MEASURING A B and h

An accurate bathroom scale, a measuring tape and a calculator are needed.

Measure the horizontal distance between the axles.

Drop a weighted line from each axle and measure the distance on the floor.- A

Weigh the bike/rider. -Wt

Prop up the rear wheel so that the bike is level with the front wheel on the scale.

Weigh the front wheel with the rider on the bike –Nf

B = A Nf/Wt

Raise the scale a small distance D

Measure the horizontal distance between the axles, just as done for (A). X

The bike/rider is now tilted upward at an angle:

Tan(f) = (D/X)

We now have a right triangle with the angle f at the rear axle. The horizontal side X, the vertical side D with a hypotenuse of A, if the wheels are of equal size or:

Hyp =A +(Rr-Rf)tan(f) or A +(Rr-Rf)(D/X)

weigh the front wheel with the rider on the bike. –Nf

h1 = [B-Hyp(Nf/Wt) ]/(D/X)

D should be changed and h1 found several times and averaged. Errors will be reduced over the average. The height h1 is the distance of the cg above the rear axle.

Now h = h1 + Rr

Rr is the radius of the rear wheel and Rf is the radius of the front wheel.

You have now found 3 very important geometric values of your bike, A, B, and h.