## Tricycles are Not Bicycles

That’s adult tricycles, of course.

You may think that, having ridden bicycles for years, riding a tricycle would be a no-brainer. But remember when you made the transition from tricycle to bicycle, probably with the aid of training wheels? At first you probably felt pretty unstable—three points on the ground keeps you level; two doesn’t. But at some point you discovered that if you leaned one way or the other the bicycle turned in that direction rather than falling over, and that fact rather quickly got into your muscle memory. Without even being consciously aware of it, you began to rely on weight shifts, rather than the handlebars, for steering.

The reason a bicycle reacts that way is conservation of angular momentum. I’m not even going to try to explain it (it takes calculus) but if you’ve ever taken a physics class you’ve probably seen it demonstrated. A student sits on a revolving chair holding a spinning bicycle wheel. If he tries to change the direction of the axis of the wheel, he will turn himself. A spinning bicycle wheel on a bicycle acts exactly the same way. Its axis tries to stay pointing in the same direction, which keeps the bicycle upright. If you force the axis to move, by shifting your weight, the result will be a rotational force at right angles to the force you put on the axis. Leaning tries to tip the axis vertically; the turn forced is horizontal.

Of course a bicycle does try to tip over if it is stopped—if the wheels aren’t turning. A wheel that is not spinning has no angular momentum—which is what makes the axis resist changing direction.

What happens if we apply the same principles to a tricycle?

I even rode my tricycle in the Golden Days parade one year, for a diabetes support group.

A tricycle touches the ground at three points, so it has no propensity to tip over while it is stationary on level ground. But that same three-point stability means that you cannot change the direction of the axis of a spinning wheel simply by shifting your weight. A tricycle has to be steered with the handlebars. Further, the front wheel will resist being turned, and if is turned too sharply when you are going fast, turning the wheel will try to tip the tricycle over. This isn’t usually a problem with a child’s tricycle, because most are direct-driven, with the pedals on the front wheel, and they don’t move very fast. My adult tricycle is a three-speed that easily exceeds 10 mph on a slight downward slope.

Even worse, if you are riding on level ground and hit a side slope, the tricycle will try to turn of its own accord. This leads to real problems with uneven ground, side slopes, and angled curb cuts on bike paths, especially since a tricycle with a rider is very top-heavy.

A tricycle is a bicycle legally, so I can ride on bike paths. I tend to avoid narrow shoulders, for obvious reasons—first because a tricycle is a good deal wider than a bike, and second because most roads are crowned. This means I am riding on a side slope where I must steer very accurately to avoid getting one of the rear side wheels off the pavement. It’s also rather miserable to “walk” a tricycle–the rear wheels keep hitting you in the back of the leg

In short, a tricycle takes some retraining of your reflexes if you are used to riding a bicycle. They are still wonderful exercise for someone like me who no longer has the balance to ride a bicycle.

## Float Chair (Homecoming Glossary)

FLOAT CHAIR: An invalid chair kept at a more or less fixed height by levitation. Unlike our wheelchairs, it can be used up and down stairs and over rough ground. A float chair can be controlled either by a brain-wave pickup or by physical controls. It may have a speed governor or have the height above ground set within narrow limits, but these features are generally adjustable and may even be controlled by the occupant.

## The Perversity of Inanimate Objects–1

Cheep.
Did I hear something?  The clock radio is on, news of Iraq, of Afghanistan, music…  I drift back toward sleep.
Cheep.
Could the radio have a beep in the program?  Not likely.  My insulin pump?  It doesn’t quite sound like the familiar warning, but I grope the pump out, thumb the button.  No warning, only the sensor showing my blood sugar—normal—for the last three hours.
Cheep.
This time I listen, look around, consider possibilities.  Wristwatches—possible, but not likely.  I haven’t moved any in months.  Pedometers, ditto.  I can rule out a cell phone, at least I think I can—mine hasn’t been used for a couple of years and must be totally discharged by now.
Cheep.
I look around the bedroom.  The older Sheltie, whose hearing is almost gone, snoozes; the younger, the one whose rear end is nearly paralyzed, shifts and whines nervously in her crate.  The KUAC posters and the arrangement of artificial flowers in a gift basket hang as usual on the white walls, and in any event are not subject to bouts of cheeping.  The radio…  Come to think about it, I once traced a cheep to another clock radio, in another room.  But that was an inadvertently set clock chime, once an hour, on a clock that I have not managed to set since I lost the instructions.  And that radio is not in this room—is this sound?  I look at the closed wooden door to the hall as another cheep sounds.
It’s time to get up in any event; might as well open the door and see if I can locate the sound.  I struggle out of bed and hobble over to the door.  Of course whatever it is isn’t cheeping just now.  I close the door and care for the dogs and myself, trying to ignore the cheeps.
They are definitely louder in the hall, but the cheeps are too brief to locate.  I call the older dog to the kitchen door, at the other end of the hall.  Uncharacteristically, the younger leads him, so eager to get out into the run she almost trips me.  I work my way back down the hall, waiting for the cheeps and trying to judge where they are loudest.  Near the door to the office, I think.  That narrows it down to the uninterruptible power supplies, neither of which shows a warning light, and the smoke alarms.  Probably one of the smoke alarms saying it needs its backup battery replaced, but which?  The one in the hall, or the one four feet away in the office?  In either case, I will need the stepladder–both alarms are on the ceiling, far above my reach.  Do I even have the right kind of battery?
I drag the stepladder in from the garage, and call the dogs in for their breakfasts.  The younger dog clings to my ankles, clearly demoralized by the cheeping.  I finally shut her in the back room, stand in the hall under the smoke alarms, and shut the office door.
Cheep.  But it’s softer this time, so the smoke alarm in the office is probably the culprit.  Now all I have to do is remember how to change the battery without the instructions the previous house owners took with them.
Just climbing the stepladder is a problem, with a bad knee and an impaired sense of balance.  I manage to unscrew the alarm from the ceiling, where it hangs from the house wiring.  I see something I think is the battery compartment, but how does it open?  The instructions, if they are instructions, are molded into the white plastic over my head.  Have you ever tried to read small, faint print, over your head, through bifocals, while trying to balance on a stepladder?  I finally give up and try Googling the brand name on the Internet.  All I can find out is that my smoke alarm is so old it should have been replaced.
Cheep.  The last time this happened, I wound up breaking the battery connections and had to replace the alarm.  As long as I don’t electrocute myself, I can’t do any worse this time.  And if I break this one, I’ll have the electrician replace all of them with models I can replace the battery in.  I climb the stepladder again, the good leg always higher, determined to find that battery.
The compartment cover won’t come off as I pry at the edges, but pulling at the place where the wires go into it seems to have some effect.  I persist, working awkwardly over my head, teetering on the ladder, until the cover finally gives and I see the 9 volt battery with its silly little snaps.  Carefully I pry the snaps off the battery, still reaching awkwardly over my head–this is how the other battery connection got broken, with one of the snaps coming off the connector rather than off the battery.  Success!  Now if only the replacement battery I’ve found is good…
It takes both hands to fasten the snaps on the new battery, while I teeter on the stepladder.  I hold my breath, waiting for another cheep to tell me that the new battery is dead or that the sound was coming from somewhere else.  Blessed silence.  Even the dogs seem to draw a breath of relief.
Now all I have to do is get the wires tucked back into a too-small space and screw the wretched smoke alarm back into the ceiling.