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  1. #1
    Senior Member Kadowaki's Avatar
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    Heavy bike for downhill?

    I know there is a minimum weight limit for bikes. On this clip Ullrich changes bikes at the peak of the last climb. Is there any rule against riding a heavy bike downhill? What are the restrictions to allowing pros to switch bikes during a race?

    http://www.youtube.com/watch?v=lfLQVNavI8Q&NR

  2. #2
    Dances With Cars TRaffic Jammer's Avatar
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    It was switched because the bike he used going up was so light it would have had very little in the way of handling characteristics on the way down. There is a general minimum weight, though I don't know what it is, something ridiculous.

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    Dirt-riding heretic DrPete's Avatar
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    Quote Originally Posted by Kadowaki
    I know there is a minimum weight limit for bikes. On this clip Ullrich changes bikes at the peak of the last climb. Is there any rule against riding a heavy bike downhill? What are the restrictions to allowing pros to switch bikes during a race?

    http://www.youtube.com/watch?v=lfLQVNavI8Q&NR
    I'm guessing that the miniscule advantage of adding a couple pounds to the bike would be offset by stopping to switch bikes.

    The UCI weight minimum is 6.8kg, or 15lbs.
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    Dances With Cars TRaffic Jammer's Avatar
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    Come to think of it.. some of their climbing bikes have different geometries as well.

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    Senior Member Keith99's Avatar
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    The rules on this change over time based on abuse. At one point it wsa illegal to change bikes during the race except for bike failure. One rider used a light bike to climb and some creative use of wire cutters to get his failure. There are rules about getting food and water during climbs in part to prevent weighting the bike for the decent. Not sure if there are bike max weights. If riders start using specialty bikes for decending, as in weight, not handling characteristics, you can bet they will be prohibited.

    Side note: The U.S. won the bobsled in one of the early winter olympics. They did it by having 4 huge guys so the sled and riders were a couple of hundred pounds heavier than other sleds. Afterwards the rules were changed to have a maximum weight of sled and riders.

  6. #6
    Edificating dmotoguy's Avatar
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    the difference shouldnt be that much at all.. the extra weight will only help directly after the hill, carrying the momentum on the flats, and the additional few pounds will do next to nothing.
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    Senior Member Kris Flatlander's Avatar
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    It'd almost be smarter to just hand Ulrich a water bottle filled with lead pellets or something for his free cage and then swap it at the bottom. This is assuming that the "food rule" didn't occure at that time. Wonder how much a lead water bottle would weigh anyways, 5 lbs?

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    Senior Member
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    ahh old tricky dick.

    how do you know he didnt just have a shifter misalignment or a brake thing and maybe that's why he switched.

  9. #9
    Senior Member Duke of Kent's Avatar
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    I'm willing to bet this is the reason: he was using his deep-dish LW's or ADA's on the climb, and wanted to switch to low-pro wheels for the descent. Much easier to handle in the wind coming up from the valleys. It would be far quicker to switch bikes than wheels in this situation.

    About climbing vs. regular racing bikes: they wouldn't ride bikes that are significantly different. They might have their stem another cm higher and maybe a cm shorter for climbing days, for a SLIGHTLY more upright position, but the rest of it doesn't change much at all. Their position is already dialed in to achieve the most efficient and powerful use of energy.
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  10. #10
    Aut Vincere Aut Mori Snuffleupagus's Avatar
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    Quote Originally Posted by Kris Flatlander
    It'd almost be smarter to just hand Ulrich a water bottle filled with lead pellets or something for his free cage and then swap it at the bottom. This is assuming that the "food rule" didn't occure at that time. Wonder how much a lead water bottle would weigh anyways, 5 lbs?
    Oh oh oh I know the answer

    Pb (lead) has a density of 11.35g/cc. A 24oz water bottle has about 710cc.

    Therefore a 24oz water bottle filled with lead would weigh ~8060g. Or about 17.75lbs. A coupla those bad boys, and you'd be haulin' butt.

  11. #11
    Senior Member?
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    just for the sake of argument, I'd like to note that a heavier bike/rider combo will skid out sooner in curves, and would thus have to brake sooner. Since pros frequently push their tires to the limit of traction, this may be a consideration of the descent is twisty.

  12. #12
    Senior Member Everest's Avatar
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    Quote Originally Posted by Kris Flatlander
    It'd almost be smarter to just hand Ulrich a water bottle filled with lead pellets or something for his free cage and then swap it at the bottom. This is assuming that the "food rule" didn't occure at that time. Wonder how much a lead water bottle would weigh anyways, 5 lbs?
    Actually this happened in the 50's, Robic had water bottles filled with molten lead.
    Last edited by Everest; 01-04-07 at 06:23 PM.
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  13. #13
    Senior Member Keith99's Avatar
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    Quote Originally Posted by Snuffleupagus
    Oh oh oh I know the answer

    Pb (lead) has a density of 11.35g/cc. A 24oz water bottle has about 710cc.

    Therefore a 24oz water bottle filled with lead would weigh ~8060g. Or about 17.75lbs. A coupla those bad boys, and you'd be haulin' butt.
    Answer surprised me a bit, but it is right. You did it the hard way though. Since a 24 OZ water bottle is 1 1/2 lbs of water and the density of water is 1 g/cc you just needed to multiply 1.5 x 11.35 to get the answer.

  14. #14
    Ink-Stained Wretch pinky's Avatar
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    I'd venture he switched to low-profile rims with alloy brake surfaces. Those deep dishes are probably ADAs which weren't holy renowned for perfect braking surfaces especially back when carbon brake pads weren't really much better than cork. Maybe even a clincher so he has less chance of melting the glue off the rim.

  15. #15
    Senior Member Kris Flatlander's Avatar
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    Quote Originally Posted by Snuffleupagus
    Oh oh oh I know the answer

    Pb (lead) has a density of 11.35g/cc. A 24oz water bottle has about 710cc.

    Therefore a 24oz water bottle filled with lead would weigh ~8060g. Or about 17.75lbs. A coupla those bad boys, and you'd be haulin' butt.
    Quote Originally Posted by Everest
    Actually this happened in the 50's, Robic had water bottles filled with molten lead.
    That's really interesting actually, an absolute ton of weight if you fill up both cages. Wouldn't want to forget those in before the next climb ! Thanks for the calculations Snuffleupagus, looks like it's a tad more than 5 lbs.

  16. #16
    raodmaster shaman
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    Quote Originally Posted by pinky
    I'd venture he switched to low-profile rims with alloy brake surfaces. Those deep dishes are probably ADAs which weren't holy renowned for perfect braking surfaces especially back when carbon brake pads weren't really much better than cork. Maybe even a clincher so he has less chance of melting the glue off the rim.

    that would be my guess. the wheel he went up on might have been too sketchy to descend on. were the uphill only lightweights around then?

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