eeewwww... def wash shorts after every ride... never wear twice in a row...

I have a net bag that hangs in the laundry, and all cyclists chuck their cycling gear in there - socks, jersey, shorts (and for me, crop top).

That way, if I can't wash straight away, they are aired and don't sit in a corner getting damp and growing stuff

Then they go through a normal machine wash, and pref a sun-dry otherwise they get hung in the kitchen near the windows...

The other reason to be "onto it" with washing and never wearing twice unless unavoidable is "refuse" if you will from other parts of the behind... one of the riders in the house regularly leaves a trace of skid-marks in his shorts... now for girls, letting fecal bits near your girly bits can cause major probs... another reason to ALWAYS wear clean shorts.