How much to eat on a sportive

One of the many topics covered in the tri-talk podcasts was how much you need to consume in terms of calories during an even.

There is a handy calculator here http://www.tri-talk.com/TriTalkNC/TriTalkNC.htm

that allows you to play around with various variables and come up with an estimated cals/hour.

It confirms something I have learned by experience, that I don't need to eat as much as I expected. On my most strenuous sportive last year (Tour of the Black Mountains) I burned 4800 cals or so over 6:30 hours at an average effort of around 80%MHR. It reckons I need to consume between 250-300 cals per hour, which is not too much.

Backing this up is my Dragon experience, the only time I have ever bonked in my life. On this event I went for 6 hours doing 4000 cals at 80% drinking only water (becuase I forgot my sports drink) and eating about 4 bananas and about (because I lost most of them) 8 flapjacks. I think this adds up to around 2000 cals so I guess I had around 2000 cals stored in glycogen.