Resistance too easy

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victorrubin
Posts: 7
Joined: Tue Sep 29, 2020 8:30 am

Resistance too easy

Postby victorrubin » Mon Nov 02, 2020 1:03 pm

On my second Nero and when resistance is set to the highest level I'm finding it too easy. When I had my old Nero and resistance was set to highest level I had to change to my easiest gear and use the small chainring but with this new one I can still stay in the biggest chainring.
I have calibrated it.
Any ideas?

bikesteff
Posts: 10
Joined: Sun Nov 29, 2020 10:09 am

Re: Resistance too easy

Postby bikesteff » Wed Dec 09, 2020 9:32 pm

Which spin down value did you get after calibration?

Best regards,
Stefan

victorrubin
Posts: 7
Joined: Tue Sep 29, 2020 8:30 am

Re: Resistance too easy

Postby victorrubin » Wed Dec 09, 2020 10:05 pm

7099

bikesteff
Posts: 10
Joined: Sun Nov 29, 2020 10:09 am

Re: Resistance too easy

Postby bikesteff » Thu Dec 10, 2020 4:54 pm

Thats interesting. I am also wondering how Nero is doing the calibration. I am using a "normal" racing bike with 25 mm road wheels but a little bit less pressure than on the road and I am getting a value around 3200 in my cold (1-5 degree celsius) garage. The first time I have done calibration in my room I got 2500 and the tire pressure was higher. My personal waight is 80kg. Don't know what is going on there ... I thought the spin down value would be less in case of less tire pressure (I guees that this is just the time in seconds from 37 km/h to 0 km/h ).

Yesterday I have done different "calibrations" by influencing the spin down value (pedal a little bit longer or using the brakes) such that I got Spin down values ranging from 800 to 7000. Then I measured the power value at 30.2 km/h for each calibration and interpolated everting into a straight line equation: y=-0.0271*x + 341.22. This means that the power to the system for spin down x = 7000 would be approx. 150W @ 30.2 km/h. In case of e.g. x = 3400 I would get about 250W @30.2 km/h. In your case I would expect the the power you are putting on with a higher spin down value would be also higher if compared to my spin down values. Unfortunately I forgot to do some more measuremts with the same spin down value but at different velocities but I don't erally think that this would make much difference. On the other hand I do not know how they calculate the power for hill climbing because this should be much less influenced by the spin down value.

How can you apply a certain power value to the system? Is that possible to set this directly or only by a specific training?

victorrubin
Posts: 7
Joined: Tue Sep 29, 2020 8:30 am

Re: Resistance too easy

Postby victorrubin » Thu Dec 10, 2020 4:55 pm

A lot most of that went over my head - sorry.
Elite told me that he values are in mili seconds. I did mine in a room about 20C on 25cc tyres on a road bike and I weigh approx 77Kg with pressure about 100psi

bikesteff
Posts: 10
Joined: Sun Nov 29, 2020 10:09 am

Re: Resistance too easy

Postby bikesteff » Fri Dec 11, 2020 1:48 pm

Ok, thats less weight than I have and more pressure in your tires than I typically apply. On trainers I usually use a little bit less pressure, I know I should measure it precisely but I would guess something between 4-5 bar (65psi).

** Elite told me that he values are in mili seconds
Of course, you are right, I meant milliseconds not seconds. When using the MyEtraining app and your calibration, what is the power @30,2km/h (18.7 mph)?

Yesterday I used a new calibration spin down value for climbing up mount vent in Zwift and got approximately the same FTP (2 points higher) like last week using a spin down calibration with lower values (I am using the same weight = 80kg in Zwift for a long time). Using my measured calibration "curve" (it is linear) mentiond above I would have expected a difference of at least 7% but that was in my personal opinion not the case. I am also wondering why the spin down value was higher this time although my tires pressure must have been lower (I didn' filled them up).

So my personal opinion is that you can not really trust the spin down calibration for whatever but on hill climbing the power seems to be less influenced by the spin down and "maybe" the power values are getting more accurate since they are mainly influenced by the resisitance of the magnetic brake.

So, when you say, the resistance is lower if compared to an old Nero do you mean the resistance when climbing up hills? In that case we could also compare the power values for hill climbing in a specific case.

I just bought some power measuremt pedals but I am not sure about if I will keep them and, yet, I have not installed them. Do you know if other trainiers like Wahoo Kickr Core have sensors for power measurement? In my opinion I would expect that this is not the case because they also use a spin down calibration which would not be necessary then. Or am I wrong?

victorrubin
Posts: 7
Joined: Tue Sep 29, 2020 8:30 am

Re: Resistance too easy

Postby victorrubin » Fri Dec 11, 2020 2:04 pm

**what is the power @30,2km/h (18.7 mph)?
Between 180-184
I have no faith in the Power values from the trainer. When riding on Zwift my FTP automatically increased from 195 to 220 but when I went back on to my static trainer it was too hard so I had to dial down the value manually on Zwift.

bikesteff
Posts: 10
Joined: Sun Nov 29, 2020 10:09 am

Re: Resistance too easy

Postby bikesteff » Fri Dec 11, 2020 2:23 pm

** I have no faith in the Power values from the trainer.
Yes, I don't either. Here are some power values I measure with the elite app together with different spin down calibrations (using bike brake as well as longer pedaling), all measured @30.2km/h and approx. 76 cadence:

ms Watt
888,000 320,000
1230,000 310,000
2011,000 288,000
2714,000 270,000
3457,000 248,000
3691,000 238,000
4658,000 213,000
7050,000 155,000

So with your calibration (7000ms) I would expect something around 155 Watt on my trainer which could explain why you feel less resistance (higher power value for the same calibration). I guess I will use power pedals in the future and hope that the communication/integration in the Nero will work as promised. I do not like the static trainers and using roller for a long time (I have an very old undestructable Tacx ... very good quality).

victorrubin
Posts: 7
Joined: Tue Sep 29, 2020 8:30 am

Re: Resistance too easy

Postby victorrubin » Fri Dec 11, 2020 3:09 pm

I am waiting for stock to come in so I can order a power meter (crank based) unfortunately I cant use pedal based because I use SPD shoes and I cant find any to suit. I have to buy a single meter because dual meters give unreliable data on a shimano hollowtech system which I have.
I was using rollers for about a year but was forced to buy a static trainer due to a serious bike accident since I couldn't support myself on them.

When you ride a gradient of 6% if you have dual chain rings do you have to change to the smaller chainring?

bikesteff
Posts: 10
Joined: Sun Nov 29, 2020 10:09 am

Re: Resistance too easy

Postby bikesteff » Sat Dec 12, 2020 9:55 am

If I understood it correctly, then there is an opportunity to use SPD's together with Favero's powermeter pedal. Maybe this is an alterantive for you?
I just bought them a little bit cheaper on sale but still not shure if I want and need them (here is a link https://www.youtube.com/watch?v=ybAFIhKahnM)

In case of using a single power meter you might get higher or lower values because you can never be shure if you are applying the same power on both sides. There are some guys who compared the single power meter results to Zwift and Tacx systems and got a big difference. Later they explained that the reason for this was a power difference of about 10 Watt between left an right.

** When you ride a gradient of 6% if you have dual chain rings do you have to change to the smaller chainring?

Hmmm, thats difficult to give you an answer since our friction seems to be different and I am trying to use the smaller chainring as long as possible in Zwift because on real streets I am mainly using the bigger chainring. I hope to compensate this a little bit because on SRAM AXS Red I need to change both rings in case of use. Don't really know if this makes sense ... . I guess with 6% I could use the bigger chainring, too, but I am usually using the lower ring in Zwift. Only for power higher than about 250W on almost flat "streets" (like London) I am going to big chainrings in Zwift. I am using the SRAM AXS system and can go up to 35/11 @ 35 km/h. At 48/24 I have almost the same speed as with 35/17 ... so I guess I could go to big chainrings with 6% but I usualy don't. I will try it next time.


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