How Much Weight Can A Bicycle Carry

2006-06-01 (updated 2012-02-02)

Theoretically, a human being can haul a load of almost unlimited size given unlimited time and unlimited equipment. Practically, however, equipment, geography, and time puts limits upon what is physically possible.

Our experience has been that most people can comfortably pull 300 lbs (137 kg) with a typical mountain bike and cargo trailer or cargo trike. How quickly a person can move load of that weight will depend on his or her physical condition. Someone in reasonable physical condition can generally pull a 300 lb load at 10 mph (16 km/hr) on level ground if there's no wind. A person exerting the same effort could pull a load of 600 lb. (275 kg) at a speed of about 8 mph (11-13 km/hr), and a 1000 lb load at about 6 mph.

Pulling a load up a hill

Climbing a hill with a load, however, takes considerably more effort. Pulling a 300 lb load up a slight 2% grade at 10 mph, for instance, requires about three times as much effort as on level ground, while a 600 lb load up such a hill requires 4.5 times as much effort. Riders compensate for this by shifting into a lower gear and going up the hill more slowly. This reduces the amount of effort required but increases the amount of time it takes to climb the hill by a proportional amount.

Moving heavy loads, therefore, requires that equipment have low gears. How low the gears need to be depend upon the weight of the cargo to be carried and the size of the prevailing grade. The lowest gear of most mountain bikes is between 16 and 22 gear inches (see our section on gearing and gear inches for an explanation). We've found that a bike equipped with a low gear of 18 gear inches is sufficient to allow most people to pull a trailer carrying 300 lbs up a moderate (4%) grade. While it is possible to pull a load greater than this up such a grade, it takes considerably more effort.

Human Power Load Calculator

Below is a simple calculator to estimate how much weight a typical healthy individual could transport on a warm day in still air using a bike and trailer or cargo trike. Things like wind speed, equipment condition, and personal health can have an enormous impact on results, so use this only for rough approximations.

Calculator Explanation

A bicyclist moving in a straight line at constant speed has four sources of resistance to overcome:

1. Air (wind) resistance - given by the formula:
   F_w = 1/2 * Cd * A * ρ * V²
   
where:
• Cd = coefficient of drag (about .9 for a standard bicycle)
• A = cross-sectional front area of bicycle, rider, & cargo
• ρ = density of air
• V = wind speed relative to the cyclist


2. rolling resistance - caused by the tires rolling over the ground. This is given by:
   F_rr = C_rr * W * cos(atan(G))
where:
• C_rr = Coefficient of rolling resistance (about .006-.010)
• W = total weight of rider, vehicle, and cargo
• G = grade (slope of the hill, in percent)


3. gravity - the effort required to climb a hill. This is given by:
   F_g = W * sin(atan(G))
where:
• W = total weight of rider, vehicle, and cargo
• G = grade (slope of the hill, in percent)


4. friction - in the chain, bearings, etc. This is usually considered to be about 5% of the applied power in a bicycle:
   F_f = .05 * F_applied

Power is the product of force and velocity. Thus, the total power required is:

P_applied = (F_w + F_rr + F_g + F_f) * V

Using the above equations and solving for W:

W = ( (.95 * P_applied / V) - F_w ) / ( C_rr * cos ( atan(G) ) + sin ( atan(G) ) )

Categories: Cargo Biking