dazza500 wrote:I'm trying to follow a 1600kcal per day controlled diet but I need to find out pretty accurately how many extra cals I'm burning on the bike.

A useful guide to different terrain and levels of work would be a good start.

I haven't investigated recently, but there are plenty of on-line calculators that can tell you how much energy is needed to ride a certain distance at a certain speed up a certain hill. Perhaps bikeroutetoaster or something can combine the calculation with a certain route defined on a map.

This tells you how much physical energy is needed, in units of Joules or kcal. You might then reckon that your body is 25% efficient at converting food to energy, so multiply by 4 to find the amount of food energy that would be needed.

But beware of this "multiply by 4" as that might already be done by the calculator.

The energy per hour depends heavily on air resistance (hence on speed) and hills, and a decent hill will clobber energy. My normal riding is on the flat so I can take it as easily as I want, expending almost no energy. If I wanted to deliberately burn energy, I would use the hills.