street tires on ice

spokewrench

Well-Known Member
Region
USA
My Radrunner ( 20 x 3.3” semi knobby) was a big disappointment on snow and ice. It wanted to float on a loose surface. It wouldn’t even steer until I reduced pressure from the mandated 30 psi to 10. At that point, rolling resistance was horrific.

This is my third winter with my Abound (20 x 2.4” street tread) and its first big winter storm. I tried it on 4 inches of sleet pellets with the standard 50 psi. Up and down a 4% grade, u-turns, pedaling, throttle, and braking. No skidding and surprisingly little rolling resistance. A couple of hours later, the sleet had a layer of ice almost thick enough to support my weight. Pedaling without the motor, resistance was higher, but slipping still wasn’t a problem.

Go figure! Maybe the rubber in Schwalbe Pickups has a higher coefficient of friction on ice than some compounds. Besides the tires, the difference I see is a longer wheelbase, 50 vs 45”.

Two days after the storm, streets were clean and dry. Three days after the storm I was on the sidewalk along the highway. The road is narrow and curvy, so I like to stay out of the way of traffic. I encountered a hundred-yard stretch of bumpy, rutted ice where slush thrown from a plow had solidified.

Wearing sneakers, I dismounted. With some ice, it’s safer to be on a bicycle than on foot. After a few steps, I decided this was such a case. I relied on the throttle so I could keep most of my weight on a pedal at 6 o’clock, for stability. It amazed me that I didn’t slip at all.

The danger was not out on a bike but at home on foot. My garage opens north, where there’s a long shadow in winter. The ice layer hadn’t melted. Sooner or later I’d fall. The solution was easy. Shovel a little sand and gravel from my tub and spread it with a broom. That stuff washes onto streets from driveways. With a small shovel and a tub on a bike, it’s readily avaliable at low points on streets. When I wasn't underway, 60 pounds of gravel on the 32” rack of my Radrunner was clumsy. My Abound rack is only 24” high. That’s much better.
 
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Knobby tires squirm/pinch when they contact the surface so loose adhesion. Sort of like walking on ice, once you slip a bit all adhesion is lost and now you have lost all grip to the surface.
 
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