I second that corrosion.

Does anybody have any idea why my bike doesn't work?

This is why I can't have toys. I've never been able to look after things.

Not that it was in tip-top condition when it went into the shed for winter, but six more months of damp and guano has played merry hell with the metal parts. The rear derailleur cable snapped last October. When I arrived at golf this evening, the back brake also locked on. Not solid, but enough to make even the downhill roads uphill roads.

For the life of me I've no ideas why.

But I do have very strong suspicions.