Bmx Gear Ratio Chainstay Length

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R Front gear cog teeth.

Bmx gear ratio chainstay length. In the charts below Ive bolded the most common combos. Most Pro BMXers Run Approximately 54 gear inches. TSPCL 025 F R 2 SquareRoot CSL CSL 00796 F - R 2 Where.

I run about a 54 to 57 inch gear on my cruiser 17 in back and 40 in front usually with 180mm cranks depending on the track but I run 1740 most everywhere. Divide Front Gear by Rear Gear and Multiply by Tire Diameter. I know in BMX chainstay length and gearing is pretty well established everyone runs similar gearing and chainstay lengths.

4 teeth represent ½ half an inch on the chainstay length. Tech Tip 2. For Exact Gear Measurement.

Forum Main General BMX Talk gear ratiochainstay length. 3617 - 550 Unusable on most DJ frames 36 would hit chainstay 3416 - 552 3014 - 557 Note. With a little rudimentary geometry I was able to put together a spreadsheet that you can enter an approximate chain stay length front and rear sprocket size and wheel size that will calculate the gear inches number of links and actual chain stay.

Notice that the model isnt quite right--Dl and Du arent exactly equal to the length of the stay. CSL Chainstay length in inches. You then take that number in this case 28125 and multiply it by 20 the diameter of a BMX wheel.

Crank it Down Historically and for years bmx racing hovered around the physics of a 4416 gear ratio powered by a set of 180mm length cranks. You can fine tune the gearing after you get the first straight gearing settled. 28125 x 20 5625 the gear size.

13½ half 14 14½ half 15. But its close enough. TSPCL Theoretical Shortest Possible Chain Length.

4416 gear ratio with 20x175 tire is the most commonly used combination in BMX. 1 full link is equivalent to 4 teeth. L Total length of chain Du Distance along upper chainstay run approximately equal to chainstay length Dl Distance along lower chainstay run equal to Du Db Distance around chainring Ds Distance around sprocket.

The 4 tooth rule applies here. Jul 12 2004 4820 0 Sleepy Hollar. Gear Inches are used to give a numberical value to how a particular chainwheelcog combination will feel.

The unusable combinations are for most frames. The first straight makes the race. This is Riley Smith Video 1.

If your gear size is large 58 or greater you will go faster but take off slower. Daily Grind in Houston. If you have a ratio that works you can add or subtract 2 teeth from both the ring and cog to have the same exact tension.

F Front gear cog teeth. Classic BMX gearing evolved over the years to be 4416which has 55 gear inches. Roll-out Number of Chain Ring Teeth Number of Sprocket Teeth X Outside Wheel Diameter in Inches The formula above isnt quite correct because the result must be multiplied by PI 3142 to give actual inches of roll-out called Gear Inches by track cyclists.

Or you can create a list of chainstay lengths and gearing options. Urbaindk The Real Dr. The most popular gear ratios are pretty close to a 55 inch which just seems to feel best for most people.

You can apply this simple formula to cruisers BMX bikes with 24 wheels by multiplying the gear ratio by 24 instead of 20. On a 20 bike I run a 4516 gear setup which is similar to my 24er. I have no idea how the magic number of 00796 was derived but the formula appears to provide a pretty good approximation to the shortest possible length of 12 inch pitch bicycle.

If 3218 is truly a Magic gear ratio for this frame than you could try 3016 which will be a slightly higher ratio 177 ratio versus 187. Victor Zapien - You Cant Keep a Good Man Down. BMX Dirt Jumping.

The following simple rules are all you need to remember. James Jimmah Pease for SM.

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