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Discussion Starter #1
So I just installed my Cycleracks rear rack. Thanks Don & Marc. Now I would like to put a SOLID gear box on it. My idea is that I want to mount my rotopax to the back of the box and the lid still open freely. I don't have the rear hoop on my rack so I have 14" to work with front to back, including the 3 1/2" rotopax. I would like to stay within the 18" side to side as well. Any ideas or suggestions would be most appreciated.
Resized_20180801_165427.jpeg
 

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Hey Cowboy...can't help you with your question, but just noticed your license plate .
Thank you for your Service my friend...I appreciate you!
 

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Discussion Starter #3
My honor to serve. No worries everyone, found a tool box that fit perfectly, mounted it, tried it, hated it. On to the next bright idea.
 

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i tried the rotopax on top of the top box on top of the cyclerack. didn't work out for me. the fuel tank was too heavy for the hings on the top box and the top box and fuel tank were too heavy for the cycle rack. it worked a lot better with a bigger gas tank, no BS with fuel transfer and the extra fuel weight worked better up front 25.JPG
 

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Kinda like this?



I like the idea of a 2x4 underneath to support it more. I should look into that.
 

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So I just installed my Cycleracks rear rack. Thanks Don & Marc. Now I would like to put a SOLID gear box on it. My idea is that I want to mount my rotopax to the back of the box and the lid still open freely. I don't have the rear hoop on my rack so I have 14" to work with front to back, including the 3 1/2" rotopax. I would like to stay within the 18" side to side as well. Any ideas or suggestions would be most appreciated.
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Hey NVcowboy, thank you for your service! Too many people these days don't have a clue what you guys do for our freedoms and show no appreciation for the sacrifices our soldiers make!

IMHO you bought the best rack in the market. I also run a Cyclerack without the rear end hump with a 18" x 18" x 12" box (Hardigg military surplus from Sportsmanguide) fixed installed on it. On a normal day, I carry about 40lbs but I pushed it to 65lbs and occasionally take it off-road. See my profile pic...

After 3 years, the weld on the rear mount plate succumbed to fatigue. Not a welding or material issue, just that the rack flexes with that kind of weight and starts to swing around that weld point because the TW200, unlike most other bikes, does not have a real mount point any further back. Don and Marc are awesome guys and they replaced the rack... after 3 years of usage!!! These days, where do you find a company that stands by its product this way???!!!!

So I was thinking along the lines of a wood piece or something similar as TopPredator is suggesting, and that probably works well for most cases. At the time I was (and quietly still am) planning a Singapore to Beijing trip with my TW. I was going to put significantly more on it than 65lbs... side cases with tools and spare parts, bag and tent on the top case.... so I knew that the sub-frame which is under the rack would not support that weight, especially with off-road bumps and an occasional catching air.

Consequently, I put my engineering hat on and designed something I could print to solve the problem:
KIMG7896.jpg

The design is based on the direct line between the mount points changing length when the rack swings, so the force is actually push-pull between the mount points (horizontal) vs. push-pull is the direction of gravity (vertical). The subframe back there is not made to withstand a lot of vertical forces but it can handle plenty of force horizontally.

I'm running with it for 2 years now and so far so good. With only 12kmi on this design I consider it a "tested prototype". I have not thought much about selling this directly, but if you're interested I'll send you one (for free ;) ) for trying it out to let me know what you think how I can improve it and most importantly if you were able to break it!

Cheers, Bert.
 

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Discussion Starter #11
Thanks Bert.
I would love to continue to test your prototype. I plan on putting a great deal of weight on myself and NV has some formidable terrain. Much appreciated. I'll PM you my vitals.
 

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Hi. I have a Rotopax installed on the rear of my rack behind my Action packer. I custom built my rack with a paralell tube below at the rear, thinking this could be a way to support the fuel can with strength and stability. So far its holding up well.
My rack has 2 rearward mounts at the tail lights, a rest on the rear fender pad, and a long L attaching to the rear lower seat area. I added a rest bottom for the fuel tank to rest on, and I find it helps allot for stability. Your rack could be modified easily for an adaption like this.
if you want more photos let me know.
Ron rack3.jpg
20180826_191349.jpg 20180826_191357.jpg 20180826_191422.jpg
 

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I had a one gallon rotopak cantelevered off rear of a cyclerack for awhile. tank.jpg
Aggressive riding with only a moderate load caused significant failures. subframe.jpg
Here the entire subframe either broke it's mounting tabs or broke the frame itself in addition to the crossmember that normally breaks. This was using a Cyclerack which also transmits some of the load to the passenger footpeg mounting locations. My cyclerack broke there too, broken tab visible below. damage.jpg
My point is that the subframe is inadequate for many of the loads we wish to carry. The further to the rear any load is the more stress it transmits to various mounting points. While the custom rack looks great it's longevity would greatly increase if some form of compression strut from rear of rack to footpegs could take some of that cantilevered load.
 

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Discussion Starter #14
With the "dampener" I got from wersonst, it bolts through the cross member. It goes around the next to last bar on the cycleracks. After I loaded it up with my gear there was still a sliver of light showing through. It doesn't hold it in place, it's only supposed to cushion some of the deflection. After inspecting it following my trip it still looked good. However I will continue to monitor it and check the cross member periodically. If it starts to damage it in any way I'll let Bert know so he can do what he does and invent something better. But I like it so far. Probably better the rack breaks before the bike.
Resized_20180817_105701.jpeg
 

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As mentioned above, the very best place for extra fuel is between your legs in a larger tank. With the CR you do get a great deal more support as it attaches to the rear foot peg brace but there is still a great deal of force on the rear sub frame. I have seen a buddy strap a nice buck on to his CR that weighed close to 130 pounds but he sure did not go blasting through the woods with that amount of weight on the CR.

GaryL
 

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Discussion Starter #17
So... point being, when fully loaded, try not to go full on Bo n Luke. (Fred):D I mean there IS a warning sticker on the back saying not to exceed 7 lbs., so try to keep it reasonable on the CL as well.
 

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I feel like the Tinman Tim rack I have alleviates some of the issue by the way it ties in. Its hard to tell from the picture exactly how it mounts, but the piece on top of the main crossbar of the rack slides between the rear frame tubes, and the hinged portion of the frame ends up above the crossbar but below the rack (the picture of it mounted on the blue framed bike was just me playing around to see how it fit the peg mounts, etc). That way the rack isn't being supported by the thin metal brace going between the rear frame tubes.
 

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With the "dampener" I got from wersonst, it bolts through the cross member. It goes around the next to last bar on the cycleracks. After I loaded it up with my gear there was still a sliver of light showing through. It doesn't hold it in place, it's only supposed to cushion some of the deflection. After inspecting it following my trip it still looked good. However I will continue to monitor it and check the cross member periodically. If it starts to damage it in any way I'll let Bert know so he can do what he does and invent something better. But I like it so far. Probably better the rack breaks before the bike.
View attachment 183760
Just a friendly disclaimer ;) NVcowboy installed it 1 cross bar further back than what it is designed for. That far back, the subframe is a quite a bit softer. So this is a new test case. :rolleyes:

Fred's pic is showing the last cross member of the main frame, which is not the strongest to begin with. Give it a little corrosion and a few bangs and there it goes. Early prototypes of what became the dampener were just forwarding the momentum to that cross member... and blew it right out in the very same way. What NVcowboy is testing right now are 2 pieces made of 2 different materials. The black part is a custom high temp PLA; I don't even know what's actually in it. It is softer than ABS and holds up very well to high temps (I have a dual horn bracket just above the exhaust manifold which doesn't show any sings of distortion after 1 year. Granted, I did sinter it....) The white part is nylon with air cushions, which is even softer.

The dampener is holding the rack cross bar and cushions any vertical motion by deflecting into a forward/backward force along the frame instead of perpendicular to it. That way, the rack cannot build up any kinetic energy vertically. Vertical motion would make it flex and pivot around the rearmost rack weld, which will ultimately break the weld.

However, the dampener has an intentional break point. The limits were set as follows and were verified experimentally: I load my rack with 65lbs and go putzing around off road. If that holds, it's deemed good enough. If I drop the bike hard on the rack with nothing else cushioning the fall, I want the dampener to fail. I.e., the rear wall "United We Stand" will break off. I can easily adjust that resilience, but when I do, that last cross member of the frame will likely blow out (again). In my eyes: Bike over rack over dampener, just like NVcowboy.

Smitty Blackstone, these buggers cost about 28 hours printing, $40 bucks material plus shipping. I'd rather have NVcowboy put it through the ringer, me fix any issues and then have you get one. What'd ya think?

GaryL: Amen! ... and how were the back straps?

YBW, that looks like a good one. Side case mounts built right in. How/where does it mount at the rearmost point? Can you shoot a pic from the side?

Cheers mates!
 

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The rear is supported by the pannier mount. I had to modify the passenger peg brackets to still be able to carry a passenger though. A somewhat quick and dirty job (I did it just today) but I figure I can clean up/perfect when and if I tear down for an overhaul. These pics were also taken before I picked up the 6mm Nylocs for the bolts...
 

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