Gearing problems

Discussion in 'Beginner's Area' started by eman8, Mar 17, 2010.

  1. eman8

    eman8 New Member

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    I have a 2002 Orange Zero with Race Face North Shore XS cranks. I want to run an 18t freewheel on the rear hub, but I just found out that the smallest chainring I can fit on the crank is 24t. Would this gearing be too weird for trials? I really don't want to shell out money for new cranks and I already have the freewheel. Thanks!
    -E
     
  2. AlexC

    AlexC New Member

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    i have a 20T that i've never used lol. but what kind of hub are u using on the rear? fixed or free?
     

  3. netto

    netto New Member

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    it will be too hard for any kind of static moves that require instant torque. If you are just starting out, then just ride it the way it is. If you are starting to learn how to gap and sidehop, i would save up for a new set of front front freewheel cranks and run the freewheel on the crank. then you can run a 15 or 16t cog on the hub.

    if you need any help with this, send me a pm or an email through wherestheseat.com:)
     
  4. 7185

    7185 Guest

    The most common trials gear ratios are:

    18:15 = 1.200
    18:16 = 1.125
    22:19 = 1.158
    22:18 = 1.222

    With a 24t chain ring you could run any of these ratios:

    24:20 = 1.200
    24:21 = 1.143
     
    Last edited by a moderator: Mar 17, 2010
  5. eman8

    eman8 New Member

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    What is the minimum bb spindle length needed to run ffw cranks?
     
  6. mich_aelmtb

    mich_aelmtb New Member

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    ACS makes 20 and 22 tooth freewheels. They're around 20 bucks although you won't likely find such large freewheels at the lbs. You or them would have to order it. It would be an unorthodox drivetrain, but would get the job done and be easy on chains.
     
  7. ateam

    ateam Old Man, Poser, Newbie, "Huba Huba"

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    JDada, did you not post this a while back? I saved it as it is very useful, especially for a newb.

    Here are the ratios I've heard here on OTN. As you can see, 18/12 is way out on the outskirts of the range.
    18/12 = 1.50
    22/16 = 1.38
    22/17 = 1.29
    18/14 = 1.29
    22/18 = 1.22 common
    18/15 = 1.20 common, retail default for FFW
    22/19 = 1.16 common
    18/16 = 1.13 common
    The most common trials gear ratios are:
    18:15 = 1.200
    18:16 = 1.125
    22:19 = 1.158
    22:18 = 1.222
     
  8. eman8

    eman8 New Member

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    If I upgrade to ffw cranks, do I need to upgrade my bb too?
     
  9. bipyjamas

    bipyjamas Snaps: 5

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    Probably not if you use the freewheel on the back and a fixed cog on the front and your BB is ISIS.
     
  10. netto

    netto New Member

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    for most 26" bikes, you will need a 128mm bottom bracket to clear the chainstay. Not too sure about your orange.
     
  11. sk8dad

    sk8dad every ounce of fun

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    This might be old news for some, but for those who aren't aware, gear ratios are only part of the equation. Crank and wheel/tire combination also have bearing on the amount of force your foot can transfer to pavement through the drive train. Sheldon Brown has a great web site and an online calculator for this (gain ratio). The gain ratio can be applied to all bike types including stock, 24, or mods. If you calculate the same gain ratio for a stock and for a mod, you should end up with the similar feel in the drive train.

    One note, though, gain ratio does not account for the leverage of the frame during rear wheel moves, so drive train effort aside, the bikes still (obviously) feel different.

    write up: http://www.sheldonbrown.com/gain.html
    calculator: http://www.sheldonbrown.com/gears/

    If you need more rigorous derivation, I can post that too.
     
  12. werkinit

    werkinit werkinit

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    I've been using 22/20 for years on my "short bike" and have it on my current "long bike".

    Normal compact drive cranks on the front. I switched to a 20t acs claws freewheel and single speed hub in the back after using shimano for years so I would have better engagement.

    You may be able to scrape together a 5 bolt crank from some bikeshop basement somewhere and run a 20t chainring if you can find one. Good luck with that one though.

    Grab some compact drive cranks used and run gears in the back so you have options. Then go from there.
    You can score compact drive cranks for cheap off the web I'm sure.
     
  13. dmiller403

    dmiller403 prefer my ride 'stock' w/ dual disk

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    I had a 20-15 ratio. Sucked i had to do about a 3/4 complete pedal to do a pedal up. When my 18-15 i only had to do about 1/4 turn. Im tryn 17-15 ratio. Hope its nice. I will admit the speed with the 20-15 ratio was good but pedaling from slight roll backward was tough