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  1. #1
    scruffy nerf herder
    Reputation: funknuggets's Avatar
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    Roller Shock....a bike frame material mystery...

    Im not a scientist, nor do I play one on tv, but help me figure something out. I have two bikes, one I typically put on my trainer, and I use one on my older CycleOps rollers. I just started my base and only had one bike in the basement, so I was riding my steel framed Lemond. Nothing special, Conti 3000s, carbon fork. I was riding that bike on my rollers without incident.

    However, I put my LOOK carbon bike (ksyriums, Rubino Pros) and ride on there, you would think I am on some type of electric generator, cause when I get off the bike, I get one HELLUVA static discharge.

    Is this normal, is there anything I can do, and what causes that difference? How come the static conducts differently from one bike to the other. I would think the steel one would have been the one more subject, but thats DEFINITELY not the case...
    Last edited by funknuggets; 12-07-2004 at 07:37 AM.
    so sayeth the funk....

    Chris

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  2. #2
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    stay grounded..

    A simple way to eliminate static discharge is to stay grounded. Unless you've repeated this process on the same day with both bikes, to insure the same humidity level, it's hard to blame the frame material, but that could be the culprit if you remain ungrounded on the carbon bike.

    I ride my LOOK carbon frames on a trainer and never had that problem, but I'm in the basement on concrete, not on carpet.

    Electronics assembly is usually done in rooms with grounded, electrically conductive floor tile to eliminate static discharges that can fry sensitive electronics. Assemblers often wear grounded wrist bands while sitting at assembly benches.
    Last edited by C-40; 12-07-2004 at 07:57 AM.

  3. #3
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    The steel bike conducts the charge to the ground through the trainer. The carbon bike does not conduct so the charge just builds until you ground yourself by putting your foot down. You should probably ground yourself periodically or the jolt from a long training session may kill you

  4. #4
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    I thought you were gonna say you went a lot faster on the carbon bike, and that it also had a better ride quality.

  5. #5
    scruffy nerf herder
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    Interesting you would say that...

    How on earth do rollers get "flat spots"? For some reason, this year, the rollers, which were folded and moved about .... 6 feet for winter, now seem to have a bump in them which is not perceptable when looking at the roller. I thought maybe it was the tire/tube/wheel, but it also occurs on the other bike as well.

    And per your earlier statement... my fit is a little better on the Look, so the ride quality is better, especially since the steel bike has like a 130 stem that is relatively squirrelly on the rollers, but not unbearably so. I also find that a heavier rim/tire combo rides differently too, I think it holds momentum and helps on the rollers, but It could be my imagination

    And for the humidity, we keep it constant with our heating unit. And I WAS wearing different shoes. One with a carbon/composite sole, one with an Aluminum/composite sole. Could that be the difference?
    Last edited by funknuggets; 12-07-2004 at 08:01 AM. Reason: my spelling sucks.
    so sayeth the funk....

    Chris

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    "The RBR Lounge. You won't ever find a more wretched hive of scum and villany. We must be cautious."

  6. #6
    Get me to In&Out
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    Quote Originally Posted by bikist
    The steel bike conducts the charge to the ground through the trainer. The carbon bike does not conduct so the charge just builds until you ground yourself by putting your foot down. You should probably ground yourself periodically or the jolt from a long training session may kill you
    Um...I though carbon was an excellent conductor of electricity
    Cyclists really need to learn a little Rule #5.

  7. #7
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    Question

    Maybe you should train more on your lemond?

  8. #8
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    CF conducts well

    Quote Originally Posted by spookyload
    Um...I though carbon was an excellent conductor of electricity
    Yes, it is an excellent conductor. However, when it is imbedded in an epoxy resin matrix, the structure is a good insulator - the epoxy insulates the CF.

  9. #9
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    This is an extremely weird deal! The only thing I can think of is that the static caused by the spokes' friction in air is transmitted through the hubs into the frame of the LeMond and maybe dissipated back into the air. Ions would begin to leave the steel bike at about 16 to 18 kV, which you could definitely accumulate if you rode long enough in dry air. (There's no current, though, so it doesn't hurt you too bad.) On the Look, maybe the charge builds up in the plastic frame, and in your body, so you get zapped when you get off.

    What about your contact points? Does your Look have a carbon stem/bar/seatpost that would insulate you and let a charge build up? That might be a piece of the puzzle.

  10. #10
    scruffy nerf herder
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    My reply...

    What about your contact points? Does your Look have a carbon stem/bar/seatpost that would insulate you and let a charge build up? That might be a piece of the puzzle.
    My LOOK bike has carbon frame, stem, bar, and seatpost, and kysrium SSC wheels. Does that help or hinder your theory? The Lemond is steel, aluminum seatpost and handlebars, and whatever that stem is made out of with 105 laced to CXP 33s.
    so sayeth the funk....

    Chris

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    "The RBR Lounge. You won't ever find a more wretched hive of scum and villany. We must be cautious."

  11. #11
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    The spinning tires on the rollers are creating a charge which is stored in the bike. The carbon acts as a capacitor. When you get off the bike and ground yourself you discharge the capacitor.

    Mythbusters ;)

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