What do they really weigh?

Discussion in 'Thumpers' started by montesa_vr, Mar 1, 2008.

  1. LukasM

    LukasM Long timer

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    Patrick,

    Why do you think that is? If you placed the non-measured wheel at equal height and just supported the bike from falling over to the side, this should work very accurately. Provided that your bathroom scale is accurate, of course. They operate in pretty much the exact range we need for one wheel.
    #81
  2. earthroamer

    earthroamer Stuck in Pindadesh

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    Eggzakly. Sometimes I wonder if you guys ever took high school physics. The wheels push down the same whether they on the garage floor or a set of scales. The wheels don't know what they are on. As long as the tires are the same elevation and the bathroom scales are accurate in the 2-300 lb range it's simple physics.
    #82
  3. 5050

    5050 Adventurer

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    Operative words - wheels at same elevation. When tipped the cg moves in the direction of the lower wheel thus biasing weight to the lower wheel and decreasing the weight born by the higher wheel. Which end of a washing machine feels heavier going downstairs - the upper or lower? Easier to wheelie going uphill or down?
    #83
  4. 30Bones

    30Bones Long timer

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    As a former KLR owner and now a 640e owner, That right there is such a HUGE difference it's unreal. Even if the weights are +/-20#. Not to mention the motor output is far greater.
    #84
  5. montesa_vr

    montesa_vr Legend in his own mind

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    In theory, I believe it is possible to get an accurate weight one wheel at a time. In practice, the numbers are so variable that they are useless. Besides the problem that 5050 points out of the scale changing height with weight on it, there's the quality of the scales. I have never seen a bathroom scale, digital or analog, that I can't get to show varying weights depending on how I stand. Furthermore, my weight varies as much as 15 pounds from one bathroom scale to another.

    I've said it before, and I'll repeat it here. I only use weights from a few magazines because I know they weigh the bikes the same way on the same scale with a full tank of gas. Maybe the weights I have listed aren't absolutely correct, or accurate, but they are consistent. And since they are consisent, they are absolutely usefull for comparison. So I don't care if your DR650 only weighs 347 pounds on your certified meat scale. For all I know, your scale is more accurate than the one at Cycle World. But I can't weigh all these bikes on your certified meat scale. And what I'm really interested in is relative weight -- how much heavier a DR650 is than a WR250R, for example. And I like to be able to look at the list and have some confidence that the difference is 66 pounds.
    #85
  6. Django Loco

    Django Loco Banned

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    This is it exactly. If the bike is not level then this method may not be accurate.
    Also, how do you determine front to rear bias? How much do you count from each wheel? Just simply add the two weights together? Or work a percentage based on manufacturers listed front to rear bias?

    Doesn't sound right to me but I never took Physics!

    Sorry, I'm old school, prefer a real scale. I did measure the weight of a motor once. I got on the bathroom scale, noted the amount then held the motor close to me and held still. Just the slightest movement of the motor changed the scale ready by 15 to 20 lbs. on a 100 lb. motor.
    #86
  7. bmwktmbill

    bmwktmbill Traveler

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    #87
  8. mikegreen

    mikegreen n00b

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    What is this "pounds" you guys talk about. Where's the kilo's
    #88
  9. montesa_vr

    montesa_vr Legend in his own mind

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    In the U.S., the school system has been teaching the metric system since the 1970's, but the polticians are afraid to make it our standard of measurement, so we still rely on feet, pounds, pecks, pints, rods, and other antiquated measures. If Obama really wants to be the science president he could push for us to advance in this area, but I haven't heard a proposal.
    #89
  10. dgrs2

    dgrs2 Where'd I leave my knee??

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    I weighed my 2004 KTM 950 Adventure on a friends race car scale. Full wet, crash bars, heppco, becker hard cases, KTM top case. 525 lbs. With myself on it with bags full of camping gear, 8 man tent, back pack filled, extra doodads for fixin, 855 lbs. Have to weigh my 03 KTM 625 SXC. I'll let you know.
    #90
  11. Dolly Sod

    Dolly Sod I want to do right, but not right now

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    There is no front to rear bias. You add the two weights up and you get the weight of the bike.

    FWIW, I've weighed my 1989 Transalp, ABS DL650, and R90/6.

    I got 450lb on the TA, which is damn close to the listed 448 in this thread.

    I got 510 lbs for my DL650, but I've got the ABS version, and have a skid plate, crashbar and luggage rack on my bike. Plus I've got at least 3-5 lb of tools under the seat.

    It's not a problem leveling the bike. A 2x4 on it's side in almost exactly the same height as my bathroom scale. And yes moving around on the scale will cause the weight to bounce, but if you hold still, it's right.
    #91
  12. Django Loco

    Django Loco Banned

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    Thanks for the heads up. No doubt my technique was probably a bit off.
    I'll try this next time I can sneak the scale out to the garage! I imagine with a few attempts of placement and leveling I can probably get this to work,
    I'll give it a try.
    #92
  13. Dolly Sod

    Dolly Sod I want to do right, but not right now

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    Just remember to clean the tire tracks off before putting it back in the bathroom. :lol3
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  14. earthroamer

    earthroamer Stuck in Pindadesh

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    As in any measurements, the devil is in the details. Just because you can't perform the experiment, doesn't mean that it can't be done.

    My bathroom scales (Healthometer Digital Lithium Scale HDL114) give me the same reading (pounds or kilos) to a tenth of pound, no matter how many times I stand on it or how I stand on it (within reason). Whenever I go to my doctor for a physical (twice a year), I weigh myself on my scales before I leave and she weighs me on her's, which she claims are calibrated. The weights never vary by more than a pound. I weigh about 200lbs :puke1, so I know that my scales accuracy is in the neighborhood of about 1%, which happens to be the claimed accuracy for these scales. The scales are exactly 1.5" high, which just happens to be the thickness of a 2x4. So I run the bike up on the scales on one wheel and a 2x4 on the other and measure each wheel. The sum of the two readings will equal the weight of the bike to within 1%.
    #94
  15. earthroamer

    earthroamer Stuck in Pindadesh

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    BTW, three cheers for montesa_vr for tabulating and posting his research on motorcycle weights. I am making copies of this, probably the best information I've seen in one place.
    #95
  16. montesa_vr

    montesa_vr Legend in his own mind

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    Sounds like you have a working process -- your numbers are right in the ball park. Thanks for the tip.
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  17. montesa_vr

    montesa_vr Legend in his own mind

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    Thanks for the scale recommendation. Maybe if I had a scale like that I'd go back to weighing myself. Then again, maybe not. It's been about three decades since I saw the sunny side of 200 pounds.
    #97
  18. rideLD

    rideLD The further the better!

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    Great job compiling the list! :clap

    Did not see this one in the list
    2009 BMW G450x 274lbs, Full Tank, Dirt Rider April 2009
    #98
  19. bikemoto

    bikemoto Tyre critic

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    Ummm, why is a 2" x 4" piece of wood only 1.5" thick???
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  20. earthroamer

    earthroamer Stuck in Pindadesh

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    Nominal size of a 2 x 4 is 1.5" x 3.5". Something to do with rough cut and finished.