Seems too easy...

[ouroboros]

So I was trying out my new Long Thresholds ERGVideo. Love the new comments/fades/first person perspective btw!

Funny thing is, it seems alot easier than on my Powertap outside. Granted it's around 30 degrees C right now in the Middle East but say 270 watts for 20 mins has me at 80 pc heart rate outside and 300 watts on the ERGVideo only has me at 70pc (22 degrees C and a fan on inside)

So my cadence is only about 75 to 80 rpm, could this be another factor as well as the temperature. I'm sure it's not the calibration as I'm doing it all the time to check this!

[ergvideo]

You will have to compare our ct to your powertap. all control of the ct is under racermate software control. Also check calibration.

Also be aware that ct is most accurate between 14 and 25 mph. lab units best. When you kick it into a huge gear and ride at what shows as 250W and you are doing 30mph, this is where you will see ct inaccuracies kick in. I think it is a combo of nonlinear rolling resistance and perhaps others. Also below 12 mph. It's one reason the threshold test is not a flat course, but a 2% grade. this keeps most people in the speed zone at which CT is really bang on.

I suggest looking at 1 minute intervals in ranges useful to you (suppose your threshold is 250. Try 150, 180, 210, 240, 270, 300.) Do the first run holding your wheel speed at 18mph. now repeat same intervals at 22 mph, and another set at 27mph. Indeed, at the low watts settings, at 27 mph your power will not track the load since it is all >rolling resistance. I would suggest a press on around 2.0 just so that you can see some regulation at these high speeds and low watts. Anyway, upshot is you will see probably best agreement betwen your pt and ct at the 18 and 22mph, and bigger differences at the high speeds.

It isn't actually unusual to see differences, and some people send back their ct for recal. I can say I have never had to, and I have owned 10+ so far, 9 were lab units.

When I ride ergvideo, I pick gears that have me in a happy cadence zone of 80-120 and resulting speeds between 14 and 25 mph. Again, your speed doesn't matter at all. putting out 300W is putting out 300W.

paul

[ouroboros]

Thanks for the comprehensive reply - yes I should really hook up my other bike that has the PT on it. But my training bike is so nicely setup now on the CT/PC!

I think it was because I was riding in too low a gear on the threshold rides. Sticking at 80 cadence in a middle gear has got my hr up to where I expected it to be