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Friday, December 4, 2009

Dualie Wheels, Mk II

I've discussed dualie wheels for the rear before, so that I can have more support back there, and less worry about a blown tire or tube, broken spokes, rims, etc. It's less of a worry once I have rear suspension, but the concern for a blown tire still exists, since as heavy as the bike is it is difficult to fix on the road. Less so if I use the suspension system I'm doing now, where the dropouts are fully behind the cargo pods, so I can at least get to them easily, but still not easy to do.

So I'm considering building a whole wheel from scratch, using the bearings and tube from this:
to make the axle, and welding up a hub, spokes, etc from there.

It's just small enough diameter that I can still fit the threaded part off of a regular hub (minus the bearing cups) over it with clearance, if that part is a bolt-on cover over the bearings.

Then I'd weld up a tube to fit between the bearings, weld on some flanges I can drill out for spokes and for bolting on the freewheel threading off a hub on the right side, and directly bolt on a sprocket on the left side (for motor use).

The flanges would be probably around 6" in diameter, so that I have plenty of clearance for spokes to be replaced without taking the wheel apart (unlike most bike hubs, where you have to take the freewheel or cassette off of it first, since it always seems to be drive-side spokes that break).

That also allows for many more spokes than usual, so I could use 72 spokes, 36 per rim, and have them fully supported. I might choose to not even weld them together, so that they are "independently suspended" as it were, with the spokes.

The rim would otherwise be the dual-rim welded with spacers as suggested by Scrapyard Don above.

It's difficult to imagine from what I am saying, I'm sure, but I have a fairly clear idea of how I'd do it, if I can find all the right parts in my junk pile. I'll try to come up with some sketches at some point.

1 comment:

  1. Interesting idea. The cool effect of independently suspended wheels at close quarters like that would be awesome. That MIT student with his dual-wheeled unicycle-style motorcycle, the now-failed, now-revived Vectra trike, etc. have used this.

    It just looks killer and has the added benefit of stability. The question is how much it takes away in terms of traction/road resistance.


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