Interesting that it's been a well known fact and the source of advertising campaigns (More than anything else, campaigns by the sunscreen companies themselves as well as the Cancer council) for years down here in Australia that Suncreens must be reapplied every two hours or so... esp if you're sweating or participating in water activities...

Since sunscreen moisterisers for body are bloody expensive I've been starting to mix 50:50 lots of body moisturiser and 30+ (max Australian rating) Sunscreen together so my shaved legs don't dry out.

I never walk out of the house without putting this mix on, I haven't been burnt since November last year (when I FORGOT) and I have "trial size" sunscreen bottle I keep refilling. It fits perfectly in my jersey pockets and I reapply every 2 hours or so when riding or just out and about.

My mum's had 3 skin cancers removed, my dad one, and I used to work for a Skin cancer screening centre. I never leave home without it!