Chain noise from front mech won't go away

[Davidc]

Suggestions welcome on this one:

I changed the chainset on my Dawes Horizon a couple of weeks ago, from the 28, 38, 48 original to a 22, 32, 44. The new one is the same make as the original, a Truvativ 5D (SRAM).

The front mech is a Shimano Alvio.

I set it up for the new chainrings and after taking 4 links out of the chain it all worked. BUT on the road, under load I had chain noise in the highest 2 (back) ratios with the large and middle front chainwheels.

Fine. As ever for that problem I readjusted the angle of the front mech. The chain ran quietly as expected except in the top ratio, large front smallest rear. Readjusted it again. No change. And again. Now it was at the limit of adjustment for the low gears. Still the same chain noise.

I've checked Sheldon, and Bicycle Tutor, and the Shimano instruction sheet and I can't see what else there is to do. I've set up this type of gear more times than I like to think about, and never had this one before.

It's just the very highest gear, and it wasn't doing it with the original larger chainring.

If I can't stop it it'll just have to stay - don't use that gear much and it's not bad enough to be doing any damage. It's just very irritating.

Over to the wise citizens of CC!

 

[Sheffield_Tiger]

How is the spacing of the chainrings out from the frame compared to your old chainset.

Had to change BB on my MTB when I dumped the OEM suntour chainset for a 10yo (but hardly used) Shimano set, the rings were shifted out just enough to screw with the chain line and leave me with similar chain noise

 

[Crackle]

You've lowered the front mech too I presume.

All chain bolts tight

Not got a chain ring the wrong way around

They're the first obvious stuff I can think of which you've probably already checked/done. Did similar myself not long ago and I had a click which was a bolt not seated properly.

 

[Davidc]

The spacings sholdn't have changed. To save money I bought the splined BB chainset and unbolted and transfered the wheels to my square BB one, so there shouldn't be any change. It's the first time I've not had any spacers to deal with too, as these seem to be machined so they don't need or have any.

I moved the mech down, and set up the gap at about 2mm, as told to by the various experts. My only concern with that is that with the 48 chainring the curve of the mech matches that of the chainring, with the 44 one its visibly different. The outer ring will only go on one way round so can't be that.

What's stumped me is that always in the past this has just been something that adjusts out by changing the angle of the front mech, but this time I get to the limit imposed by the other end of the range just before the noise goes. As I said above its minor enough to ignore as far as any damage goes, but its really annoying.

I may try changing the chain over. The one that's on there has now done about 1000 miles so could be beginning to wear, but I can't see how it would cause this sort of noise.