Advertise on Bikeforums.net



User Tag List

Results 1 to 7 of 7
  1. #1
    Senior Member Grim's Avatar
    Join Date
    Jun 2008
    Location
    Atlanta
    My Bikes
    Cannondale T700s and a few others
    Posts
    2,992
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Do you know how hard it is to peddle 20 amps!?!?!?!?!!?

    Between weather, buring vacation days, commitments requiring me to drive etc I have not been able to do much commuting since Thanksgiving.

    Couple years ago the business behind the one I work for moved. They are a fitness supply place.. They had a parted out StairMaster Momentum exercise bike they tossed. The electronic were gone as was all the covers. All the was left was the drivetrain with the alternator they use for resistance by running it against a massive resistor.

    When I saw it I immediately thought of my kids that cant seem to turn lights or TV's off when they leave a room so I thought I would make them peddle to watch the TV. Never got around to building it.

    Got around to messing with it today. Needed power to to kick it into charging. I think in it stock configuration they were using a variable resistor on the field circuit to control the output voltage and the resistance at the peddles as a result. I need to drive a 12v-110 inverter so I diced to run it straight 12v to the field with a MASSIVE 150ah house battery from my camper that is need of a charge. Well as I peddle faster the voltage comes up making it harder to peddle as it increases the amperage to the battery.

    Holy crap! It is all I can do to peddle this bugger for more then a few minutes at a time trying to get the battery up to charge.

    I need to get a 12.6v regulator on the field to make this easier and prevent blowing out the inverter.
    Attached Images Attached Images
    You cant have a signature unless it fits in this box

  2. #2
    Gear Hub fan
    Join Date
    Nov 2008
    Location
    Reno, NV
    My Bikes
    Civia Hyland Rohloff, Swobo Dixon, Colnago, Univega
    Posts
    2,830
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Hard to get more than 50w to 100w out of human work on a bike for any length of time, particularly w/o a cooling breeze blowing on the rider. One reason why you sweat so much when riding a bike on a resistance trainer or riding an exercise bike. Racers can do better but they have a cooling breeze on them when racing. I suspect for TV watching power you would want the output required from the rider to be under 25 watts.

    For that you will need to choose a low power requirements TV if you actually get the project working.

    IIRC you can get light switches with a sensor that turns off the lights when no one is in a room. You could also wire the TV power outlet to such a switch. Everything turns off after a short time if no one is in the room.
    Gear Hubs Owned: Rohloff disc brake, SRAM iM9 disc brake, SRAM P5 freewheel, Sachs Torpedo 3 speed freewheel, NuVinci CVT, Shimano Alfine SG S-501, Sturmey Archer S5-2 Alloy. Other: 83 Colnago Super Record, Univega Via De Oro

    Visit and join the Yahoo Geared Hub Bikes group for support and links.
    http://groups.yahoo.com/group/Geared_hub_bikes/

  3. #3
    afraid of whales Mr IGH's Avatar
    Join Date
    Apr 2009
    Location
    Front Range, CO
    Posts
    2,609
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    750Watts equals 1HP. At 12V and 10A you're at 125W, but you need to factor in efficiency, say it's ~50% overall, that's 250W input power which is 1/3HP. It takes a pretty fit cyclist to do that for any length of time.

  4. #4
    Senior Member
    Join Date
    Apr 2006
    Location
    Aurora, CO
    My Bikes
    CAAD9-1, Windsor Cliff 29er
    Posts
    1,306
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Grim View Post
    I thought I would make them peddle to watch the TV.
    I try not to be a grammar Nazi but this is actually pretty funny. If you don't know what I'm talking about look up peddle and pedal in a dictionary.

  5. #5
    Senior Member Grim's Avatar
    Join Date
    Jun 2008
    Location
    Atlanta
    My Bikes
    Cannondale T700s and a few others
    Posts
    2,992
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by cooleric1234 View Post
    I try not to be a grammar Nazi but this is actually pretty funny. If you don't know what I'm talking about look up peddle and pedal in a dictionary.
    Ooooh hell! hahaha!

    I think the spell check got me on that. Seriously I have some brain damage from lack of O2 a few years ago. My already poor spelling has been worse since that happened. My train of thought is fine just comes out of the fingers jumbled up. I probably misspelled it peddal and it recommended "Peddle" first and it didn't click I was picking the wrong one.
    You cant have a signature unless it fits in this box

  6. #6
    Seņior Member ItsJustMe's Avatar
    Join Date
    Sep 2005
    Location
    Michigan
    My Bikes
    Windsor Fens, Giant Seek 0 (2014, Alfine 8 + discs)
    Posts
    11,663
    Mentioned
    3 Post(s)
    Tagged
    0 Thread(s)
    At some science museums they have a hand cranked generator. I can get one up to about 500 watts - for about 10 seconds. If I had to maintain it, I probably couldn't do more than 50, and that probably only for a few minutes. Using legs, most of us could probably maintain 150 watts for a fair amount of time.
    Work: the 8 hours that separates bike rides.

  7. #7
    Senior Member Grim's Avatar
    Join Date
    Jun 2008
    Location
    Atlanta
    My Bikes
    Cannondale T700s and a few others
    Posts
    2,992
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by ItsJustMe View Post
    At some science museums they have a hand cranked generator. I can get one up to about 500 watts - for about 10 seconds. If I had to maintain it, I probably couldn't do more than 50, and that probably only for a few minutes. Using legs, most of us could probably maintain 150 watts for a fair amount of time.
    I gave up for the night. My legs are buring after about 5 minutes and I don't want to blow out my knees. That battery is down a lot. Hope it isn't hosed. Thats a $300 battery. Going to top that battery off tomorrow with the charger. Mostly I just need the resistance that battery is giving me for the work out not to actually power anything. If it is too easy once charged I'll throw the inverter on it and plug in a light or two or try the TV or the blower on the fireplace insert till I find a good amount of resistance that I can maintain.

    It is pretty quite thankfully. Have to scream over the Advent trainer my wife has her bike on. This thing makes about a 10th the noise.
    You cant have a signature unless it fits in this box

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •