I-magic vs. Computrainer numbers..

[turquise1]

I have been doing computrainer TTs here and using I-magic for indoor (using catalyst) training. After my last TT on Computrainer, I tested myself again on my I-magic and had alot better times but lower power outputs, so I am kinda confused, and do not know which one to depend on..

Did anybody have a chance to compare these trainers' numbers?
(especially Power output..)

Cheers,

Oz

 

[ric_stern/RST]

I have been doing computrainer TTs here and using I-magic for indoor (using catalyst) training. After my last TT on Computrainer, I tested myself again on my I-magic and had alot better times but lower power outputs, so I am kinda confused, and do not know which one to depend on..

Did anybody have a chance to compare these trainers' numbers?
(especially Power output..)

Cheers,

Oz

Neither the Tacx or the Computrainer *actually* measures power output, they're both based on estimates (as i understand it). If you want to know your correct power output you'll need an actual power meter such as an SRM or Power Tap.

I've only used a couple of Computrainers, and these have been generally in the ballpark as regards good estimates (although one i used was way off). Computrainer can and do recalibrate their units for better accuracy. Most of the Tacx's i've used have been much less accurate and each unit tends to differ from another unit.

i would say that you can't make any generalisation about specific numbers for comparing the two different units.

Ric

 

[turquise1]

Neither the Tacx or the Computrainer *actually* measures power output, they're both based on estimates (as i understand it). If you want to know your correct power output you'll need an actual power meter such as an SRM or Power Tap.

So I guess the question will be : Did anybody have a chance to measure both of these units for accuracy (when they are properly calibrated) using Powertap, SRM (when they were also properly calibrated) etc...?

 

[ric_stern/RST]

So I guess the question will be : Did anybody have a chance to measure both of these units for accuracy (when they are properly calibrated) using Powertap, SRM (when they were also properly calibrated) etc...?

see my reply above -- i've done this! it isn't possible to calibrate a Tacx and results have differed wildy between each machine. Similarly, I have seen differences with a CT, and then suggested the owner gets it recalibrated. however, if you don't have a known accurate external measure you won't know if your CT is off and needs calibrating

ric

 

[turquise1]

see my reply above -- i've done this! it isn't possible to calibrate a Tacx and results have differed wildy between each machine. Similarly, I have seen differences with a CT, and then suggested the owner gets it recalibrated. however, if you don't have a known accurate external measure you won't know if your CT is off and needs calibrating

ric

Actually, I have talked to several I-magic users (on the Internet) who had a chance to test their equipment with Powertap. There are some calibration methods which gets you very close to Powertap numbers under 400W. I am not sure about CT though. Seems like its power output numbers are higher than usual.(in one occasion it showed 300W going 23.7mph on flat terrain, so I guess it wasnt calibrated?, but then this is a serious TT competition, I would only hope that it was..)
I was just hoping somebody had a chance to test them both with PT. (Thats what I was trying to find out here anyways..)

 

[kennf]

Remember also that the CT has you program your weight (including bike) and recommends that you re-calibrate the unit for drag before each session. This is intended to reduce variations caused by tire pressure and the tightness of the friction unit.

 

[turquise1]

Remember also that the CT has you program your weight (including bike) and recommends that you re-calibrate the unit for drag before each session. This is intended to reduce variations caused by tire pressure and the tightness of the friction unit.

I know, I-magic has the same 'rolldown' calibration with required tire pressure and rider+bike weight..

 

[biker-linz]

I know, I-magic has the same 'rolldown' calibration with required tire pressure and rider+bike weight..

I have both a PT and an i-Maigc and IME the i-Magic is hopeless. It varies wildly according to cadence (among other things) and consistently reads way low. CTs have a rather better reputation.

Lindsay.

 

[Phil TurboVids]

With the new Fortius Software thats included with the Real life Videos & new virtual world you can calibrate your i-magic so you can get it to show the same numbers as your powertap! (in the zone you aim to train )

www.tacx-video.com

 

[closesupport]

I have been doing computrainer TTs here and using I-magic for indoor (using catalyst) training. After my last TT on Computrainer, I tested myself again on my I-magic and had alot better times but lower power outputs, so I am kinda confused, and do not know which one to depend on..

Did anybody have a chance to compare these trainers' numbers?
(especially Power output..)

Cheers,

Oz

It seems that when you use catalyst you can adjust the breaking system between 5-250, where as you can't on the VR training routes this is why they differ so dramatically so by adjusting the braking system in the catalyst to match those powers that are generated on the vr terrains. then you know your almost right or there abouts.

 

[ric_stern/RST]

It seems that when you use catalyst you can adjust the breaking system between 5-250, where as you can't on the VR training routes this is why they differ so dramatically so by adjusting the braking system in the catalyst to match those powers that are generated on the vr terrains. then you know your almost right or there abouts.

Unless you can calibrate a Tacx by running it alongside an SRM or PT it won't be accurate (in regards to power) in my experience. Others have found exactly the same.

ric