Since you can't always have a gear chart by your side. It's
important to know how to calulate your gear ratio yourself.
All you do is 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.
If your gear size is large 58 or greater, you will go faster,
but take off slower. It will take longer to reach top speed.
Snapping out of the gate, going uphill, powering out of turns,
etc. will be harder with a high gear. On the other hand, a
low gear size of 55 or less will result in a better start,
but lower overall speed.
Experiment and don't be afraid to try different gear ratios.
You'll see what works best for you.
How do I know what size gears
I should ride?
Use the chart below to help you
decide what size gears you should be riding.
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.
|
Gear
Chart for 20" X 1.50" wheels
|
| Chainwheel |
34 |
35 |
36 |
37 |
38 |
39 |
40 |
41 |
42 |
43 |
44 |
45 |
46 |
47 |
48 |
| Rear 14 |
46.8 |
48.1 |
49.5 |
50.9 |
52.3 |
53.6 |
55.5 |
56.4 |
57.5 |
59.1 |
60.5 |
61.8 |
63.2 |
64.6 |
66.0 |
| Rear 15 |
43.6 |
44.9 |
46.2 |
47.4 |
48.8 |
50.1 |
51.3 |
52.6 |
53.9 |
55.2 |
56.5 |
57.7 |
59.1 |
60.2 |
61.6 |
| Rear 16 |
40.9 |
42.1 |
43.3 |
44.5 |
45.7 |
46.9 |
48.1 |
49.3 |
50.5 |
51.7 |
52.9 |
54.1 |
55.3 |
56.5 |
57.7 |
| Rear 17 |
38.5 |
39.6 |
40.8 |
41.9 |
43.1 |
44.1 |
45.2 |
46.4 |
47.5 |
48.7 |
49.8 |
51.0 |
52.2 |
53.1 |
54.3 |
| Rear 18 |
36.4 |
37.4 |
38.5 |
39.6 |
40.6 |
41.7 |
42.8 |
43.9 |
44.9 |
46.0 |
47.0 |
48.1 |
49.2 |
50.3 |
51.3 |
|
Gear
Chart for 20" X 1.75" wheels
|
| Chainwheel |
34 |
35 |
36 |
37 |
38 |
39 |
40 |
41 |
42 |
43 |
44 |
45 |
46 |
47 |
48 |
| Rear 14 |
47.4 |
48.7 |
50.2 |
51.6 |
53.0 |
54.4 |
55.7 |
57.1 |
58.5 |
59.9 |
61.3 |
62.7 |
64.1 |
65.5 |
66.9 |
| Rear 15 |
44.3 |
45.4 |
46.8 |
48.1 |
49.4 |
50.7 |
52.0 |
53.3 |
54.6 |
55.9 |
57.2 |
58.5 |
59.8 |
61.1 |
62.4 |
| Rear 16 |
41.5 |
42.7 |
43.9 |
45.1 |
46.3 |
47.5 |
48.8 |
50.0 |
51.2 |
52.4 |
53.7 |
54.9 |
56.1 |
57.3 |
58.5 |
| Rear
17 |
39.0 |
40.2 |
41.3 |
42.5 |
43.6 |
44.7 |
45.9 |
47.0 |
48.2 |
49.4 |
50.5 |
51.7 |
52.8 |
53.9 |
55.1 |
| Rear
18 |
36.8 |
37.8 |
39.0 |
40.1 |
41.2 |
42.3 |
43.3 |
44.4 |
45.5 |
46.6 |
47.7 |
48.8 |
49.9 |
51.0 |
52.0 |
|
Gear
Chart for 20" X 1 1/8" wheels
|
| Chainwheel |
34 |
35 |
36 |
37 |
38 |
39 |
40 |
41 |
42 |
43 |
44 |
45 |
46 |
47 |
48 |
| Rear 14 |
48.6 |
50.0 |
51.4 |
52.8 |
54.3 |
55.7 |
57.7 |
58.6 |
60.0 |
61.4 |
62.8 |
64.3 |
65.7 |
67.1 |
68.6 |
| Rear 15 |
45.3 |
46.7 |
48.0 |
49.3 |
50.7 |
52.0 |
53.3 |
54.7 |
56.0 |
57.3 |
58.7 |
60.0 |
61.3 |
62.7 |
64.0 |
| Rear 16 |
42.5 |
43.8 |
45.5 |
46.2 |
47.5 |
48.7 |
50.0 |
51.2 |
52.5 |
53.7 |
55.0 |
56.2 |
57.5 |
58.7 |
60.0 |
| Rear 17 |
40.0 |
41.2 |
42.3 |
43.5 |
44.7 |
45.9 |
47.0 |
48.2 |
49.4 |
50.6 |
51.8 |
52.9 |
54.1 |
55.3 |
56.5 |
| Rear 18 |
37.7 |
38.8 |
40.0 |
41.1 |
42.2 |
43.3 |
44.4 |
45.6 |
46.7 |
47.8 |
48.9 |
50.0 |
51.1 |
52.2 |
53.3 |
|
Gear
Chart for 20" X 1 3/8" wheels
|
| Chainwheel |
34 |
35 |
36 |
37 |
38 |
39 |
40 |
41 |
42 |
43 |
44 |
45 |
46 |
47 |
48 |
| Rear 14 |
51.0 |
52.5 |
54.0 |
55.5 |
57.0 |
58.5 |
60.0 |
61.5 |
63.0 |
64.5 |
66.0 |
67.5 |
69.0 |
70.5 |
72.0 |
| Rear 15 |
47.6 |
49.0 |
50.0 |
51.8 |
53.2 |
54.6 |
56.0 |
57.4 |
58.8 |
60.2 |
61.6 |
63.0 |
64.4 |
65.8 |
67.2 |
| Rear 16 |
44.6 |
45.9 |
47.3 |
48.6 |
49.9 |
51.2 |
52.5 |
53.9 |
55.2 |
56.5 |
57.8 |
59.1 |
60.4 |
61.7 |
63.0 |
| Rear 17 |
42.0 |
43.2 |
44.5 |
45.7 |
47.0 |
48.2 |
49.4 |
50.7 |
51.9 |
53.2 |
54.4 |
55.6 |
56.9 |
58.1 |
59.3 |
| Rear 18 |
39.7 |
40.7 |
42.0 |
43.2 |
44.4 |
45.5 |
46.7 |
47.9 |
49.0 |
50.2 |
51.4 |
52.5 |
53.7 |
54.9 |
56.0 |
|
Gear
Chart for 24" X 1.50" wheels
|
| Chainwheel |
34 |
35 |
36 |
37 |
38 |
39 |
40 |
41 |
42 |
43 |
44 |
45 |
46 |
47 |
48 |
| Rear 14 |
55.9 |
57.5 |
59.1 |
60.7 |
62.3 |
64.2 |
65.8 |
67.4 |
69.0 |
70.6 |
72.2 |
73.8 |
75.7 |
77.3 |
78.9 |
| Rear 15 |
52.1 |
53.7 |
55.2 |
56.7 |
58.2 |
59.8 |
61.3 |
62.8 |
64.4 |
65.9 |
67.4 |
69.0 |
70.6 |
72.0 |
73.6 |
| Rear 16 |
48.8 |
50.3 |
51.8 |
53.2 |
54.6 |
56.0 |
57.5 |
58.9 |
60.3 |
61.8 |
63.2 |
64.6 |
66.2 |
67.6 |
69.0 |
| Rear 17 |
46.0 |
47.3 |
48.7 |
50.0 |
51.4 |
52.8 |
54.1 |
55.5 |
56.8 |
58.8 |
59.5 |
60.8 |
62.3 |
63.5 |
64.8 |
| Rear 18 |
43.4 |
44.7 |
46.0 |
47.2 |
48.5 |
49.8 |
51.1 |
52.4 |
53.7 |
54.9 |
56.2 |
57.5 |
58.9 |
60.0 |
61.4 |
|
Gear
Chart for 24" X 1.75" wheels
|
| Chainwheel |
34 |
35 |
36 |
37 |
38 |
39 |
40 |
41 |
42 |
43 |
44 |
45 |
46 |
47 |
48 |
| Rear 14 |
58.3 |
60.0 |
61.7 |
63.3 |
65.0 |
66.9 |
68.6 |
70.3 |
72.0 |
73.7 |
75.3 |
77.0 |
78.9 |
80.6 |
82.3 |
| Rear 15 |
54.4 |
56.0 |
57.6 |
59.3 |
60.7 |
62.4 |
64.1 |
65.5 |
67.2 |
68.9 |
70.3 |
72.0 |
73.7 |
75.1 |
76.8 |
| Rear 16 |
51.0 |
52.5 |
54.0 |
55.5 |
57.0 |
58.5 |
60.0 |
61.4 |
63.1 |
64.5 |
66.0 |
67.4 |
69.1 |
70.5 |
72.0 |
| Rear 17 |
48.0 |
49.4 |
50.8 |
52.2 |
53.6 |
55.1 |
56.5 |
57.9 |
59.3 |
60.7 |
62.1 |
63.6 |
65.0 |
66.2 |
67.7 |
| Rear 18 |
45.3 |
46.5 |
48.0 |
49.4 |
50.7 |
52.0 |
53.3 |
54.7 |
56.0 |
57.3 |
58.5 |
60.0 |
61.4 |
62.6 |
64.1 |
|
Gear
Chart for 24" X 1.1/8" wheels
|
| Chainwheel |
34 |
35 |
36 |
37 |
38 |
39 |
40 |
41 |
42 |
43 |
44 |
45 |
46 |
47 |
48 |
| Rear 14 |
54.9 |
56.5 |
58.1 |
59.7 |
61.3 |
63.1 |
64.7 |
66.3 |
67.9 |
69.4 |
71.0 |
72.6 |
74.4 |
76.0 |
77.5 |
| Rear 15 |
51.3 |
52.8 |
54.3 |
55.8 |
57.3 |
58.8 |
60.3 |
61.8 |
63.3 |
64.9 |
66.3 |
67.9 |
69.4 |
70.8 |
72.4 |
| Rear 16 |
48.1 |
49.5 |
50.9 |
52.3 |
53.7 |
55.1 |
56.6 |
57.9 |
59.5 |
60.8 |
62.2 |
63.9 |
65.1 |
66.5 |
67.9 |
| Rear 17 |
45.2 |
46.6 |
47.9 |
49.3 |
50.6 |
51.9 |
53.2 |
54.6 |
55.9 |
57.2 |
58.6 |
59.9 |
61.3 |
62.4 |
63.8 |
| Rear 18 |
42.7 |
43.9 |
45.2 |
46.6 |
47.7 |
49.1 |
50.3 |
51.5 |
52.8 |
54.0 |
55.3 |
56.6 |
57.9 |
59.0 |
60.4 |
|
Gear
Chart for 24" X 1.3/8" wheels
|
| Chainwheel |
34 |
35 |
36 |
37 |
38 |
39 |
40 |
41 |
42 |
43 |
44 |
45 |
46 |
47 |
48 |
| Rear 14 |
58.3 |
60.0 |
61.7 |
63.3 |
65.0 |
66.9 |
68.6 |
70.3 |
72.0 |
73.7 |
75.3 |
77.0 |
78.9 |
80.6 |
82.3 |
| Rear 15 |
54.4 |
56.0 |
57.6 |
59.3 |
60.7 |
62.4 |
64.1 |
65.5 |
67.2 |
68.9 |
70.3 |
72.0 |
73.7 |
75.1 |
76.8 |
| Rear 16 |
51.1 |
52.5 |
54.0 |
55.5 |
57.0 |
58.5 |
60.0 |
61.4 |
63.1 |
64.5 |
66.6 |
67.4 |
69.1 |
70.5 |
72.0 |
| Rear 17 |
48.0 |
49.4 |
50.8 |
52.2 |
53.6 |
55.1 |
56.5 |
57.9 |
59.3 |
60.7 |
62.1 |
63.6 |
65.0 |
66.2 |
67.7 |
| Rear 18 |
45.3 |
46.5 |
48.0 |
49.4 |
50.7 |
52.0 |
53.3 |
54.7 |
56.0 |
57.3 |
58.5 |
60.0 |
61.4 |
62.6 |
64.1 |
Is your bike set up properly?
Just like people are built different,
bikes are built different too. Use the sizing charts on this
page to help you make sure your bike is set up properly.
How do I know what size frame
I should ride?
Use the chart below to help you decide
what size frame you should be riding.
|
Frame
Sizing Chart
|
| Frame Size |
Micro - Mini |
Mini |
Junior |
Expert |
Expert XL |
Pro |
Pro XL |
Pro XXL |
| Top Tube Lenght |
15"-16" |
16"-17.5" |
17.5"-18.5" |
18.5"-20" |
19"-20" |
20"-20.5" |
20.5"-21" |
21"-22" |
| Riders Height |
4'0" & under |
4'0"-4'6" |
4'4"-4'10" |
4'8"-5'4" |
5'2"-5'8" |
5'6" - 5'10" |
5'10"-6' |
6' & over |
| Riders Weight |
40-65 lbs |
50-85 lbs |
60-100 lbs |
70-110 lbs |
75-125 lbs |
100 lbs & over |
140 lbs & over |
160 lbs & over |
How do I know
what size wheels I should ride?
Use the chart below to help
you decide what size wheels you should be riding.
|
Wheel
Sizing Chart
|
| Riders
Age |
Under 5 |
5 to 10 |
9 to 12 |
12 to 14 |
14 to 19 |
19 & up |
| Riders
Weight |
55lbs & below |
55-80lbs |
80-115lbs |
115-145lbs |
145-190lbs |
190lbs & up |
| Wheel Size |
18 x 1" |
20 x 1-1/8"
24 x 1-1/8" |
20 x 1-3/8"
24 x 1-3/8" |
20 x 1.50
24 x 1.50 |
20 x 1.75"
24 x 1.75" |
20 x 2.00"
24 x 2.00" |
|
It is recommended
riders who weigh 145lbs or more should run atleast a
20 x 1.75 tire on the front wheel.
|
How do I know
what size cranks I should ride?
Use the chart below to help
you decide what size cranks you should be riding.
|
Crank
Sizing Chart
|
| Inseam |
up to 15" |
15" to
16" |
16" to
17" |
17" to
18" |
18"- 20" |
20" - 24" |
24" - 28" |
28" - 30" |
30" - 32" |
32" - 34" |
34" + |
| Crank
Length |
135
mm |
140
mm |
145
mm |
150
mm |
155
mm |
160
mm |
165
mm |
170
mm |
175
mm |
180
mm |
185
mm |
How do I know
what size stem I should ride?
Use the chart below to help
you decide what size stem you should be riding.
|
Stem
Size Chart
|
| Rider
Height |
4'0" &
Under |
4'0" - 4'6" |
4'4" - 4'10" |
4'8" - 5'4" |
5'2" - 5'8" |
5'6" - 5'10" |
5'10" - 6'1" |
6' &
Over |
| Stem Size
|
Mini |
Mini / Mini
XL |
Mini/ Mini
XL |
Pro |
Pro |
Pro / Pro
XL |
Pro / Pro
XL |
Pro XL /
Pro XXL |
General bike information if
you plan on racing.
Any standard BMX bike will do.
So before you go investing $100's of dollars in a race bike,
start off on what you have or something low cost. If you decide
you like it and want to stay racing, then start looking or building
that perfect race bike.
Handlebars can not exceed 30" in
width. Handlebar grips are required & must be sufficient
to fully cover & enclose all metal & openings
on the handlebar ends.
You can not have the following
items on your bike.
Reflectors -Freestyle Pegs - Kickstands - Chain Guards - Front
Brakes
Rider requirements.
All riders must wear the following:
Helmet (preferably full-faced) with a working strap,
no snaps.
Pants.
Long sleeve shirt.
Enclosed shoes.
