Speedometer Error: Difference between revisions
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*The speedometer hub gear ratio is 23:9 - For every 23 turns of the front wheel, the speedo cable turns 9 times. | *The speedometer hub gear ratio is 23:9 - For every 23 turns of the front wheel, the speedo cable turns 9 times. | ||
*The first gear set inside the speedo head has a ratio of 10:1 - For every 10 turns of the speedo cable, the cross shaft spins 1 time. | *The first gear set inside the speedo head has a ratio of 10:1 - For every 10 turns of the speedo cable, the cross shaft spins 1 time. | ||
*The second gear set has a ratio of 16:1, so every 16 turns of the cross shaft turns the longitudinal shaft 1 time. | *The second gear set has a ratio of 16:1, so every 16 turns of the cross shaft turns the longitudinal shaft 1 time. | ||
*The last gear set ratio is 14:1 - Every 14 rotations of the longitudinal shaft turns the 10ths wheel of the odometer 1 time. | |||
The last gear set ratio is 14:1 - Every 14 rotations of the longitudinal shaft turns the 10ths wheel of the odometer 1 time. | *If you do the math, the overall ratio between the wheel and odometer is (14x16x10x9)/23, or 876.5:1. | ||
If you do the math, the overall ratio between the wheel and odometer is (14x16x10x9)/23, or 876.5:1. | |||
Tire size variables: The stock front tire for the 250 Ninja F is 100-80/16. The diameter is 22.30" and circumference is 70.06". The stock size tire rotates 904.37 times in one mile. This will make the odometer read 1.03 miles for each mile traveled, roughly 3 percent error under. A common replacement size for the front tire is 100/90-16, which has a diameter of 23.09" and a calculated circumference of 72.53", variable by tire model. This size rotates 873.58 times per mile and will make the odometer read .997 miles for each mile traveled, about 1/3 of a percent over actual miles. In both cases, this is a relatively small error. | Tire size variables: The stock front tire for the 250 Ninja F is 100-80/16. The diameter is 22.30" and circumference is 70.06". The stock size tire rotates 904.37 times in one mile. This will make the odometer read 1.03 miles for each mile traveled, roughly 3 percent error under. A common replacement size for the front tire is 100/90-16, which has a diameter of 23.09" and a calculated circumference of 72.53", variable by tire model. This size rotates 873.58 times per mile and will make the odometer read .997 miles for each mile traveled, about 1/3 of a percent over actual miles. In both cases, this is a relatively small error. | ||
If your definition of accurate is zero percent error, then yes, there is some error in the odometer reading. But in the real world, that's just not possible. Every little thing will affect odometer accuracy, including tire wear, road temperature, tire pressure, and ambient temperature. For everyday purposes the Ninjette's odometer accuracy, though not a perfect 100 percent, can be considered to be spot on. More importantly, the ratio of front wheel turns to odometer wheel turns can never change or vary, unless gear teeth are physically stripped or broken. If that's the case, then the typical result is a complete failure to function rather than a decrease in accuracy. | If your definition of accurate is zero percent error, then yes, there is some error in the odometer reading. But in the real world, that's just not possible. Every little thing will affect odometer accuracy, including tire wear, road temperature, tire pressure, and ambient temperature. For everyday purposes the Ninjette's odometer accuracy, though not a perfect 100 percent, can be considered to be spot on. More importantly, the ratio of front wheel turns to odometer wheel turns can never change or vary, unless gear teeth are physically stripped or broken. If that's the case, then the typical result is a complete failure to function rather than a decrease in accuracy. | ||