- A rear wheel drive is good for
outdoor use off sidewalks. The push provided by the rear wheel drive can get it up and over most smaller
obstacles allowing it to travel well over lawns, light snow, rough ground and trails as well as up driveway
curbs. It handles higher speed smoothly, making it the best choice if you want a chair that will travel any
distance efficiently and quickly. Indoors, a rear wheel drive has a somewhat larger turning radius but works
well. It moves smoothly without the lurching that is synonymous with mid-wheel drive. It steers and turns corners
intuitively making it easy to drive.
A problem with mid-wheel drive that never seems to be mentioned by the manufacturers but does come up in
discussions by mid-wheel drive owners is called Caster Jerk. This is not the typical flutter of any caster. It is
a jerk or lurch to the side.
Any wheelchair has some caster jerking as the casters swivel 180 degrees from forward to backward. There is
resistance to the swivel until it reaches 90 degrees and then it finishes the swivel quickly causing a little
jerk in direction. The movement is slight and soon ignored.
With a mid-wheel drive, however, there are four casters attempting to change direction 180 degrees. The jerk is
accentuated and can be a problematic lurch to the side. This is minor and easily accommodated to in average size
rooms where the casters have enough distance to travel to move more smoothly through the swivel. This can be
adjusted with steering control settings or may require moving the entire seat on the base. It cannot be
In small spaces, it becomes a significant problem if it is necessary to back up, turn, and pull forward again to
position the chair correctly. When there isn't enough space/distance for the casters to swivel smoothly, they
jerk the chair quite powerfully to one side. The leg rests and foot plates bash walls, scratch furniture, and
inflict great pain on any ankles that get in the way! The jerk occurs even after the joystick is released and
even if you attempt to steer to the opposite side. Perhaps the most frustrating aspect of caster jerk is that
once you are in a tight space you can't adjust the position of the chair without repeated jerks. Times when
you are likely to encounter jerking include maneuvering in a small bathroom to position the chair accurately
beside the toilet or at the sink, at a computer desk where you need to be centered and straight on, in a van
where you need to face forward in alignment with the tie downs, in doctors and dentists exam rooms, restaurants
and buildings with small entries.
If the jerking problem isn't severe, most users become accustomed to, and they love their mid-wheelchairs, but
will admit jerking does occur and is annoying. People for whom the mid-wheel drive is their first chair accept
the problem as part of wheelchair life.