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Thursday, September 10, 2009

Dualie Wheels

My mind is still working out wheel problems and solutions, all on it's own, because it keeps popping them up at the oddest times to tell me about them.

One of them would basically have me running "dualies" in the back, so even if one tire pops I still have the other, etc. It would use a double rim, with independent tires and tubes on each, but both laced to the same hub.

This would require a wider hub and axle, so I'd need to modify an existing one to lengthen it. The hub should be easy to do, but I'm not totally certain about the axle. I think I would have to do the axle first, and in addition to welding a section of another axle into the middle of it, I'd also want to lathe that down to flush surface and then weld some tubing over that that is longer than the added axle piece.

Then I would use one of the thicker-bodied hubs, cut it in half, place the axle between them (since it will no longer fit thru the axle hole from outside), and weld them together with proper diameter tubing sleeved over the outside of the central hub.

I'm not sure if everything would remain as hard as it should after doing that, so it might not work as well as I'd like.

I'd need to use longer spokes for some of the cross-lacing, and I have some older likely 700c wheels that might have the right length. I am not certain how it will affect wheel strength to do this kind of lacing, where every other spoke will go to opposite rims.

Another option is if I have any hubs with enough space between holes to drill new spoke holes in them, I could drill a complete new set of holes in each flange, and lace up each rim to it's own set of holes.

A third option is to weld a second set of flanges on the hub, and give each rim it's own pair of flanges, just as if it were two wheels physically joined.

I'm not yet sure if I should weld the rims together or leave them so they can individually flex to handle loads on their own--I suspect the latter would be more effective.

The wider effective tire would probably make straightline riding a bit more stable, but introduce some funkiness in turning. Double contact patch means double rolling resistance, but it also means double drive power and double braking power.

Well, that is, if I also build a rim brake that's twice as wide. :) Or come up with some way to build disc brakes out of my junkpile of regular brakes, 5.25" harddisk platters, and other stuff like that.

I'm still pondering it, and may never even attempt it. More web research is in progress to see if anyone else has tried this and hopefully posted their results.


  1. It sounds good with each rim getting a full set of spokes. It is a cool idea.

  2. I've been looking at what I have laying around, and the best I can probably do without serious modifications beyond width of hub and axle is a set of (I think) 48-spoke hub flanges laced to 36-spoke rims, with each rim getting 24 spokes, 12 from each flange.

    They're the hubs that are currently in my old trailer (the one built out of two rear triangles and some computer desk and lawn chair parts). On 20" wheels with the Kenda flame tires. Not using that trailer now, and I have other wheels I can put on it if I needed to use it, so free to experiment....

  3. Another alternative would be to find one of those really wide rear wheels and tires that walmart was selling on those chopper type bikes. One of them should be heavy duty enough but you might have to put heavier spokes on it.

    Those little gas scooters that had double rear wheels were easy to turn. I tried one. You really couldn't tell it had dual wheels on the back so if you do use two rims, that really shouldn't be a problem.

  4. I actually want to do this not so much for the width as for the extra tire, one of the same reasons semi trucks do it--if they have a blowout, they don't have to worry about anything immediately, as the other one still supports the weight there.

    That said, if all I could find was a wide rim and tire, I'd settle for that. :)

    However, I've never ever seen one on a bike that wasn't someone's pride and joy, definitely not in the scrap piles or thrift stores.

    Good to know that the dual tires shouldn't be much of an issue turning--I was a little worried about that part.

  5. I'd be afraid that without all the spokes, the rims will bend too easily. My impression was that way about turning with the double rear wheel, too, that it should work OK.


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