You know what pisses me off. Tires and comparing between brands, like I get that an Assegi DD has more grip and rolling resistance than a DHRII EXO, but how do those stack up against a Magic Marry Soft or a Vigilante Tuff/Handling? I think we need an ASTM standard for testing mount bike tires. Rolling resistance, braking an accelerating traction and leaned in cornering grip. How would right such a testing standard. We need a methodology, a control tire, the actual testing apparatus. Being for off road use makes this all more difficult because I dont think a normal friction drum like these tests are done on road going tires would make for an accurate representation of trail conditions. Would we have to do the tests in 2-3 types of soil? Like hardpack, mud, and loose over hard? Just like car tire for treadwear the numbers are reported as an extrapolated amount based off of performance vs the control tire. Like say we call our control tire a 5 at everything, a tire that has half the rolling resistance and 50% better braking traction would be reported as having a rolling resistance of 2.5 and a braking traction of 7.5. Or a tire with 10% more rolling resistance and twice the tration would get a 5.5 and a 10. Doing it like this rather than a letter rating like car tire traction or as an out of 10 system like some manufacturers already do within their own line gives us future growth potential.
For rolling resistance and traction both ways I think it should be a fairly simper apparatus. Just a rigid fork, with mounts for weights to get the total weight less tire to 85kg, a very strong wheel, 203mm brake with brake pressure sensor and probably an electrically driven master, mounted to the front of a 4 powered wheeled cart/vehicle with computer controlled speed with a pivot to allow only up and down motion with a force sensor in between. The tire will first be mounted in the rotation direction recommended by the tire manufacturer, to a wheel of the manufacturers recommended width, tubeless tires mounted tubeless with a control sealant (probably stans), and tubed tires mounted with a manufacturer supplied tube. Tires inflated to some specified psi. Warmup runs will be performed until hub and braking components come up to a predetermined operating temperature. Rolling resistance test would be performed at a constant speed and the results compared against a control tire,a number of runs will be averaged for the force measured. The braking test will also be performed at the same time, it will mimic the constant speed of the rolling resistance test, however the braking pressure will be varied to achieve the maximum force into the testing apparatus, multiple runs will be averaged. The acceleration traction will be measured by mounting the tire in the oposite rotation direction and the testing performed the same as the braking test. If we determine multiple surfaces are necessary the same procedure will be repeated on those surfaces.
Now where that gets screwy is with the different wheel widths and diameters required to measure the different size tires, do we keep the same hub as the control tire and keep re-lacing the wheel for different rim widths? Or do we just assume that the same hub design, freshly lubricated and warmed to the same operating temperature is going to provide a negligible contribution to rolling resistance? And also assume that different rim designs also have a negligible effect on rolling resistance and braking traction.
I don't have a good idea yet for measuring lateral grip. For cars they just mount them up on a variety of "current model year" cars that the tires are likely to be used on and have a few test engineer drivers run them on the figure 8 skid pad and average their performance.
For rolling resistance and traction both ways I think it should be a fairly simper apparatus. Just a rigid fork, with mounts for weights to get the total weight less tire to 85kg, a very strong wheel, 203mm brake with brake pressure sensor and probably an electrically driven master, mounted to the front of a 4 powered wheeled cart/vehicle with computer controlled speed with a pivot to allow only up and down motion with a force sensor in between. The tire will first be mounted in the rotation direction recommended by the tire manufacturer, to a wheel of the manufacturers recommended width, tubeless tires mounted tubeless with a control sealant (probably stans), and tubed tires mounted with a manufacturer supplied tube. Tires inflated to some specified psi. Warmup runs will be performed until hub and braking components come up to a predetermined operating temperature. Rolling resistance test would be performed at a constant speed and the results compared against a control tire,a number of runs will be averaged for the force measured. The braking test will also be performed at the same time, it will mimic the constant speed of the rolling resistance test, however the braking pressure will be varied to achieve the maximum force into the testing apparatus, multiple runs will be averaged. The acceleration traction will be measured by mounting the tire in the oposite rotation direction and the testing performed the same as the braking test. If we determine multiple surfaces are necessary the same procedure will be repeated on those surfaces.
Now where that gets screwy is with the different wheel widths and diameters required to measure the different size tires, do we keep the same hub as the control tire and keep re-lacing the wheel for different rim widths? Or do we just assume that the same hub design, freshly lubricated and warmed to the same operating temperature is going to provide a negligible contribution to rolling resistance? And also assume that different rim designs also have a negligible effect on rolling resistance and braking traction.
I don't have a good idea yet for measuring lateral grip. For cars they just mount them up on a variety of "current model year" cars that the tires are likely to be used on and have a few test engineer drivers run them on the figure 8 skid pad and average their performance.
