Wandering off-topic slightly, I had a very interesting experience last weekend.
I took part, as an 'extra' in the filming of a public information film about mass decontamination. The producers wanted a cross-section of cultures represented in this film, so naturally there one or two Muslims among us.
Part of the filming/contamination procedure entailed seperating into male/female groups and then changing into sterile clothing (big, hooded, orange ponchos and face-masks), then showering, and then putting on a different set of clothing - baggy paper suits and waterproofs - and new face masks.
One of the ladies in my group was Muslim, in full set of veils and robes, which she was prepared to remove in the privacy of a ladies only changing area. We all got to discussing the various cultural implications of the procedures, and she said one of the reasons she took part was to show other Muslim women that they can be part of our community without losing dignity or compromising their faith. This lady's body was still completely covered when she was in view of the men, as was her face and head, because of the hood and mask. She had her small daughter with her, who also took a full part in the proceedings, so that was an education for her too.
Getting back to topic, I actually consider it courtesy to remove my helmet when I'm not actually on the motorbike. In fact, most petrol stations like you to remove them before you start to fill up - which is fine by me. After all, I've nothing to hide.