| Gear Chart |
In BMX racing, the gears you run can make or break you. It's important that you know how to change gears
and when. Track conditions and other factors may warrant a gear change. You need to know a little about
gears and gear ratios before making gear changes yourself. A gear ratio is the number of times your rear
sprocket (or freewheel) turns for every full 360 rotation of your front sprocket (or chainring).
It's really simple; you take the number of teeth on your chainring and divide it by the number of teeth on your
freewheel, that gives you your gear ratio. For example, if your front sprocket is a 45 tooth, and your rear
sprocket is a 16 tooth, then your gear ratio would be 2.8125 (45 divided by 16 = 2.8125). You then take
that number (in this case 2.8125) and multiply it by 20 (the diameter of a BMX wheel). 2.8125 x 20 = 56.25
(the gear size). You can apply this simple formula to cruisers (BMX bikes with 24" wheels) by multiplying the
gear ratio by 24 instead of 20. Easy enough? You can use this formula to help solve common problems. For
example, which gear size is bigger - a 42/15 or a 45/16? Unless you have a gear chart handy, this formula is
the only sure way to answer that question. In doing the math, you'll find that a 45/16 gear ratio is just slightly
bigger than the 42/15.
If your gear size is large (about 58 or greater), you will go faster, but you will accelerate slower; it will take
longer to get going and 'wind out'. 'Winding out' or 'topping out' refers to when you are at top speed; pedaling
the bike does not make it go any faster. Snapping out of the gate, going uphill, powering out of turns, etc. will
be harder with a high gear. Conversely, a low gear size (about 52 or less) will result in faster acceleration, but
lower overall speed. For most racing situations, a 55 gear size is almost perfect; not too high, and not too low.
However, a different gear may be more appropriate, depending on track conditions. The overall slope of the
track (uphill, downhill, etc.), length of the track, angle/slope of starting gate/hill, overall track layout, and the
track surface are just some of the conditions that might warrant a gear change.
Experiment with different gears and see what works best. You'll be glad you did.
Gear Size Chart
Wondering which gears you should be running? Check out the chart below and maybe it will help narrow
down those decisions. The Top row of numbers is the number of teeth on your chain ring. The Rear "XX"
column is the number of teeth on your rear sprocket. Where the two numbers intersect is your gear ratio for
the gears selected.
What do these numbers mean? Well for every complete revolution of your cranks you go that many inches.
For instance if you have a Rear Sprocket of 16 and a Front Sprocket of 43 and the size of your wheels is 20"
X 1.75" then you would get 52.4, meaning you traveled 52.4 inches every time your cranks go all the way
around.
Chart will be uploaded soon.
and when. Track conditions and other factors may warrant a gear change. You need to know a little about
gears and gear ratios before making gear changes yourself. A gear ratio is the number of times your rear
sprocket (or freewheel) turns for every full 360 rotation of your front sprocket (or chainring).
It's really simple; you take the number of teeth on your chainring and divide it by the number of teeth on your
freewheel, that gives you your gear ratio. For example, if your front sprocket is a 45 tooth, and your rear
sprocket is a 16 tooth, then your gear ratio would be 2.8125 (45 divided by 16 = 2.8125). You then take
that number (in this case 2.8125) and multiply it by 20 (the diameter of a BMX wheel). 2.8125 x 20 = 56.25
(the gear size). You can apply this simple formula to cruisers (BMX bikes with 24" wheels) by multiplying the
gear ratio by 24 instead of 20. Easy enough? You can use this formula to help solve common problems. For
example, which gear size is bigger - a 42/15 or a 45/16? Unless you have a gear chart handy, this formula is
the only sure way to answer that question. In doing the math, you'll find that a 45/16 gear ratio is just slightly
bigger than the 42/15.
If your gear size is large (about 58 or greater), you will go faster, but you will accelerate slower; it will take
longer to get going and 'wind out'. 'Winding out' or 'topping out' refers to when you are at top speed; pedaling
the bike does not make it go any faster. Snapping out of the gate, going uphill, powering out of turns, etc. will
be harder with a high gear. Conversely, a low gear size (about 52 or less) will result in faster acceleration, but
lower overall speed. For most racing situations, a 55 gear size is almost perfect; not too high, and not too low.
However, a different gear may be more appropriate, depending on track conditions. The overall slope of the
track (uphill, downhill, etc.), length of the track, angle/slope of starting gate/hill, overall track layout, and the
track surface are just some of the conditions that might warrant a gear change.
Experiment with different gears and see what works best. You'll be glad you did.
Gear Size Chart
Wondering which gears you should be running? Check out the chart below and maybe it will help narrow
down those decisions. The Top row of numbers is the number of teeth on your chain ring. The Rear "XX"
column is the number of teeth on your rear sprocket. Where the two numbers intersect is your gear ratio for
the gears selected.
What do these numbers mean? Well for every complete revolution of your cranks you go that many inches.
For instance if you have a Rear Sprocket of 16 and a Front Sprocket of 43 and the size of your wheels is 20"
X 1.75" then you would get 52.4, meaning you traveled 52.4 inches every time your cranks go all the way
around.
Chart will be uploaded soon.
| For Reference Only |
 |  |