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It is thorn season in Florida and I notice an increasing number of
cyclists walking their bikes home with flats. I understand kevlar
solutions are good for glass shards and against other large traumatic
events but kevlar is a weave and may not do as well against thorns.
My solution has been thorn resistant inner tubes which work well
against the small thorn varieties in Florida. A thorn proof inner
tube gives an additional 3 - 4 millimeters of thickness protection in
the tread area that seems adequate for typical thorns.
These thick inner tubes are three times heavier than normal tubes and
rolling resistance at low pressure for wide tires might be noticeable.
At pressures above 100 pounds most of the flexing is closer to the
tread so the inner tube is not as involved. The tires do not show any
increased rolling resistance or feel any warmer than usual after a
long ride. I am not concerned as much about extra weight while the
tires are spinning up as I am about a chronic frictional loss from
reduced rolling resistance over a 50 mile ride.
Kevlar is a weave and there must be friction between strands as the
tire flexes, particularly since the kevlar solutions place the kevlar
layer closer to the tread where the tire experiences more flex. Also
kevlar is not elastic so you would think that would cause more energy
loss since it does not rebound.
Anyone have any experiences that could quantify the increased rolling
resistance? Tou need to set some parameters of course. For 1 1/4"
tires inflated to over 100 PSI on a level road rolling at 18 miles per
hour with no additional head or tail wind for example. In my
experience the rolling resistance when using thorn resistant inner
tubes is not great enough to require a 19 mile per hour pedaling
effort. Does the same hold true for other thorn solutions?
cyclists walking their bikes home with flats. I understand kevlar
solutions are good for glass shards and against other large traumatic
events but kevlar is a weave and may not do as well against thorns.
My solution has been thorn resistant inner tubes which work well
against the small thorn varieties in Florida. A thorn proof inner
tube gives an additional 3 - 4 millimeters of thickness protection in
the tread area that seems adequate for typical thorns.
These thick inner tubes are three times heavier than normal tubes and
rolling resistance at low pressure for wide tires might be noticeable.
At pressures above 100 pounds most of the flexing is closer to the
tread so the inner tube is not as involved. The tires do not show any
increased rolling resistance or feel any warmer than usual after a
long ride. I am not concerned as much about extra weight while the
tires are spinning up as I am about a chronic frictional loss from
reduced rolling resistance over a 50 mile ride.
Kevlar is a weave and there must be friction between strands as the
tire flexes, particularly since the kevlar solutions place the kevlar
layer closer to the tread where the tire experiences more flex. Also
kevlar is not elastic so you would think that would cause more energy
loss since it does not rebound.
Anyone have any experiences that could quantify the increased rolling
resistance? Tou need to set some parameters of course. For 1 1/4"
tires inflated to over 100 PSI on a level road rolling at 18 miles per
hour with no additional head or tail wind for example. In my
experience the rolling resistance when using thorn resistant inner
tubes is not great enough to require a 19 mile per hour pedaling
effort. Does the same hold true for other thorn solutions?
