Weighing a bike

[Monsterlover]

Using a rear stand, can i put the front on a bathroom scale.. .

then using just a front stand, can I then put the rear on a bathroom scale, add the two numbers together and get an accurate weight?

I have to do one end at a time, since I have only one scale

[lemond]

Just look up your particular model and year's wet weight. the way you are doing it involves too much math because you have to consider the weight displaced at each end...

[He Man]

only if your bathroom scale is made for fatties the size of Peter Griffin+

Also, depending on the angle, there will be different amount of weight on either end. youd have break up the weight using vectors.

If you REALLY wanted to weigh your bike. Just bring it to a scrap metal yard and ask the guy if you can hop on for 2 seconds.

If you pick up a nail its not my fault.

[Jobu]

Just look up your particular model and year's wet weight. the way you are doing it involves too much math because you have to consider the weight displaced at each end...

You ever heard of mods?

only if your bathroom scale is made for fatties the size of Peter Griffin+

Also, depending on the angle, there will be different amount of weight on either end. youd have break up the weight using vectors.

If you REALLY wanted to weigh your bike. Just bring it to a scrap metal yard and ask the guy if you can hop on for 2 seconds.

If you pick up a nail its not my fault.

You'll get no more than 230 LBS on the scale at one time (unless your weighing a Harley).  So any scale will work.

If you lift the front end and rear approximately the same amount when weighing it, your going to get fairly accurate results, with best results seen when the bike is completely level with the scale.

When I weighed mine this way, I used a 2x4, which approximately the same height as the scale, to lift the front while I weighed the back.  Then I used the rearstand to lift the back (about the same amount) while I weighed the front.  I got almost exactly 400 LBS for my bike, which I would think is slightly low, though I have replaced or removed several parts, plus the tank was low on fuel.

[A.duc.H.duc.]

Just get a better scale, they make lots of bathroom scales for fat people.

Then just support your bike under the center so the whole weight is on the scale. It's worked for me.

[dogcatcher]

Make friends with someone at your local post office.  They have a large floor scale in the rear parking lot where they load the vans.

[bigiain]

Just look up your particular model and year's wet weight. the way you are doing it involves too much math because you have to consider the weight displaced at each end...

Not really, if you can keep the bike level while you do it, the math becomes just adding the two numbers you get. It's pretty insensitive to small errors too, so long as you keep the wheels within 1 inch of level, you'll have an error of less than 1 part in 1000 (assuming a ~55 inch wheelbase and a c of g height of 25 inches) - the calculation for the error factor is (1/(C*tan(sin^-1(x/W))))/W - where x is the height difference between the two wheels. W is the wheelbase, and C is the height of the center of gravity.)

Which just means "keep it level on the bathroom scales by proping the other wheel up to about the same height as the scales, and you'll be fine".

So long as your scales go up to 220lbs or so (and I find it hard to believe anyone would sell bathroom scales in America that wouldn't weigh at least that much) your plan will work fine. (personally I wouldn't bother with the stands, I'd just roll it onto the scales at one end and a block of timber about the same thickness at the other, and hold it upright while I read the scale, then swap the scale and timber around and do it again, then add the two weights - you'll easily get within a few oz of the actual weight.

big

[Monsterlover]

I thought this would work, thanks for confirming

[hypurone]

Most landscaping supply yards have drive on scales that are very accurate. I used the local one to weigh my truck, car and bikes!  Also, most high end motorcycle shops that prep for racing have them.

[Norm]

I usually take bikes to a certified scale at the scrap yard for an accurate total weight, but I use the bathroom scale method to determine weight bias with and without a rider. If you use the bathroom scales, play around with the weight bias, it makes a BIG difference in how the bike handles.

[Monsterlover]

^
I had considered bias.

I'm buying ducpainter's blown up 750ss, swapping in a 900 and going to use it for track duty (since it's already setup for that)

One thing I have in mind to explore is cutting the whole back off of it and building an aluminum sub frame.

I really want to take weight off this bike.  Cheap and/or free things will be done first, of course.

Another thing id really like to do is put holes in all the gears under those side covers to cut down on rotating weight.

I should really buy a Bridgeport.

[Rob Hilding]

snip

If you pick up a nail its not my fault.

Now we know how IZ gets all them nails in his tyrz

[DarkStaR]

Why not just use 2 scales.  Their cheap enough.

[Monsterlover]

Not cheaper than me

[beethoven]

Have a weigh in party and invite all your friends with a "bring your own scale and carton" entry fee. What with 10 scales, bikes and cartons the end results could be worth reporting or even  filming.