The box says something like 1 every 20 mins, but at that rate you'd be better off hanging up your bike and taking the car everywhere!

I'm not sure there's a right or wrong answer here - everyone must have different requirements, and when combining with other food and drink it becomes even more complicated to say how many you'll need.

I just take a few with me and try to remember to have one every 45 mins or so, alongside the usual drinks and the odd flapjack type thing.