@Bones8

Thanks for that. That's very helpful.

I have an ANT+ / Bluetooth speed / cadence sensor and am actually now probably going to get the Garmin Edge 500. There's a 25% off offer on at the moment.

The calculator you gave is very useful. Like you, I don't need to know the exact calories burned. I just want a ballpark figure. That's how I calculate calories burned for core / weights workouts and walking.