It had to happen sooner or later. I had a great ride out to a mates place in the hills. It's and old hall being done up and we were leaving (both to go home) at the same time. I mount the trusty steed and..the battery was flat.., the key left on..

..now old mate is speeding away!
It's ok, I think, a big downhill would help and theres one right there! Uh uh.. had a chance to try a different gears and speeds and she just wouldn't live!!
I rolled perhaps a steep klm with just a few pushes before being faced with a steep uphill.. A sheepish call back to matey and a jump start fixed things..
Must say i'm a bit spooked about being 'bushed', left pushing a long way from anywhere.. hmmm, maybe there's room for another battery under there!
Anyhow.. point is.. as I was freewheeling I could feel and hear a clunk/grab from somewhere low, in revolutions every few meters..
I'm not really sure how further describe or to find it again to listen closely at that speed without the motor running.. any ideas where to suspect / take a look?