Originally Posted by CB HI

Stability test are the norm when designing any vehicle, be it bicycle, motorcycle, car, truck, boat, ship, plane or rocket. Some of these stability test include the effects of an instantaneous perturbation to the steering control system or the steering surfaces. Some of these test include the operator as part of the steering system in the test, while others only test the vehicle without the operator actions. Different industries use different terms for these stability test. JF’s term “steering displacement test” is a reasonable description of some of these test. Even if it does not show up in google searches, so what.


JF states “I have no reason to expect that diamond-frame bicycles and recumbents have any class differences in this. Each one is different.”
I agree with this provided the test does not include the operator as part of the steering system.
When the operator is included as part of the steering system, there is at least one factor which differentiates a bent from a diamond frame. On a diamond frame, the cyclist can lift his butt off the saddle and disconnect the center of mass from the lean of the bicycle (in other words - the cyclist can significantly change the lean of the bicycle without significantly changing the center of mass). On a bent, I do not, and know of no other bent rider who lifts their butt off the seat and then leans the bicycle independent of the center of mass.
The lack of this tool is one reason a bent requires more cyclist skill and more practice to ride with the same precision.