Im familiar with how fluid trainers provide their resistance (basically a fan moving through fluid for resistance), but Im trying to explain to some people how magnetic trainers work. Anyone care to enlighten me?
Bonus points if you can explain any differences between magnetic and fluid trainers (besides magnetic=quieter and fluid=smoother)
You’ve got to love google.
Types of Ergo’s
There are a variety of types of trainers, the most common being Wind trainers, Mag trainers and rollers. Wind trainers have been around the greatest length of time. These machines work on the principle that as you pedal faster, the fan spins faster creating an increase in wind resistance. Magnetic trainers work on the opposing of two magnets with in a certain distance of each other, so resistance is increased by having the magnets closer to each other within the hub. Both the wind trainer and the magnetic trainer work on clasping the rear axle, with resistance being applied to the back wheel in the form of a roller. An increase in friction (pressure) is then applied via the roller being pushed harder against the tyre, or the magnetic plates being forced closer together. Rollers are typically used by elite riders, as they require a reasonable sense of balance. If you are having trouble with even pedal strokes these can assist you to balance it out – or you’ll end up on the carpet trying. However it is very difficult to load up much resistance on rollers. The wind trainers are often noisier than the magnetic trainers, however at the same speed, magnetic trainers do not provide the same resistance. Therefore, for a better work-out at the same speed a wind trainer or rollers are better suited to actual road riding.
extracted from: http://www.irule.co.nz/cms/html/modules.php?name=IRuleHome&file=article&sid=382&topicid=3.36.19