Let's say a rider is planning a long
tour with lots of long climbs at the end of some tough days. The rider
wants to be sure to have a gear that is low enough. The rider estimates
that the steepest climb will be 8% at a worst-case speed of 1.75 m/s.
The rider can maintain a 45 cadence at this speed. What would the
suggested gear be? The following table suggests a 39x28, the lowest
one the rider has, but not as low has he wants. Maybe the rider should
consider a triple. Good advice: "Take your low gears."
Recommended Gear
| Closest Gear |
39x28 |
|
| Gear Inch, Closest |
36.8 |
inch |
| Rollout, Closest |
2.936 |
m |
| Maximum Speed |
1.75 |
m/s |
| Wheel Diameter |
671 |
mm |
| Desired Gear Inch |
29.2 |
inch |
| Desired Rollout |
2.333 |
m |
| Frontal Area |
0.5 |
m2 |
| Coefficient Wind Drag |
0.5 |
dimensionless |
| Air Density |
1.226 |
kg/m3 |
| Weight |
75. |
kg |
| Coefficient of Rolling |
0.004 |
dimensionless |
| Effective Stroke |
70. |
degree |
| Grade |
0.08 |
decimal |
| Wind Resistance |
0.5 |
kg m/s2 |
| Rolling Resistance |
2.9 |
kg m/s2 |
| Slope Force |
58.8 |
kg m/s2 |
| Crank Length |
170. |
mm |
| Maximum Cadence |
45. |
rev/min |
| Pedal Speed |
0.8 |
m/s |
| Average Pedal Force |
136. |
kg m/s2 |
| Effective Pedal Force |
350. |
kg m/s2 |
| Power |
109. |
watts |
|
