(First published in 2017 and revised by Harrison Smalley in 2022.)
The Problem:
There is good research evidence into the effects of vibration on people who use a wheelchair and in particular those who have a spinal cord injury1. Studies have shown that wheelchair users are exposed to levels of vibration that are considered unsafe and that this can affect health and life quality 2. This is a risk factor for all wheelchair users, and it has been shown for people with spinal cord injury that this increases the amount of muscle fatigue and potentially damaging connecting nerves 2.
Manufacturers of wheelchairs have tried to address this issue by adding suspension or designing wheelchair frames from innovative materials. Unfortunately this has not fully addressed the problem, as wheelchairs with suspension only marginally improved vibration control but incurred a large weight penalty and an increase in frame costs 3. Carbon fibre showed some promise in frame design 4 but was very costly to manufacture.
The Solution:
At Loopwheels we have addressed this problem by replacing spokes by a composite material including carbon to create an ‘in-wheel‘ spring that absorbs vibration and shock, without the weight penalties of a suspension chair or the cost penalties of a full carbon frame.
Methodology
To test vibration reduction qualities of the Loopwheel it was compared with a standard metal spoked wheel that is usually the original equipment found on a basic wheelchair. (Note, this testing was done in 2017 using our original Loopwheel design for wheelchair, the Loopwheel “Classic”).
The wheel was positioned directly over a vibration plate. The wheel was then loaded with a weight (10kg). An accelerometer is then positioned on the frame holding the load. The accelerometer measures the vibration coming through the wheel. Each wheel was then tested at three different frequencies (7, 10 and 13 Hz). This frequency range was chosen as this has been shown to be in the range of the most problematic frequencies for human health (1-20Hz) 4.
To make sure all comparisons were equal, all wheels had the following specification:
- 24” wheel size with a bead seat diameter (BSD): 540mm
- ½” bearings, taken from the same production batch (manufactured by MBL)
- Schwalbe Marathon Plus tyres
- Schwalbe Schrader inner tubes
- Tyre pressure: 110 pounds per square inch (PSI)
- Black aluminium powder coated push rims (wide offset)
Results:
Raw acceleration data was plotted for all three conditions along with root mean square acceleration.
So How Much Do Loopwheels Reduce Vibration vs Normal Wheels?
The Solution:
The Loopwheels reduce vibration by 68% at 7Hz, 52% at 10Hz and 76% at 13Hz.
Overall we conclude that Loopwheels significantly reduce the amount of harmful whole body vibration a wheelchair user will experience through their rear wheels. This is turn can help to manage pain and fatigue, and thus allow a wheelchair user to travel further or for longer before feeling the impact of the whole body vibration.
Other related research studies and test results on Loopwheels:
The rolling efficiency of a Loopwheel.
Do wheelchair users get more back pain? And if so, what can we do about it? 2022
Fatigue in wheelchair users, 2022
University of Pittsburgh Vibration Study, 2024
References
1. Vorrink SNW, Van Der Woude LH V, Messenberg A, Cripton PA, Hughes B, Sawatzky BJ. Comparison of wheelchair wheels in terms of vibration and spasticity in people with spinal cord injury. Assist technol Res Ser. 2010
2. Garcia-Mendez Y, Pearlman JL, Boninger ML, Cooper RA. Health risks of vibration exposure to wheelchair users in the community. J Spinal Cord Med. 2013
3. Kwarciak AM, Cooper RA, Fitzgerald SG. Curb descent testing of suspension manual wheelchairs. J Rehabil Res Dev. 2008;45(1):73-84. doi:10.1682/JRRD.2006.11.0142.
4. Chenier Felix, Aissaoui R. Effect of Wheelchair Frame Material on Users’ Mechanical Work and Transmitted Vibration. Biomed Res Int. 2014;2014. doi:10.1155/2014/609369.
5. Katu US, Desavale RG, Kanai RA. Effect Of Vehicle Vibration On Human Body – RIT Experience.