| MadSci Network: Engineering |
Dear Ralph,
You are correct. The front brake definitely exerts more braking force than the rear brake. You'll find that this holds true for bicycles, motorcycles, cars, etc. The reason for this has to do with the way that weight shifts as you brake, and the way friction works between the tires and the ground.
The braking force that you feel is the result of friction between the tire and the ground. Your brake slows down the tire, and the resulting friction between the tire and the ground is what slows down your bicycle. An important fact to know about friction for this question, is that the frictional force is proportional to the normal force between the two objects. In other words, you get more friction if there is more weight on the objects producing the friction. You can easily prove this to yourself right now. Grab something on your desk (like a book) and drag it towards yourself. Now do it again, but push down on the book as you drag it. It got a lot harder didn't it? That is exactly what is happening with the brakes on your bike.
When you brake, your weight and the weight of your bike/car/etc. shift forward. You should recognize that feeling of pitching forward when you slam on the brakes. This puts a greater amount of weight on the front tire. At the same time, it takes weight off of the rear tire. Since there is more weight on the front tire and less on the rear, the front tire will be able to produce more friction with the ground, and produce more braking force.
If you have more questions about friction in general, there are many answers in the Mad Scientist Archives about friction that may help. Hope that answers your question.
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