I'm trying to simplify this design below. Instead of making a trike, I just want to make a simple trailer.


I want to use their methodology for attaching an axle / wheel to an aluminum frame.

From what I can tell they are using 30 mm square aluminum tubing with a 3 mm thickness and a 12 mm hole for the axle.

They are using a "reinforced axle M12 8.8" for the axle.

The numbers make sense; a 12 mm hole would make sense for a M 12 axle.

Obtaining aluminum tubing to their specs is pretty easy, but what kind of axle / wheel combo do I need to attach to this.

They don't list the components they use or how to obtain them.

I need a starting point on how to get this axle wheel combo. For example what would it be called - i.e. what could I google. What is the length of the axle? Does it come attached to a wheel / tire already? ... ?

Googling pulls up "thru" axles which are have two connection points not just one which is what I am looking for.

I have found some links from wheelchairs but ideally there would be a trike parts "store" or similar that sells these.

Seems to be tons of "thru axles" but can find parts for "non-thru axles"

1 Answer 1


They're glossing over the subject of trike hub and stub axle non-standardization.

Tadpole trikes use stub axle hubs. Stub axle hubs are anything where the axle is a protruding stub supported on only one side. Many wheelchairs have them too, though my rough understanding is those are typically lighter, lower-strength, and quick-releasable, so there's little if any parts crossover with trikes (though there are some higher performance/sportier chairs out there and I believe the subject may get complicated).

Trike stub axle frame attachment fittings aren't universal (or at least if there are any cross-brand standards, they haven't taken over). Look through the various trike parts sites (Utah Trikes for example) to find some examples of systems. It appears ICE and HP Velotechnik both do 12mm, though someone that really knows tadpoles may be able to recognize what the hubs are in your pdf just by looking at the view we get of them.

For the 8.8, they're talking about 8.8 grade steel fasteners.

The instructions don't talk about any kind of recommended hub dimensions or dishing guidelines. In other words, even among 12mm stub axle hubs, there isn't necessarily any universiality with the distances of the flanges from the bearing contact and thus from the frame member, and even if there were you would still need to know what dishing offset to use if any. These are pretty important elements from a vehicle design standpoint, since they establish the stance of the front wheels, so it's suspect that they're not mentioned.


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