Buggington

Hello

I've been battling against my chain for a while - it seems to be constantly noisy, even though I don't really use the bike that much at the moment. The chain's always kept clean and reasonably well oiled, so it's a mystery as to why it's being so noisy. Any ideas?

The other thing that's been getting to me is shifting up through the gears when I'm on the largest chainring; shifting through 1, 2, 3 is fine, but then it struggles to change up again until I try to go for 6th or 7th when it's fine again. Any ideas why this might be, and how to make it stop doing this? The indexing seems to be OK when it comes to shifting down, so I'm at a loss.

Thanks

cny-bikeman

There can be multiple dfferent or simultaneous reasons for chain noise (which is of course subjective anyway) as well as for shifting problems. It is simply impossible to do diagnosis from one symptom, rather it becomes a guessing game, which wastes time and teaches you little. My opinion is that you need a mechanic to evaluate the chain noise, as it is extremely dfficult to see, let alone hear exactly what is going on remotely. As for the shifting problem you need to provide more information:

"it struggles to change up again" sounds like a personal problem, not a mechanical issue. What does the drive train do, and in which gears (front/rear combos) that is not acceptable?

When did the problem start, and did it coincide or follow any equipment changes, accident, etc?

What standard adjustment/maintenance procedures have you tried so far? (Following Park, Sheldon etc.)?

FBinNY 

Obviously we can't hear the chain over the internet but here's a few things to check.

First there's the normal purr or buzz of chaindrive, who's volume changes with chain lube and chain/sprocket condition, but never gos away.

I'm assuming you have worse than that, so the next suspect is bad trim. IMO this is the most likely issue, since you have asymmetrical shift response.

I always have problems when folks number gears, whether they're starting from the outside or inside, nor do I know for sure which way the RD us sprung (98% are sprung to the outside or high).

So assuming that you have a typical high-normal RD which springs to the outside, and it shifts fine toward low, by cable, and sluggish to high by spring, than you have the classic sticky cables. This also cause poor trim following upshifts, while rarely causing trim problems after a down shift.

There's an easy test to confirm the diagnosis. Following a problem upshift, while the RD is still noisy, firmly pluck the bare wire away from the frame like a guitar string and let it snap back. If guitar plucking solves or improves the poor trim, then it's 99% confirmed that the cables are sticking. Sometimes you can fieldstrip, lube and reattach the cables, but just as often the housings are worn at the insides of the curves and the only remedy is to replace them.

Other causes of chain noise include poor/no lube, worn idlers, worn sprockets, mis-aligned RD hanger to name a few. But the asymmetrical shifting is sort of a tip off to check the cables first.

ultraman6970

W/o hearing or seeing the bike is hard to know what is wrong, my best guess is that you have problems of tension in the cable or friction somewhere and the RD is just setting in the wrong place. Besides that is hard to know.

Not rocket science what is working wrong. Now if you can't really see any difference between a RD in the right place and in the wrong place then you deserve to pay for the repair

No idea what you call 1st gear, so there is even a slight possibility that you are crossing the chain big time. If thats the case then you found the problem, but again is hard to know w/o having the bike in front.

Good luck

Buggington

Thanks for all the replies. There are too many for me to go through and quote, although I would say that ultraman was a little harsh about the RD placement

CNY - It seems unacceptable in going up to gears 4 and 5 - it seems to take a long time to go up (around 10 seconds), just constantly clicking away, sounding as though it's on the verge of eureka, but not quite getting there.

The cables have not long ago been replaced due to it bluntly refusing to change up unless I let out loads of extra cable, so I doubt it's that, although I have ridden in VERY heavy rain since those were done.

It's a basic Shimano Tourney RD, done about 2000 miles on it. No idea which way it's sprung unfortunately, but I went into an LBS today and will take it in there next week to see what they can do. I guess I can pay for that repair then

Thanks for all the help - over the next week I'll have a play with the cables.

gyozadude

Cable housing can make a huge difference. I've personally purchased the Walmart Bell cables/housing combo pack on sale and I've tried them only to find out how bad they really are. Without a liner and with very soft housing coils, the actual cable almost immediately grooves the interior and increases friction by a huge amount. And because the coils are soft, they bend easily and form kinks, especially near cable caps.

The whole shifting is aggravated by a bike that has cable clips and no braze-on stops. This forces the entire derailleur cable to endure the friction of 4ft or more of cable run. No wonder the shifting on the back is bad.

Now, your situation might not be as bad. But just swapping cables isn't necessarily going to fix the problem. Swapping cables AND housing, using lined housing, lubing the cables, making sure the cable routing is smooth and continous and not kinked, then overhauling the RD to make sure the springs can overcome the friction when shifting to smaller cogs (i.e. higher gears) can make the shifting seem like night and day.

bkaapcke

SRAM chains talk to you when they get worn by rattling. They won't measure as 'worn out' but the noise lets you know they are. Other brands may do this too. bk

ultraman6970

Is super easy to find out what can be wrong... put the bike upside down.... have a friend. wife or who ever to shift the bike up and down and see how the RD moves or if the RD wheelies aren't aligned with the cassette or freewheels cogs.

Check the cable tension as well, pretty easy... just touch it, the cable has to be tensioned, if lose like a spaghetti then is clearly that the problem goes that way.

If the Tension is ok and the RD is not aligned with the cogs then the fix is pretty easy.. just ask here how to fix that.

cny-bikeman

I'm sorry, but this one is not "super easy." The reason is this:

• If shifting is OK when moving to larger cogs that would indicate indexing/tension is set properly, the shift lever is working OK, and the derailleur and lever are properly matched.
• If shifting is OK on the small chainwheel in both directions that would normally indicate that cable friction is not a problem.
• If shifting to smaller cogs is a problem only in the middle that would also normally indicate that in general cable friction is not a problem, as the derailleur spring pull is weaker as one moves outward.

TO THE OP - Please, if we are to provide help we need full information, so please try to answer any direct questions, such as:
and also report once you have tried suggestions, such as FB's about plucking the cables.

I also need to confirm that there is truly no problem on those middle cogs when on the smaller chainwheel(s)j.

Using the information we have so far I have two possible causes:

Erratic shifting can often be traced to misalignment of the pulley cage, resulting from twisting of the derailleur or the hanger (much less so if just bent inward). The expected behavior from that problem would be that one chainwheel has problems but another does not, which seems true in this case. The dilemna, though, is that I would expect problems would tend to occur at either inside or outside cogs, not in the middle, as a twisted orientation results in the top pulley being most out of line at the two extremes (in opposite directions) rather in the middle. It has to do with the geometry of the pulley rotation when not parallel with the cassette in both vertical planes.

The experienced mechanics here who have dealt with that type of problem likely know what I mean, but I may be overlooking something. In any case it certainly would be advisable to make sure both hanger and pulley are aligned. Hanger alignment is easy, pulley misalignment has to be judged by eye or by temporarily installing a new derailleur.

I do have one other theory, but it's a bit of a stretch. Rather than overall cable friction there may be a problem with the shift cable at one particular spot - a fray, rough portion, small kink, etc). When that portion of cable passes through a ferrule or similar "obstacle" it hangs up. Once enough slack is created by continuing to shift toward the outside the derailleur spring pulls the cable sl by that point and resumes working OK.

The reason that idea is a stretch is that the rear shift cable position is exactly the same no matter what front chainwheel is being used, so I would expect the same problem to occur with the other chainwheel(s). It could be that the derailleur is misaligned and the cable has a problem, or it could be that the derailleur being closer to the cogs when on the smaller chainwheels is a factor.

"A slim chance is better than none," so even though the cable has been replaced I would suggest carefully instaling a new rear shift cable.

I would suggest the following approach, testing after each step:

1. Hanger alignment (should be done as a matter of course with stubborn rear shift problems)
2. New shift cable (quick and inexpensive, eliminates another possible cause)
3. Replace derailleur (the only thing left as a possible cause)

I believe there is no way that the problem could still be present after those three steps.

Buggington

Yikes - I didn't realise this would be such a hot topic. Having done a little more messing I've worked out that the noise is mainly coming from the front chainring - it's worse when I have more pressure on the chain, like when I'm maintaining about 18-20 mph.

I have no idea when the noise really started - it's been on and off for a while, which is kind of annoying.

The erratic shifting is something I've yet to find the time to investigate properly - I'm going near a bike shop on Monday so I might have to drop in there - these university open days are really getting in the way of my bike maintenance. Going back to Ultraman's flipping it upside down, as I look at the derallieur from the top everything should all be in line? I seem to remember that it's slightly out, with the bottom of the derallieur further from the wheel than the top. Would a misaligned derallieur cause issues when changing down?

In the meantime, thanks for all your help, and I need to get that and the now dodgy front brake sorted (fork oil explosion - new pads required?).

Thanks again, and apologies for the lack of information; still new to all this forum stuff.

cny-bikeman

We still don't have answers to questions posted previously that would allow more accurate diagnosis

See above: "Erratic shifting can often be traced to misalignment of the pulley cage, resulting from twisting of the derailleur or the hanger." There's no point in turning the bike upside down. Just take it to a shop and explain the problem. Good luck!

Buggington

Thanks! The bike's starting to look a bit unloved, so I think this LBS trip is going to be an expensive one D':