billyk
Guru
Having had to practice keeping myself from leaning forward on a hard stop so as not to lift the rear wheel, I looked through the forum for clues. I came up with two different statements from John Tolhurst.
Referring to the 60 degree angle with the COG that makes hard braking safe:
On Tue, 2012-10-02 17:07, in the Conversion kit forum, ak-tux said:
According to John Tolhurst, as long as the angle between the COG(centre of gravity) and the FRONT BRAKE from the horizontal is not more than 60 deg you will not go over the bars under normal circumstances.
John T replied 2 hours later:
To clarify, if you get that 60 degrees, you can deaccelerate at half a g-force without lifting the rear wheel, and 0.5g is the rate of deacceleration that you discover if you apply calculus to the braking distances cited in the EU regulations for bicycles.
But then on Thu, 2012-09-13 00:14, in the Ride Reports forum John T wrote:
Watch the angle between the centre of gravity and the FRONT TIRE ROAD CONTACT PATCH. If it gets too vertical, you'll lift the rear wheel too easily under hard braking. No more than 60 degrees from the horizontal, so you can brake at 0.5 gravity and meet the EU braking code.
So which is it: the angle between the COG and the brake? Or the front tire patch? I assume the latter, since the position of the brake is not well-defined, but since we hang on JT's every word as the gospel truth (at least I do), I'd like to know for real.
Referring to the 60 degree angle with the COG that makes hard braking safe:
On Tue, 2012-10-02 17:07, in the Conversion kit forum, ak-tux said:
According to John Tolhurst, as long as the angle between the COG(centre of gravity) and the FRONT BRAKE from the horizontal is not more than 60 deg you will not go over the bars under normal circumstances.
John T replied 2 hours later:
To clarify, if you get that 60 degrees, you can deaccelerate at half a g-force without lifting the rear wheel, and 0.5g is the rate of deacceleration that you discover if you apply calculus to the braking distances cited in the EU regulations for bicycles.
But then on Thu, 2012-09-13 00:14, in the Ride Reports forum John T wrote:
Watch the angle between the centre of gravity and the FRONT TIRE ROAD CONTACT PATCH. If it gets too vertical, you'll lift the rear wheel too easily under hard braking. No more than 60 degrees from the horizontal, so you can brake at 0.5 gravity and meet the EU braking code.
So which is it: the angle between the COG and the brake? Or the front tire patch? I assume the latter, since the position of the brake is not well-defined, but since we hang on JT's every word as the gospel truth (at least I do), I'd like to know for real.
