How much power are you generating?

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europa
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How much power are you generating?

Postby europa » Thu May 17, 2007 10:51 am

Well go here and find out

http://www.kreuzotter.de/english/espeed.htm

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beauyboy
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Postby beauyboy » Thu May 17, 2007 11:08 am

Very interesting, making a guess from using the thing, I must be able to put out around 200-250 watts of energy. Not bad :P

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Postby rdp_au » Thu May 17, 2007 11:22 am

Interesting time waster here at work....

It confirms my observations from my weekend ride. On the flat and downhill, the recumbent is significently faster. Of the bike configurations offered, only the 'Superman position one hour speed record' bike is faster. Going up hill, however, the difference is only 1-2 kph. From this, I can only conclude that the speed with which bikes were passing me going uphill was purely due their hugely greater power output! Now that's a sobering thought.

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tuco
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Postby tuco » Thu May 17, 2007 11:22 am

Cruising around at 32km/h, about 260W, sprint finishes in races at about 49km/h, 830W.

Interesting to see the difference between hands on top and hands on the drops. It's about 250W less at 49km/h on the drops.

What's the superman position?

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ShanDog
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Postby ShanDog » Thu May 17, 2007 11:26 am

very nice waste of time.

It looks like I'm doing about 180-200 watts on the flats... Not too bad I think

twowheels
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Postby twowheels » Thu May 17, 2007 11:27 am

Just thinking out loud here. Wouldn't it be possible to devise a bicycle trainer that generated power back into the grid in the same way photovoltaic cell power can be?

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Bnej
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Postby Bnej » Thu May 17, 2007 12:46 pm

twowheels wrote:Just thinking out loud here. Wouldn't it be possible to devise a bicycle trainer that generated power back into the grid in the same way photovoltaic cell power can be?


Yes. But you wouldn't get all that much power. I mean, if you rode the bike for an hour pretty hard, you might get enough to run a light bulb for an hour, or two CFs.

I often wonder when I go to the gym, you have self-powered exercise bikes and then you have treadmills plugged into the wall. Now, how come they don't just plug the bikes into the treadmills so you can have the rider take on the runner!

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Postby sogood » Thu May 17, 2007 1:07 pm

Bnej wrote:Now, how come they don't just plug the bikes into the treadmills so you can have the rider take on the runner!

That would be called computer gaming! 8)
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Postby twowheels » Thu May 17, 2007 1:46 pm

or why the treadmills aren't just a big belt between two rollers (with intermediate rollers), why are they powered at all? treadmills could be fitted with the same power inverter as bike rollers ... think, think, think ...

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Postby chain_reaction » Thu May 17, 2007 2:00 pm

Slightly of the topic...

A friend of mine decided to throw a yoga ball at the back of another mate who was running on the treadmill. The ball bounced of his back, of a wall then hit the back of the tread mill sucking it under lifting up the treadmill. Needless to say the guy on the treadmill had some tread marks on his arse. :D

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Postby MJF » Thu May 17, 2007 2:57 pm

twowheels wrote:Just thinking out loud here. Wouldn't it be possible to devise a bicycle trainer that generated power back into the grid in the same way photovoltaic cell power can be?


Yes... but as you go through each transformation, you lose power. Electric alternators are around 90% efficient, then you have an inverter at around 90-95% efficiency. So call it a 20% power loss. Assume you can pedal for 12 hours (AT) 100W, that's only ~ 1Kw/h (worth about 10c-12c). The 'average' Australian house supposedly uses ~ 21Kw/h a day.

(Edit : Fixed a Typo)
Last edited by MJF on Thu May 17, 2007 3:16 pm, edited 1 time in total.

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Bnej
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Postby Bnej » Thu May 17, 2007 3:04 pm

twowheels wrote:or why the treadmills aren't just a big belt between two rollers (with intermediate rollers), why are they powered at all? treadmills could be fitted with the same power inverter as bike rollers ... think, think, think ...


Nah, because you don't physically push your foot backwards when you walk/run, rather you shift your balance forward and put your other foot in front to stop the fall.

The treadmill moves the ground to simulate this movement - of course, it's not as effective because the treadmill is doing some of the work.

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Postby mikesbytes » Thu May 17, 2007 9:20 pm

Interesting. To maintain 17.9kph on a 10% hill, I have to produce 500w. So if I know the slope of the hill and record the time to get up, with a bit of playing, I can calculate the wattage.

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MichaelB
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Postby MichaelB » Fri May 18, 2007 9:10 am

Here is a link to another power formula from the Cycle2max website

Cycle2max Power Formula

Gives you the data on why and how

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Postby Mulger bill » Fri May 18, 2007 10:37 am

Not enough it seems :oops:

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Postby twowheels » Fri May 18, 2007 11:56 am

... so a bike would do quite well to generate power for low voltage downlights perhaps ...

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tuco
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Postby tuco » Fri May 18, 2007 12:13 pm

twowheels wrote:... so a bike would do quite well to generate power for low voltage downlights perhaps ...


Doubt it. If you're old enough, think back to the good old days of bike lights powered by dynamos. How good was that head light?

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Postby mikesbytes » Fri May 18, 2007 1:50 pm

twowheels wrote:... so a bike would do quite well to generate power for low voltage downlights perhaps ...


In the US you can get a TV that only works when you are cycling on a power generating stationary bike.

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Postby twowheels » Fri May 18, 2007 7:28 pm

yeah, you would generate a lot more power if you were just feeding the resistance of the dynamos/generators, rather than also trying to propel a mode of transport, you could also ease up on the gears or adjust the gears for optimum spin.

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