FAMILY MEDICINE® COLUMN
By John C. Wolf, D.O.
Associate Professor of Family Medicine®
Ohio University College of Osteopathic Medicine

[THREE-WHEELED BYCYCLES ONLY SAFE AT VERY SLOW SPEEDS]

Question: I'm 81 years old and physically active. I recently had a bicycle accident and sustained a broken collar bone and several broken ribs. I want to get back to riding again and am thinking about getting a three-wheeler. Would these be safer than my bicycle?

Answer: Transportation, whether on foot, horseback, on two or three-wheeled bicycles or by motorized vehicles is potentially dangerous. We don't generally think about these risks because of the number of times we successfully travel to other places without injury.

As you can attest, using a bicycle is not a risk-free activity. The most serious injury, death, occurs to about 800 bicycle riders each year. Most of these tragic events are the result of a bicycle-motor vehicle collision, and many of the victims are children. Often these accidents result from a traffic error committed by the bicyclist, not the operator of the motor vehicle. As you can attest, though, bicyclists can, and often do, sustain serious injuries without the involvement of another vehicle.

A three-wheel bicycle is safer than a two-wheeled one in some situations, while it is dramatically less so in others. Since the broad triangular base makes the three-wheeler hard to tip over, it is, quite obviously, more stable than a two-wheeler when standing still.

The situation can be different, however, when moving. The center of gravity of the bicycle and rider combination is fairly high. When turning a two-wheeled bicycle, the bicycle and rider lean into the turn. This changes the angle at which the bicycle wheel and the forces it carries, interact with the road. This point of balance is constantly changing as the speed and rate of turn changes, thereby requiring moment-to-moment subtle adjustments of the rider. Though this constant balancing act has exacting requirements, it is successfully mastered most of the time.

A three-wheel bicycle doesn't lean in a turn. At slow speeds this is very stable and safe. As the speed increases or the turn becomes more abrupt, however, a potentially dangerous situation develops. The tendency to tip over can't be compensated for by the rider leaning in the appropriate direction. In this situation, it is relatively easy to exceed the safe limit and tumble off the three-wheeler instead of safely negotiating the turn. In fact, this became such a serious problem with three-wheeled-all-terrain vehicles that the federal government created regulations that eliminated them from the market. Three-wheeled bicycles are only safer by the extent to which their riders limit their speed.

If you are presently unable to ride a regular bicycle, then a three-wheeled one may be a useful form of transportation - but it must be used with good judgment and at very slow speeds. If it's use is primarily for exercise, then consider walking, swimming or exercise equipment as a safer alternative.

Family Medicine® is a weekly column. To submit questions, write to John C. Wolf, D.O., Ohio University College of Osteopathic Medicine, Grosvenor Hall, Athens, Ohio 45701.