1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Speed of a bicycle chain

  1. Nov 1, 2009 #1
    1. The problem statement, all variables and given/known data

    A bicycle has wheels 67.3 cm in diameter and pedal cranks 17.5 cm long. The cyclist pedals at a steady angular rate of 71.5 rev/min. The chain engages with a front sprocket 15.2 cm in diameter and a rear sprocket 6.45 cm in diameter.

    2. Relevant equations
    v=rw



    3. The attempt at a solution
    I converted the revs/min to rad/s and then used that value times the radius of the front sprocket and got 1.138 m/s but this is wrong. I then tried to calculate the tangential velocity at the back sprocket with the same rate of pedaling and that radius and added it to the value I got from the front sprocket but this was wrong as well. Do i need to take into account the length of the pedal crank?
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Nov 1, 2009 #2

    Delphi51

    User Avatar
    Homework Helper

    Welcome to PF, Free.
    Looks interesting, but there is no question. What are you trying to find?
     
  4. Nov 1, 2009 #3
    Sorry lol, I forgot to include the question. (a) Calculate the speed of a link of the chain relative to the bicycle frame.
     
  5. Nov 1, 2009 #4

    Delphi51

    User Avatar
    Homework Helper

    The method sounds good, but I don't agree with the answer!
    Can you show the details of the calculation so we can look for the error?
     
  6. Nov 1, 2009 #5
    (1min/60sec)*(71.5revs/min)*(0.152m)*(2*pi rad/1rev)=1.138
     
  7. Nov 1, 2009 #6
    Wow, I just realized I forgot to divide the diameter by 2 to get the radius lol. I'm such an idiot lol.
     
  8. Nov 1, 2009 #7

    Delphi51

    User Avatar
    Homework Helper

    Ah, I knew it had to be some little thing. Easy to do!
    I should have noticed I had half your answer.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Speed of a bicycle chain
  1. The Bicycle chain (Replies: 1)

  2. Speed of chain? (Replies: 5)

Loading...