I had promised to post a topic on how to properly measure a chair so here it is. It is quite long but will hopefully answer any questions you might have.
Also please remember you have to live with the chair, not the reps, so make sure you are comfortable before buying anything.
!. Seat Width: Measured from outside of seat tube at back post to the opposite tube. If measuring first time, measure from outermost point of one hip (while seated) to opposite hip.
2. Seat Depth: Measured from front of seat sling to the furthermost back part of seat sling (or to back upholstery). When sitting up straight be sure to measure from back of knee to far back of butt. Then take off about 2 in (length depends on how you are comfortable) to ensure that knees do not rest against seat sling. This way the pressure is distributed better and your knees aren't rubbing.
3. Front Seat Height: Measured from floor to the top of seat tube where the tube bends. This measurement determines how far off of ground you will sit. So it truly depends on comfort level. Also be sure to take into consideration the cushion you use, as this will put you higher up. This measurement is very important for transfers and ability to fit under desks, tables, etc.
4. Rear Seat height: Measured from floor to top of seat tube where it meets the back post. The difference between front seat height and rear seat height is what we call squeeze (dump). The amount of dump varies and has many affects on positioning. Mostly in regards to stability. I have attached a document explaining the effects of dump.
5. Back Angle: Angle measured from front of back post to floor. 90 degree meaning the backrest is perfectly perpendicular to floor. This option varies highly from chair to chair so be sure to reference order form.
6. Center of Gravity: Measured from front of back post to the center of rear axle. This is probably the most crucial measurement. The proper center of gravity is based on personal preference. The further forward the axle sits relative to back post (greater center of gravity) the more maneuverable the chair becomes. However, the further forward the center of gravity the tippier the chair becomes. This really depends on your preference and I recommend trying different setting till you find your comfort zone.
7. Footrest Width: Measured from inside of front frame tube to inside of opposite frame tube. All chairs vary in allowable widths.
8. Rear Wheel Spacing: Measured from outside of frame tube to inside of tire. This will effect how far from the seat your tires are. As with everything else spacing option vary by chair and are also affected by camber. It also makes total width of chair and will affect ability to get into certain buildings.
9. Camber: Angle of axle relative to frame. This dictates whether your tires slant outward. Zero degree camber means tires have no slant. Increasing camber will affect maneuverability as well as make total chair width greater.
10. Front Angle: Measures angle at which you feet will sit relative from frame front to floor. 90 degrees mean your legs will rest perpendicular to seat front. Try to demo different frame angles to find comfort zone. Changing this angle may greatly affect the spacing between back of knee and seat sling. Be sure to account for that change.
11. Seat Back Height: Measure from top of back post to top of seat tube at rear of frame. Height options vary by chair and depend on one's core stability and comfort. See attachment for further info.
12. Seat to Footrest: Measure from front edge of seat sling to top of rear footrest. On most chairs seat to footrest must be 2" shorter than front seat height.
I hope this was helpful. Always reference order forms as the have specifics for each chair. As well as diagrams which are very helpful. If you have any questions or if I forgot something, let me know. Also if you would like a printable version of this please Private topic me with email. This guide will be revised and included in a massive document library, with product reviews, order forms, etc. that will be featured on our new website which is under construction.
Live Well Medical Supplies