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Endurance Bicycle

Variable resistance bicycle
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My job involves sitting down at a computer for most of the day so I felt very good about myself when I took up cycling to work. Thing is though, while I feel much fitter now, I don’t feel I’m getting as enough of a work out, as I did 6 months ago when I started. The solution? Why not combine an ordinary bike with an exercise bike. If you aren’t getting enough of a work out on an exercise bike you can just increase the resistance. So why not design a bicycle which allows the rider to adjust the resistance of the back wheel.

Why not just use a higher gear? Well because for large stretches of my journey (down hill and flats) I already use the top gear and regret not having more. Also if you keep your rpms high and jump up a few gears your moving a lot faster, not always wise in traffic etc.

One way I can think of implementing this is with a simple dynamo attached to the back wheel (not very elegant but ok for my example) with its resistance varied by a microcontroller hooked up to controls on the handle bars, similar to ones for the mechanical gears. This of course could be used for generating power etc. but thats not the point, its just to supply resistance.

The only problem I envision is that after using the endurance bike for a few months if you were to then use a regular bike you’d run the risk of melting its wheels. (I probably need more vision though)

I’ve googled for a while and haven’t found this anywhere though I have a feeling it’s probably been baked. (I’m one of those glass is half empty people)

q2cannonfodder, May 14 2004

(?) Training parachute http://www.power-sy...id=1327&c=22&sc=124
[half, Oct 17 2004]

Electric Bicycle http://www.halfbake.../Electric_20Bicycle
Just add a lightbulb and a dimmer switch. [Worldgineer, Oct 17 2004]

The Solution! http://www.bedientp....com/January02.html
widely known to exist? [stilgar, Oct 17 2004]

[link]






       //you'd run a risk of melting its wheels//   

       Somehow I doubt you could get that much stronger. You'd break chains before you melted wheels. (I've been there. Biking between school, work, and crew practice, I used to do on average about 4 hours of intense lower body workout every day, six days a week. I could easily keep up with in-town traffic. I had a 86- tooth sprocket up front and a 9-tooth in the back, and ended up breaking two chains. After swapping the 86 tooth for a 110 tooth elliptical sprocket and tossing the 9-tooth, I stopped breaking chains.   

       I could top out around 45 mph on flat ground, and faster than I'd care to go on a downhill stretch, and never once did I melt a wheel.
Freefall, May 14 2004
  

       Well done, for cycling to work. More people should do it.
To solve your problem, there are a number of alternatives that could also be used:
The simplest one is to take a detour; go a bit further.
The next simplest is get a training bike which has big fat tyres, and slightly under-inflate them.
Another is to go like hell up the hills, and brake all the way down them.
Wear big flappy clothes: not the skin tight cycling shorts and tops.
Actually, just using a normal dynamo with your lights on all the time has quite a big braking effect.
The list could go on...but I think these should help :) Happy cycling!
Ling, May 14 2004
  

       I’m imagining an elliptical trainer hooked up to a generator, the generator hooked up to a motor, the motor driving four small wheels that propel the trainer up the street. And then...a bench press where the weights drive an generator to charge a battery, where the battery drives...
ldischler, May 14 2004
  

       I've seen some cheap exercise bikes that add resistance by means of felt brake pads on an ordinary brake caliper with a tensioning knob mounted on the handlebars. You could add something like that quite easily.   

       I've seen others that add resistance with a hard rubber wheel that presses against the spinning wheel with variable force.   

       I've run across a kit at some point that allows you to use a regular bicycle as a stationary bicycle. Those probably have some sort of resistance adding device.   

       Use a drag chute.
half, May 14 2004
  

       Just add weights to your bike.
hippo, May 14 2004
  

       //drag chute// Yeah, sounds like a great idea until a large truck drives by at high speeds.   

       //weights to your bike// That won't do much for level areas and will do too much for hills.   

       I like [half]'s felt brake pad idea - it should be easy to set up.   

       You could also use the halfbaked electric bicycle, and channel some energy into a light bulb (link).
Worldgineer, May 14 2004
  

       I was thinking of a more high tech solution where you could set the load and RPM you wanted and then it would automaticaly re-adjust itself to maintain those settings. Though this would be fairly complex I suppose

The felt brake pad would work, though it would wear away quite quickly I'd say. Maybe a light metal disk at the hub of the wheel could be used to generate electricity, for frictionless resistance?
q2cannonfodder, May 17 2004
  

       If you want a technical solution, use an exotic permanent magnet on the rim. The eddy current braking effect is variable with speed i.e. the faster you go, the more braking effect you would have. It wouldn't heat your rims up any more than felt pads would.
The distance of magnet to rim would control the general braking effect.
Ling, May 17 2004
  

       I like the frictionless concept of the pm on the rim. Wouldn't more than one magnet be needed to prevent a herky jerky ride when a heavy braking force is being created?   

       The hard rubber (maybe metal, or exotic heat dissipating composite) wheel with its centerline aligned to the centerline of the bicycle wheel, being pressed toward the center of the bicycle wheel, rotating on an axle parallel to the wheel's axle could deform the tire and generate significant resistance without a tremendous amount of wearing of components. Though, I think it would be quite difficult to measure the added load and therefore difficult to control electronically.
Gromit, May 17 2004
  

       Alternativley, get a job where I work and you are more than welcome to pop round to my house on your way, pick me up and I'll recline in a luxury sofa-on-wheels type contraption while you tow my lazy arse to work behind you. This is ideal because as you get stronger, my inactivity will probably cause me to get heavier to compensate. Its a sacrifice I'm willing to make.
dobtabulous, May 17 2004
  

       [Gromit], the braking effect would be as smooth as small smudged smear in smoothland.
The braking effect will be consistent as long as the rim is consistent in cross section, and the distance from rim to pm is consistent.
For more effect, use more magnets.
Ling, May 17 2004
  

       Had to read your comment twice before I fully understood it [Gromit] (my fault not yours, it is a Monday after all) I think you could have a problem with grit and dirt from the road building up on the smaller wheel. Though I suppose thats true of everything else on the bike as well.

[dobtabulous] If your hiring software developers (lazy no good ones) you've got a deal

[ling] I like the sound of your idea, but it doesn't quite fit I think. It would have to be able to generate a lot of resistance at low speeds for when there's traffic, I'd be in a granny(low) gear pedaling quickly but the wheels would be moving fairly slowly. When I'm traveling quickly the tire would be moving faster but I'd require less added load, because I'd be in a higher gear.
q2cannonfodder, May 17 2004
  

       Thinking about it, to do the frictionless current generating solution I'd have to use the axle of the pedals, which would always spin at a relatively constant rpm. I could replace the inner small cog (which is never used anyway) with a plain metal disk and then use a stong magnet as ling suggests to create an eddy current braking effect in the disk.
q2cannonfodder, May 17 2004
  

       I think that solves one problem, and makes another: the force from a certain magnet and material depends on speed. The torque depends on the distance from the bearing.
The speed of the small chainwheel will be slower than the rim, and the braking torque will be lower since the magnet is very near to the bearing.
unless the magnet is very large, I think you wouldn't really notice much effect.

How about using the dynamo to power a small electromagnet on the rim? Then it could be switched on and off. But again, no drag at low speeds. Oh well...
Ling, May 17 2004
  

       i have your solution. as it exists, it may be enough to bake this, although i can't claim any credit as it is very wide spread. i propose a bike swap. i don't know what you ride, but i have a Huffy Braemar with a buckled rear wheel, a rusty chain and ungreased axles. each of these apply considerable ammounts of resistance. if you don't want my bike, i suggest steadily downgrading your own as your need for extra work increases.
stilgar, Jun 01 2004
  

       but I'd still like the option of traveling wihtout the resistance sometimes*



*(any time I use the bike, I'm actually a lazy git)
q2cannonfodder, Jun 02 2004
  
      
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