Brakes coaster brakes

Discussion in 'Bicycle Repair' started by noble b, May 31, 2012.

  1. noble b

    noble b Member

    how do coaster brakes work with a motor cause to my understanding (feel free to call me out if im wrong) you have to petal as fast as the wheel is moving and how can you do that if your going 30 or more.

  2. Al.Fisherman

    Al.Fisherman Active Member

    I really don't like coaster brakes, although I've built some bikes with them as that is what my friend wanted. You don't need to be peddling 30MPH or how ever fast the bike is traveling.
  3. noble b

    noble b Member

    Then how does it work cause you pedal backwards to brake so I'm just not comprehending this.
  4. Al.Fisherman

    Al.Fisherman Active Member

    It works the same as if there isn't a engine mounted. When using coaster brakes, there is quite a bit of stress on the inner parts.
  5. loquin

    loquin Active Member

    Pedaling backwards just causes the brakes to engage mechanically. If you are coasting downhill, you don't need to pedal, do you? If the motor is pushing you, you are (as far as the rear axle is concerned) coasting, also.

    When you brake, the downward force due to weight shifts from the rear wheel to the front. Since the amount of braking action depends upon the amount of downwards force, the rear wheel is very easy to lock up when you're near 20 mph (or more.) This also means that, when you're at speed, front wheel braking is MUCH more effective than rear wheel braking. (You can control the amount of braking much more precisely with your hands than with your feet, also.)

    It's important to have BOTH front and rear brakes on a motorized bike, since you have the potential to be traveling at a much faster average speed than when pedeling. If you have a front brake, a coaster brake is OK on the rear, but a rim brake or disk brake is better. (Better control, less likely to fade than a coaster brake.)

    Remember, the amount of energy that the brakes have to get ride of as heat, is proportional the the square of the speed you are at; the brakes on a bike at 20 MPH has to get rid of 4 times the energy as one traveling at 10 MPH, all other things being equal, one traveling at 30 MPH has 9 times the energy as one at 10 MPH, and one traveling at 40 MPH has 16 times the energy...