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I have been looking into possibly building my own cargo bike (inspired by the xyz cargo bike). That said, I am interested in possibly modifying the design - including how the steerable wheels are attached to the frame.

When I research how others have solved attaching these wheels to the frame, I often see them attached using rod end bearings that seem to have a fairly significant axial load on them. (To be clear, I don't think the xyz cargo bikes use this technique).

My questions are:

  • Am I misunderstanding what kind of bearing they are using here? They look like rod end bearings to me, but I am a rank amateur when it comes to this kind of stuff.

  • If these ARE rod end bearings, is it OK to apply this kind of an axial load to them?

Thanks!

Examples below:

[Rod End bearings used as wheel connector example 1

[Rod End bearings used as wheel connector example 1

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Overengineered. An M8 rod end will have around 5kN dynamic load rating. A wheel with 50kg has 0.5kn static load. From my very limited knowledge of engineering rod ends are typically rated for axle loads of 10%-15% of load (although load factor comes into it).

For a home made bicycle/tricycle, short life from accelerated wear is not a serious concern - the builder installs a new one cheaply. The over engineering removes any real risk of catastrophic failure, and being home build, the corporate risk lawyers have not had there say in in the engineering design.

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  • Thanks! That makes some sense. As it happens I will probably do something closer to what the xyz bike design was originally designed to use, but this was always scratching at the edge of my brain.
    – bvz
    Commented Sep 17, 2022 at 4:44
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    Good answer, but I would still avoid this design. As dirt gets into the bearings (which it will very quickly in any real use scenario) they'll soon perform much worse. And with such a bike, even moderately sized potholes can readily bring you to the 5 kN load rating, since there's not much chance for the rider to relieve the impact, the way you can on an upright bike.
    – leftaroundabout
    Commented Sep 17, 2022 at 15:43
  • Agreed. It seems like the nicer cargo bikes avoid using this design.
    – bvz
    Commented Sep 18, 2022 at 21:34

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