gear ratio

dod 1
dod 1 Posts: 34
edited November 2007 in Workshop
Is there a big difference between a bottom gear of 39/28 and a 34/25 just wondering which one to go for

Comments

  • andyp
    andyp Posts: 10,579
    Have a look here for a tool that will enable you to work this out yourself.
  • John.T
    John.T Posts: 3,698
    Good old Sheldon. We would be lost without him.
    My Fleet.
  • Down the Road
    Down the Road Posts: 949
    39/28 = 1.39 to 1

    34/25 = 1.36 to 1


    There for the compact is lower.
    Racing is life - everything else is just waiting
  • dod 1
    dod 1 Posts: 34
    39/28 = 1.39 to 1

    34/25 = 1.36 to 1

    I know this may sound stupid but how much difference does the above make
  • Anonymous
    Anonymous Posts: 79,665
    zilch.
  • dennisn
    dennisn Posts: 10,601
    Put another way - For each complete revolution of the chainrings the 39-28 gearing will
    move the rear tire about 2 1/2 inches(65 mm) further than the 34-25. I used a 27 inch
    outside diameter tire for this calculation. Your tire may vary

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