Squawking noise on and off

[shieldr]

I haven't had gearbox bearing trouble but I think it's more of a low rumbling noise rather than a high pitch squawk. A high pick squawk seems more like something is rusty like a chain or a rusted wheel bearing/ sprocket carrier bearing. That's what I'd be leaning towards but it's only a guess. Is the chain oiled? If the chain has tight spots you tend to notice them through the front sprocket because it has to go around a smaller diameter. If you could get a few pictures of the chain and sprocket up or a video of the noise that might help.

The chain looks in great nick to me and a video of the squawk could be tricky as it only happens on the road.  I will take a close look at the chain and then get the rear wheel off next. Cheers.