TT power
- Thread starter powermad
- Start date
Well, the figures aren't that interesting without the weight of the riders. A heavy rider needs to produce more Watt than a lighter rider to maintain the same speed. Anyway, my threshold is at 320 W and I weigh 73 Kg
The answer will be dependent upon many factors, including, but not limited to
topgraphy of the course
environmental conditions
aerodynamic equipment used
bike position
size, frontal area and CdA of the rider
mass of the rider
Furthermore, power that can be sustained for ~1-hr is generally far in excess of power at lactate threshold (which is generally defined as a 1mmol increase in lactate over resting levels). There was a discussion on this last year.
It's also, not of great use to just state an absolute power output without specifying any anthropometric data (e.g., if you can 260 W and are 1.52m tall, and weigh 50 kg, your velocity on a given course would be far greater than if you're 1.80m and weigh 85 kg!)
Ric
CdA and/or frontal area are far more important than body mass, with body mass making little or no difference on flat or generally flat circuits.
Ric
It's also imperative when talking about power meters, to state, which meter is used as there can be errors and differences associated with certain ones. For instance, Power Tap hubs read about 2% less than (correctly calibrated) SRM cranks, due to power being 'lost' within the drive train.
Ric
Ric
That is an interesting point Ric, I would assume then that SRM cranks give an indication of what is happening at the pedals (i.e. the power produced at the pedals) and PowerTap what is happening at the hub.
I assume that powertap is better when predicting performance (particularly when different bikes are used) and SRM's are better when training (i.e. the riders power output is the same no matter what the bike is).
Is this correct? (I appreciate that the difference is very small!)
I assume that powertap is better when predicting performance (particularly when different bikes are used) and SRM's are better when training (i.e. the riders power output is the same no matter what the bike is).
Is this correct? (I appreciate that the difference is very small!)
Obviously, the difference is small, say 5 W at TT power for good riders. You might possibly, think of the SRM as being the power that gets to the pedals and is therefore, what the rider produces, whilst with the PT this is what's available to the rear wheel and thus affects the velocity of the wheel. But, because the difference is so small especially at typical training power it doesn't really make much difference, but is worth bearing in mind!
Both systems are very accurate and both have their advantages and disadvantages.
Ric
Yes, but to go back to the first post, what power output do I need to hit 25mph?!!! I know it depends on a variety of factors, so I typed them into the analytical cycling web site. Apparently its 593W for the local 25 course I use a lot, for my weight of 78kg. Now Chris Boardman broke the hour with, I think, around 430W. So where do AC get their figures. Am I missing something?
Shibumi,
Your power output at a specific speed, will be highly dependent upon the topographical and environmental conditions encountered within the race, plus of course your equipment choices and your position itself. Furthermore, there's also your own body shape that you need to take into account.
As a vague idea to ride at about 40 km/hr on a pan flat road, i put out ~ 270 - 280 W on very standard road equipment, i'm 1.75m and ~69/70 kg
Ric
Your power output at a specific speed, will be highly dependent upon the topographical and environmental conditions encountered within the race, plus of course your equipment choices and your position itself. Furthermore, there's also your own body shape that you need to take into account.
As a vague idea to ride at about 40 km/hr on a pan flat road, i put out ~ 270 - 280 W on very standard road equipment, i'm 1.75m and ~69/70 kg
Ric
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