Eddy Current Brake for Aluminum bike rollers

thingiverse

WARNING: Use extreme caution with Neodymium permanent magnets. A single 1" cube magnet exerts a pull-force of ~30-40lbs, and if two are stuck together, they can cause serious injury to your fingers. Furthermore, they are extremely hard to separate once attached. These magnets are also very brittle, prone to cracking and chipping when snapped together. If you own aluminum bike rollers that lack sufficient resistance for a good workout, adding Neodymium permanent magnets will significantly increase the resistance. I only needed one cube magnet, but two can be used if extra resistance is desired. With just one N52 magnet, I achieved ~250 Watts at 15mph, and the resistance increases exponentially with speed. To space the magnet about 1mm from the roller, use a credit card. These magnets will work on TruTrainer rollers, but the bracket size may need to be adjusted for other types of rollers. However, they will not function on rollers made of non-metal materials. The downside of using these magnets as a brake is that coast down time will decrease and the roller will heat up due to power dissipation. To assemble this brake system, you will need one or two 1" cube magnets, a 1" long 1/4" screw/bolt, and a matching nut or wingnut.