rruff wrote:A note about the rims that exhibit this behavior: On the road, the same spokes that are subject to lateral loads (at the bottom of the wheel) will already have their tension reduced due to holding the bike and rider up. In addition the rear wheel will experience torque loads which will reduce tension on all pushing spokes. So the lateral stiffness of these rims would be worse (maybe a lot worse) in practice than what is shown on these graphs. Determining just how much difference would take more analysis. Some might already be past the point where the stiffness rapidly declines.
Thanks a million rruff for this nice input.
The spokes on such a wheelset do not have any tension. They merely work with 0 tension at rest, and deal with some tension/compression loads that depends on the rider weight at each wheel revolution.
It would be nice to see what happens with a load from the bottom of the wheel in addition to the lateral one.
I'm not sure it would obligatory reduce the lateral stiffness.
Indeed the bottom load would tend to put some compression on the spokes near this load. These spokes will tend to bend for sure, but this would happen to both sides of the wheel, not only the side where the lateral load is applied.
Thus, while the spoke on one side of the wheel bends and has lost stiffness due to bending, the one on the other side has bent too but in the opposite sense. So before losing its stiffness while bending again on the other side, it has to come back to standard position where it is stiff.
Regarding the torque loads, the central flange is supposed to deal with this while gaining tension. It must not be part of the lateral testings I think.
Epic-o wrote:Adrien, Do you know what are the typical lateral loads during standing pedaling? I tried to do some calculations but it's not as simple as I thought
This can be determined through some trigonometric formulas. We know rider weight, weight distribution on both wheels, wheel angle with the ground, and the direction of the lateral load. Put these info into the right formula
This result could be controlled as a real application with a known rider/bike weight, the right distance from brake pads to rims, and a marker on the brake pads. If the rim is marked, it rubbed the pads. We could check with the 180° data measured on the bench.
I must say that I didn't have time to perform such a test yet.