Motorex Helmet Care
The Motorex Active Foam works well to get your bike helmet clean and smelling fresh.
Okay, no schoolboy jokes about helmet care, please. This stuff really works. Judging by the picture on the front, it is aimed primarily at motorcyclists, but it works equally well with cycling helmets.
What you do is spray the stuff and it immediately foams up. It looks like hair mousse, if you're the sort of metrosexual individual who knows about such things. You leave it to work its magic for a couple of minutes then wipe it off with a dry cloth. Easy-peasy.