Any question answered...

Is the rear wheel definitely straight? If you've pulled it slightly off-centre it will have adjusted the angle of the cog against the chain slightly.

Sounds too obvious to be the case though, and I guess if you've been fertling with the chain that's probably not it.

Totally stripped down the drivetrain this morning. BB was smooth. Thoroughly cleaned and oiled (again!) every part. Seems to have sorted it. Obviously there was some grit in there I didn't get first time around. Worries over!

It's pretty horrible isn't it. It was cycling across Japan in August that taught me I had sweat glands in places like my knee caps and elbows. I think even my sweat glands had sweat glands. Try going really slowly.

&

Superb! Yeah you just end up shiny with sweat all over. And covered in those little sweat bubbles in the upper layer if your skin, because you can't sweat fast enough. Gross.

On the plus side I've been cultivating some middling facial hair to cover the scars on my face until they've healed more, and now I can use my upper lip like a salt lick. Quite satisfying.