In the Wattbike we have built a product that accurately measures Watts. It was not as easy as it might sound to do, but we have created a product that accurately records power output, from which other useful data can be calculated – i.e. energy (work) in Joules and speed (based on a calculation from British Cycling). It displays heart rate from Polar, Garmin ANT Sport and Suunto ANT chestbelts. All of the data created is accurate, so should we be thinking about the adding an estimate of calories burned? 

If you are riding on a Wattbike as part of an overall fitness regimen, rather than to improve performance then Calories would be a useful addition, but is it devaluing the product by adding an estimation of the calories burned to generate that amount of power? For me I think the value of calories out weighs the disadvantage, but the difficulty will be ensuring that users understand the difference between an estimation of Calories and the accurate measurement of Power. We will add it to the request list.