Tacx power

dooverylittle

Hi all, I was just wondering does anyone know what CP270 mean in a tacx training program. I know that cp is criticial power, and I know how to determine it, But I dont know what the 270 represents.

http://www.tacx.com/en/tacx-coach/training_van_de_maand/Flow_ergotrainer.dot

Thanks for any help.

markdrayton

dooverylittle wrote: »

Hi all, I was just wondering does anyone know what CP270 mean in a tacx training program. I know that cp is criticial power, and I know how to determine it, But I dont know what the 270 represents.

http://www.tacx.com/en/tacx-coach/training_van_de_maand/Flow_ergotrainer.dot

Thanks for any help.

Friel (and others?) use CPX to mean "highest sustainable power for X minutes", hence CP12, CP30, CP60. The CP model is usually used to estimate CP60 (ie, max sustainable for 1 hr, sometimes referred to as just "CP") from several shorter durations by constructing a CP curve. See http://www.trainingbible.com/joesblog/2008/03/07-08-power-profiles.html for more.

However, I'd think it unlikely anyone would be interested in CP for 270 minutes because a) at that duration the CP curve is almost flat (it's more or less the same as CP120 or CP300) and b) that's 4.5 hours.

I expect in this context it means a CP60 of 270W.

Lumen

That chart makes no sense to me.

Why do they say "CP270" if they mean "270W"?

If "CP270" means 270W, why would you start the workout at 270W for 5 minutes if the intervals only go up to 210W?

Why does the session start with "Cool down" before "Extended Warm up"? Cool down from what?

markdrayton

Doh, yes. I couldn't see it at first so I had no context to go on. Having looked at it it seems they really are talking about power for given durations, though I can't really see what the workout is aiming to achieve. The difference between CP120 and CP270 power is going to be almost nothing. On my CP curve (as drawn by Golden Cheetah) my CP120 is the same as CP240, and the line is flat.

That workout looks like "ride endurance pace, sometimes with big gears, sometimes with small gears".

Lumen

Ah, OK.

So "CP270 | 5 minutes" means "the power you could sustain for 270 minutes, for 5 minutes".

markdrayton

Lumen wrote: »

Ah, OK.

So "CP270 | 5 minutes" means "the power you could sustain for 270 minutes, for 5 minutes".

That's my interpretation and also why I'm confused about this: if you could sustain that power for 4.5 hours, what use is training at that power for 5 minutes? I suppose the intention is to ride for x minutes at CP120 then y at CP240, a kind of over-under session but at durations these durations it's only ever going to be an endurance effort. The difference in intensity is pretty small.

If you want to do two hours of endurance-level riding on the turbo I think your first challenge will be finding the mental strength for it. I'd ride at whatever pace it took to stop me getting sick of it.

Lumen

markdrayton wrote: »

That's my interpretation and also why I'm confused about this: if you could sustain that power for 4.5 hours, what use is training at that power for 5 minutes?

It's a warm up. Or cool down.

I think extrapolating to 4 hours is well beyond the limits of the CP model which is not designed to deal with for very short or very long efforts. Would be simpler to express directly as a % of CP20/CP60/FTP which are easier to measure.

Or just use Coggan power levels.

billy.fish

Tacx...Power...W

Please don't use them in the same sentence unless in the form: This Tacx turbo does not measure power, it calculates (not measures) wattage (W) as a function of speed and weight and bares no real use other than to itself

Its not a measure of power its a number it generates.

cantalach

billy.fish wrote: »

Tacx...Power...W

Please don't use them in the same sentence unless in the form: This Tacx turbo does not measure power, it calculates (not measures) wattage (W) as a function of speed and weight and bares no real use other than to itself

Its not a measure of power its a number it generates.

All power meters employ a calculation - power isn't something you can measure directly. They estimate the torque by way of strain gauges and then multiply this by cadence (a quantised value) to arrive at the power.

Clarification: the torque-times-cadence calculation I'm describing here is how something like and SRM works - not how a Tacx works.

billy.fish

cantalach wrote: »

All power meters employ a calculation - power isn't something you can measure directly. They estimate the torque by way of strain gauges and then multiply this by cadence (a quantised value) to arrive at the power.

Clarification: the torque-times-cadence calculation I'm describing here is how something like and SRM works - not how a Tacx works.

I understand that.

The Tacx 'calculates' power in possibly the least accurate way possible bar getting monkeys to decide numbers that they found tasty

DirkVoodoo

billy.fish wrote: »

I understand that.

The Tacx 'calculates' power in possibly the least accurate way possible bar getting monkeys to decide numbers that they found tasty

Are these monkeys ANT compatible? I am interested, VERY interested.