Squeaking on the upper cogs.

PS This is happening on the big chain ring.

neon said:

My chain (I think) has just started making a high pitch squecking noise when on the two biggest cogs of cassette on 105 road bike. The chain is well lube. Is the chain reaching its use by date?

don't know.. chain stretch is how you check for use by.. measure 12 inches of chain. There should be no more than 1/8 inch error in that 12 inches, meaning that if you are lined up on a pin you should be lined up dead center on a pin 12 inches away. If that at the end of 12 inches is further apart than that, measure how much. If it's 1/8 inch longer the chain is worn and is time to replace.

The squeak I have no idea about.

neon said:

PS This is happening on the big chain ring.

Then use the small one... 😄

You're crosschaining so the chain is streched laterally from the 53 ring in the fron to your larger cog in the rear. More stress on the side to side versus front to back. Big big and small small is a given no-no. You probably got away with it until now because the chain had less play in it being newer. Your chain is not rashed yet, but your gear combinations are exacerbating the wear issue.

capwater said:

Your chain is not rashed yet, but your gear combinations are exacerbating the wear issue.

And most likely causing the squeak. The chain plates are rubbing on the cog teeth much harder than they should. It's only squeaking because everything is clean. As soon as the chain gets a bit dirty it's sure to change to an expensive grinding noise.