What are your gear ratios?

Discussion in 'Fixed & Singlespeed' started by rustang64, Nov 10, 2009.

  1. rustang64

    rustang64 New Member

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    Just wondering what all people have as their gear ratios. I ride lots of hills so I have a 46:16 (2.9:1).
     
  2. hophead

    hophead New Member Tavern Member

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    Road = 53:20
    Mtn: anywhere from 32:20 for the steep rocky stuff to 32:16 for flowy rolling singletrack.
     

  3. HandsomeRyan

    HandsomeRyan ♥'s Bicycles

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    48x16 freewheel
    48x18 fixed
     
  4. rustang64

    rustang64 New Member

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    48:12 sounds pretty beefy... I'm not sure I could do that here, lotsa hills.
     
  5. JohnGMcEneany

    JohnGMcEneany Guest

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    I have used such a ratio since age 15 and have ridden 50 miles at a time including many steep hills and descents on such a bike.
     
  6. Industry_Hack

    Industry_Hack Total noob (& forum admin) Admin Staff Tavern Member

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    Same here.
     
  7. letsgetsandy

    letsgetsandy New Member

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    48x17 or 48x15 in the city and for the track i run a 50x15
     
  8. London

    London Guest

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    I ride in some open areas near the coast. Wind is more of an issue than hills. 48x12 is not something I'd want to get caught with fighting 35 knots going home. I think a strong young guy could handle that, but I'm not so strong anymore and have always been a spinner. Big, long gears kill me. 48x18 and no more.
     
  9. IanHighfield

    IanHighfield New Member

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    55x14-13-12 on flat trial course as per distance.
    52x15 on hill climb race under 7% average
    50x16 on hill climb race under 11% average
    48x18 on hill climb race over 11% average grade.

    I'm somewhat old school on hill racing. Most UK hillers now use gears. About 20% do not. I like the weight saving and the threat of failure. This make a lad work as hard as he should.
     
  10. retromike3

    retromike3 retromike3

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    gear ratios?

    I'm used to gear inches. If you divide the chainring number by the cog number and then multiply by the diameter of the rear wheel you get how many inches you will go in one revolution of the peddle. I like running a small gear, something like 65 inches. But I'm a fat old guy.


    Mike Frye-the bike guy:cool:
     
  11. Rhythm

    Rhythm Guest

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    Flip flop running
    70 GI on one
    74 GI on the other
     
  12. Doohickie

    Doohickie Older than Hack

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    46x18 freewheel. My 700x28c tire measures 27", so I guess that would be 46x27/18 = 69 gear-inches?
     
    Last edited: Jan 4, 2010
  13. Rhythm

    Rhythm Guest

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    27" wheels differ from 700c by around 8mm if I remember correctly.

    A helpful sight for gear ratio, gear inches, cadence etc is BikeCalc.com - Fixed Gear Calculator

    You were close but your at 68.3 GI, not like its a huge difference.
     
  14. Doohickie

    Doohickie Older than Hack

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    Nominally I think you're correct, but I measured my tire with a tape measure and yeah, it was 27" even.
     
  15. IanHighfield

    IanHighfield New Member

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    Mike, I like to think in gear inches also, but you're off a bit. That number you come up with after doing your formula represents the old fashion Pennyfarthing big wheel diameter. Example: 50x15 gearing = 90 inch gear if using a 27 inch tyre. That 90 inches is what a Pennyfarthing's wheel diameter would have to be in order to equal a modern 50x15 with 27 inch tyres.

    Distance traveled is gear inch (90 in this case) times 3.14. (circumference of wheel) You get 282.6 inches of travel for one turn of the pedals. That's about 23.55 feet per pedal turn.

    Think of that one turn of the pedal of your modern bike in 50x15 as equal to one turn of the pedal for a Pennyfarthing with a giant 90 inch front wheel.

    Hope that's been made clearer.

    Now to further muddy the creek, take that 23.55 feet of travel per pedal stroke and multiply by cadence. Say 90 rpms. 90 x 23.55 = 2119.5 feet of travel per minute. You've gone 2119.5 feet in just one minute. Now multiply that "minute" distance by 60 to get your distance traveled in an hour.

    2119.5 x 60 = 127,170 feet traveled in an hour. Divide by 5280, which is a mile, and you have your miles-per hour-figured by cadence and gear.

    127,170 divided by 5280 = 24.09 mph. If you can maintain a 90 rpm cadence with a bike wearing 27 tyres (700s) and geared 50x15, you'll be going 24 mph.

    Mike, back to your 65" gear. Assuming a 700/27" tyre, you will travel 204.1 inches per pedal cycle. That's 17 feet. Let's say you only turn 60 rpms. That sends you 1020 feet per minute. Times 60 minutes = 61,200 feet per hour. Divide by 5280 (mile) and you are traveling 11.6 easy miles-per-hour. Crank it up and go faster. At 90 rpms, you'll be around 17.4 mph. 65 inches of gearing is a very useful sizing. You can do quite a bit without killing yourself.
     
  16. trx1

    trx1 New Member

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    i usally run a 39/17 with a 180mm crank on my rides.