Measuring Gear Sizes

There are several ways to measure gear size.  People speak of sprocket sizes, gear ratios, gear inches, development, rollout and ratio gain.  What do they all mean?

QUESTION 1.  Gear ratio refers to…?

1. The number of teeth on the crank sprocket divided by the number of teeth on the wheel sprocket.
2. The total range of gear sizes, from the lowest gear to the highest gear.
3. The number of sprockets on the pedal crank times the number of cogs on the wheel.
4. The number of teeth on the rear sprocket divided by the number of teeth on the front sprocket.
5. None of the above.

QUESTION 2.  Gear inches refers to…?

1. The circumference of the drive wheel divided by gear ratio.
2. The diameter of the drive wheel times gear ratio.
3. The radius of the drive wheel times pi times gear ratio.
4. Half the circumference of the drive wheel times gear ratio.
5. None of the above.

QUESTION 3.  Meters development refers to…?

1. The metric circumference of the drive wheel times gear inches.
2. The metric diameter of the drive wheel plus pi times gear ratio.
3. The metric circumference of the drive wheel times gear ratio.
4. The metric circumference of the drive wheel divided by ratio gain.
5. None of the above.

BONUS QUESTION:  Ratio Gain refers to…?

1. The metric development of the drive wheel divided by crank length.
2. The circumference of the drive wheel divided by crank length times gear ratio.
3. The diameter of the drive wheel divided by crank length times gear ratio.
4. The radius of the drive wheel divided by crank length times gear ratio.
5. None of the above.