Robert Dempster

Resident in Pietermaritzburg (PMB)!
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Wikipedia - The Corona Virus

*** Welcome to my PMB blog, the umpteenth! ***

The Corona Diaries
Page 4
Lock-down - Days 5-7
Stationary Cycle Trainer - The Big Ezee

4 April 2020

Wikipedia - The Sun's Corona

The first stationary exercise bike prototype had to be abandoned because of the excessive noise that ematated from it from the moment the pedals turned. The noise was being created by the outer pipes bashing against the inner pipes as they rotated around them. The next problem would have been that the drag created by this process was in excess of what was required. Drag is of course both good and necessary as it requires the cyclist to make an effort, and in so doing, exercise.

So with drag in mind, and admittedly inspired by what I had tried to purchase before the lockdown was a reality (a Giant Cyclotron Magnetic Indoor Trainer), I had to start again. So I set about trying to use the hub motor from Bruce's trashed Ezee Forza ebike, not as a motor, but as as a generator. To do so I would need to position it up against the back wheel of another of Bruce's bikes such that when the cyclist riding the bike did so, s/he rotated rotated both the bike's raised back wheel, and the motor now functioning as a generator. Once we had a frame in place to hold the bike's back wheel off the ground, we tested the generator for drag, and Voila, it worked as expected.

So I immediately set about building a framework to hold the front wheel steady, and another to hold the ebike motor's rotor (pic SEB170) against the bike's back wheel such that it rotated when the back wheel rotated. The inside of the rotor is lined with permanent magnets that now rotated around the motor's stator or armature (pic SEB140) that was in turn fixed to the support framework.

The ebike motor was now functioning as a generator, and while it was not perfect, it worked. It was in effect now producing electricity in proportion to the effort of the cyclist pedaling the bicycle. Unfortunately this prototype also makes some noise, but nothing like the first prototype. The level of the noise is not excessive enough to disturb neighbours,and anyone else who happens to be in the house while it is being used. I world guess that the noise is similar to that made by a lawn mower being used somewhere in the neighbourhood. What is interesting, is that the level of the noise emitted decreases as the speed at which you are pedalling increases, and could in that sense be considered to be a feature of the system. A feature that we are going to have to live with.

It is of course VERY different from cycling in the KwaZulu-Natal Midlands. Twenty minutes spent pushing the pedals of this exercise bike provides a good workout. Done twice a day it will probably see us return to our own bikes in better condition than when we left them.

If you are interested in aspects of what else went into this project, you will find annotations attached to the images included below.

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Getting it to work on a device that has a touch-screen is a problem that I still have to solve.

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SEB300.mp4 - action - short video clip

Money can't buy happiness, but it can buy a bicycle.

If you have any comments, corrections, suggestions or plain criticism, I would appreciate it if you would communicate the same to me.

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