TimC wrote:

Is it possible that it's a cheap supermarket class mountain bike with
steel wheels?

Steel wheels simply will not ever stop in the rain.

That is simply not true. There is a small window of opportunity to stop
between the rims going red hot and flash boiling dry the water and the
tyres and tubes exploding from heat fatigue.

You can make a
perpetual motion machine out of them.

Only on a loaded touring bike coming down from Dingo Gate to Moonan
Flat. Thank goodness for shoe leather.