best spinning bike with power meter image
dinotheori
I would like to make an electric exercise bike that produces 12 volts and allows me to adjust the resistance simply by increasing/decreasing the electical load. Driving the right alternator via a belt from a back bicycle rim should be the simplest way to make that.
Thank you Tony and Bruce, these answers are very helpful. I'm most interested in being able to use an as-is alternator without internal modification. I would be going with the motorcycle battery idea. I would use this bicycle to get exercise because the traffic is too bad to keep up a good cardio rate. It seems ridiculous to not capture that energy if it is technically possible to do so. I would running an air compressor, water pump, a hydrogen generator or whatever will store the energy... maybe even just a car battery, but if I could vary the power setting on a compressor or a pump and change my resistance that way... yee ha!
Answer
I understand what you are trying to do. However I've never heard of an automotive alternator with permanent magnets. They USED to have generators that had perm mags but that was a very long time ago and they don't make them that way any longer.
Being a Power Generation & Distribution engineer, I know a little about alternators. They work by sending a varying voltage to the coil (rotor) that is spinning within the outer coils (stator). The AC is rectified by diodes and then is sent to the cars electrical system, recharging the battery and powering other electronics.
To make what you are describing I have seen videos of people who remove the rotor (inner coil of wire) and replace them with speaker magnets. That's the only way I believe you are going to create what it is you are looking for. Now, if you don't want the expense and trouble of doing all that work then you can go to most any bicycle shop and buy this same generator you are looking for. I don't know how much they cost but they're out there.
OR you can just hook up a regular alternator to a car battery (or motorcycle battery) and build the circuit the same way as it is in the vehicle and make the same thing. The only drawback with that is you need to do some wiring and have a battery hanging around. But building a generator on your own, you still have wiring to do.
And you haven't even considered how you're going to meter the load. You may accomplish that by several switches that turn on different wattages of light bulbs. Using a little "Diode Logic" you should be able to create a varying load to suit your desires. However, isn't it just easier to get out there and ride? That's what I do.
Hope this helps.
'av'a g'day mate.
")
I understand what you are trying to do. However I've never heard of an automotive alternator with permanent magnets. They USED to have generators that had perm mags but that was a very long time ago and they don't make them that way any longer.
Being a Power Generation & Distribution engineer, I know a little about alternators. They work by sending a varying voltage to the coil (rotor) that is spinning within the outer coils (stator). The AC is rectified by diodes and then is sent to the cars electrical system, recharging the battery and powering other electronics.
To make what you are describing I have seen videos of people who remove the rotor (inner coil of wire) and replace them with speaker magnets. That's the only way I believe you are going to create what it is you are looking for. Now, if you don't want the expense and trouble of doing all that work then you can go to most any bicycle shop and buy this same generator you are looking for. I don't know how much they cost but they're out there.
OR you can just hook up a regular alternator to a car battery (or motorcycle battery) and build the circuit the same way as it is in the vehicle and make the same thing. The only drawback with that is you need to do some wiring and have a battery hanging around. But building a generator on your own, you still have wiring to do.
And you haven't even considered how you're going to meter the load. You may accomplish that by several switches that turn on different wattages of light bulbs. Using a little "Diode Logic" you should be able to create a varying load to suit your desires. However, isn't it just easier to get out there and ride? That's what I do.
Hope this helps.
'av'a g'day mate.
")
Can you recommend a make/model of a good indoor spinning bike?
mrmagoo
Any advice on a good make/model for an indoor spinning bike? thanks
Answer
Hands down the best indoor bike is the CycleOps with a PowerTap for $1900:
http://www.rei.com/product/736225
Without the power meter you can get it for $1100:
http://www.rei.com/product/736222
Another one that's good is the Lemond RevMaster, also $1000 and up:
http://www.lemondfitness.com/products_info.php?id=5
I would recommend a trainer or rollers though, to use with a regular outdoor bike. Much cheaper!
http://coachlevi.com/cycling/pros-cons-stationary-trainers-and-rollers/
Hands down the best indoor bike is the CycleOps with a PowerTap for $1900:
http://www.rei.com/product/736225
Without the power meter you can get it for $1100:
http://www.rei.com/product/736222
Another one that's good is the Lemond RevMaster, also $1000 and up:
http://www.lemondfitness.com/products_info.php?id=5
I would recommend a trainer or rollers though, to use with a regular outdoor bike. Much cheaper!
http://coachlevi.com/cycling/pros-cons-stationary-trainers-and-rollers/
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