12-25, new rig, 53-14 goes pop-pop-pop

[Tom]

and only the 53-14. It's not hi/lo adjustment, shifts great and that's the only combo that does it and it's not the rattle of a chain wanting to go somewhere else. It's a steady pop-pop-pop from the cluster. 39-14 stays quiet.

What the hell is it? The loose ball bearings in my head?

[ada@prorider.or]

and only the 53-14. It's not hi/lo adjustment, shifts great and that's the only combo that does it and it's not the rattle of a chain wanting to go somewhere else. It's a steady pop-pop-pop from the cluster. 39-14 stays quiet.

What the hell is it? The loose ball bearings in my head?

well i suspect the 14 cog is not correct since the rear derr. has another angle on 53-14 then 39-14
how many chain link pins do you have on cog to derr jockey wheel?
meaby pic?

[Tom]

The chain seems a bit slack. I am going to take a look at it this evening.

[Serotta PETE]

Some items to check

- chain tension slack (although it should probably do the same thing on 11 or 12 tooth
- is it a new chain and old cassette?
- that cog has problems and needs to be exchanged
- Cage alignmnent

[Dave]

Don't know why chain length is such a mystery. Here's the right way to do it, but chain length will NOT cause the problem you describe. In the 53/14 the chain is nowhere near an extrme condition.

I suspect the problem is the cog installed backwards or a damaged cog, assuming it's the second or third cog.

Two simple tests will determine if the chain is the correct length. First, it must not hang loose in the little ring, little cog combination. If there is no tension on the chain in the little ring, little cog combination; remove two links (one inch) at a time, until there is. When the ends of the chain are brought together, some movement of the lower pulley should occur, indicating tension is being applied. Two more links (another inch) may need to be removed, beyond the point of absolute minimum tension, to keep the chain from rubbing on itself as it passes under the upper derailleur pulley. If you want to see how much lower pulley movement will occur, without removing the extra inch of chain, shift up four teeth (11 to 15 or 12 to 16). This has the same effect as removing two links. Once this is done, the chain is set to the maximum useable length. Removing additional links will do nothing but reduce the derailleur's capacity.

Second, the chain must be long enough to avoid over-extending the rear derailleur when shifted to the big ring and biggest cog combination. If the chain is set to the maximum length as described, it should always pass this test, unless your setup exceeds the derailleur's stated wrap capacity. If you deliberately exceed the derailleur's capacity and the derailleur is over-extended in the big ring/largest cog combo, then you must either avoid that combo or add another inch and avoid using the little chainring and the smallest 3 or 4 cogs (since the chain will hang loose).

[X'd Out]

it turned out to be a bent cog, you could check your 14 and see if it is bent.

[Tom]

Last night, before I was going to do any adjustments I figured it might make sense to be working with a clean drive train. Forty five minutes later, after sacrificing the brush I used to use to clean out my brewing airlocks, I had a clean drive train. We've had a bumper crop of silt on the roads this year and I had a cement like deposit all over everything even though I've been giving the whole thing a once-over after every third ride or so. The Park cleaner box did nothing to this stuff. You had to brush it off every surface and pick between the plates.

After cleaning, nearly silent. A half turn of the barrel adjuster and it was silent.

Great. Basic maintenance. I promise to never neglect it again.