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peterob

Veteran
Location
Chester
Yes, very true. Until very recently, I hadnt realised the temperature power swing on the early version Kickrs. Which would explain why my winter numbers were better than my spring and summer power. With my setup in the conservatory and prone to temperature swing winters being very cold. :okay:

Yeah, my (your) Kickr seems to vary a fair bit with temperature. My performances have been a lot more consistent since using my vectors for power (albeit somewhat down from where it was :laugh:)
 

peterob

Veteran
Location
Chester
Its been brought up on YouTube that height has significant speed penalty, more so than weight. I think Zwift in this respect is off calculation with its algorithm

If I get chance I'll ride it twice at different heights on same bike, hopefully similar power to see the reported difference
At 6'2" I agree the algorithm is off
 
OP
OP
C

CXRAndy

Guru
Location
Lincs
Yeah, my (your) Kickr seems to vary a fair bit with temperature. My performances have been a lot more consistent since using my vectors for power (albeit somewhat down from where it was :laugh:)

Hi Pete, I dropped on a thread where a guy recorded temperature of his Kickr and commented how early on in training sessions his power was higher and with time and temperature the kickr normalised its readings compared to other compared power meters he owned.

The only instance I had was once I did a spin down reset after comparing power with my Stages PM. The Kickr was high but came within 5W after spin down.

At least you get 20% gradient resistance. I think the kickr just needs to be in a warm consistent environment and probably do a spin down before racing event would make it reliable in readings.

Wahoo suggest spin down is done after
15 mins of use to warm up the drive components, but it would also do the same for the electronics too.
 

Whorty

Gets free watts from the Atom ;)
Location
Wiltshire
Its been brought up on YouTube that height has significant speed penalty, more so than weight. I think Zwift in this respect is off calculation with its algorithm

If I get chance I'll ride it twice at different heights on same bike, hopefully similar power to see the reported difference
I knew it played a part, but was a little surprised by how much. At 75kg, that guy is 1kg lighter than me even though significantly taller.

One up for us shorties :wahhey:
 
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bridgy

Legendary Member
Location
Cheddar
Not very scientific .... but experienced something quite interesting on the ToW stage 6 TT yesterday. This was after my HID mechanical, as I was working my way back through the field. I was overtaking all riders until I caught up with one guy who was clearly strong and was staying with me (he eventually pulled away and bet me!). On the companion app I clicked on him to see what watts he was pushing as his w/kg on the flats were c.3.8 and I was only pushing c3.1 yet we were travelling at the same speed. I assumed he was lighter than me and pushing the same watts as me (about 235). However, he was actually pushing 270+ most of the time. So, this guy was pushing both more watts than me, and had a higher w/kg than me, yet travelling at the same speed.

The only difference I could see was in height. He was 200cm tall and I am 171cm - quite a big difference (my 5'7" to his 6'6"). We all know that height is an advantage in Zwift, but this suggests it's more of an advantage than I certainly expected.

Now, we were on TT bikes, so the aero position I assume is key in Zwift to speed, but I wonder if other bike types have the same effect.

In short then (excuse the pun), this lanky geezer needed to push out around 10% more watts on the flats to travel the same speed as me due to the height difference.

Like I say, not very scientific but it was quite marked. For anyone interested, it's the guy who is ranked 100 in the stage 6 race I did yesterday (D Dachs - 200cm tall and 75kg heavy).
Some testing of this has been done and discussed in this article - https://zwiftinsider.com/how-height-affects-speed-in-zwift/

The article suggests you get the equivalent of 5-10 watts extra for every 15cm less height. The guy you were racing against was 30cm taller and averaged 30 watts more overall - but he did finish 23 seconds faster. So overall, roughly in line with the findings in the article, albeit at the upper end of the difference?
 

bobinski

Legendary Member
Location
Tulse Hill
Yes, very true. Until very recently, I hadnt realised the temperature power swing on the early version Kickrs. Which would explain why my winter numbers were better than my spring and summer power. With my setup in the conservatory and prone to temperature swing winters being very cold. :okay:

The Neo has ruined my ability to produce 300+W for long periods :laugh:

I reckon all the latest are reasonably close in measurement if they us a PM onboard. Obviuosly there are still ways to manipulate the E training, either weight/height doping or riding methods, sawtoothing being the easiest to boost ave power

Andy, your old Kickr version 1 is known to read high. There's a lot of talk about it on the closed Zunr forums. They actually reset the group KOM and other times partly so that Kickr v1 users lost their advantage and its a very different looking table now. Software updates were supposed to sort but even now apparently you can run a late version kicker with kickr 1 version firmware and benefit from a watts boost. Riding in the cold exaggerates the difference. Doesnt really matter in the scheme of things except frustrating for users looking for both accuracy and consistency.
 

bridgy

Legendary Member
Location
Cheddar
I wasn't aware that the Kickr could be that innacurate, but I suppose it just goes to show that if a high end trainer like that can throw out some slightly dodgy results, pretty much all results on virtual cycling like Zwift have to be taken with a bit of a pinch of salt
 

<Tommy>

Illegitimi non carborundum
Location
Camden, London
I think you can obviously take this stuff as seriously or not as you want to. The weight thing, height thing, variance in turbos. We can mention variance in power meters too... if you look at dcraimaker comparisons power meters vary a fair bit too... so I wouldn’t assume they are more reliable than turbos sometimes.

I just decided a long time ago to treat it like a computer game because otherwise what’s the alternative? It doesn’t matter to me if people cheat or not or if their results are juiced up somehow. I just try my hardest against what’s in front of me.

In the grand scheme of things I probably compare my results more against other neo users because they are the most comparable to mine. Not because it matter to me if they are more or less accurate.
 

bobinski

Legendary Member
Location
Tulse Hill
I wasn't aware that the Kickr could be that innacurate, but I suppose it just goes to show that if a high end trainer like that can throw out some slightly dodgy results, pretty much all results on virtual cycling like Zwift have to be taken with a bit of a pinch of salt

Paul, Just V1. Later versions are more accurate apparently especially if running up to date firmware.
 
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