If it has a front wheel, just mount a 12 volt alternator to the frame and charge a few batteries connected in series. If its an air resistance excercycle use a belt ftom the prop cog to the alternator.
There is a lot to charging batteries or running inverters(dc to 120ac). It also depends on the type of batteries you use.
If you just want to see what you can attain then you certainly can mount a small DC motor with a 2 to 3 inch rubber wheel on it to your bike frame with the small wheel touching the rear tire.
As a point of reference a trained competition cyclist can do a sustained 1/4 hp.
There are 746 watts in one hp so 746/4 = 186.5 watts. Not a lot but it can do real work if utilized properly.
Say 200 watts. If you peddled for an hour (and were a competition cyclist), you would have created 200 watt hours or 0.2 kwh of power. If you pay 10 cents per kwh (I pay 6 cents)... 1 hour of peddling would be equivalent to 2 cents worth of grid power. 2 cents!!
I vaguely reply looking into this prior to Y2K. I posted this question on a similar forum and received several magazine articles (I think from the 70's) regarding how to hook up a stationary bike to run a smalll television. Sorry I can't be more help---I have no idea what happened to those articles.
I remember old articles of how to do this to power small tv. I thought it was a great way to limit tv watching by kids. You want to watch tv you have to earn it by generating your own electricity. Might be a good idea if I did this to power my computer.
The bike would be more efficient if you hooked it directly to whatever mechanical appliance you might need to operate. A grain mill, ringer washer, meat grinder, water pump, etc. I tried hooking up a small 12 volt generator off a tractor and powering it by peddling. Wow. I'd rather bike uphill in the Himalayas. Alternators require even more power, so that's out. But, peddling would beat hand-cranking in a direct mechanical application such as the above-mentioned. What exactly are you wanting to power ?
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