Analytic Cycling Logo Tire Rolling Resistance

Jobst Brandt has
published data for tire rolling resistance. His data forms the basis for this analysis. He has also provided an explanation along with the data.

We expressed this data as families of curves and identified them by a generic description of a tire. We calculate rolling resistance as the nominal Crr for the surface multiplied by the ratio of one tire to another. We picked the tire with the lowest rolling resistance (Premium Clincher) as a standard to which the other tires are compared. Hence the Crr used in the formulas becomes

  Crr = NominalCrr x RollingResistanceTire1/RollingResistanceComparisonTire

As Brandt explains, the glue line in tubulars glued with road glue gives a flexible contact between the tire casing and the rim. This causes rolling resistance losses. Track glue dries stiff and prevents these losses. Track glue requires a perfectly clean rim. Once glued, the tire cannot be removed for repair. If removed, the rim will have to be throughly cleaned to base metal before mounting another tubular. The data show that if one does this, one has a tire with rolling resistance that is equivalent to a Premium Clincher.



Figure 1—Plot of families of tires (Premium, Utility, & Touring) for Clinchers (black) and for tubulars mounted with road glue (red) and track glue (blue).


Tire Descriptions
Premium Thin tread, thin high-thread count casing, thin tube
Utility Thicker tread, more layers of casing under tread, typical tube
Touring Thick tread, thick sidewalls, typical tube


Anecdote:

A rider asked how much time it was worth to ride clinchers in a 3k pursuit. Our analysis said it would be about a 2.5 second advantage to ride clinchers over tubulars glued with road glue. After some research the rider concluded that tubulars were the only choice since the the rider's federation was providing the tubular disc wheels.

The rider's mechanic tried mounting tubulars with shellac, an alternative to track glue (he could not find track glue). Shellac would not stick to rims previously glued with road glue; he could not get the rims clean enough. He tried other adhesives, but could not find one that would be stiff and not dissolve the base tape.

The moral of the story is that, although track glue is a theoretical possibility, don't take for granted that you can make it work.

 

 

© 2004 Tom Compton