Gear Ratio question...

  • Discuss Gear Ratio question... in the BMX Bike Tech forum in area BMX-Forum Community; Hey people I’m building me another custom bike but I have a general question what is the best gear ratio for street and park I’ve heard its 28-10 than... ...
OutlawsMC

OutlawsMC

New Member
Gear Ratio question... post #1
Hey people I’m building me another custom bike but I have a general question what is the best gear ratio for street and park I’ve heard its 28-10 than I’ve heard it 25-9 help me out give me your overviews on your gear ratio what’s faster what’s more reliable and what is quicker to speed up and pump threw street sessions thanks guys…
 
J

jawn

Guest
Gear Ratio question... post #2
Not to be a dick, but this is quite probably the most asked question on the forum. If you search you'll get more info (worded in many many different ways) much quicker than waiting for replies to this thread.
 
B0N0

B0N0

New Member
Gear Ratio question... post #3
25-10 or 25-9
 
mack_turtle

mack_turtle

New Member
Gear Ratio question... post #4
the teeth on a 9t driver will wear out a lot faster than a larger driver. also, the bearings in most 9t drivers are a lot smaller than the bearings in a 10t or larger driver. 28-10 is a slightly higher ratio than 25-9 and 30-11 so it's good if you are riding big ramps or trails.
 
ruzakruzak

ruzakruzak

New Member
Gear Ratio question... post #5
The classical ratio is 2.75 (chainwheel teeth count / driver(freewheel) teeth count).

25/9 = 2.777778
28/10 = 2.8
30/11 = 2.7272727272
 
Red Horn

Red Horn

New Member
Gear Ratio question... post #6
28-10 is a slightly higher ratio than 25-9 and 30-11
By only 0.4 and 1.4 Gear Inches. Not much at all.

The classical ratio is 2.75 (chainwheel teeth count / driver(freewheel) teeth count).
Gear Inches are expressed as; chain wheel (divided by) free wheel or cassette (times) tire size.

From Wikipedia, the free encyclopedia

Gear inches is a system that assigns numerical measurements to bicycle gear ratios, to indicate how low or high a gear is.

28/10x20=56
25/9x20=55.6
30/11x20=54.6
 
Last edited:
ruzakruzak

ruzakruzak

New Member
Gear Ratio question... post #7
Yeah, right. Thanks Wikipedia, thanks Red Horn !

Just, please notice you have assumed that we all have 20 inches wheels, which is not true, because we must take into account the tire size, which differs between a 2.25 tire to a 1.75 tire... maybe a 30/11 chain wheel with a 2.125 tire is in fact exactly the same than a 28/10 with a 1.9 tire ??

I'll stick to my formula, it's easier for my bad head ;)
 
Red Horn

Red Horn

New Member
Gear Ratio question... post #8
The overall diameter of tires will change the actual ratio slightly. But are not factored in. It is complex enough for some people :lol:. Good point though :wink:.

maybe a 30/11 chain wheel with a 2.125 tire is in fact exactly the same than a 28/10 with a 1.9 tire ??
Could be possible.
 
kheridr

kheridr

New Member
Gear Ratio question... post #9
both the same
 

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