Zwift Chat

[Joffey]

Thanks all. It does make me wonder why people go to the extra expense of measuring both sides independently then!

Because cyclists like giving their money away easily for STATS!!!

 

[ColinJ]

Because cyclists like giving their money away easily for STATS!!!

I confess to being surprised how interesting I am finding power data!

For example: There are a couple of short false flats on the A646 coming back from Burnley. They are nothing much when feeling fresh but always feel a right slog after a long, hard ride such as my Forest of Bowland rides. The power meter reveals why... I could be trundling along at 175 W and suddenly have to up that to 250+ W to maintain my speed.

Some of the minor lumps on the same road between Hebden Bridge and Todmorden get me up to around 350 W for a few seconds.

 

[Norry1]

Thanks all. It does make me wonder why people go to the extra expense of measuring both sides independently then!

So they get a more accurate view of overall power. One sided pedals in your example would give a total power of 94 or 106 which is over 10%

 

[ColinJ]

So they get a more accurate view of overall power. One sided pedals in your example would give a total power of 94 or 106 which is over 10%

Good point!

So, single-sided allows monitoring of progress, but double-sided would be better for accuracy.

Do smart turbo trainers tend to measure L, R, or L&R?

 

[Peter Salt]

Good point!

So, single-sided allows monitoring of progress, but double-sided would be better for accuracy.

Do smart turbo trainers tend to measure L, R, or L&R?

A turbo trainer measures power on the axle. It wouldn't know which is left and which is right.

 

[bridgy]

A turbo trainer measures power on the axle. It wouldn't know which is left and which is right.

Tacx Neo trainers (and smart bikes) can measure left/right power I believe - not that I've ever looked at that data myself!

 

[alex_cycles]

Thanks all. It does make me wonder why people go to the extra expense of measuring both sides independently then!

Because they can

 

[Legs]

A turbo trainer measures power on the axle. It wouldn't know which is left and which is right.

Tacx Neo trainers (and smart bikes) can measure left/right power I believe - not that I've ever looked at that data myself!

The Tacx Neo trainers know which pedal is in the power phase by detecting the proximity of the pedal spindle on the upward pedal stroke. However, I agree with @Peter Salt that, in order to determine L/R power, the trainer has to make an assumption about the proportions of instantaneous power being delivered by the push and pull legs, since it can only measure a single, combined, power at the hub. That's probably quite straightforward when the pedals are at 1 o'clock and 7 o'clock, but perhaps not as clear-cut when at 5 o'clock and 11 o'clock.

https://www.dcrainmaker.com/2018/11/smart-trainer-hands.html

 

[13 rider]

After Sundays 4hr epic ride for FRR stage 8 ,I woke on Monday morning with a very sore back did sitting on the turbo cause it ? Not 100% sure as I occasionally suffer from a bad back . So Monday was a complete rest day . Anyway overall results are in after stages and 10hrs 21min 58secs of racing I finished 36th of 55 riders who finished all 8 stages , 35mins 28secs down on Egap GC time ( I don't really understand Egap buts it's some way of balancing faster more well attended time slots ) . 35th /55 in the green Jersey and 32nd /55 in the Polka dot Jersey. It was a good series for me felt competitive in most stages and a best finish of 5th on a stage

 

[alex_cycles]

After Sundays 4hr epic ride for FRR stage 8 ,I woke on Monday morning with a very sore back did sitting on the turbo cause it ? Not 100% sure as I occasionally suffer from a bad back . So Monday was a complete rest day . Anyway overall results are in after stages and 10hrs 21min 58secs of racing I finished 36th of 55 riders who finished all 8 stages , 35mins 28secs down on Egap GC time ( I don't really understand Egap buts it's some way of balancing faster more well attended time slots ) . 35th /55 in the green Jersey and 32nd /55 in the Polka dot Jersey. It was a good series for me felt competitive in most stages and a best finish of 5th on a stage

I thought eGap simply means if you win the race in your Cat you get 0s eGap and everyone else gets the number of seconds they were behind the winner of their race. The idea there being that if you had a very well populated heat it's only the relative times that count, rather than the absolute times. This makes it a bit fairer for comparing a heat of 10 riders against a heat of 40.

 

[13 rider]

I thought eGap simply means if you win the race in your Cat you get 0s eGap and everyone else gets the number of seconds they were behind the winner of their race. The idea there being that if you had a very well populated heat it's only the relative times that count, rather than the absolute times. This makes it a bit fairer for comparing a heat of 10 riders against a heat of 40.

You may be correct but the last tour I did the winner was decided on overall time ,this tour the guy in 11th overall is 5mins faster than the winner but has an Egap of 11mins but the winner has an Egap of zero suggesting he won every stage ?

 

[alex_cycles]

You may be correct but the last tour I did the winner was decided on overall time ,this tour the guy in 11th overall is 5mins faster than the winner but has an Egap of 11mins but the winner has an Egap of zero suggesting he won every stage ?

FRR is never the same twice. It's like he's searching for a Holy Grail
Like Zwifters who don't whinge or sandbag

 

[ColinJ]

A turbo trainer measures power on the axle. It wouldn't know which is left and which is right.

It struck me when I was out today that the Quarg IS measuring the output from both legs because the strain gauge is in the spider rather than the crank. It just doesn't know which leg is providing which peak in the power readings through the crank cycle.

My faulty 4iiii power meter was built onto one 105 crank so that would have only measured the output of my L leg. Doubling that would have exaggerated my power because my L leg does more work than my R.

 

[alex_cycles]

It struck me when I was out today that the Quarg IS measuring the output from both legs because the strain gauge is in the spider rather than the crank. It just doesn't know which leg is providing which peak in the power readings through the crank cycle.

My faulty 4iiii power meter was built onto one 105 crank so that would have only measured the output of my L leg. Doubling that would have exaggerated my power because my L leg does more work than my R.

But unless you need the absolute numbers it would never affect anything.

If you were training based on FTP etc. it would be perfectly fine because the measurements are all relative.

It's only when you start racing on zwift or doing something where the absolute values have consequences that it would matter at all.

 

[ColinJ]

But unless you need the absolute numbers it would never affect anything.

If you were training based on FTP etc. it would be perfectly fine because the measurements are all relative.

I had to think about what you meant there...

If the meter readings were out for the ftp calculation they would also be out for the training zones so that would not be a problem?

That makes sense!