Crr help

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still-chasing
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Crr help

Post by still-chasing »

Can someone please explain the difference between using Crr fixed and Crr adjusted and Crr setting in Ibike?
What's the advantage and disadvantage of using each setting? Do you always set for the lowest value?
What setting do you guys use?

Thanks!
still-chasing
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Re: Crr help

Post by still-chasing »

If crr adjust is calculated from coast downs, how are crr fixed calculated?

Thanks
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racerfern
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Re: Crr help

Post by racerfern »

In the coastdown and calride analysis screen you're presented with these three choices. You can use fixed:

Crr fixed is activated by inputing a known Crr value into an iBike setup screen:
setup > Racr > Yes > Est Fric > Yes > Enter Fric number (55=.0055)
You can also "type" your desired Crr into the analysis window and see the changes. Later, you can input that number into the iBike.

You can use adjusted:
In other words use the Crr value determined by the coastdown procedure.

You can use Setting in iBike:
In other words, use the Crr setting CURRENTLY in the iBike prior to accepting the analysis of the coastdown/calride process you're looking at.
Fernando
still-chasing
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Re: Crr help

Post by still-chasing »

So, the most accurate of the 3 settings is "Crr adjusted" since this is from coast down values and should be set to this setting?

Thanks
rcmaps
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Re: Crr help

Post by rcmaps »

Yes, in most instances. Especially if the road conditions (and tyres including tyre pressure you are using) are similar to the one you did your calibration rides on.

However, it the road is significantly rougher or smoother, then you have the ability to alter the Crr in the software (or ibike) if you think you need to.

Hope this helps.
still-chasing
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Re: Crr help

Post by still-chasing »

Ok. Thank you.
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racerfern
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Re: Crr help

Post by racerfern »

OK, my turn. I just installed Hutchinson tubeless Fusion 3 tires on Shimano WH900 wheels. What should I expect for Crr?
Fernando
jesawdy
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Re: Crr help

Post by jesawdy »

I use Hutchinson Fusion 2 tubeless tires and I just use a fixed Crr of 0.0055 which is what Boyd has recommend for the roads around here (Boyd is near Greenville, SC and I am in western NC). Personally, I would not really expect the tubeless tire to have significantly different rolling resistance. While it is sorta touted as such by some, the real advantage is to run lower pressures for comfort and the increased flat prevention. I keep running lower and lower pressures in mine... I'm down to 80-85 psi rear and ~75+ psi front (I am 160-165 lbs).

Along the same lines, do people use different Crr's for tubulars?



-Jeff
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racerfern
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Re: Crr help

Post by racerfern »

After yesterday's century that had pavement from glass smooth to almost gravel, I'm sold on tubleess tires. I ran 85 front and 95 rear (which I plan on lowering further). It absorbed nasty bumps nicely and was as smooth as silk on newly paved sections. I'll report back after I do some coastdowns because I think rolling resistance has decreased.
Fernando
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racerfern
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Re: Crr help

Post by racerfern »

Thanks for the feedback. My LBS, Bike Religion in Newport Beach also recommended using a bit of sealant. We split one can between the two wheels. The guys there have a lot of success with that because unless it's a massive cut the sealant just does its job and you keep on riding.
Fernando
jesawdy
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Re: Crr help

Post by jesawdy »

I rode all of last year without a flat (well, went tubeless in April or so). I used Stan's rim tape, valve stems and Stan's latex sealant solution on 2 different Neuvation wheelsets without incident. No problems other than getting the tires on the rims was quite the challenge. I just upgraded to a Shimano tubeless ready wheelset - tire mounting was much easier, but getting the tire to seat properly and hold air was a challenge (the rims were used and had a lot of dried sealant that was a bear to remove). Once cleaned up and with the tires well soaped, they seated and sealed just fine. I used the Stan's latex sealant again.
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