hi.

My tacx flow says I'm cycling 6w/kg = 360watt (60kg). But I can hold this power for about 30minutes.

I correctly calibrated it. I calibrate it every time I start cycling on the tacx trainer. And every time the calibration factor is different (mostly -1,+1,+3,+4) but every time I got an average of 360 over a 30minute ride.

Av. on the road (road bike) with-out wind is about 41km/h for 1 hour. But hey, I'm 60kg! So that 6w/kg seems to be correct?

??? strange??? :confused:

I help with testing of cyclists, on the road, track and in the lab. We've come up with some equations based on literature and I put your numbers into them. Assuming you are 5'10'' and depending if you were in arrow bars or on drops you would be producing approximately 180-200 watts at 41km/h. To produce 360 watts you'd be going 52 km/h. Granted, you probably weren't on a track, there is wind, and other things that can't be accurately accounted for and would add to the power output. But if you really want to know you watts, and have the money, get a power tap or a SRM. They seem to work real well when compared to our velotron. Besides sustaining 360 watts at 60 kg would mean that your Lactic threshold would be at about 72 - 76 and a VO2 max would be higher possibly above 80. And Lance's is at 82.

I help with testing of cyclists, on the road, track and in the lab. We've come up with some equations based on literature and I put your numbers into them. Assuming you are 5'10'' and depending if you were in arrow bars or on drops you would be producing approximately 180-200 watts at 41km/h. To produce 360 watts you'd be going 52 km/h. Granted, you probably weren't on a track, there is wind, and other things that can't be accurately accounted for and would add to the power output. But if you really want to know you watts, and have the money, get a power tap or a SRM. They seem to work real well when compared to our velotron. Besides sustaining 360 watts at 60 kg would mean that your Lactic threshold would be at about 72 - 76 and a VO2 max would be higher possibly above 80. And Lance's is at 82.

First off, I wouldn't trust the trainer "calibration." The only thing that will truly tell you how many watts you're producing is a power meter.

Next, 180-200 W for 41 kph??? What are you smoking? You'd have to be a total stick boy to pull off that kind of performance. 220-230 W for 40 kph is about the lower limit. Myself, at 5' 9.5" and decked out in aero gear (TT frame, integrated aero bars, trispoke front, disc rear, aero helmet, skinsuit) needs about 250-260 W to go 40 kph most days (sometimes a little more, others a little less). 180-200 W for 41 kph comes out to around a CdA of 0.2 or so. Very few people, if any, can get that low. Top Euro pros may TT in the 450 W range. With a CdA of 0.2, they'd be hitting nearly 56 kph. Know any that do?

First off, I wouldn't trust the trainer "calibration." The only thing that will truly tell you how many watts you're producing is a power meter.

Next, 180-200 W for 41 kph??? What are you smoking? You'd have to be a total stick boy to pull off that kind of performance. 220-230 W for 40 kph is about the lower limit. Myself, at 5' 9.5" and decked out in aero gear (TT frame, integrated aero bars, trispoke front, disc rear, aero helmet, skinsuit) needs about 250-260 W to go 40 kph most days (sometimes a little more, others a little less). 180-200 W for 41 kph comes out to around a CdA of 0.2 or so. Very few people, if any, can get that low. Top Euro pros may TT in the 450 W range. With a CdA of 0.2, they'd be hitting nearly 56 kph. Know any that do?

Agree, that power output seems really low for a 40 Kph speed.

Based on your trainer's readings, you obviously should be out spanking the pros.

I'm 182cm... :p

I took a photo of my bike-position.

My frontal area is 0.33m^2

I think my cw value is 0.9-1.0. I have aero wheels on my roadbike (Bora)


6watt/kg is indeed much. But 360watt (60kg) isn't much on a flat road. So I think that's why I can only cycle 41km/h if I do a TT on my roadbike.


But how accurate is the Tacx?? It seems to be accurate, because every time I got alsmost the same av. power.

Accurate to others is not really important. Use your Tacx trainer to guage your workouts and your progress.

I'm 182cm... :p

I took a photo of my bike-position.

My frontal area is 0.33m^2

I think my cw value is 0.9-1.0. I have aero wheels on my roadbike (Bora)


6watt/kg is indeed much. But 360watt (60kg) isn't much on a flat road. So I think that's why I can only cycle 41km/h if I do a TT on my roadbike.


But how accurate is the Tacx?? It seems to be accurate, because every time I got alsmost the same av. power.

That means it's reliable, assuming you're putting out about the same average power output, it doesn't make it accurate.

If everytime I got on my home scale I weighed 180 lbs, yet my actual weight was 160, my home scale would be very reliable and it would be very inaccurate.

I just picked up on the 6 W/kg. If you were really doing 6 W/kg for 30 minutes, you wouldn't be posting here. From everything I've seen, the Tacx underpredicts on low wattages (say 200 W and below) and overpredicts on the higher end (240-250+ W). If you're only doing 41 kph on the road with those assumed CdA numbers, you aren't generating 360 W.

I'm 182cm... :p

I took a photo of my bike-position.

My frontal area is 0.33m^2

I think my cw value is 0.9-1.0. I have aero wheels on my roadbike (Bora)


6watt/kg is indeed much. But 360watt (60kg) isn't much on a flat road. So I think that's why I can only cycle 41km/h if I do a TT on my roadbike.


But how accurate is the Tacx?? It seems to be accurate, because every time I got alsmost the same av. power.