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So how do you weigh a motorbike?

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by MV, Oct 31, 2013.

  1. Easily, accurately & in your shed, preferably :)

    The bathroom scale method is a nice idea, lower the front on, making sure the rear is level & the wheel is in the middle of the scale, lather rinse & repeat for the other end. Add the two together & you've got the total weight, the added bonus being you can work out weight distribution front to rear.

    But is it accurate? Are there any better methods?
  2. two scales, both capable of 150ish kg (depending on your bike) front wheel on one, back wheel on the other.

    Or, get ot of the shed and onto a weighbridge. How accurate do you need? To the kg? to the gram?

    again, depends on what sort of max weight your bike is likely to have, but there is also..

  3. Stand on the scale and weigh yourself then pick the motorbike up and weigh yourself holding the bike. Subtract your weight and there you have it, the motorbikes weight.

    (Serious answer, I don't know but I'd like to know an easy way)
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  4. if you want a ghetto approach you could get a length of 4x2, probably about 2.5m long, put something underneath the midpoint to act as the fulcrum, put the bike on one end, and start piling something of a known weight on the other. Once the bike starts to left, count the items on known weight and thereyou have it. :)

    1l of water more or less equals 1kg.
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  5. 1. Mark the water level on your swimming pool.
    2. Roll the bike in.
    3. Mark the new water level.
    4. Calculate the volume of water displaced.
    5. Calculate the mass of the water displaced, which will equal the bike's mass.

    You may want to try other options, though.
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  6. Read manufacturers the spec sheet.
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  7. Trackbike, easier to do it in the shed :)

    To the kg would be fine.

    Ha! I would sooner read the Herald Sun, probably more accurate.

    Plus, which one? Front end is Yamaha, rest of the bike is Honda.
  8. No, you're working out the volume, not the mass (weight)...
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  9. Isn't the rule, 1lt = 1kg?
    Seem to remember something along those lines in year 11 physics?
  10. And then, once you have weighed the bike, you can work out the density. Well done Archimedes...

    Seriously, you could find a scale that hangs the bike from a rafter, such as this one

    I have no idea how much for something like this would cost landed in Aus.
  11. How did I know? ;)

    Your bike is still in pieces, presumably. What you could do is weigh each part, document its weight in a table (preferably in a spreadsheet), then add them all up (easy in a spreadsheet, but mind-numbing manually). The trouble is that you're probably still missing a few things, so you'll have to make some guesses until you get the parts you're looking for.
  12. I thought about doing it that way, but I'm lazy, & as you say, still missing a lot of pieces!
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  14. Damn no edit feature...

    Plus, I'd like to weight the TRX without first stripping to parts, but that's an aside really, I can just ride that to a weighbridge.
  15. #15 Geoff3DMN, Oct 31, 2013
    Last edited: Oct 31, 2013
    Yes (subject to nominal pressure and temperature) but the bike displaces water by the volume of the bike and not the weight of the bike.

    When you measure the displaced water you're measuring a bike shaped blob of water which won't weigh the same as a bike shaped errr bike :)

    The above assumes of course that the bike sinks.

    Me? I'd look up the closest public weighbridge on the VicRoads website, ride the bike there and pay the weigh bridge people to weigh it!
  16. Get a set of suitable scales

    Lower kick stand into scales

    While standing on left side of bike grab the bike bike throttle and grab rail and roll the bike over onto the kick stand

    Balance the bike and read the scales
  17. The test you suggested will only work for things that float (density less than the fluid you're floating it into). Eg: boats (they're hollow, so their total density is less than that of water), most types of wood, etc. Bikes don't float, so this test method won't work unless you know the density of the bike's materials.

    1 litre of aluminium will weigh about 2.7kg. 1 litre of steel will weigh about 7.8kg. There are many different materials used in a motorcycle, and many parts are hollow (eg: fuel tank, engine, tyres), so you can't assume a density. The test you suggested only works out the volume. Unless you also know the density (which we don't know), you can't calculate the weight from the volume.

    Besides, who wants to throw their bike into a pool? Washing the pee out of the bike would be a nightmare! :ROFLMAO:
  18. Ok, so we can work out the density of a bike easily ;)

    Can anyone see a problems with the bathroom scale method? There's only 2 points of contact for the vehicle, getting the weight of each & adding them isn't fundamentally flawed, right?
  19. Density is volume divided by mass. You could weigh the bike, measure its volume, calculate the density, then calculate the weight (which will be equal to the measured weight)...

    The bathroom scale method is the best method. You just have to make sure that the bike's level, and your scales will take 150kg at the absolute minimum (you are weighing a Viffer...).
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