Published 1/04, Copyright 2004, WheelchairJunkie.com
Differentiating among today's ultra-high-end manual chairs
By Mark E.
I'm practicing a shell game for the Atlantic City Boardwalk. No, it's not a three-shell game where
you have to keep your eye on the little yellow ball underneath one shell as the others spin around each
other on the table. Rather, I've created the high-end ultralightweight wheelchair shell game where I
take minimalist chairs like the Quickie Ti, TiLite ZRA, Kuschall Fusion, and Otto Bock Voyager, spin
them around, and then you have to tell me which chair is which model?|
Indeed, much like identical
shells on a table, it's difficult for consumers to distinguish among models in the recent trend of minimalist
ultralightweight manual wheelchairs. After all, when you line up these lightest of lightweights, they
are strikingly similar. But, much like a shell game, beneath the look-alike forms, there are underlying
differences seen by the keen eye, turning a wavering guess into a sure bet.
Everything Old Becomes
Brought to prominence in 1985 by Rainer Kuschall, the most noted European wheelchair innovator,
the minimalist frame design - now also called "cantilever" or "monotube" frames - is not new by any
stretch. Nevertheless, the design worked well then and now, providing ultralightweight, transportability,
and performance. Maybe the revitalization of Kuschall's design is the ultimate sign of its practicality,
or maybe the proliferation of Kuschall's design is a reflection of the industry spinning its own wheels?
In either case, one fact is true: there's no shortage of minimalist chairs on the market, and it's not
easy telling them apart.
Moving From Form to Function
All of the minimalist chairs on the
market seem to draw from the same specifications sheet, with scant differences in weights, features,
and options - that is, if you're looking for a rigid, ultrahigh-performance chair around 20lbs., they'll
all fit the bill. However, if you closely analyze the models - say, the TiLite ZRA versus the Quickie
Ti - the differences come through, especially in the methods of mounting hardware and ease of adjustments.
After all, in this performance arena, it's not just how they look on paper; rather, in this realm of
minimalist mobility, it's about how they function in the field.
experience as much stress as rear wheel axle plates. On conventional box- or over-the-hub frames, the
axle plates (or camber tube mounts), are supported for and aft, providing exceptional strength under
horizontal forces. Minimalist frames, however, mount the axle plates off the seat tube only, extending
the camber tube several inches below the mounting point. This single, extended mounting point is an
especially vulnerable area, requiring well-engineered hardware and component interfacing (you don't want
to go forward while your wheels head rearward). The manufacturers address this area by either clamping
the hardware onto the seat rail, or bolting through the seat rail, both of which offer insights into
different schools of adjustability.
TiLite's ZRA, for example, is one of the models that clamp
the axle plates onto the seat tube. To adjust the ZRA, you merely loosen two bolts on each side with
an Allen wrench, sliding the axle plates to the desired fore-aft center-of-gravity position, retightening
the clamps in place. However, with this infinite adjustability, and no indexing, comes the possibility
of misalignment, resulting in one axle plate placed ahead of the other (this may cause the chair to pull
to one side). For this reason, TiLite recommends using a ruler to measure the location of each clamp,
Contrary to clamp-on hardware, the Quickie Ti's axle plates bolt through the
seat rails, offering fore-aft adjustment in ½" increments. To adjust the axle plates, you must remove
two bolts on each side, reposition the axle plates, and then reinstall the hardware. While this process
is more involved than a clamp system, the Quickie Ti's through-bolting guarantees perfect alignment,
which is vital on this level of performance chair.
Much like the varied means of rear axle plate
hardware, the caster mountings on this genre of minimalist manuals also differ. Both TiLite and Quickie
use a bit less sure systems than the type of eccentric bolt method of which most are familiar. To adjust
the caster angle on a TiLite ZRA, you loosen a nut, then turn a bolt, which rotates the mount (if you
remember the cam-type adjustment on Invacare's Pro-T, the process is very similar). As you rotate the
mount, there's no indexing to match the alignment of one caster to the other caster, again, opening up
the possibility of misalignment (like most caster angle adjustments, a 90-degree square is required to
confirm positioning, but without indexing, it's exceptionally tedious). The Quickie Ti's process is
a bit more involved, requiring Torx wrenches to loosen the hardware, and also a square to confirm alignment;
however, meshing teeth on upper and lower splines allow both an enhanced sense of indexing and security.
When it comes to hardware on the TiLite ZRA and Quickie Ti, the differences are revealed - that
is, ease of adjustment versus guaranteed alignment. It is through such study, then, that you, as a consumer,
can better analyze the products and prioritize your wishes.
No More Spinning the Wheels of Luck
As you may suspect, the adjustments and hardware go on and on in this look-alike genre, from toe-in/toe-out
to backrest angle adjustments. However, by picking a few key areas as we have - and ideally more - you
can take chairs with no seeming difference, open them up to reveal vital aspects, and make an informed
decision. Of course, you'll also have the skills to beat me on the Boardwalk, as when I spin these minimalist
chairs around and around, you'll look at the axle mounts, casters, and backrest, and easily tell me which
is which. But, no worries - I'm practicing my 24" black mag wheel "shell" game, too.