What is the best way to wash a bike helmet?
The straps are getting a bit rank from sweat and I'd like a better alternative to just hosing it down.
From time to time, I soak it in water with a bit of glicerin soap ("neutral", recommended on manuals) disolved, in a bucket. I leave it a whole day submerged (have to put something heavy over the helmet, otherwise it floats out).
My rationale is this: when you submerge, the natural diffusion process inside liquids makes the soap penetrate the sweat, and part of the sweat to disolve in the water. Soap has a natural tendency to suspend fat, and fatty acids released by skin are the hardest part to take away from the straps (the minerals, like salt, ammonia and the like, go away from diffusion even without soap). Also, these are consumed by bacteria and produce the stinky substances.
After this process is done, I wash it by replacing the whole water many times, while diving it repeatedly and vigorously inside the bucket.
Drying in a sunlit place (not necessarily direct sun) in a dry and windy day is ideal to kill the last bacteria and eliminate the last vestigial stinks.
I have already disassembled the fittings through which the straps run, tied a thread to one of the straps ends, and pulled the straps out, leaving the thread behind. Washed the straps alone, and pulled them back using the thread. My conclusion: too much work, risk of not getting it right, and not so much better than the previously described procedure.
Hope it helps.
Rather than any complicated method or products, I do the following:
Shampoo or body wash works great. Then I just clip the straps over a line to hang the helmet to dry.