froglegsinc.com) has long offered caster forks and wheels to provide a smoother ride for ultralightweight wheelchair users.

But now, consumers who use other types of wheelchairs can also enjoy more comfortable and functional rides. Seating Dynamics (www.seatingdynamics.com) recently introduced a suspension series for the Quickie/Zippie IRIS manual tilt-in-space wheelchairs. The company plans to offer compatibility with other tilt-in-space models in the future.

Two other manufacturers have approached manual wheelchair suspension from a different angle: by providing the suspension system within the chair’s wheels.

Loopwheels (www.loopwheels.com) is based in the United Kingdom and makes 24″ and 25″ wheels to fit most manual wheelchairs. On its Web site, the company says, “Our wheelchair wheels are optimised to carry more than 50kg and less than 120kg [approximately 110 and 265 lbs., respectively]. In the future we may be able to make Loopwheels for children and lightweight adults. At the moment, people weighing 50kg or less may not feel as much benefit from our wheelchair Loopwheels as people who weigh more.”

Softwheel, based in Israel and distributed in the United States via Numotion (shopnumotion.com), currently offers the Acrobat with in-wheel suspension in 24″ and 25″ sizes (magnesium or aluminum).

In a recent review of studies focusing on vibration and wheelchair users (“Vibration Exposure in Everyday Wheelchair Use”), Softwheel pointed out the dangers of whole body vibrations (WBV) experienced when wheelchairs roll over rough surfaces or obstacles.

“This can lead to lower back pain, disc degeneration, and other potentially harmful effects to the body. In addition, WBV and significant vibrations can result in increased fatigue, decreased comfort, motion sickness, a risk for tips or falls, and interference with daily activities,” Softwheel’s paper said.

There’s no doubt that launching a manual chair off a curb, for instance, can be jolting. But research suggests that smaller everyday jolts — for instance, when rolling from carpet onto a hardwood floor — also take a cumulative toll. That observation makes manual chair suspension strategies important to keep an eye on.