Moment Equilibrium and Bicycle Tire Reactions

Use Weight Distribution Simulation III below to help you with the exercises on this page.

The applet above is similar to the Weight Distribution applets seen previously. Recall from your last encounter with this type of applet, you were asked to predict what phenomenon explains how your weight is distributed to the front and rear tires of the bicycle.

What you should be aware of is that not only do forces have to be balanced to maintain an object in static equilibrium, but moments must also be balanced. To understand this in greater detail, look at the Moment Equilibrium concept page.

Revisiting the problem introduced earlier in the module, suppose that during normal riding your weight was distributed as follows, 150 lb on the seat, 25 lb on the pedals, and 10 lb on the handlebars. Using the force and moment equilibrium conditions, calculate the front and rear tire reactions. Confirm your answer with the applet. Necessary dimensions are given in the table below.

Once again suppose that you encountered a hill and were in a "climbing" position such that you now had 20 lb on the seat, 125 lb on the pedals, and 40 lb on the handlebars. Calculate how the front and rear tire reactions will have changed and then check your results with the applet.

Dimensions
Point x-coordinate
Rear Axle 0.00"
Seat 8.75"
Pedals 17.0"
Handlebars 36.0"
Front Axle 41.7"

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