Of Noobs and Output Monitoring

Sesquepidilian

Usual pre-emptive apologies if this is asked often but I've looked back 4 pages. I'm still fairly new to cycling, probably about 6 weeks, and I'd like to better manage my energy input/output.
While it seems to be an inexact science how can I monitor my energy expenditure when riding ? Mainly as an aid to diet choice and so on.

Alex_Simmons/RST

How accurately do you want the information?

At one end of spectrum, you can get lab tested for gross mechanical efficiency and use a power meter on your bike to record energy output and use the lab determined GME value to calculate energy metabolised.

At the other end, you can simply use an estimate of kJ metabolised based on duration you are riding with approximate ranges typical for cyclists at various levels of ability.

An unfit person, will metabolise ~ 4-5 Cal/kg per hour riding overall.
Modest fitness ~ 5-7 Cal/kg/hour.
Good Fitness (club rider/lower category racer) ~ 7-9 Cal/kg/hour
Upper category racers and professional riders will be higher.

These are estimates based on overall riding over course of a season, not one specific ride (e.g. you can ride an hour easy, moderately or hard, each with quite different metabolic demands).