Big bike makes clattery noise...

[aww999]

Hi all, totally pointless question but I thought I'd ask it anyway...

I was on my way to the cashpoint last night doing 30 through a fairly empty town centre, when a bike came past me, full throttle in a low gear, at about 45mph, and then lifted right off.

It made this weird, really loud mechanical clattery noise as it lost speed, and I have no idea what was causing it. Sounded kinda cool though - like when you used to put a clicker thingy on your Raleigh Grifter

What was it - the chain or something? Never heard it before and I was intrigued.

[aww999]

No, the bike was running fine - he tried to get me to race him at the traffic lights at the end of the road, then howled off like only a sports bike can