My helmet fits perfectly in my bathroom sink. After each ride, and right before I jump into the shower, I put a little dish-soap and a tablespoon of bleach in the sink and add just enough water to cover the bottom portion of my helmet with the straps soaking below. My helmet will start to float when the proper water level is reached. Then I jump in the shower.

Always be cautious when dealing with full strength bleach, or even diluted bleach, as it can easily discolor clothing, towels, etc.

After I have showered, I will drain the sink water, then refill the sink with clean water to rinse the helmet and straps, and I hang the helmet up to drip-dry inside the bathroom stall. Sweet and simple. It has become somewhat of a ritual for me now...the beginning stage of OCD perhaps!