alsiedee

Last April I bought a Trek 2.1 WSD™ (specs below). I'm repeatedly having to have my shift cable adjusted at my LBS as I keep losing my big ring - the chain just won't stay there after shifting. While I know that I should learn to fix this myself, is this really normal? Has anyone had this problem and can shed some light on why this keeps happening? Is it something specific to my components, my bike, or something I might be doing to cause this?

Long version of problem: Within a few rides after buying my bike I was back in the bike shop because it was taking 2 clicks to shift into the front big ring - not a big deal, but wasn't sure this was normal. My LBS adjusted a cable & everything was fine - for a few rides. It was soon taking 2 clicks to shift again & I decided not to worry about it, it wasn't a big deal. Then, I totally lost the big ring - the chain just wouldn't stay there after shifting. Back to LBS for adjustment. It shifted on 1 click for a few rides, then 2 clicks, then, in my first tri, again lost the big ring. bummer. This has happened repeatedly, most recently in a tri this past weekend. (note: I wasn't shifting under load; it was on a flat/downhill.) I'll be making yet another trip to my LBS today to get the cable adjusted (and really paying attention so I can do this at home) but it doesn't seem to me like you should have to adjust your cables every few rides - or do you?

confession: I'm a horrible cross-chainer - love my top & bottom gears - but I thought this would potentially stretch your chain, not the shift cables. Could this be contributing?

Thanks for any help/suggestions -
Ally

Drivetrain
Shifters Shimano 105 STI, 10 speed
Front Derailleur Shimano 105
Rear Derailleur Shimano 105
Crank Shimano R-600 50/34 or R-553 50/39/30
Cassette Shimano 105 12-27, 10 speed

Components
Headset Aheadset w/cartridge bearings, integrated, sealed, alloy
Brakeset Shimano Tiagra w/short reach Shimano 105 STI levers

UberGeek

This sounds like a problem with the front derailleur... The cage is adjusted too high, allowing it to shift off the chain-ring.

Next trip from the LBS, apply some Threadlok (Light duty one, you don't want to permanently seal the threads) to the derailleur adjustment screws. I have a feeling they are vibrating out of adjustment due to your cross-chaining.

BikeWise1

Is this a double or triple?

HillRider

Cross chaining is more than just a chain-wear problem. It makes for the worst possible chainline and amplifies any tendency to "ghost shift" as you are experiencing. So, learn your gears so you don't cross chain and have the high limit screw checked to see if it's a bit too tight. A 1/4 turn might be enough to solve, or at least reduce the problem. Also, as recommended, check to be sure the front derailleur is sufficiently close to the big ring. If it's mounted too high it will definitely contribute to shifting problems.

While I suppose it's possible, I've never had a limit screw change it's setting spontaneously so I don't think that's an issue.

alsiedee

It's a compact double.

alsiedee

I'll work on not cross chaining (sigh) - I just often need that lowest gear to get up the hills around here. (my previous bike was a low-geared (18 gear) mtn bike..) The top gear will be easier to avoid; I'll just need to learn to be aware of what gear I'm in.

Thanks.

tiberon

Your lowest gear should not be cross-chained.

ultraman6970

User problem in my opinion, then the shifting starts messing up. If you are going to use 53x26 just use 39x17, it is almost the same and the chain wont be crossed, and then the LBS will start loving you again because u arent a PITA client

DCB0

bad advice.

desertdork

If the derailleur is positioned correctly, and user error is not an issue, then it might be worth verifying: (1) There is nothing preventing the derailleur's pinch bolt from securely clamping the cable, and (2) The longitudinal wires in the cable housing are not migrating through a ferrule.

UberGeek

How so?

Lot's of systems use threadlok to keep adjustment screws in place. It's easy enough to break if you are using a screwdriver, but vibration wont work it loose.

If it's good enough for an air frame, it's good enough for a bike

DCB0

I am well aware of threadlocking compounds, how to use them, and why to use them. But your advice was bad for two specific reasons:
1. Derailleur adjustment screws or nuts already have a small nylon insert to keep them in place. They do not vibrate loose on modern bikes.
2. It is not the limit screws that are going out of adjustment. The OP description of the problem does not fit with a maladjusted limit screw.

ryanwood

+1 if you were having an issue shifting initially, you may have partially worn through a ferrule.

I have bar end shifters on my touring rig and I used to have a problem with pulling on the shifter too hard causing excessive wear on several ferrules. To my untrained eye, I thought the cable was somehow magically stretching every month, but the LBS found several points were the cable was actually wearing through the housings and ferrules. After replacing cable and housings and training myself to take it easy on the shifters, all is well.

alsiedee

Okay, so just got back from LBS. They found that my shift cable had chewed all the way through the ferrule. (This may actually be the second time this has happened - I forgot to mention that the original cables had to be replaced once already.) They put a stronger ferrule on & replaced the cable.

There's a big local tri this weekend (also why I needed my bike fixed right away), so to have them help me at all was awesome. The mechanic gave me the old cable & suggested I come back next week and have someone look into what might be causing this. I'll ask them about some of the other things you all have suggested, too.

Also, about the cross chaining - I think I misunderstood what combinations cause that, and am probably not actually doing that. (I thought it was using the lowest & highest gears; need to actually look at my rear cassette next time I'm out to see when the chain is actually in the extreme positions.)

Some of you were quick to cite "user error". It would actually be more helpful if you would let me know what exactly I might be doing that's wrong - I don't really know.

Again, thanks everyone for taking the time to make some suggestions. If you have any additional comments about the problem, what caused it, or what I should do differently to keep it from happening again (or what I should ask the bike shop to look into), that would be great.

Thanks.

UberGeek

Sure they do, given enough vibration, enough turns through it (Like taking it to the LBS 3 times to be adjusted)... Even nylon inserts wear out, and are not fail-proof. It's why aviation uses cotter pins + nylon locking nuts.

Interesting, I'll make sure I let Park Tool know that their page needs updating:

https://www.parktool.com/blog/repair-...ur-adjustments

Infidel79

The passage you quoted from the Park tool website is indeed a bit confusing, and I think poorly written. I think what it means is that if the cable is too tight, then the inner limit is thus established by cable tension, not the inner limit screw. Therefore, if the cable tension is reduced (i.e., "if the inner wire tension were to change"), then the inner limit would also change, up until the point at which the derailleur encounters the limit screw. I think the part about the chain falling off the rings assumes the limit screw was not adjusted properly in the first place, and the cable tension subsequently becoming too loose.

Since we're talking about not being able to stay in the big chainring, this explanation doesn't seem to apply to the current scenario. The only way a limit screw coming out of adjustment could cause the OP's issue is if the outer limit screw were to spontaneously tighten itself from road vibration, thus preventing the derailleur from reaching the big ring in the first place. I think this is highly unlikely. A poorly installed cable housing is a much more plausible scenario in this case, as has already been determined.

UberGeek

Unless, one is cross-chaining (Which the OP stated). But, it's moot, since he's already determined the cause.

goagain

The way I understand cross-chaining, it's using a low gear in front with a high gear in back, or vice versa. (using both large rings together or both small rings). It's not just using a low or high gear. I was wondering why you liked to cross-chain, but you probably aren't, as you said. Good luck with your ride.

cyccommute 

The kind of vibration you are describing never happens on a bicycle unless, I suppose, you tied it to an airplane landing gear Basically once a limit screw on a bicycle derailer is set, you never have to mess with it again...unless you tie it to a landing strut.

You are, by the way, misinterpreting what the Park website says. If you were to set up the cable so that it had too much tension, the derailer might not rest on the limit screw. If the cable tension changes, then the derailer would start to rest on the limit screw and the derailer would drop off to the inside.

alsiedee's problem is related to a similar change in cable tension caused by the wires in the compressionless housing moving. She needs a better quality housing and better ferrules.

Mondoman

goagain is right on the cross-chaining. It's called that because the large chainring in front is normally on the opposite side from the large cog in the back, so running large/large or small/small means that the chain *crosses* all the way over from side to side between front and back.

Recent posters: I'm betting the OP prefers that we use a female pronoun in our references to her.

digibud

That is why you start by setting the High/Low stops with no cable tension by detuning the cable and pulling it by hand to set the High and letting it loose to set the low. That way you know the High/Low stops are not being affected by the cable tension itself. After that you can begin to tension the cable for proper shifting. With regard to front derailleurs, the most common thing I've seen is the derailleur set too high. While Shimano says something like 1-3mm, the fact (as far as I know) is that the closer it is the better it is as long as it clears. Many lbs won't bother with this tweak because it can cause the derailleur to get moved so it's not perfectly parallel and that can be a real challenge to line up perfectly. Getting your front in exactly the right position will help thing a lot. I realize this may not apply to the OP's situation so ...end of hijack...

DCB0

What problem related to the OP do you think cross chaining would cause? You have lost me.