# Trailer failure (how not to DIY)



## nonsleepingjon (Oct 18, 2002)

I built my own trailer. It failed. I learned a lot in the process so maybe version 2.0 will work out a little better. 

I wanted a decent sized cargo box on a single wheel design. This would provide ample cargo room with moderate water resistance, ease of access to gear/groceries/etc, ability to lock the lid semi-securely, and the single wheel should track nicely behind the bike for maneuvering and handling. 

The trailer has a vertical extension that ends in a handle so that it can be pulled by hand. I figured that would make it easy to pull around a grocery store or around a camp site. The handle also served as part of the attachment to the bike.

I went with a seat post attachment mainly because it was easy to fabricate, but also because it provides a higher attachment point (which I read was more stable due to the increased angle of trailer wheel to hitch --- not sure if that's true or not). The extension bar swivels horizontally about the seat post, and the handle of the trailer rotates vertically, which combines for freedom of movement in every direction.

Some pictures of the build are below: basic frame design (minus some reinforcing bars and cargo box); completed trailer; trailer hooked up to bike via extension bar.


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## nonsleepingjon (Oct 18, 2002)

*method of failure*

The trailer actually worked great in the first few test rides. It tracked behind the bike, leaned in to turns, and behaved better than I expected for something I welded together out of a cut up bed frame.

The problem arose once it was loaded. The angle iron and frame design allowed for torsion along the length of the trailer (think of an inverted pendulum). Even with heavy stuff in the bottom of the cargo bin, the trailer would oscillate and there wasn't anything I could do to get it under control (speed up, slow down, etc). After about a mile it tilted to the point of failure and popped out of the clamp that held it to the extension bar. In a way, that was a good thing because otherwise it could have taken me down with it.

As a second attempt, I tried lashing the trailer handle directly to the rear rack, but that ended in failure after about another mile. Again, the oscillations increased until the trailer was basically out of control. Thankfully I was able to pull over, but not before it bent the rack and busted a weld on the rack as well.

//As a testament to my awesome amateur welding ability, all the welds on the trailer itself survived all these ill fated trial runs. I'm kind of proud that the trailer out lasted the rack.


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## nonsleepingjon (Oct 18, 2002)

*ideas for version 2.0*

For version 2.0, I'm going to try several things (and am also open to suggestions)

Create a wider, sturdier frame out of tubular steel. That should decrease the amount of torsional flex that allowed the oscillations to occur.
Build a short vertical truss around the frame to increase rigidity.
Create a sturdier connection point to the bike I'm still debating on single point attachment at the seat post or moving to a dual connection point at the bike rear axle. Both seem to work well on several commercial trailers I've seen online.
I should be able to lower the frame several inches below the trailer wheel axle without compromising ground clearance. That should lower the center of gravity and increase stability.

That's the story for now. I'm interested in any comments/critiques/suggestions and will post again if/when version 2.0 is ever built.


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## dustyrider (Aug 10, 2007)

Goose neck trailer's use a type of ball joint don't they? Seems to me this could eliminate the need for two joints.

When it comes to your frame redesign you may want to consider a few of the designs shown here and here. 

Personally, I don't see any benefit to the goose neck trailer over one that attaches to your stays. Nice work by the way I don't have access to a welder so I just scooped up an old used Burley.


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## Fixed (May 12, 2005)

*attachment?*

I think I'd try attachment at the rear axle. That's probably about the sturdiest area of the bike, plus there would be less material, with less weight and less flex. Have to allow it to pivot up and down, though. Maybe buy a skewer for a trailer like a Yak, and work around that?

Might be better to copy a proven design? Looks like fun.


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## PeanutButterBreath (Dec 4, 2005)

Seems like you would need a much sturdier attachment system for a single wheel trailer. Any slop that allows the trailer to tilt will cause it to wander back and forth and that could eventually develop into the oscillation you describe.

Unless you can tighten up the joints and attachment points, a two wheel trailer might be the better option.


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## nonsleepingjon (Oct 18, 2002)

PeanutButterBreath said:


> Seems like you would need a much sturdier attachment system for a single wheel trailer. Any slop that allows the trailer to tilt will cause it to wander back and forth and that could eventually develop into the oscillation you describe.
> 
> Unless you can tighten up the joints and attachment points, a two wheel trailer might be the better option.


That could be a contributing factor as well. I've seen commercial products using both styles that seem to work just fine, so at this point I'm more focused on the trailer but the hitch needs to be reworked as well.

One wheel trailer with seatpost attachment: Aevon

One wheel trailer with axle attachment: BOB, Monoporter

There are videos on youtube for all of these trailers showing them fully loaded over a variety of terrain with no issues. From what I can tell, the common theme across all of them is a sturdier (less flexible) frame.


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## Fixed (May 12, 2005)

*$69!*

Only $69.99 at Nashbar now. You'd probably put that much in parts.

https://www.nashbar.com/webapp/wcs/stores/servlet/ProductDisplay?partNumber=NA-TLR-BASE&catalogId=10052&storeId=10053&langId=-1&cm_mmc=Email-_-Nashbar-_-100604Fr-_-Products&[email protected]

*Nashbar Cargo Trailer*



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Nashbar Cargo Trailer is constructed from chromoly steel and is powder-coated for a great looking, durable finish. The design uses a series of triangulated struts resulting in a strong and durable platform for carrying your stuff. Total Weight: 12 lbs, Weight Capacity: 35 lbs, Platform Dimensions: 31.5 in. (Length) x 15.5 in. (Wide) x 5 in. (Deep)
More Info... lose Move 
Arms are thicker than previous model
Replacement arms are available, arms can also be retrofitted to previous model
previous model. (TSH 9/12/07)
Additional Information --- Trailer is compatible with quick release
skewer compatible hubs only. Will not work with solid axle hubs
GG0708 




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## asifa3 (Dec 22, 2020)

Hey, There are so many DIYs available on Youtube. Building a trailer itself is hard work. I would like to suggest you Axle Surgeons CA, If you can arrange. They can solve all your trash.


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