FTP test - hill v flat

[AussieRob]

If I do the 20 min TT test on a 20+ min hill, will I get a misleading result? In theory I should be able to put the same amount of power down on the flat, but it is very difficult to do so in practice.

Thanks

Rob

 

[peterwright]

If I do the 20 min TT test on a 20+ min hill, will I get a misleading result? In theory I should be able to put the same amount of power down on the flat, but it is very difficult to do so in practice.

Thanks

Rob

The result should be fine. As you say it is just a bit easier to output a steady power on an incline.

 

[RapDaddyo]

I had the same experience initially. I think it is due more to technique than physiological limitations. Riding uphill and upwind, we have a fairly constant resistance to push against. I think it takes less concentration to maintain a target power under these conditions. When there is less resistance (flat, downhill or downwind), I think it takes more concentration to maintain a target power and a somewhat different technique. I find that I need to ride in a slightly lower cadence when there is less resistance, to give me more room to increase cadence to maintain power when it drops below my target. I have spent a lot of time learning to "manage" power to fairly tight tolerances, for my own reasons. So, I've done a lot of experimentation with power management techniques. I have come to understand power management to be a separate, specific skill that must be learned and practiced. But, there is a payoff.

 

[Woofer]

If I do the 20 min TT test on a 20+ min hill, will I get a misleading result? In theory I should be able to put the same amount of power down on the flat, but it is very difficult to do so in practice.

Thanks

Rob

If the flat road is safe enough for you to concentrate on riding hard, the difference is mostly in your head.

 

[kmavm]

I had the same experience initially. I think it is due more to technique than physiological limitations. Riding uphill and upwind, we have a fairly constant resistance to push against. I think it takes less concentration to maintain a target power under these conditions. When there is less resistance (flat, downhill or downwind), I think it takes more concentration to maintain a target power and a somewhat different technique. I find that I need to ride in a slightly lower cadence when there is less resistance, to give me more room to increase cadence to maintain power when it drops below my target. I have spent a lot of time learning to "manage" power to fairly tight tolerances, for my own reasons. So, I've done a lot of experimentation with power management techniques. I have come to understand power management to be a separate, specific skill that must be learned and practiced. But, there is a payoff.

Bingo. This has been my experience as well. In fact, learning to actually push into slight downhills, etc., has been a major benefit of training with power for me. I also can identify with RDO's tip about keeping a slower cadence going to have some "headroom" for unexpectedly easy stretches of road.

Lots of people subjectively find they can maintain high powers more easily uphill, though. Dr. Coggan once suggested on the topica list that this is basically a "skills" weakness. I find it mentally more challenging as well, because for a given increase in power, the increase in speed is smaller on the flats. Power basically linearly improves speed uphill, but on the flats you've got that nasty quadratic of wind resistance working against you, so you get less positive mental feedback per Watt.

Also, be aware that if you have a powertap like me, the slower chain speed can cause lower drivetrain losses; i.e., the higher power you experience uphill may be a measurement artifact. There was a topica thread on this, and the guesstimate arrived for the magnitude of this effect wasn't chump change; something like 5W, IIRC.

 

[sugaken]

Wow... I have the exact same problem and was thinking to post here...

Now that I know it's a skill (or lack thereof), I'll just try to learn to do better on the flats.

Thanks and keep up the good work, guys!

 

[AshesGlory]

This is incorrect. The power required to overcome gravity on a climb is proportional to the bike speed, but the power required to overcome wind resistance on a windless day is proportional to the cube of the bike speed.

Lots of people subjectively find they can maintain high powers more easily uphill, though. Dr. Coggan once suggested on the topica list that this is basically a "skills" weakness. I find it mentally more challenging as well, because for a given increase in power, the increase in speed is smaller on the flats. Power basically linearly improves speed uphill, but on the flats you've got that nasty quadratic of wind resistance working against you, so you get less positive mental feedback per Watt.

 

[RapDaddyo]

This is incorrect. The power required to overcome gravity on a climb is proportional to the square of the bike speed, and the power required to overcome wind resistance on a windless day is proportional to the cube of the bike speed.

But, I think kmavm's point is that a given percentage increase in power produces almost a 1:1 percentage increase in speed on a climb (depending on the grade, of course) and a much smaller percentage increase in speed on the flats (and a negligible percentage increase in speed on a descent). So, it "feels" like a more direct payoff for the increase in power. And I agree.