How to calibrate Newton on a CX / gravel bike

How to calibrate Newton on a CX / gravel bike

Postby blp » Wed Jun 07, 2017 5:48 pm

Hi guys;

I bought a CX bike I will be using for CX races in the fall and for gravel grinds this summer. I have scoured the forum looking advice on Cal ride and Coast tests, but they seem to elude me.

I did a Cal ride on pavement and the power looked fine on pavement, but I'm not sure on gravel. Do I perform a Cal ride and Coast ride on the type of surfaces I expect to ride on, for example mud, hardpack or loose gravel? To me that makes sense.

The included file is a bit of a mix of pavement and packed gravel. East of the bridge, which you can't see unless you have the NT file, at 5.3 km from start to 14.75 km, is gravel. Crr is .0079 (seems high for Challenge Chicane 300 tpi tires at ~4 bar pressure)

Thanks
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blp
 
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Re: How to calibrate Newton on a CX / gravel bike

Postby blp » Thu Jun 08, 2017 4:28 pm

From Tom Gore, Velocomp Tech Support Wizard:

"when you set up the unit, did you use Isaac? Go to: DEVICE—>SETUP DEVICE… When you get to the road type, select Rough? If you did this, then the cal ride, you should be all set. The Firmware you are running 5.15, has incorporated our DCRR rolling resistance firmware, that allows the unit to recognize changes in road surface. I don’t recommend doing coast downs etc. They are really not necessary. I think that the Crr of .0079 is good for gravel, loose ground."

I replied "I did set up in Isaac, but as I recall, I was a bit stymied as to road surface.

I was thinking about the Crr at .0079, and realized on the actual surface that is probably closer than a theoretical, steel drum dynamometer, figure.
Tire choice? Utility or touring? I’m using Challenge Chicane open tubular tires. They have a file pattern tread, 300 tpi and I run them at about 4 bar / 55#. Or does that matter in the end?"

Tom responded with "So you chose Tubular, I would select premium or utility, should be fine with either, then enter in the 55psi, and all should be well. The software is better at this, than my guesses, so it will establish your Crr."

I hope this helps anyone with the same sort of question.

Thanks Tom, always helpful.
blp
 
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Re: How to calibrate Newton on a CX / gravel bike

Postby jd.anderson » Fri Jul 28, 2017 11:12 am

Thanks for the info...

So if I have my Powerpod calibrated for my road bike, but want to switch it over to my CX/gravel bike, I know that I need to set up a new bike profile with all the info on bike, surface, tires, etc., but do I actually need to do another calibration ride? Won't that overwrite the original calibration ride? Hoping I don't have to do a new calibration every time I switch it between bikes...

Cheers,
James
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Re: How to calibrate Newton on a CX / gravel bike

Postby Velocomp » Fri Jul 28, 2017 4:28 pm

You will set up a separate profile for each bike (profile 1 and profile 2, for example). You will do a calibration ride for each profile, and have separate wireless sensors for each bike.

PP will use the sensor IDs to figure out which bike you're riding, and switch profiles automatically.
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Re: How to calibrate Newton on a CX / gravel bike

Postby jd.anderson » Fri Jul 28, 2017 4:37 pm

Awesome. Thanks John. Just wasn't sure about the calibration ride. I assume this calibration should be done on the surface where you're doing most of your riding (e.g. out and back on a gravel road for a gravel/cx bike)?
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