Analytic Cycling Logo Gear Selection, Long Climb

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 
 

©1997 Tom Compton