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Discussion Starter · #1 ·
What do you get when you combime:

A frugal (but perhaps resourceful) grad student, some basic VB.NET programming, some electronic tidbits, a magnetic trainer and the loan of a powertap for a weekend or two?



From left to right:
warmup, stretch, 12 second all out effort, back to easy spin, another 12 second all out effort, back to easy spin, stretch, 1 minute effort, break (phone), 6 minute effort (ie. CP0.2, CP 1 and CP6)

In short, I turned an ordinary trainer into one which I can use to log workouts in any which way I wish and also use for power-based training.
 

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Discussion Starter · #3 ·
I borrowed a powertap to get speed vs. power curves for the different settings on my trainer. Now that I have those, I use a computer to monitor my wheelspeed on the trainer at a given setting and calculate the power from the wheel speed and log it to a file
 

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Yanner said:
I borrowed a powertap to get speed vs. power curves for the different settings on my trainer. Now that I have those, I use a computer to monitor my wheelspeed on the trainer at a given setting and calculate the power from the wheel speed and log it to a file
Ah very clever....

Now I guess the only problem is what happens when someone messes with your tire pressure, or the thing that adjusts how tight your tire is against the flywheel.

Maybe you can figure out a way to calibrate it without the powertap now, although I'm not sure how....but then again I am probably not as clever as you.
 

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If you can borrow that powertap again

~ScaryFast~ said:
Ah very clever....

Now I guess the only problem is what happens when someone messes with your tire pressure, or the thing that adjusts how tight your tire is against the flywheel.

Maybe you can figure out a way to calibrate it without the powertap now, although I'm not sure how....but then again I am probably not as clever as you.
you might be able to work out a calibration routine to take care of the above comments.

Both Computrainer and TACX us a 'spin down' calibration, where deceleration of wheel speed from a specific velocity after pedaling is stopped is used to determine the resistance of the bike/trainer system.

Since F=ma no matter what bike or trainer you are using, it would be interesting to think about if a calibration procedure could be universal for any bike and trainer within a range of tire pressure and contact pressure. If so, you could possibly market a system such as yours as a way to get reasonably accurate power readings from a trainer for far less that the cost of a tap or computrainer.
 

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I think it would be cooler if you could take the resistance unit off of the trainer and attach an electric motor that would serve as a generator. The output of the generator would give you wattage information. On top of that...it might save you on your power bill!
 

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Johnny K said:
I did the same thing here...borrowed a powertap and made a chart comparing wheel speed to wattage. It works great and I don't have to shell out a grand for a powertap.
Too bad you can't ride your trainer on the road though ;).
 

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generate electricity

msrothwe said:
I think it would be cooler if you could take the resistance unit off of the trainer and attach an electric motor that would serve as a generator. The output of the generator would give you wattage information. On top of that...it might save you on your power bill!
Kurt Kinetic already developed a trainer (the "Kinetic Energy" Trainer) that generates and then stores electricity. Here's a link:
http://www.kurtkinetic.com/news.php?type=headlines&news_id=72
I learned about it at Interbike, but I'm not sure if they're selling it yet.
 
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