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Old 02-17-2015, 09:50 AM   #1
CafeRacer99 OP
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Picking up your dropped bike - how much weight?

Question for the nerds: What is the percentage of weight one is lifting when picking up a dropped bike?

If the loaded bike weighs 500 lbs, and the tires are in contact with the ground the whole time, how much weight are you actually lifting?

Thanks!
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Old 02-17-2015, 10:05 AM   #2
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Quote:
Originally Posted by CafeRacer99 View Post
Question for the nerds: What is the percentage of weight one is lifting when picking up a dropped bike?

If the loaded bike weighs 500 lbs, and the tires are in contact with the ground the whole time, how much weight are you actually lifting?

Thanks!
That is entirely dependent on the motorcycle. My 900 lb. Goldwing was easier to pick up than my 560 lb. FJ 1200.
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Old 02-17-2015, 10:09 AM   #3
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I can pick up my Super Tenere with out issue probably around 600lbs without gear.
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Old 02-17-2015, 10:31 AM   #4
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There are too many variations to the below questions to answer generically.

1. Where is the vertical CG of the bike?
2. What is the angle of the bike when laid over (big difference between dirt bike and GSA)?
3. Where are your handholds in relation to the CG?

If you can answer me these questions 3, then simple trigonometry will give you the number you requested.
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Old 02-17-2015, 10:55 AM   #5
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Every bike is different. My 690 enduro falls over and I bend over and pick it up. My Road Glide Ultra falls over and I do the walk-backwards gig.

The KTM will land on the Handle bars and be at a flatter angle to the ground.
The RG will land on the crash bars and be at about a 30 degree angle to the ground. So these are two different examples.

The weight you are lifting depends on the distribution of weight on the bike. (Is it top heavy or evenly distributed)

For simplicity you could assume that the weight is distributed evenly across the height of the bike.

If the bike is laying flat than you would be theoretically lifting half of the weight. So my KTM would be about 160. But it is top heavy so realistically about 190. (just a guess)

If the bike is on a crashbar than the weight would be (weight x cosign of the angle x 1/2). So a guess at my Harley is 920 (yeah, right) x .707 (cosign of 30 degrees) * 1/2. About 325 lbs. Again, the fat biatch is top heavy so probably closer to 400.

Add in gear, a downhill angle, if the bike slides away from you while lifting......
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Old 02-17-2015, 10:57 AM   #6
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As mentioned - lot's of variables. Including where the weight is located on the bike.

Whatever the force required it's a small portion of the bikes weight usually. I'm not a big guy and the only bike that ever made me almost throw in the towel and cry uncle when trying to lift it up was my old C10 Concours. It slipped on some wet grass as I was sidehilling along at my parents farm and ended up lying with it's tires facing slightly uphill and a full 7 gallons in the tank.

She had me on the ropes there for a bit as I tried to lift that whale back upright. I tried to spin it around so the wheels would be facing downhill... Yeah a C10 doesn't really have a pivot point like a boxer does, so I ended up just having to lift it through horizontal, and boy did that suck. If I should ever find myself in that position again I'm just going to break out the matches and marshmellows. LOL.
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Old 02-17-2015, 11:18 AM   #7
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Quote:
Originally Posted by CafeRacer99 View Post
Question for the nerds: What is the percentage of weight one is lifting when picking up a dropped bike?

If the loaded bike weighs 500 lbs, and the tires are in contact with the ground the whole time, how much weight are you actually lifting?

Thanks!

Based on the leverage factor you'd have to know where the center of mass is to start, what angle you are starting at, then as you lift the center will move inward toward the fulcrum (tires) until it is upright, requiring zero lift. Pure physics, math and all that stuff.

In other words, there is no one answer. Too many different bikes. That's why a 300 lb 500 feels heavier than a 300 lb 250, the 500 has more of the weight up high.
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Old 02-17-2015, 12:27 PM   #8
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Originally Posted by markk53 View Post
Based on the leverage factor you'd have to know where the center of mass is to start, what angle you are starting at, then as you lift the center will move inward toward the fulcrum (tires) until it is upright, requiring zero lift. Pure physics, math and all that stuff.
How your front wheel is positioned matters also. Turn the front wheel towards the ground and you move the fulcrum up towards the center of mass, making the lift easier.
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Old 02-17-2015, 12:33 PM   #9
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Quote:
Originally Posted by mtnbikeboy View Post
There are too many variations to the below questions to answer generically.

1. Where is the vertical CG of the bike?
2. What is the angle of the bike when laid over (big difference between dirt bike and GSA)?
3. Where are your handholds in relation to the CG?

If you can answer me these questions 3, then simple trigonometry will give you the number you requested.
Ok, I'll bite. Assume 600 lb bike. Seat is 33 inches off ground. Assume CG of 20 inches. Handlebars 38 inches above ground.

Say it's 80 degrees from vertical.

The weight will lessen as bike goes vertical. What is weight at 80 degrees?
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Old 02-17-2015, 12:42 PM   #10
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10 from horizontal is basically flat as far as the trig is concerned.
x distance for mass =19.696"
x distance for seat = 32.499"

Sum moments about tire contact patch: a deadlift of 363.4# is required. This goes down to 315.8# if you use the handlebar height.
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Old 02-17-2015, 12:46 PM   #11
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https://www.youtube.com/watch?v=-8Er4FFEQ8I

My Super Tenere is just under 600lbs. wet with no other accessories meaning it's stupid heavy. It being tall doesn't make lifting it up any easier. Using the technique in the above video, picking it up is easy peasy.

Try lifting it with your chest facing the bike? Good luck.
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Old 02-17-2015, 12:51 PM   #12
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Originally Posted by scfrank View Post
Ok, I'll bite. Assume 600 lb bike. Seat is 33 inches off ground. Assume CG of 20 inches. Handlebars 38 inches above ground.

Say it's 80 degrees from vertical.

The weight will lessen as bike goes vertical. What is weight at 80 degrees?

cosine of 10 degrees is .98 If your cg is 20" up on a 38" bike ( if no fairing or insignificant weight above seat than use 30 inches) so call that .52 (20/38)

600 lbs x .98 x .52 = 309.5

If you use seat height than that would be 20/30 or .667

600 lbs x .98 x ..667 = 392

So it is likely somewhere in between.
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Old 02-17-2015, 04:57 PM   #13
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I figured there would be people here who could do the math! Thanks!

My bike is a Super Tenere too. I've pick the bastard up a few times.



I want a number to use for goal setting in weight training. So if the weight is approximately 400 lbs, I'll use that number as a goal for multiples in the deadlift, for example.

Enjoying the discussion! Thanks!
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Old 02-17-2015, 05:20 PM   #14
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Not enough info...

What time of day is it?
How long in the saddle?
How many previous "pick ups" have occurred?

Bikes gain weight over the course of a day, ya know!


Kidding aside, unless you go to a lot of trouble the educated guesses above give you a workable answer. To truly know would take an overhead scale and a mechanical pick of the toppled bike; more trouble than needed for this exercise.
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Old 02-17-2015, 06:13 PM   #15
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If the bike is on fire can be a huge factor also...
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