shifters - and someone has explained how to trim it - though it is only available to me if I have shifted up from the granny chain (per my LBS). I will try your experiment this afternoon. I tried to trim yesterday with the smidgen click on the shifter - but little seemed to help when I was in the middle chain. That does not mean that I was trimming it correctly...

Seriously, get off the bike and watch the derailleur move. It's really cool, and it's the best way to see how it works. Watch how the chain line changes as you go through the cassette. Watch how the chain gets closer and farther from the der plates.

Seeing how it all moves and works together will help you diagnose things when they're goofy. Anything you see helps the mechanic, too.

And if you figure out why the chain is rubbing on the der cage so hard that it's making noise and trying to shift all by itself, you might be able to fix it on your own! (which is always VERY cool!)

[OakLeaf]

You'll need to be turning the crank and the wheel for it to shift. A workstand is really helpful here, but you can find something to hook the top tube or the nose of the saddle on, or have a friend hold the rear of the bike up off the ground for you (I know you've mentioned grip issues, so holding it yourself might not be feasible).

[KnottedYet]

Or you can do what I do: ride, shift, stop and look. ride, shift again, stop and look.

I've tried to hold the bike up and spin the pedals and shift and every dang time I've somehow managed to drop the bike on my own head. It's like magic.

Someday Santa will bring me a repair stand. (and a house, and a dedicated garage just for playing with bikes!)

[withm]

You may be able to use the rack on your car (depending on what rack system you have) to support the bike while you spin the pedals and shift.

Before I got a repair stand, I could set my bike rack up on my deck railing. Enabled me to do a few repairs this way, but the low height made it hard on my back to do anything too involved.

But since this problem only shows up in the middle ring, and she has said she's had the chain come off a few times, I'd check for a worn or bent sprocket on the middle ring. Sight down the middle ring while slowly turning the pedals and make sure that every tooth is aligned.

[Catrin]

The FD behaved better on my ride today - but there were not many hills today so I spent a good amount of time in the big chain. After dinner I will get my rack back on my car and get the bike up there and see what I can see.

Thanks for the advice on how to proceed and at least it will help me discuss it a bit more intelligently with my LBS if I need to later this week. They will be installing/adjusting my new saddle so it will be good timing.

I really hope it isn't a bent sprocket - that sounds expensive The fact remains that whatever the problem is - adjustment or something else - it seems focused on that middle ring. To the best of my memory THIS bike has not fallen over on that side...

Once I move in the fall, I am going to start saving for a work stand. I think it will make everything easier and help to keep that nice new apartment looking nice.

[KnottedYet]

I really hope it isn't a bent sprocket - that sounds expensive

Naw. $20-$25.

[Catrin]

The crank teeth look fine - at least to my inexperienced eye they do.

I did note that for some reason the chain in the middle chain ring does rub the side of the FD quite a lot. I also noticed this happening whether I trimmed it or not. Perhaps it still isn't adjusted quite right?

[KnottedYet]

The crank teeth look fine - at least to my inexperienced eye they do.

I did note that for some reason the chain in the middle chain ring does rub the side of the FD quite a lot. I also noticed this happening whether I trimmed it or not. Perhaps it still isn't adjusted quite right?

Try moving it more. Two smidgens. Three smidgens. Four smidgens. Move the shifter enough that the cage is centered relative to the chain. (trimming it means centering it or at least moving it enough that the chain isn't hitting the side plates of the der cage) Play with it. Move the cage so the chain touches one side, then move the cage so it touches the other side. Get a feel for just how much you can move that cage within the arc around the middle chainring without actually shifting the chain to the next ring.

It's like doing the waltz with your shifter, derailleur, chainrings, and chain. Find their happy place, where they work together and keep the beat.

It could also be that the cage is set at a sharp angle to the chain line where you just can't trim it.

If you can't figure it out and do take it to the LBS, have them show you exactly what is going on and exactly how to fix it. Knowledge is power!