Dynamo hub settings

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escobar
Posts: 3
Joined: Sun Mar 01, 2020 5:17 pm

Dynamo hub settings

Post by escobar »

Do I need any specific setting to use the Powerpod in a bike with a dynamo hub? Like rolling resistance, for example?

If I don't and knowing I also use a wheel with a regular hub, should I have a separate profile for each case?

Thank you.
Velocomp
Velocomp CEO
Posts: 7793
Joined: Fri Jan 11, 2008 8:43 am

Re: Dynamo hub settings

Post by Velocomp »

Please email technicalsupport@velocomp.com for a specific response.
John Hamann
escobar
Posts: 3
Joined: Sun Mar 01, 2020 5:17 pm

Re: Dynamo hub settings

Post by escobar »

Velocomp wrote: Mon Mar 02, 2020 2:34 pm Please email technicalsupport@velocomp.com for a specific response.
Well, I did so, on Nov-30.

Since I've got no answer so far, I decided to try my luck here.
Velocomp
Velocomp CEO
Posts: 7793
Joined: Fri Jan 11, 2008 8:43 am

Re: Dynamo hub settings

Post by Velocomp »

Hmm...there's a 99.9% chance Tom's response is in your spam folder.

Please try again. If you don't have a response in a few hours I will be amazed.
John Hamann
escobar
Posts: 3
Joined: Sun Mar 01, 2020 5:17 pm

Re: Dynamo hub settings

Post by escobar »

Velocomp wrote: Mon Mar 02, 2020 4:14 pm Hmm...there's a 99.9% chance Tom's response is in your spam folder.

Please try again. If you don't have a response in a few hours I will be amazed.
I guess I'm among those 0,01%, then (yay!)

Will try again.
AussieDon
Posts: 16
Joined: Tue Feb 05, 2019 1:43 am

Re: Dynamo hub settings

Post by AussieDon »

Hi Escobar,

Did you find that you needed to make adjustments to the PP profile for your bike with the hub dynamo? I also have a hub dynamo on my Specialized Roubaix and I tend to have it on all the time as I think it makes me more visible. I have a Shutter Precision SV-8 hub which has a quite high efficiency rating and not much drag.

I hadn't really considered that the drag from the hub would effectively add to the rolling resistance but I think it would be an option for you if you're finding the power reading a bit low. The Crr does change when you select different types of riding surfaces. Selecting 'mixed ashphalt' vs 'good ashphalt' will change the Crr by .002+ which might be just enough to account for the hub drag.

I'm interested to hear how this worked out for you.
Velocomp
Velocomp CEO
Posts: 7793
Joined: Fri Jan 11, 2008 8:43 am

Re: Dynamo hub settings

Post by Velocomp »

AussieDon wrote: Thu Aug 06, 2020 6:08 am Hi Escobar,

Did you find that you needed to make adjustments to the PP profile for your bike with the hub dynamo? I also have a hub dynamo on my Specialized Roubaix and I tend to have it on all the time as I think it makes me more visible. I have a Shutter Precision SV-8 hub which has a quite high efficiency rating and not much drag.

I hadn't really considered that the drag from the hub would effectively add to the rolling resistance but I think it would be an option for you if you're finding the power reading a bit low. The Crr does change when you select different types of riding surfaces. Selecting 'mixed ashphalt' vs 'good ashphalt' will change the Crr by .002+ which might be just enough to account for the hub drag.

I'm interested to hear how this worked out for you.
When you ride with the dynamo "on", do you feel a perceptible increase in wheel friction?
John Hamann
AussieDon
Posts: 16
Joined: Tue Feb 05, 2019 1:43 am

Re: Dynamo hub settings

Post by AussieDon »

It's hard to tell, I've tried riding with the dynamo off and then on but the terrain where I ride is rolling hills so it's difficult to correlate. What I can say that when the dynamo is on and I spin the wheel by hand it slows down much quicker than when the dynamo is off, so there's definitely some drag there.

There have been some lab tests on dynamo hubs and for my SP PV-8 hub,when the dynamo is on the drag takes about 8 watts of power to overcome.

https://www.cyclingabout.com/dynamo-hub ... b-testing/

That doesn't sound like a lot but on a long ride when I'm riding tempo, it's still something.
Velocomp
Velocomp CEO
Posts: 7793
Joined: Fri Jan 11, 2008 8:43 am

Re: Dynamo hub settings

Post by Velocomp »

That's good information!

Here is what I would do:

1) Open one of your ride files where you have used the dynamo for the entire ride

2) Look at the average watts for the ride

3) Select the "Analyze/Tweak CdA,Crr command"

4) Slightly increase the Crr value. For example, if the starting value is 0.0054, increase it to 0.0064.

5) Each time you increase the Crr value, you'll see the average watts increase. Increase the Crr value until your watts shown are about 8W higher.

6) Use the tweaked value of Crr in your dynamo rides.

The tweaked value of Crr is the additional drag placed on your bike by the dynamo.
John Hamann
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