Laser level to determine rolling resistance?

[handlebar]

I prefer pedaling my Radrunner where possible. I wish I'd bought a model with narrower tires and a bigger rim diameter.

With equal tire sizes, rolling resistance depends partly on air pressure. There comes a diminishing return for more pressure. On a bumpy road, too much pressure can even increase resistance by letting the vehicle be thrown higher; that energy is lost. More pressure means more wear and tear on the machine. More pressure means a rounder cross section, reducing resistance to sliding sideways, up onto mud or snow like the prow of a toboggan.

Rubber hysteresis causes the rolling resistance. With less air pressure, treads bend more, and hysteresis is the tendency of rubber to absorb that energy and turn it into heat. If I knew how to choose low-hysteresis tires, I might enjoy low pressure and low rolling resistance together. For now, I'd like numbers to show my rolling resistance at various pressures.

If you coast down a slight decline and onto a flat or slight incline, your rolling resistance in pounds will be your gross weight times the difference in height divided by the distance along the pavement. On a lightly traveled street, I could use brightly colored duck tape to mark my start and stop points. Pacing the distance would be accurate enough. I'd just need to find the change in height.

Some fairly inexpensive levels with green lasers are supposed to be good for 100 feet outdoors. They produce a flat line to show what's level and a vertical line to show what's plumb. Turning off the vertical line would keep all the light close to the ground. I have a camera tripod that adjusts from 20 to 54" high. I could set up the tripod at my finish point, aim the level toward higher ground, measure the height,  and carry a white paper along the edge of the road. I'd stoop to check the intensity of the line and when it got faint, mark the spot. I'd measure the height of the line, then move my tripod to do it again.

I haven't heard of a law against using a builder's level along a deserted street. The light would probably be knee high or lower, and I'd be within 100 feet. Should I buy a laser level?

[JimInPT]

Should I buy a laser level?

If you do decide to get one, I can recommend this one; works very well especially for the price (snagged a Lightning Deal for $30) - I've so far used it to hang a kitchen ceiling pot-rack and a VR-headset overhead cable-pulley system.  My  touch of OCD insisted on square and centered, or the voices in my head would get annoyed.   

https://amzn.to/34zxgcY

It should be plenty visible during twilight; I haven't used it outdoors yet but it's very bright indoors.

[JimL]

In my earlier life, we had occasion to check various road surfaces.  We discovered that all of them (and especially pavement) had considerable rippling effect from heavy vehicles use.  At very high speeds we could actually see the surface fluctuations using an FFT spectrum analyzer with a magnetic G-pickup on our vehicle. 

Interestingly, the slight variation in rolling tire circumference could be seen as periodic variation of vibration intensity (often 7-9 second cycles at normal highway speed.)  Most vehicle owners thought they were feeling intermittent bad patches in the road, but it was really their own tires getting in and out of "vibration sync"!

You might want to try "coast down" tests at various air pressures, to get some comparative data.  You can find good instructions/methods on the internet.

For longer distances, we used Google Earth to read elevation points.  You can calculate distances using the "1 minute of arc = 1 nautical mile (about 6000 feet)" rule.  You can look for road sections that are easy to distance measure on the screen (exactly east-west, or north-south).

Longer test sections can really help balance useable results.  Repeatability is everything with this kind of testing.

[handlebar]

Should I buy a laser level?

If you do decide to get one, I can recommend this one; works very well especially for the price (snagged a Lightning Deal for $30) - I've so far used it to hang a kitchen ceiling pot-rack and a VR-headset overhead cable-pulley system.  My  touch of OCD insisted on square and centered, or the voices in my head would get annoyed.   

https://amzn.to/34zxgcY

It should be plenty visible during twilight; I haven't used it outdoors yet but it's very bright indoors.

Thanks. They say green can be seen farther outdoors in daylight. Here's one I've been considering.
https://amzn.to/3Lz8L08

Darn! How did they get such a long URL?
They say 85 feet outdoors at 100 lux. A slightly more expensive model is advertised for 165 feet outdoors, if you buy their receiver.  That gives me an idea.

A little headlamp will light up a reflective stop sign 1000 feet away. I get a board 2" wide and maybe 3 feet long and fasten it to a base so it will stand vertically on the street. I put white reflective tape on the face. Measuring from the pavement, I use a felt-tip marker to make a line across it every six inches.  Suppose the reflected laser light is visible from 100 feet in daylight. My tripod has a crank to raise and lower a camera. I crank it until the reflection dims on the lowest line, 6" off the pavement. At my end, I measure and find the laser beam is 30" of the pavement. So the pavement is 24" higher at the reflector, for a 2% grade. I'll bet I can get away with using a dab of yellow acrylic paint to mark the curb at increments of 1 foot rise.

It looks as if Class 2 laser levels aren't very hazardous. A Class 2 pinpoint laser could cause damage if you stared in to it without 23 feet, but a level spreads the light in a horizontal plane.

[handlebar]

In my earlier life, we had occasion to check various road surfaces.  We discovered that all of them (and especially pavement) had considerable rippling effect from heavy vehicles use.  At very high speeds we could actually see the surface fluctuations using an FFT spectrum analyzer with a magnetic G-pickup on our vehicle. 

Interestingly, the slight variation in rolling tire circumference could be seen as periodic variation of vibration intensity (often 7-9 second cycles at normal highway speed.)  Most vehicle owners thought they were feeling intermittent bad patches in the road, but it was really their own tires getting in and out of "vibration sync"!

You might want to try "coast down" tests at various air pressures, to get some comparative data.  You can find good instructions/methods on the internet.

For longer distances, we used Google Earth to read elevation points.  You can calculate distances using the "1 minute of arc = 1 nautical mile (about 6000 feet)" rule.  You can look for road sections that are easy to distance measure on the screen (exactly east-west, or north-south).

Longer test sections can really help balance useable results.  Repeatability is everything with this kind of testing.

The coast down test needs a long stretch of flat pavement. It includes aerodynamic resistance. For now, I'm interested in "mechanical" resistance only. if the speed is low and there's no wind, air resistance won't make much difference. A bicycle can't start to coast from a dead stop or coast to a dead stop, so accuracy would depend on how close your end speed was to your push-off speed.

Around my house, the side streets are badly rippled. I don't know whether to blame truck traffic, pavement expansion under the summer sun, or frost. The main roads are much smoother.

[Altema]

Interesting project, and for Amazon links, you can just delete the "ref=" and everything after it, like below.
https://amzn.to/3uMuo76

I have little choice in terms of rolling resistance because of using Tannus Armour, so if I want to maximize range, I'd need to remove them.

[handlebar]

I have little choice in terms of rolling resistance because of using Tannus Armour, so if I want to maximize range, I'd need to remove them.

As a teen, I rode an English bike a couple of thousand miles a year. I may have had one flat a year. There was one exception. At the end of 11th grade, a classmate and i went camping. It entailed riding our loaded bikes 20 miles on gravel roads. I think I had three flats (like rifle shots) on that stretch. Each took only a few minutes to patch, but it was embarrassing. (I didn't know what caused those flats. Recently, I learned that inner tubes get brittle as they age. Mine had probably been in service more than 10 years.)

Then, for 30 years, I rode motorcycles up to 30,000 miles a year and never got a flat. I think a bicycle tire at 60 psi or a motorcycle tire at 32 tends to put a rounded cross section on the road, and that tends to push puncture hazards to the side.

On roads around here, the stock Radrunner seat was so rough that I reduced tire pressure to 15psi. I moved the seat back with a layback post. As with the original 1885 Rover, that put most of my weight on the pedals for maximum comfort. I was comfortable at 25 psi, but I worried about fragile cargo like eggs. I cut it to 20 psi. Now it's back at 25. If I buy eggs, I buy cereal and lay the box on its side as a cushion for the egg carton. Maybe I'll try 30 psi.