A small drag parachute, or an old headlight generator would do the same thing and probably be a lot cheaper.

Get some wider tires, lower the air pressure quite to the lowest recommended PSI, add some Mr. Tuffy or other tire liners and some True Goo sealant. Voila! Slow wheels. And a lot cheaper. Or train on a cheap mountain bike with drop bars, same riding position and fat knobbies at 40-50psi (sealant and liners optional). Or if you have disc brakes, just keep light pressure on the levers continuously as you pedal. You\'ll have to replace brake pads and rotors more often, but this contraption will need the cam and \"resiliently deformable blades\" replaced on a regular basis, as well. If you don\'t want your fingers to get tired, wrap Velcro straps around the brake levers to apply the light pressure or use the cable adjuster barrels or disc pad adjustment knobs to take up all slack. Not as good an idea with rim brakes since you don\'t want to have to rebuild wheels with new rims often.

Most bikes have gears; more resistance can be achieved simply by shifting. Similarly, one can just try to go faster, since wind resistance increases at an exponential rate (and is free). Regardless, lack of strength is relatively unlikely to be a problem compared to sub-optimal aerobic fitness--consider that elite cyclists are more prone to blood doping than steroid use. Muscles are worthless if they can\'t get enough oxygen, and the extra weight is a penalty when going uphill.

Re; dreamer.redeemer
The point is to train for a higher speed while going slower for a variety of reasons, including but not limited to, to ride with a \"lesser\" rider, speed limits.
Taping playing cards to your spokes would also work.

Because if there\'s one thing that is proven to sell gadgets and inventions, it\'s the way they make someone\'s life harder. *rolls eyes*

Or just find a hill...

dreamer,
Higher gears don\'t provide the other benefits they claim, \"TriSport suggests that the wheel could also be useful for holding one\'s self back when training with a slower rider, or for maximizing the benefit of short-duration rides.\" Sometimes, you don\'t have time to get out to the open road and it\'s impossible to go full speed on city streets without endangering yourself or others.

LOL - Epic Answers to a Stupid IDEA.
Ahhh the OLD CRAP plain sleeve bearing bottle generators and kind of flat dirt bike tires...
I\'d actually like to see the tour of Frangers, done in REAL STYLE, using proper old chinese rickshaws, with the fold over roof, and 2 of the biggest fattest Australian tourists as passengers - making regular hamburger, ice cream and toilet stops.....
Actually if you really did want resistance training - that would beat everything.

I wonder if there is any additional strain on the dropouts. And also, I wonder if the resistance of the front hub could cause a wash-out in a low-grip situation (such as cycling on wet/greasy/frosty winter roads).

I have an electric bike, and when I want it to pull me up the hill I touch the throttle. To slow down, or have resistance training, I just put in in \"reverse mode\".
Why not just buy a stationary bike, and put wheels on it?
Or, why not..... are you kidding me???!!!!