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They're fine. The new 565 also has a much beefier axle and wheel than the older models, so that helps. If you have the old, tiny diameter axle, then it might be a good idea to change to the new, big axle swingarm and wheel bearings. The ONLY time I ever saw any signs of being overstressed was an old 562 with the tiny wheel and axle. And it took a LOT of abuse to get it to that point even. (Did it myself). Prior to me getting that sidecar, it was on an 1100 Goldwing and was trouble-free for the owner. I put it on a CB750 Honda and beat it like a rental car, till the axle bent. Then made a new swingarm with a big axle. No failures since. As for weight, I'd really rather have 'too light' and add ballast, than a big old pig of a sidecar that is heavy before anyone or anything is put in it. I like to use water for ballast. That way if I put a person or load in, I can just dump the water rather than double up on the weight.
Looks great. I just purchased a 2000 Jackal with a Ural. I like your windscreen, how well does it work for you? That is the next thing I need for mine.