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# Lean angle due to a tire thickness of a bicycle

## Description

The finite width of the tires alters the actual lean angle of the rear frame from the ideal lean angle described above. The actual lean angle between the frame and the vertical must increase with tire width and decrease with center of mass height. Bikes with fat tires and low center of mass must lean more than bikes with skinnier tires or higher centers of mass to negotiate the same turn at the same speed.The increase in lean angle due to a tire thickness of 2t can be calculated by the ideal lean angle and the height of the center of mass. For example, a motorcycle with a 12 inch wide rear tire will have t = 6 inches. If the combined bike and rider center of mass is at a height of 26 inches, then a 25° lean must be increased by 7.28°, a nearly 30% increase. If the tires are only 6 inches wide, then the lean angle increase is only 3.16°, just under half.

Related formulas

## Variables

 θ Lean angle (rad) t Half tire thickness (inch) ϕ Ideal lean angle (rad) h Height of the center of mass (inch)