Answers  to basic Powerchair Quiz
This is pretty BASIC stuff. I would expect any "expert" to get all of this easily.  Lets get something straight. Reading powerchair spec sheets, and knowing all their "measurements" and going on some courses about trick seating and "options" wont help you if you don't understand the basic requirements! These are here! 

If you are an "expert" and disagree with anything on this site I welcome the discussion!

1, A powerchairs maximum width should be the same as the person seated in it. Any wider than that and it hinders mobility indoors. Any narrower than that and there is nothing to be gained in doorways or in confined spaces. And it means that space has been wasted that could have been utilized for batteries (range or performance).  Under no circumstances use the manufacturers claimed figures as this usually is with a very narrow cushion... My own powerchair is 25.2 inches total WITH an 18 inch wide cushion.

2. The correct length for a powerchair is as short as possible with the distance between two walls being limited by the occupants head, and feet while seated. If there is any part of the powerchair behind them stopping them touching their head on a wall then its simply too long. That means indoor mobility in confined spaces is hindered. In MID DRIVE powerchairs this should include casters extended to the "longest" direction. If you think this is not possible check out my own powerchair. its 40 inches total length. Under no circumstances use the manufacturers claimed figures as this usually doesn't include foot riggings, or measures the rear casters in the most "advantageous" position...

3.   6 MPH for a powerchair with group 34 or 24 batteries and an average weight outdoor user is best.  4 MPH for a chair with smaller batteries like 50Ah or less. 8mph for very light users who don't expect all day range or great torque. If you don't totally understand this then you have no right claiming to be a professional!  However less than 6 MPH is almost unusable outdoors, and has safety implications even crossing a busy road. So this means 6MPH and group 24 (34) batteries of around 70Ah are essential for any serious outdoor use. So powerchairs that don't use batteries of this size are of no use at all outdoors.

4. Control systems for a 6mph powerchair are borderline at 80 amps. 100 is better for ramps or turning in difficult circumstances. Unless the user is very light. Smaller systems are "OK" in slower powerchairs. But slower powerchairs do not belong in the indoor/outdoor category at all. And not all control systems are created equal. differences here Controllers

5. Programming a powerchair correctly for each user is absolutely essential. In many cases this requires an OEM level programmer. I would estimate that 90 percent of users do not have their powerchairs programmed correctly for them and that their health care professional hasn't a clue how to help or even knows they could! Read powerchair programming here

6. Seat height affects many things relating to powerchairs. Here are a few simple obvious affects:

a) swinging side to side in an ark higher up above a powerchair on uneven outdoor surfaces is uncomfortable, but worse it causes shear forces and pressure damage.
b) It also leaves the powerchair more likely to tip over sideways on a lateral slope - trust me it hurts!
c) It also means that a powerchair wants to tip backwards easier on a ramp. Meaning that the Centre of gravity (the user) has to be moved forwards making the chair nose heavy on a level surface. Causing less ease of manoeuvrability, making the chair physically longer, and eating battery power faster due to the energy needed to turn increasing.  So aftermarket seating that sits you higher than stock is best avoided at all costs. Because it reduces your mobility in a number of ways.

7. There are several affects

a) Puncture free or foam filled tyres are harder to push so eat batteries faster. They therefore reduce range, and further reduce battery longevity.
b) Puncture free tyres always give a harsh ride. This causes comfort, muscle spasm, and pressure sore inducing shear forces. It also increases weight on the drive wheels which hinders any suspension control and wastes battery power.  

8. Wheel and caster sizes.

a) Casters have NO suspension. Our world is VERY rough and uneven. 10 inch x 3 air filled casters are far superior outdoors to anything else. That would be a 3.00 x 4 tyre. It has enough "give" in its large sidewall to take away some of the vibration and shocks. This helps prevent muscle spasm, vibration, (so your feet stay on the footplate!) and rides over the uneven landscape well. They are "fat" enough to give some floatation on sand, snow and mud when outdoors too. Provided that the chair is not "nose heavy". Little weight should be on the caster wheels in a well designed chair. Smaller, and solid casters are really not suitable outdoors at all. Unless you accept the loss of comfort, and risk of problems and the reduced mobility. Although smaller and harder ones are great indoors. But a well designed chair will still be fine indoors with the larger casters. Most are not well designed though. Punctures cease to be a problem completely if the chairs c of g is rearward, as there is little weight on the casters. (rear wheel drive). And as a precaution OFF ROAD puncture seal can be added too.

b)  Rear drive wheels or Mid drive wheels should offer floatation and comfort. They should have big sidewalls and be very soft.  For the real world is full of sand, soft grass, mud, snow and worse and non of it is smooth! So they should be wide / fat balloon style ideally. My own chair uses 6 inch wide ATV tyres on the rear. Its total width is NOT any wider than I am, and under 25.2 inches total. That's narrow. A clever trick with full sized batteries needed for all day 6 mph use. Unfortunately there are no similar powerchairs available yet, until the "experts" catch up!  So you are stuck with 3.00 x 8 tyres usually, which give a very harsh ride outdoors even if the chair is fitted with "suspension" Never even look at a chair with smaller drive wheel sized tyres and wheels than this for outdoor use. Thinks like this are simply hopeless and frankly dangerous.

9. Batteries!  The BEST quality group 24 batteries that you can buy have neither enough power (amp capability) for ramps or turning id difficult situations or enough range for an active heavy powerchair user to get on with his day. And they will not last 1 year before replacement. Very expensive and a pain in the butt. So any powerchairs with smaller batteries than 70Ah are useless. That means much fancy seating, and almost all "small" cheap powerchairs are a complete non starter...

10.  There ARE NO CONTENDERS!  The conflicting requirements of fat soft comfortable outdoor "floaty" tyres, to give good off road and outdoor performance on pavements and sand/snow and full sized batteries, for 6mph low seat and all day range and the small 40 inch long (including everything) x 25,2 inch wide maximum defeats all the big manufacturers. There is simply no good outdoor/indoor powerchair. So you need to compromise one way or another.

Actually that's a lie. My own powerchair does all of the above. But I built it myself and you cant buy one. One day the manufacturers will catch up! But don't hold your breath!  I did it because I was sick of the experts lack of any clue!  It suits almost every powerchair user in ONE powerchair...