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Jan. 4, 2019, 6:57 p.m. -  Steve Mathews

Unfortunately pretty well everything you just said that I said is simply flat out wrong. It's essentially a 2D planar free body diagram (missing force vectors at the wheels, to be fair, so not a true FBD of the whole vehicle, only the rider). The rider pivots around the BB unless there's chain tension to prevent it, and the load on your hands is what balances the moment generated by the horizontal delta between your centre of mass and your BB. You've made multiple incorrect assumptions here, including the notion we're analysing it at rest - steady state planar acceleration in the Z direction (ie being leaned into a corner during steady-state conditions) is where this is relevant. If the resultant resolved force vectors from the tyres aren't in plane with the rider, the bike/rider mass rolls one way or the other, but that isn't the point of the explanation, so the 2D analysis is entirely reasonable. You also didn't pay attention to the video whatsoever, to be frank, and clearly didn't watch the previous one, since it's been made very clear that if your CoM is directly above the BB, the weight on the front wheel is not zero as you say was claimed, but apportioned directly by the front centre and rear centre ratios. IE if your front centre and your rear centre were the same length and you were balanced over the BB with your hands off the bars, 50% of your weight would be on the front wheels. There are numerous valid critiques that could be made of this 15 minute concept explanation, that was not one of them.


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