I like these sets of picture because it makes it easy to understand the concept and its impact:
It shows area in front of the steering axis is the leading factor.
More importantly it shoes the Cp location is dependent on the sum of the pressure gradients front and aft of the steering axis. Basically, the side with the most red is the one getting pushed and that tells you which way the wheel wants to turn. The impacts of how the bike will react to that are well discussed earlier in the thread. The greater the front/aft ratio, the further the Cp will be from the steering axis, and that is one of the important bits.
Now that makes it very interesting because it is universally accepted a disc is harder to ride at high yaw. Looking at this we see that a disc will naturally correct to make a rider lean into the wind, which at first sight makes it puzzling.
The problem is having the Cp on the steering axis does fix instant steering torque, but the corrolary is that the further the Cp is from the steering axis, the greater the torque moment will be. Now the second important bit is that means as effective yaw angles rapidly change while you ride (hello hambini), the torque moment deltas that needs to be dealth with increase. Your handlebars get thrown around more and you constantly try to control for it. Now that explains why a font disc can be a pain.
As it applies to deep wheel design, the problem is the Cp location is also a moving target, it changes with effective yaw angle.
It shows area in front of the steering axis is the leading factor.
More importantly it shoes the Cp location is dependent on the sum of the pressure gradients front and aft of the steering axis. Basically, the side with the most red is the one getting pushed and that tells you which way the wheel wants to turn. The impacts of how the bike will react to that are well discussed earlier in the thread. The greater the front/aft ratio, the further the Cp will be from the steering axis, and that is one of the important bits.
Now that makes it very interesting because it is universally accepted a disc is harder to ride at high yaw. Looking at this we see that a disc will naturally correct to make a rider lean into the wind, which at first sight makes it puzzling.
The problem is having the Cp on the steering axis does fix instant steering torque, but the corrolary is that the further the Cp is from the steering axis, the greater the torque moment will be. Now the second important bit is that means as effective yaw angles rapidly change while you ride (hello hambini), the torque moment deltas that needs to be dealth with increase. Your handlebars get thrown around more and you constantly try to control for it. Now that explains why a font disc can be a pain.
As it applies to deep wheel design, the problem is the Cp location is also a moving target, it changes with effective yaw angle.