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Discussion Starter #1
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
 

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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?
 

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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:)
 
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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
 

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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.
 

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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
 

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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.
 

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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.
 

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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.
 

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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
 
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