Motorcycle weight

[Testarossa]

I just weighed the T on a digital bathroom scale that I'm pretty sure is accurate within about 1%.

I got a wet weight (full tank) of 530 lb.  This is 30 lb less than the original "spec" weight of 255 kg -- WITH the fairing, steel luggage racks and top box installed. I think the fairing, luggage rack structure and top box may add up to 15 lb which means my naked wet weight is actually about 45 (20 kg) below stock.

I'm trying to figure out what I've removed from the bike over the years to account for the difference. The heaviest item is the battery -- I use cheap garden tractor batteries that last about 5 years and work just fine, thank you. That may save five or six pounds. I replaced the crash bars with head guards, installed a modern steel brake rotor, and Unipod air filters in place of the stock airbox.  No tool kit. Modern tires. Lighter starter motor, simplified wiring and Japanese switches.  Electronic rectifier/regulator and ignition. Shorter handlebar. It's hard to make all this add up to 45 lb, but I suppose it must.

BTW the scale gave me a weight distribution -- roughly 43:57 front:rear, no rider.

[bigbikerrick]

 Seth,what technique did you use to weigh the bike with a bathroom scale?
Thanks, Rick

[Guido Valvole]

How did you get it on the scale? One wheel at a time, I presume, but holding it in place how?
I've always assumed manufacturer weights were optimistic, sometimes wildly.
cr

[canuguzzi]

Unless both wheels are at the same height the weighing method would be inaccurate. Say you put the front tire on the scale but the back tire remains on the ground. The back tire will support more weight than it should for weighing and the front tire will have less weight.

Put something under the end not being weighed and with both tires at the same height you'll get an accurate measurement. Not saying the way it was done will be a big difference but putting both tires at the same height you know it will be accurate.

Or; you can take a ride to the local landfill and they probably have a scale. You can put your bike on the scale as you'd ride it, weigh it and then jump on and get another weight reading. Then you'll know what things really weigh as you ride it.

[Antietam Classic Cycle]

The weight claimed by manufacturer is rarely accurate, so who knows what it really weighed when new.

[Idontwantapickle]

Unless both wheels are at the same height the weighing method would be inaccurate. Say you put the front tire on the scale but the back tire remains on the ground. The back tire will support more weight than it should for weighing and the front tire will have less weight.

Put something under the end not being weighed and with both tires at the same height you'll get an accurate measurement. Not saying the way it was done will be a big difference but putting both tires at the same height you know it will be accurate.

Or; you can take a ride to the local landfill and they probably have a scale. You can put your bike on the scale as you'd ride it, weigh it and then jump on and get another weight reading. Then you'll know what things really weigh as you ride it.

I use a 2x8x12. Roll the bike up on the board, put the scale at the end and roll a wheel on nice and level, move the scale and repeat for other wheel.
It also helps to try a variety of items of known weight on the scale. IE weigh yourself with and without a 40 lb bag of dog food or sackret or a case of water. A pint's a lb the world around!
BTW my Norge with bags and trunk and gas is 602.

Hunter

[Testarossa]

Wheels were at the same height -- 5000 feet MSL exactly.

This is pretty simple -- the scale is only 1 inch thick so I rolled the bike onto the scale and onto a 1x6, then swapped ends. Balance the bike with a hand on the left grip and one on the grab rail, while Gail reads the scale. This is not likely to make the bike weigh lighter -- if anything, hand pressure would add weight.

Even without the 1" lift at the other end, if you calculate the trigonometry the difference is insignificant. The hypotenuse is the wheelbase, 58 inches, so the sine is .017 and the vector isn't measurable with this scale, anyway. I did it both ways, got the same result, and won't bother to use the wood block again.

I've weighed the Triumph the same way, and got 400 lb wet, which is just about right (spec dry weight was 380 lb).

[Triple Jim]

...so the sine is .017 and the vector isn't measurable with this scale, anyway. I did it both ways, got the same result, and won't bother to use the wood block again.

That's good math, but it works only on a straight line.  Since the center of gravity of the bike is considerably above the wheel contact points, tilting the bike skews the CG toward the front or rear and makes a bigger error than you calculated.  Your method of weighing eliminates the problem anyway.  And if you tried it with a 1" front-rear difference and you didn't get a significantly different result, then you proved 1" isn't a problem.

[Chuck in Indiana]

The weight claimed by manufacturer is rarely accurate, so who knows what it really weighed when new.

All big blocks weigh 550 lbs. <shrug> Luigi is too lazy to actually weigh them, you know.. so he just copies and pastes from the previous manual.

[Testarossa]

Don't want to be pedantic (I can't help it) but it's an interesting engineering question. If we assume the center of gravity with a full tank is 36 inches ahead of the rear axle and about 17 inches off the ground, then raising the front wheel 1 inch yields a change of about .4 inch at the center of gravity. The sine grows smaller, not larger -- about .0106 -- and the vector change remains unmeasurable outside a lab.

[Idontwantapickle]

All big blocks weigh 550 lbs. <shrug> Luigi is too lazy to actually weigh them, you know.. so he just copies and pastes from the previous manual.

Literally, no doubt, using a copier and some paste.

[Triple Jim]

Don't want to be pedantic (I can't help it) but it's an interesting engineering question. If we assume the center of gravity with a full tank is 36 inches ahead of the rear axle and about 17 inches off the ground, then raising the front wheel 1 inch yields a change of about .4 inch at the center of gravity. The sine grows smaller, not larger -- about .0106 -- and the vector change remains unmeasurable outside a lab.

It's not just trigonometry at play, you have to draw the statics problem.  Assuming 500 lb bike with 60" between the axles, with the CG moving away from the scale 0.4" because of the tilt, both when you weigh the front and rear, you lose more than 6-1/2 lbs. total.

[Chuck in Indiana]

Literally, no doubt, using a copier and some paste.

Absolutely. :)

[canuguzzi]

I use a 2x8x12. Roll the bike up on the board, put the scale at the end and roll a wheel on nice and level, move the scale and repeat for other wheel.
It also helps to try a variety of items of known weight on the scale. IE weigh yourself with and without a 40 lb bag of dog food or sackret or a case of water. A pint's a lb the world around!
BTW my Norge with bags and trunk and gas is 602.

Hunter

Sackrete is a very bad word around here, very bad. Ask the guy who had to sew the kevlar inside my innards about sackrete.

[not-fishing]

Bath scales, unless they're the beam balance type, are notoriously inaccurate.  say 5% or so

Unless your scales have been calibrated in the same weight range I'd figure they were off by 5% or more.

Just a simple truth.

[LongRanger]

I'm impressed that you were able to get the bike into the bathroom.

[Testarossa]

I'm impressed that you were able to get the bike into the bathroom.

Gail is very tolerant.

[wrbix]

Game scales and tie down straps are pretty cheap - GC.