The impact of motivation?

Nicolai Foss

Hi just writing this as I´m back from my first time trial - a bit puzzled by my power measurements. I´ve been riding with my powertap for almost 5 months - regularly doing standardized 20 min test preceeded by 5 min tests my best 5 min test has been 377 and 20 min test 292 watts. Today I had a setup with a newly aquired tt-bar which placed me almost on the tip of my saddle. I´m in total shock as my av power for the 15,4 kilometer tt (23 min)was 340 watts What should my ftp be set at now, I don´t know if I could reproduce this power in my regular position which on the other hand is much more comfortable over longer distances.

Ergoman

The first thing to do is check your power meter. Your average speed of 24.96 equates to about 300 watts for the average guy on a no wind, level course. That number would be more in line with your previous tests.

Bikeridindude

You might also want to make sure that it's zeroed.

Nicolai Foss

Thanks for the replies, really made me think. On one hand I would hate the numbers to be wrong, on the other it would be annoying to jave a to high ftp. I´ve analyzed the file and some old ones. The route was pancake out and back but with 6 m/s mostly oblique winds, I´m 192, 88 kg on a race bike with 32 spoke open pro wheels with a not to low clip on bar. I have a Powertap which is set to autozero and the file shows zero power at 0 rpm at the two 90 degree turns and at the turningpoint. into the headvind. I´ve subanalyzed the windiest 4k where it took 365 watts to go 38,1 into the wind and 335 to go 42,4 back. I´ve also gone to some old files where I can see I routinely go to 330-40 to go 40 k/h. So the question is should I get a new powermeter or a set of aero wheels (or a yoga class)

Alex Simmons

Sometimes the autozero isn't enough. Get into the habit of manually zeroing the torque before each ride, it only takes a few seconds.

Indeed, especially if you drove to the event and had bike and PT outside the car/on roof rack. I've often found this sends the torque zero out. I like to manual zero before I start, and then during warm up again just to be sure.

On the original question, I'm not sure motivation was responsible for all of your higher wattage in this instance but motivation is very important in performance. When I analysed all my MMPs for 2006 (5 sec out to 60 min - all the durations Cycling Peaks auto selects for each ride file), in every case it was a motivated instance. Almost always in a race (e.g. my sprint peaks came in final sprint in an open crit which I won, 30 min MMP from a State championship crit) and if not then it was in a highly motivated training session, like chasing a world champion rider on the track.

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Nicolai Foss

Can´t understand how it could overestimate power if it goes to zero (can understand if it underestimates if torque is below zero). There seems to be no way round another test next week, with the newfound motivivation that I potentially have a ftp near 300.

Another thing I found while converting my roadbike to a TT rig was that moving my saddle 3 cm forward actually made it much easier to attain higher watts - so I´ve kept it that way.

daveryanwyoming

If the PT hub records torque when there isn't actually torque then your power will be overestimated. That's the problem of not zeroing after temperature changes or other things like the roof rack problem mentioned.

It's pretty easy to see if you have a problem with torque. First look at your minimum torque for sections of your race where you know you did some coasting like a descent or while cornering. Your file should show a minimum torque of zero. If you don't have any zero torque sections(assuming you coasted) then you probably have a zeroing problem.

If you do you can export your file in CSV format and open it in Excel. Check periods where you were coasting(cadence zero) and look at the torque. You can also do an auto-filter sort on the torque column in ascending order and look for the minimum torque. If your minimum during coasting settles on some number like 3 or 4 or so then you definitely had a torque zero issue. It's possible to fix with some Excel games and then you can reimport the corrected file but I won't bother with all that detail unless you actually have a problem.

Good luck,
Dave

Alex Simmons

As Dave said, if you are coasting and torque value is positive, then torque zero is out but since the power number relies on both torque and hub speed (power = cadence x torque), while the torque may be wrongly positive while coasting, your hub is not turning, therefore the power is calculated as zero any way.

The quick way to check that is to have the top line of the PT display torque instead of watts, then you'll see if it is reading zero or something else while coasting.

Now the tricky one is if the torque zero is negative. The CPU only displays zero or positive values, I'm pretty sure a negative torque value shows as zero when coasting, hence there can still be a hidden problem and is why manually zeroing torque before each ride is still a good idea.

I deal with this constantly on my fixed gear PT track wheel. I re-zero before each effort/race etc, so you do it as part of the get on the bike routine. Only takes a few seconds.

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Nicolai Foss

Thx for your patience - now I get why torque x 0 rpm = 0 watts

But I looked at the file and it showed 0 torque (both hub and crank) in both sharp corners and the turnabout, where I didn´t pedal. Should that not imply that the values were okay?

By the way I don´t have a car, so I rode to the TT on the bike