The standard for cycling is lower although I have heard that you can get cycling helmets tested to PAS 015 so you could wear that for both. I'm too vain to wear the same for both, I have done it occassionally but you get some funny looks. If in doubt you'd want to wear a riding hat for cycling, not the other way around
I just wanted to know, because I might have to travel quite far on a bicycle to get to places to ride, and I hate cycling with a bag, so I'd rather wear the same hat for both purposes.
Because there's a pretty busy road that I may have to travel along, and I'd want to wear something that is safe enough. I'm sure cycle hemlets must have safety standards?