http://www.leadvilleraceseries.com/p...-mile-mtb-race

A recent local mileage contest multiplied mountain bike miles by 1.3 to approximate road bike equivalent miles. I think my mountain bike commuter was quite a bit more efficient than that before I put the dynamo headlamp on it. With the dynamo it might be about right.

Trail conditions obviously might require substantially more energy but that's not relevant to this discussion.