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Dynamo hub settings
Posted: Mon Mar 02, 2020 12:51 pm
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.
Re: Dynamo hub settings
Posted: Mon Mar 02, 2020 2:34 pm
by Velocomp
Please email
technicalsupport@velocomp.com for a specific response.
Re: Dynamo hub settings
Posted: Mon Mar 02, 2020 3:41 pm
by escobar
Well, I did so, on Nov-30.
Since I've got no answer so far, I decided to try my luck here.
Re: Dynamo hub settings
Posted: Mon Mar 02, 2020 4:14 pm
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.
Re: Dynamo hub settings
Posted: Mon Mar 02, 2020 4:31 pm
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.
Re: Dynamo hub settings
Posted: Thu Aug 06, 2020 6:08 am
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.
Re: Dynamo hub settings
Posted: Thu Aug 06, 2020 7:15 am
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?
Re: Dynamo hub settings
Posted: Thu Aug 06, 2020 7:42 am
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.
Re: Dynamo hub settings
Posted: Fri Aug 07, 2020 8:25 am
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.