Bicycle Tutor

I've recently started hearing a weird noise that sounds like a rattling-clunking-creaking that appears to be coming from the bottom bracket. However, it only happens when I'm actually on it, so I'm reluctant to assume that the bracket is the problem. When I first get on after a week or so of not cycling, there is no noise, then it kicks in, mildly when peddling at first then pretty much constantly when I'm moving, even just coasting. I can feel it all the way through the frame up to the saddle. Any hints?

If the noise continues even while coasting, the bottom bracket is probably not the cause. Does it make the noise in every gear? Do you have an internal gear hub or derailleur gears?

It makes a noise in every gear, and I have derailleur gears. The gears won't shift onto the outer cog on the rear either, but this is a more recent development that I'll be sorting out later. I just tried cycling without brakes actually attached and with the saddle off (not at the same time, but the noise carried on.

Maybe rear wheel bearings. The sounds are right and sometimes these get worse as you ride and the grease warms up and thins in the hub.

Trying taking your wheels off and turn the axle by hand to see if it feels smooth or rough.

I had a similar problem recently - after about two hours of fiddling it turned out to be the seat post not being greased properly where it' goes into the frame. The noise went away as soon as put some lube on it.