Noisy transmission

davecooper

I have just completely rebuilt my bike for the summer, including a strip down of the Tiagra rear mech and triple chainset and a thorough chain clean. All back together again now and I cannot get the transmission to run smoothly. The gear indexing is fine with the chain sitting square to every sprocket at all positions and the chain running perfectly over each sprocket, the gear changing also seems fine. The upper jockey wheel has been set clear of the cassette using the tension screw. However, when spinning the transmission off the ground, I can only describe the feeling as "notchy". There is a constant vibration which can be felt through the frame and pedals and this gets worse as the chainline goes away from central. All the components are the same age and have done maybe 3000 dry miles tops. Anyone got any suggestions? Could it be a stretched chain? How can I tell?

davecooper

Further to my query above, just been out to give it another spin and it feels just as if the rear bearing is goosed, which it isn't because its a brand new 105 hub that freewheels as sweet as a nut.

Meds1962

Is everything properly re lubricated after the strip down & cleaning?

always_tyred

Shimano freewheels aren't great, in my experience. I wouldn't rule out a post-cleaning issue until you have inspected the hub.

Daft question perhaps - but are you 100% sure that the chain links are moving freely? Sometimes they are free enough to coil around the cassette but aren't under enough tension around the jockey wheels.

topdude

If you have cleaned all the gunk out of the chain and it is fairly worn it will feel noisy / notchy.
At 3000 miles it probably needs replacing, use a steel rule and carefully measure a 12" length of the chain,
If it is 12" + 1/16 it is fairly worn and needs replacing.
If it is 12" + 1/8 it is very worn and you should replace the cassette as well.

Dai_bach

My first thought would be worn transmission.

To clarity Topdude's post, 12 links should equal 12" on a new chain...

davecooper

Looks like I may have a bit of wear in the chain. Seemed smooth before the strip down but I suppose a build up of lubricant, road gunk and wax from washing etc would have probably quietened it down. Now with a pristine clean transmission, the chain wear is obvious. Hadn't noticed this problem from a worn chain before but you live and learn.
First stop, new chain.

Dai_bach

If your chain is so obviously worn, there's a good chance that the cassette will be worn too. This being the case, you'll need to replace both at once.