Circular motion
The forces acting on the cyclist taking a turn are normal reaction(N), friction (f) and weight(W). The N and f can be summed up as reaction force R (acting from the ground). An angle will be associated with R by applying tan rule. If you take moments about the CG you will find that N and f produces moments that counter each other so that the cyclist do not fall. If you draw an upright cyclist, N passes through the CG and f will produce a moment that will topple the cyclist outwards.
