Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Gear ratios

  1. Feb 24, 2015 #1
    I'm confused as to how gear ratios work in bicycles. I'm given a problem which says that gear ratio = rfront/rear. It then says that the gear ratio changes from 4 to 0.7. Does this mean that the radii of the gears are changing? I'm unfamiliar with gears on a bicycle so I'm not sure if the radius of the gear can change,
  2. jcsd
  3. Feb 24, 2015 #2


    User Avatar
    Science Advisor

    Here is a picture of a bicycle gearing system. The rear wheel has a "rosetta" of 7 cog wheels with different diameters. The pedal setup has just two wheels with different diameters. The gear ratio is then (selected diameter at the pedal setup)/(selected diameter on the rear wheel rosetta).
  4. Feb 24, 2015 #3


    User Avatar
    Science Advisor
    Homework Helper

Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Gear ratios
  1. Bicycle gear ratios (Replies: 17)

  2. Bike gear ratio (Replies: 2)