I am considering adding a motorcycle carrier to the front or back of my Barth. The question is, front or back?
I prefer front for several reasons:
back would block engine access
side radiator stirs dustorms on dirt roads, making bike really dirty
Adding much length to an already long overhang to drag on rear.
I have gone through the calculations. Tires and GAWR's and GVWR are all ok with either configuration.
So considering the weight distribution change:
Current is 31%/69%
front loaded bike is 33%/67%
rear loaded bike is 28.5%/71.5%
Soliciting comments regarding weight distribution change. My thoughts are that the front loaded scenario results in a better weight ratio.
Don't forget the leverage factor of rear mounting.
A rear mounted bike weighing 400 lbs. 10 feet behind the center of the rear wheels puts 4000 foot lbs of additional weight on the rear wheels + 10x the weight of the mount. That 2+ tons should surely be considered.
The above is assuming a motorcycle, hope this is not the case.
Front mount may not be as elegant but, should load the front tires less due to shorter lever length though 1/2 as many tires.
GMC_jon wrote: Don't forget the leverage factor of rear mounting.
A rear mounted bike weighing 400 lbs. 10 feet behind the center of the rear wheels puts 4000 foot lbs of additional weight on the rear wheels + 10x the weight of the mount. That 2+ tons should surely be considered.
The above is assuming a motorcycle, hope this is not the case.
Front mount may not be as elegant but, should load the front tires less due to shorter lever length though 1/2 as many tires.
John
Using your kind of math would mean that standing on the rear ladder would put a ton of weight on the rear axle.....Leverage is good, but not that good
If at first you don't succeed, skydiving is not for you!!!
GMC_jon wrote: Don't forget the leverage factor of rear mounting.
A rear mounted bike weighing 400 lbs. 10 feet behind the center of the rear wheels puts 4000 foot lbs of additional weight on the rear wheels + 10x the weight of the mount. That 2+ tons should surely be considered.
The above is assuming a motorcycle, hope this is not the case.
Front mount may not be as elegant but, should load the front tires less due to shorter lever length though 1/2 as many tires.
John
That's not correct. The formula is not that simple. A lift/bike combination weighing approx 1000 lbs will add about 1800 lbs to the rear of a DP.
Using your kind of math would mean that standing on the rear ladder would put a ton of weight on the rear axle.....Leverage is good, but not that good
I've thought about carrying a scooter (500lbs) on the front instead of the back for the same reasons. I'm only 8200lbs on the 12,000lb front axle. Question, who sells a front mount or are we limited to custom fab work?
Don't want to fly with you guys that refuse to believe the lever math. I've calculated enough weight and balance sheets in 10k+ hrs of flying to know this works. It's not always the amount of weight that causes a problem but, where it's located.
I didn't say that weight was increased 2+ tons. Leverage transfers that amount of downward pressure on the fulcrum point. In this case, the rear tires.
Have you ever used a torque wrench? The same effect can be accomplished by taking a breaker bar or ratchet then extending the handle to 24" from the axis of a given given mounted socket and then applying 10 lbs of weight to the end of the handle. The result will be 20 ft lbs applied to a driven nut. Increase that weight to 100 lbs and try it on a 3/8" bolt and bolt sheer will result.
I'm sure you know a 3/8" bolt can support 100 lbs.
Under gross weights, if improperly located, can produce an unstable platform be it an aircraft or wheeled vehicle. Instability is multiplied if the platform is at or above gross weight.
Next time you weigh your rig check the rear axle only and then try standing on the ladder. You may be surprised.
Remove weight, the rear bumper 75 lbs, rear hitch this includes everything to do with it 75 lbs, spare tire 110 lbs (19.5) my custom made carrier weighs 50 lbs, and the scooter weighs 270 lbs. I don't load anything more than 20 lbs in the rear compartments. I checked the rear weight, and I am 1000 lbs under the max called out on the weight sticker. I know, I could carry more weight, my theory, tires last longer, brake's last longer and gas millage is better. I carry 5 gallons of water, that knocks off 500 lbs right there!
Like I said in the initial post. I did the math already. That includes the leverage effect on the mounted end as well as the lift effect on the opposite end.
Now, does anyone have useful comments about front/rear loading ratios? That is the only missing info I was asking about. Thanks
Two Jayhawks: I am looking at the ones made by www.gc-carriers.com. In order to front mount, they will add two hitch inserts to mate ones I would add to the front for only a $50 or so additional - i.e. customize of existing design.
If you want to maintain the same handling and riding characteristics of the MH as you now have, then all you need to do is maintain the same front to rear ratios by relocating cargo, fluids, etc. You already know what additional weight will do to fuel mileage and performance.
Aerodynamics have not and are not being considered as within the scope of this discussion.
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