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Hi guys

So I think I've decided to build a single speed park bike, BUT I am not sure what gear ratio to go with. Obviously I want something that I can get up to a good sprint on without spinning like mad:p , but I also think that quick acceleration is important. Is there a perfect gear ratio that everyone uses that I've never heard about?

Thanks
 

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mtbr remember
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this has been covered more times than I can count my teeth...
R1D3R, are you buildin' a bike soon or what? just pullin' man, but jeez....

and 25:9 on a 26'er would probably get you to exactly 164mph on a grade of -2.1 with a heart rate of 284bpm.... assumin' wind was comin' out yo' rear! haha...










28:12 on 24, moving to 25:11 this season...
 

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mtbr remember
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Sudden_Judgement said:
Not to thread Highjack, but I just bought a geish with a 9. I run 24''s, what would be close to a 34 13 on 24''s with the 9 in the back, 23-25ish?
first off, NICE score on the geisha, I want to pick one up...
but! I really would have gone for the 11t driver they have as an option. 9t is too small for bigwheelers, basically just for 20'ers. you're going to be VERY hard pressed to find a bmx style sprocket less than 24t... and 24/9X24 is taller than shaqdiesel. not to mention, with super microscopic drive like that on a bigwheeler, it's going to cause some major chain/drivetrain wear, puttin' that kind of torque down on minimal teeth...
 

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Sudden_Judgement said:
Not to thread Highjack, but I just bought a geish with a 9. I run 24''s, what would be close to a 34 13 on 24''s with the 9 in the back, 23-25ish?
9 tooth Cog for 24"? I'd put 21 in the front. (21/9)x24=56 That's an optimum.
 

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mtbr remember
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K4m1k4z3 said:
9 tooth Cog for 24"? I'd put 21 in the front. (21/9)x24=56 That's an optimum.
where are you going to get a 21t sprocket? MtB. granny rings don't even come that small as far as I know...

your drive train would look like this: q======o
"q" being your front sprocket and crank, and "o" being your cog and === being the squished chain connecting the two...
Chain might not even clear the chainstays it'd be so close together, just be grindin' all accross'em...

Alright, I just remembered!!! I had it saved in my computer since it was just something intriguing and different...
Anyway, KHE bikes has a special flatland setup, where there is an extra hole drilling in all of their cranks for the Ninja. This hole is super close to the spindle hole (between normal), and the Ninja sprocket is a super super tiny 20t sprocket. here are some pics. But for riding dirt and street on that thing... I still have my doubts about drivetrain wear and too much torque... as well as chainstay clearance (check your frame). one reason you never see XC SS racers running anything smaller than 16t rear and mid-30 something front...
here is the KHE hindenburg crank, notice the smaller little sprocket bolt hole. (I don't know why they didn't just make the sprocket 48 spline drive):

here is the Ninja 20t:

another view:


so, there's an option anyway... albeit, and EXPENSIVE one, since you have to buy the cranks as well, and KHE stuff is typically not very cheap.

would give you a total of around 53.3, so much easier than you are looking for, but better than 64.
 
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