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I am planning a bike to move heavy things, separate question here, and sixtyfootersdude is doing a cargo trailer that converges to some extent with my goal to move cargo here. I am not sure whether mounting a trailer wheel is the same as mounting a normal tire but bear with it I am trying to organize sixtyfootersdude's question at the same time as solving my own problem, just answer the question in the title thank you.

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Two wheeled trailer or one wheeled trailer? –  freiheit Mar 16 '11 at 18:54
    
@freiheit: you are right, a bit vague. My personal goal is to do a trailer to move heavy things, no idea what sixtyfootersdude meant with this question. Similar missing points such as "To which type of bike you are planning to mount the wheel onto a trailer?" -- no idea but my goal is to move "heavy things" like a lot of full coco bottles, I mean a lot like 30-60kg. So I need stable endurance bike mounting or design. Separate question about moving heavy things here: bicycles.stackexchange.com/questions/2868/… –  user652 Mar 16 '11 at 19:01
    
this question may well be unanswerable but I am trying to understand this question [1] better. [1] bicycles.stackexchange.com/questions/1256/… –  user652 Mar 16 '11 at 19:08
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Most cargo trailers have two wheels, so I think we can safely assume that we're talking about a two-wheeled trailer. (Or possibly a four-wheeled trailer, but that would use similar mounting mechanisms.) –  Neil Fein Mar 16 '11 at 20:03

3 Answers 3

The wheel is a pretty simple mechanism. You've got two main options:

1) Through-axle. In this case, the trailer has structural pieces on either side of the wheel. For example, this design is seen on the Bob Yak and Ibex and the Haulin' Colin trailers. The main advantage here is that you can use a normal bicycle hub and you have good structural support. The disadvantage is primarily that the wheel well increases the width of two-wheeled trailers.

2) Wheelchair hub. (See: Phil Wood) This is the design used by the Blue Sky Cycle Cart. A wheelchair hub has an axle you bolt down from only one side. This allows for a narrower body on a two-wheeled trailer, but you must design the axle fastening system carefully or risk having precession loosen it up. There is little reason to use this on a single-wheel trailer, unless for compactness when folding or using some kind of mono-suspension.

Both types of hubs can be built up with any rim. Smaller BMX-sized wheels (ERTRO 406mm) have the advantage of taking up less space, light weight, and strength, but the normal disadvantages of smaller wheels when it comes to rolling over obstacles. 24" (520mm) and 26" (559mm) wheels are larger, but you should design your trailer bed to hang below the axle for maximum stability. Larger wheels are typically only suitable for special applications or in an Extrawheel-type design.

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What's needed for the second kind of mount? My guess is that it's simplest to use regular bicycle wheels, since they're more easily available. (That's what a lot of these folks seem to be doing.) If hhh were able to find, say, two BMX wheels or even mountain bike wheels, would that be suitable to pair up with a wheelchair hub? –  Neil Fein Mar 16 '11 at 20:08
    
@Neil Finn: most wheelchairs use a through hole sized to the axle with a sharp edge on the far end to trap the balls that hold it in place. The release is a button on the outer end of the axle that allows the balls at the inner end to pull into the axle. It means you have a 10mm or 12mm hollow axle, so it's not especially strong. –  Мסž Mar 17 '11 at 21:49

You can now buy the Surly trailer wheels. They are beautiful! The hubs are only about 35mm wide! Retail for $170 per wheel.

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up vote 4 down vote accepted

lantius is almost right IMO.

  1. use a standard bicycle wheel with a thin through axle, supported from both sides. It's possible to make a really simple trailer this way that will carry quite a lot. The disadvantage is that it's wider than a single sided mount for the same track width (how far apart the contact patches are). Small wheels off kids bikes are often available cheaply or free, and will usually carry 50-100kg each for a few hundred km before they fall apart (come fail immediately, but they're free so don't worry about that).

  2. use a single sided wheelchair hub. They are light and designed so the wheels are easily removable, which is handy for a trailer that will be packed away often. But they will not carry much weight (20-40kg each) because bike trailers get used much harder than wheelchairs do. They're also somewhat expensive unless you can find a stock of wrecked wheelchairs.

  3. use a thick axle with single sided support. MTB hubs come in 15mm (Shimano) and 20mm through axle variants, and a 20mm steel bolt the right length is easy to weld onto the side of a trailer and will hold more weight than even a really well built wheel (you could even drill a 10mm hole through it to save weight. But it does need to be supported well as there is a lot of force on it). I have a trailer built that way that regularly takes 120kg or more without complaint. Unfortunately the build page for it is unfinished even though the trailer is ~3 years old. These 20" wheels are expensive($US135 each) because you will not find them second hand but they work. TriSled use those ones on their load bikes rated to over 100kg/wheel.

You will need to use small wheels on a two wheel trailer (or build your own hubs) because the side forces in corners are more than a 26" or bigger wheel can cope with. With a solid build and care when cornering a 24" wheel can work, but a 16" or 20" wheel will just work. If you build your own hubs with 100mm or more between flanges you could use bigger wheels, but you end up with a very wide wheel (you just added 100mm to the width of the trailer without adding to the load space).

Finally, you must look at Richard Guy Briggs' organ trailer. It's a bike trailer that carries a Hammond organ and player.

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I hadn't considered using a 20mm bolt in place of a through axle for a single-sided trailer. That's pretty ingenious. I also wonder if Surly will start selling their "custom" hubs they designed for their Bill & Ted trailers: surlybikes.com/frames/surly_trailer –  lantius Mar 16 '11 at 22:01
    
The main thing I want to emphasise is the concentration of force around that bolt. I find welding the two bolts onto a bit of tube to make a single axle, then attaching that to the trailer works best. Using gussets is essential on round tubing. –  Мסž Mar 17 '11 at 3:11

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