Bicycle Mechanics - slight clicking from rear mech?

It seems that I have a slight clicking from my rear mech.

It's not annoying loud and I can only hear it when riding next to parked cars or building (1m away) but not when "on the open road" so to speak (nothing solid adjacent to me ... like on a cycle path). I only notice it now because of the lack of other bike commuters as it's getting cold. Also, it only happens when I peddle and the chain gets pulled through.

I checked the drive line and it's straight and I don't think it's the need-to-adjust sound because the chains seems to be going through evenly.

Do all rear mechs make a slight sound, or is it the chain are this is where it bends the most?

Also, can I clean the mech without taking it off the bike?

Need more detail -

Is the clicking very frequent, such as would be caused by each link in the chain, or is it less frequent?

Is the clicking sound (apart from other sounds) about the same in all gear combinations?

If not, which combination of front (large/middle/small) and rear (largest/smallest) does it occur?

**When did it start and did anything happen to the bike or was anything done (maintained or replaced) at or before that time?

About frequency: if it's continuous, it probably happens once per something. Once per crank turn, once per wheel revolution, or what?

Also, it's quite difficult to accurately pinpoint where the sound comes from when you're riding. Can you have somebody ride next to you and confirm it's the rear mech? There was a case on the Forums eons ago, where a member did extensive greasing and tightening of every possible screw in the bottom bracket area only to realise the culprit was a zipper in his clothing/gear clicking against the top tube.

--J

"a zipper in his clothing/gear clicking against the top tube."

A shoelace ticking against a crank arm is also a frequent source of mysterious noise.

Need more detail -

Is the clicking very frequent, such as would be caused by each link in the chain, or is it less frequent?

Is the clicking sound (apart from other sounds) about the same in all gear combinations?

If not, which combination of front (large/middle/small) and rear (largest/smallest) does it occur?

**When did it start and did anything happen to the bike or was anything done (maintained or replaced) at or before that time?

Sorry, my bad, I should have provided more information.

It's continuous, so I suspect it's either the jockey wheels or every link in the chain.

It's consistent with cadence. It's different than the slight rubbing from the chain I get if I cross chain (big front-big rear).

It seems to have developed in the last few hundred km. It wasn't there before and I lubricated the chain and it didn't go away, therefore, I think it's something in rear mech.

It occurs in all gears and matches my cadence.

Maybe it's a normal sound?

"a zipper in his clothing/gear clicking against the top tube."

A shoelace ticking against a crank arm is also a frequent source of mysterious noise.

Yeah, I seen/heard that one even though I try to run short laces to avoid it.

It's kind of like this but not as loud:


https://www.youtube.com/watch?v=Vt-fMp5gIN8

The real issue is that it has become slightly louder recently over the last 5-600km whereas I didn't notice it before. I'm just curious whether something is amiss.

A progression in loudness would imply something related to wear or lubrication, rather than a single cause. Any further isolation will require hands and eyes on the bike. If you can hear it riding in all conditions then you should be able to hear it on a stand or on a trainer. You may want an assistent to pedal the bike so you can be free to look at the drive train from all angles. I would focus on where the chain goes through the pulleys first. If it's realy continuous it's not going to be one tooth on a pulley, so see if the chain comes onto and off the pulleys centered, and that the pulley is both parallel to the vertical and horizontal plane of the bike (not tilted in/out or left/right) when viewed from the rear.

Thanks for the excellent responses! I will check it out ASAP!

My compact double 105 5700 drivetrain does that too. It always gets quieter whenever I lube the chain, but never goes away 100%. It's most noticeable when I crosschain.