DogDipstick said:
So what strictly defines the difference between a mc tire and a bicycle tire in your assertion?
DOT certification.
Albeit, that definition is not all-encompassing, as there are off-road motorcycles that do not use DOT rated tires, but when I speak of motorcycle tires, I'm speaking exclusively of DOT-rated rubber.
I feel my tire has very little RR. I glide for hundreds of feet, after the hill, in my pinon. I have ridden alot.I can conserve enrgy well, with my slower rolling. From my experiences.
It isn't so much about how the tire feels, as it is what is its rolling resistance coefficient. It is the latter that determines the amount of power required to overcome rolling resistance versus speed for a vehicle of a given mass.
Force Rolling resistance = Crr * Mass * Gravitational Constant
The power to overcome rolling resistance varies linearly with speed.
The above model is not 100% correct from a purely technical basis, but for speeds concerning any ground vehicle moving at road legal speeds, it is very accurate.
I have a tire I try to clone, pass off a s a bicycle, but is certainly a 4 ply 8lb DOT 75mph tire by Duro in standard sizing. Not a bicycle tire. Has a 2.5" width. Not to fat, or large, like a large motorcycle tire.... but yes it is. However, I can glide as long, or longer, than a knobby, 26" bicycle tire with no weight in its assemble... ( the only other bicycle tire I have exp. to compare with)... I do see how thin and how nimble, the roadracing bicycle tire is, with its 1" cross section and large diameter..... But is this not impractical and negligible when we discuss higher powered vehicles ( with stored energy systems contributing to the traction an propulsion)?
It is possible for a motorcycle tire to have a rolling resistance coefficient comparable to a bicycle tire, if it were designed for such. A tire's width has less to do with its rolling resistance than other factors such as the compound it is made out of, tread design, belts, construction type, how it handles mechanical hysteresis, number of plys, temperature, air pressure, ect. The problem is that rolling resistance is generally an afterthought when it comes to tires designed for moped and motorcycle applications, unlike cars which go through fuel economy testing, or bicycles which have to do as much as possible with greatly less power. You'd need to set up an experiment and test the Crr value of your tires to see how it compares to any bicycle tire you have on hand. It is possible you might have a motorcycle tire that does have a low Crr value. It is also possible that your bicycle tire has a high Crr value and the motorcycle tire you are using is still worse than most bicycle tires. There ARE bicycle tires with high Crr values, but they are an oddity, specifically because humans have very poor continuous power capabilities compared to any motor, thus requiring almost universally a low Crr value to be able to propel a bicycle to an appreciable speed.
Website with Crr values for bicycle tires:
https://www.bicyclerollingresistance.com/
Study with pdf for Crr for car tires(see page 5 for chart, I had to enter the defunct link into archive.org, the link being "
https://greenseal.org/recommendations/CGR_tire_rollingresistance.pdf"):
https://web.archive.org/web/2005112...ecommendations/CGR_tire_rollingresistance.pdf
A number of car tires that you can buy today have Crr values approaching that of bicycle tires, albeit they are far too heavy to pedal a vehicle using them and accelerate as one is accustomed(not to mention disruptive to the airflow of a bicycle given a car tire's cross sectional area), but once a rider got a low rolling resistance car tire up to a bicycle-appropriate cruising speed they'd find it similarly easy to maintain that speed on flat ground. It would take a lot more effort and time to get up to that speed, due to inertia.
My application is something unique. I'm trying to build a vehicle capable of sustaining freeway speeds using an electric motor, but is low drag/low mass enough that it can still be pedaled like a velomobile to faster than bicycle speeds with the motor shut off. This means I need a narrow and relatively lightweight DOT tire rated for highway speeds that is also low in rolling resistance. Most of the candidates with low rolling resistance are for cars and are far too big/heavy, while the bicycle tires I've considered don't have enough rubber or durability for the application I require.
If you have a low rolling resistance motorcycle tire that can fit in a 16" DOT wheel, I'm all ears, because that is exactly what I'm looking for. I have some Mitas MC2 tires in my possession and will eventually try them when I upgrade my velomobile, but they are an experiment and I'm not certain if they have a sufficiently low Crr value for my application, but they are the most promising candidate I could find given that solar race car teams use them after testing many candidates. Dedicated solar race car tires could also work for my application, such as the Schwalbe Energizer series with DOT rubber(not to be confused with the Schwalbe Energizer ebike tires), but they are unobtanium in the U.S.