# Calculating Power

##### New Member
If I know my speed and cadence, can't I calculate power without a power meter?

Why would I want to buy one when I could spend a grand on a nice cycling vacation somewhere?

If I know my speed and cadence, can't I calculate power without a power meter?

Why would I want to buy one when I could spend a grand on a nice cycling vacation somewhere?
nice one ...

If I know my speed and cadence, can't I calculate power without a power meter?

Why would I want to buy one when I could spend a grand on a nice cycling vacation somewhere?

Cadence has no significance, but you can calculate power pretty easily if you:

1) know total weight
2) know or calculate speed
3) estimate friction and rolling resistance(not too hard)
5) do the test on a steep, steady grade so that speed is low; or, alternatively, know your CdA(aerodynamics) and ambient air conditions very precisely(pretty tough).

Why would I want to buy one when I could spend a grand on a nice cycling vacation somewhere?
Well (and I'm not being sarcastic here), if you're not to concerned with your improvement... I mean I have a lot of friends who just ride for the sake of riding, with no goals other than piling as many miles as they can in a season. Which is perfect if it's what you want.

In such a case then choose the vacation.

jws said:
Cadence has no significance, but you can calculate power pretty easily if you:

1) know total weight
2) know or calculate speed
3) estimate friction and rolling resistance(not too hard)
5) do the test on a steep, steady grade so that speed is low; or, alternatively, know your CdA(aerodynamics) and ambient air conditions very precisely(pretty tough).

with some of the info above you can use this http://www.kreuzotter.de/english/espeed.htm calculator to get a power estimate.

this is also kind of fun to use to find out how losing weight or making other changes can change your ride times.

Eden said:
this is also kind of fun to use to find out how losing weight or making other changes can change your ride times.
I was bored last night and did just that. Figured out my power to weight ratio now, if I were 10 lbs lighter and how much power I would need to produce to be at a Cat2 level. Fun, humbling and a great source of motivation!!!

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