Increase the resistance of a Sunlite F-2 Magnetic Resistance Trainer

The Sunlite or Forza F-2 Magnetic Resistance Trainer is a budget indoor trainer that costs around $100. It seems like a good product except for the minor detail of insufficient resistance. This particular product is not adjustable and the only way to adjust resistance is via gearing on your bicycle, if you have it. I received my unit as a gift and found that it did not really meet my requirements for a good indoor ride. Google did not turn up anything useful to remedy the situation, so I started thinking about how I could increase the resistance without getting a new trainer.

Maybe you are in a similar situation, or the trainer was sufficient for a while and you are ready to move to the next level. This may also work for other trainers like the RAD Mag, which appears to be the same basic trainer. Continue below where I describe how I was able to increase the resistance to a better level for my purposes cheaply in less than 5 minutes.

First, I decided to open the cover that encases the magnetic flywheel:

Inside you can can see a series of magnets distributed around a metal ring:

 It just so happened that I had some small neodymium magnets lying around: 

I distributed them between the existing magnets:

From here I reassembled the flywheel and found that the resistance had increased noticeably. You may also stack the magnets for even more resistance (which is what I ended up doing). That makes it trickier to get the cover back on without the magnets wanting to stick to the flywheel, but it can be done. You might also add a bit of glue to the magnets if you want to make it permanent and easier to assemble.

The magnets I used are nickel coated and measure 1/4" by 1/8", similar to these.