Buggington

Hello again guys, sorry, you're probably sick of seeing my username in this part of the forum again.

I've had an issue with a noisy drivetrain for a while and it seems to be getting worse. I took it to the LBS and they said that the front derailleur is wobbling about a bit (I can't see that), so I'm having a new one fitted (it's going rusty anyway.) The noise is almost certainly coming from the front chainring and happens no matter what the alignment of the chain is (dead straight, badly crossed) and it makes no difference. It's worse when it's under load which makes things slightly awkward, because I can't do much with it while it's on the stand. It doesn't seem to be rubbing against the derailleur,

Long paragraph over, has anyone got any idea what this might be? This is doing my head in, and the bike sounds like a bag of bolts at the moment. If I get the chance, I might grab the camera tomorrow and record the sound so you know what I'm on about.

Thanks

dsbrantjr

Are all of the chainring bolts tight?

Buggington

I've tried to do that, but where you should be able to put an Allen key or whatever it's completely round - nothing for any sort of tool to grip onto. Am I missing something basic here?

skibender

Are you sure it's chain related and not the bearing on the crank?

FBinNY 

I'll assume you know what the various clicks and creaks of BBs and loose chainring bolts sound like and have correctly blamed the chainring.

So here's a diagnostic for a worn chainring

Use the tip of a screwdriver to lift the chain outward from the ring at 3 o'clock (the 1/2 point of the wrap). A new chain on a new ring will barely lift away. With wear, the chain pitch increases while the ring gets a bit smaller allowing slack which can be lifted away. So if you can lift the chain out until there's 1/8" or more daylight under it, either the chain and/or the chainring is worn. This can cause the characteristic whirrr of chain drive to be much louder. It can also creak as the chain shifts back when pedaling under load.

If you do see wear, then you have to make a decision. The drivetrain can tolerate lots of wear (the chain on my commuter can lift away over 1/4") but will get progressively louder until at some point the chain will slip under load and you'll have no choice about replacing the ring.

If you don't want to replace stuff that still has usable life, use a heavier wet chain lube and it'll help muffle the sound.

Of course, it might be something else entirely and, like everyone else, I'm shooting in the dark because we really have nothing to go on.

Buggington

FBinNY - I've given that a go and this is the result - I'm not too sure how worn this is (I'm still quite new to this). What do you make of it?



skibender - How would I know? I suppose breaking the chain is the only solution?

Been out with the video camera this morning, and this is what it sounds like. This is it unloaded - it gets a lot louder when I'm actually riding it. I gave it an oil with some of the stuff below and it didn't improve. (Also noticed some noise from the sprockets but it didn't sound too loud to me, so it's definitely not at that end.)

cny-bikeman

Might have helped to have someone else pedal while you held the camera steady. The sound seems very much like the chain rubbing on the derailleur cage rather than a worn chain, but the sound at the rear is a bit much as well. The wear level from pulling out the chain does not look extreme, and the two chainrings I can see do not seem worn at all. The entire train looks extremely dirty, and I have seen that water mixed with lube can create more noise. You might want to try actually measuring the chain wear, and then either replace it or clean it and the rest of the drive train thoroughly, or have a mechanic check it out in person.

FBinNY 

The wear isn't unreasonable, though it may cause extra noise under load. Worn chainrings are only noisier when pedaling under load, so we can discount it as a factor here.

What Im hearing mainly is a steady rub, Double check that the chain doesn't touch the FD cage as it passes through. Also you have that thin steel chainguard, which might be the issue. Make sure it doesn't rub on the FD cage anyplace, and that the chain doesn't touch it as it engages.

No one mentioned the chain guard earlier, since you didn't say you had one. Seeing it there I suspect that it's the likely culprit so give it very careful attention, and/or if it's easily removable do so and see if that solves the problem.

cny-bikeman

The chainguard can make noise even if it's not being rubbed, though I would expect somewhat different noise (more a rattling sound).

Buggington

This is true, I do regularly clean it with Muc Off solvent using an on the bike cleaning machine. The chain normally gets a clean every 50ish miles anyway. I think it's done slightly more at the moment so it's due a clean soon. The solvent cleans it up quite a bit, at least on the outside, and in another thread earlier this week I was told about some new lubes it might be worth trying (Honda motorbike oil?), so I might give those a shot. I went to college after my post and did a five mile round trip on my commute and it actually seems to have quietened down a little, but it's still not right. I've taken another short video and in response to FBinNY's suggestion, tried to show the FD.

I've paid attention to the FD and it seems to have a little rub, see video below, in the higher gears (3-6, large chainring, second smallest sprocket) but doesn't look like it rubs in a lower gear. The chain guard is only a plastic thing and never touches the chain, so seems unlikely?

Thing is it's only plastic - I'll have a look but I'm pretty certain it's from the more mechanical parts. It strikes me that any noise it creates would be from tyre vibrations etc, not the comparatively smooth chain.

It's also worth noting that the chain is still noisier when under load - watching this it seems a lot quieter than on the road.

cny-bikeman

"The video is private." Again, if you have checked everything suggested as well as you can, and the problem is worse under load, then you need the help of someone who can be there and especially who can test under load.

Buggington

Sorry, corrected that now. Stupid iPhone. This is true, but I now need to work out how to test it with a willing volunteer, which is hard enough to find already! I might just have to take it into the LBS. Like I say, I've got a front and rear derailleur going on on Monday along with some other bits, so I might just have to ask them to have a look.