This makes sense, but the large drum and its smoothness probably reduces the contact patch deflection and the amount of heat that remains in the tire versus heating the wooden drum.
On actual roads, the asphalt can be much hotter than ambient air, along with causing larger displacements and slipping on the contact patch.
Again, not suggesting these are giant points, just bringing them up for discussion. I agree with Tom A. that convection somewhat compensates for velocity in a manner that may be modeled away, when moderate ambient temps are close to ground temps, but I think there is, plausibly, a decent effect of hot road surfaces.
This makes sense, but the large drum and its smoothness probably reduces the contact patch deflection and the amount of heat that remains in the tire versus heating the wooden drum.
On actual roads, the asphalt can be much hotter than ambient air, along with causing larger displacements and slipping on the contact patch.
Again, not suggesting these are giant points, just bringing them up for discussion. I agree with Tom A. that convection somewhat compensates for velocity in a manner that may be modeled away, when moderate ambient temps are close to ground temps, but I think there is, plausibly, a decent effect of hot road surfaces.
I did a bunch of rides outside with an IR thermometer, and I compared tire temp to the temp of a small plastic piece that was shaded, located at ~axle level on the bike. Even in bright sunshine, tire temp and the temp of the test piece were nearly identical when taking a temp reading immediately upon stopping the bike. It was those observations that made me confident in just using a Crr temperature compensation based on ambient temps.
Tom maybe you, Josh or others can comment on a statement from the paper on rolling resistance estimation: https://journals.sagepub.com/doi/10.1177/0954407018802733
“Tyre hysteretic loss has been the main essential issue in numerical prediction of rolling resistance. In other words, the rolling resistance force is a measure of the hysteretic losses. In all of the popular numerical methods used for this reason, the time histories of strains must be approximated to calculate the hysteretic loss and rolling resistance during one revolution. These methods are classified based on the technique by which strain cycles are approximated during the cycle.”
as you have so well noted as has Josh, hysteresis is the main reason for rolling resistance break point. In the above they mention time histories of strains. Would this have any impact on initial VE trials? This is outside my scope so I am interested in a hysteresis for dummies explanation. Does this mean that there is a time domain change in hysteresis that requires knowing what happened before to predict the effect?
If all you want is the bottle, I might be able to make that happen
What about this: https://www.tubolito.com/tech/ Those have a pretty large resolution (+/- 3 psi) for the purpose…I think he’d enjoy the armagnac more
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Tom maybe you, Josh or others can comment on a statement from the paper on rolling resistance estimation: https://journals.sagepub.com/...177/0954407018802733
“Tyre hysteretic loss has been the main essential issue in numerical prediction of rolling resistance. In other words, the rolling resistance force is a measure of the hysteretic losses. In all of the popular numerical methods used for this reason, the time histories of strains must be approximated to calculate the hysteretic loss and rolling resistance during one revolution. These methods are classified based on the technique by which strain cycles are approximated during the cycle.”
as you have so well noted as has Josh, hysteresis is the main reason for rolling resistance break point. In the above they mention time histories of strains. Would this have any impact on initial VE trials? This is outside my scope so I am interested in a hysteresis for dummies explanation. Does this mean that there is a time domain change in hysteresis that requires knowing what happened before to predict the effect?
No…when they talk about “time history of strains”, they’re basically describing the process by which one would quantify/calculate the hysteresis of a material.
And, I think you might be misunderstanding the “breakpoint” concept. In the total bike+rider system, at pressures below the breakpoint pressure for the conditions/use, the majority of losses are due to hysteresis in the tire carcass (i.e. due to flexing of the tire material in response to movement AND to surface irregularities). Good tires with low hysteresis properties end up returning most of that flexing input to the road surface in the trailing half of the contact patch. That’s why pneumatic tires work so well.
However, the tire is containing an air spring (which has quite low hysteresis) which makes up a big part of the “suspension” (i.e. nearly all of the spring rate) and if that air spring is inflated to too high of a spring rate (too stiff for the conditions/use) then the energy imparted into that tire by the surface irregularities isn’t used to flex the tire as much, and more of it is transmitted through the tire and into the rest of the system, where it can be dissipated in the “squishy bits” of the rider.
Thanks Tom, what I read from the quote is to be able to model rolling resistance of a tire they needed to take into account the material characteristics. Now I assume that because this is a model for automotive tires it may be more important than in bicycle tires for exactly the reasons you state, that the material hysteresis is not significant to the over all effect of the bike rider system. thanks for the explanation.
Im not sure if this has popped up in previous pages but I occasionally get a noticeable drift that makes some tests useless. It usually ends with position B almost always being faster than A. I know the easy answer is to go ABBA but I usually save those for recovery weeks.
Does temperature effect the VE calculation or possibly my Quarq numbers? Here is an example where the temp dropped more than what is likely (Starts at 34 before stabilizing at 28) - https://www.strava.com/activities/4682092261. I also went out today on an endurance ride and noticed the temp started around 61 and dropped until it stabilized at 52. The actual temperature was 60. The funny thing is that I dual recorded using a Garmin 520 and a Wahoo Bolt and both had the same temp drop. Full disclosure - I rode with GPS on both but even still the cda drift is pretty significant. I would have to move the density slider from 1.22 to 1.16 to get the start and end to show similar numbers.
Possibly, but temp affects air density the wrong way: a 9 degree F. drop in temperature should increase air density a little. So I’d be looking at tires or your power meter.
You could do a couple of things. I would try to get hourly weather data and see if things are changing over the 2+ hours. Look at barometric pressure which will greatly impact air density.
Also look at wind. You may have more of tail wind contribution in the 2nd part of the ride. I am not sure what your ride look looks like. Is it out and back or some kind of loop ?
Maybe look if there has been a big change in zero offset of the Quarq at the beginning and end of ride. You used to be able to do this with a Quarq, not sure you still can. Can you zero during the ride ?
Is this pattern reproducible ? Knowing that would help narrow things down.
Im using a 3 mile loop with decent tree coverage. I shorten them to half laps when I do proper testing.
I’ll try to do ABA with my pedal power meter added to compare with my Quarq and see if I can tease anything out. I wish it were reproducible but some days I get really clean data and other days the last position is ~10 watts faster.
The CRR was just a random number. I usually use around .005 for my training setup.
I am not certain if this really matters but I notice you have constant elevation velodrome checked as on. What happens if you check the auto correct and the constant elevation check boxes to off?
Robert, do you use Golden Cheetah for you analysis? I can’t get it to run on my MAC and I have the operating system updated, but just won’t load. Any suggestions other than Golden Cheetah?
Robert, do you use Golden Cheetah for you analysis? I can’t get it to run on my MAC and I have the operating system updated, but just won’t load. Any suggestions other than Golden Cheetah?
What version of the OS (Catalina, Big Sur…) and what version of GC ?
When you say “won’t load”, what happens ? Do you get something like the GC icon appearing as if it was running but nothing on the screen ?
I am running Big Sur 11.4. I am using the recommended GC that it detects the 64 bit one. I download it and open the dmg file to open it. I click on the icon and click on open. The GC icon just bounces on the left hand side and then after about 5 minutes it says it is not responding.
I am running Big Sur 11.4. I am using the recommended GC that it detects the 64 bit one. I download it and open the dmg file to open it. I click on the icon and click on open. The GC icon just bounces on the left hand side and then after about 5 minutes it says it is not responding.
I tried the 3.5 and 3.6 builds on Big Sur and they did not work. Same thing as you, bouncing of icon.
I went to the google group (golden-cheetah-users) where all the smart guys hang out.
I tried it on Big sur and it worked. It did the standard apple bitching about malware.
There is talks of versions of Qt (one of the main components they use to build). The conversation matches my experience. The new QT required a new XCode. The new Xcode works on old machines, but the old Xcode doesn’t work on new machines…
Thank you so much. What was weird is last night it bounced and then about 15 minutes later it just opened. It seems to sit there for a while saying, “Application is not responding”. Then it opens right up, but I will try those other versions. You guys are amazing thanks for all of your help.
