Building a solid rim for my QS205

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haulincolin   10 W

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Building a solid rim for my QS205

Post by haulincolin » Apr 22 2018 4:59pm

I've read the threads about solid rims / mag wheels / people breaking spokes. I'm well aware that a traditional spoked wheel has many advantages and a way better strength to weight ratio than a mag wheel ever could. I'm on board with Chalo's explanations about spoke tension and stretch and matching spokes and rims appropriately. All that said... I want a solid rim because:

- Weight is not an issue on my already 200+ lb tandem cargo bike with 14 kw.
- I don't want to deal with replacing spokes or relacing my wheel because it's a pain in the ass to deal with crossing such short, stiff spokes.
- The 20" bicycle rim I'm using is already a little on the big side... I'd prefer to switch to a 14" moto rim with a bigger tire, which would require even shorter spokes.

Am I still a fool for pursuing this idea? I have a CNC milling machine at my disposal so it's just a matter of taking the time to do it. The attached model shows one of two halves that would make up the rim. My intention is to thread the spoke holes in my QS (which are already conveniently the pilot size for a M5 tap), then bolt the two rim halves to the spoke flanges and to each other.
solidrim.JPG
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frontwheel.jpg
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Re: Building a solid rim for my QS205

Post by markz » Apr 22 2018 8:02pm

Interesting concept you got going on there. To do a traditional lace the spokes would be radial which is not the best for strength, I can see why you want to do it your way. You will be bolting your "spoke" plate onto the flange of your QS motor then having a "L" on that plate for the rim mount. Maybe make it a 2 piece?

Most motorcycle rims I see have bulges in them to help with spoke alignment.

Since you already have the motor, just get the rim and measure its E.R.D. then go to Justins www.ebikes.ca Spoke Calculator. We MXUS guys have it quite easy as the motors specs are already in the pull down menu, but its easy to measure and input the QS numbers.

You could just go ahead and try the radially laced concept with some cheap ebay generic spokes of say 12G straight, or if you can find double butted 12-13G. Give it a whirl and if you dig it, then get the Sapim 12G.

http://www.sapim.be/spokes

What you do not want to happen when you build your spoke plate is the flange on the motor to break, because then you are pooched.

http://www.sheldonbrown.com/wheelbuild.html#radial
There are two things to watch out for with radial wheels. Because the nipples point straight inward from the rim, they can turn more easily in most rims than when they are bent to a slight angle by a semi-tangent spoke pattern. This ease of turning increases the risk of their unscrewing themselves on the road. To prevent this, nipples on radial wheels should not be lubricated, and it is a good idea to use a spoke adhesive such as Wheelsmith Spoke Prep or one of the milder flavors of Loctite ® on them. (Or, if a rim does not have recessed spoke holes, the rim tape and air pressure in the inner tube will keep the spokes from turning -- at least with a high-pressure tire).

The other potential problem with radial wheels is that the spokes, trailing straight outward on the hub flange, can possibly rip the outer edge of the flange right off along the line of the spoke holes. This is most likely to happen with small-flange, 36 hole hubs, because there is less metal between the spoke holes. If a used hub is re-laced radially, the notches left by the old spokes can act as stress risers, further weakening the flange.

Many hub manufacturers specifically recommend against radial spoking for this reason, and will not honor warranties on hubs that have been spoked radially.

Some folks will say that no bicycle wheels should be radially spoked for this reason, so do this at your own risk. In my experience, it's generally OK with good-quality hubs that have forged shells.
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Re: Building a solid rim for my QS205

Post by flat tire » Apr 22 2018 10:32pm

You might as well design a disc for aero while you're at it. Spoked wheels are very good if built right and periodically tightened though.

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Re: Building a solid rim for my QS205

Post by amberwolf » Apr 22 2018 11:05pm

haulincolin wrote:
Apr 22 2018 4:59pm


Am I still a fool for pursuing this idea?
I dont see any reason it wouldnt work.

Also as long as the rims ID matches up right to the covers OD, the covers will help support the rim, along with the spoke flange, if you think you might need the extra.

Otherwise Id just make a lip on the inner surface of the rim pieces where they line up with the OD of the spoke flange, so theyre supported by the flange itself and not just by the bolts holding it to the flange. Might be overkill, but Id rather have overkill and not need it.... ;)

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Re: Building a solid rim for my QS205

Post by MadRhino » Apr 22 2018 11:31pm

I believe this motor is available 14 inch cast wheel for 360$ at QS motor factory. They also offer smaller and bigger motors in cast wheels, 12 inch to 16 inch.

Might be simpler to just sell yours and buy one in a cast wheel.
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haulincolin   10 W

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Re: Building a solid rim for my QS205

Post by haulincolin » Apr 24 2018 1:07pm

I'm pretty sure those 14" cast ones have a 200mm axle which is too wide even for my gigantic custom fork. Also they don't appear to be available in the same specs as the high end 205 (V3, 50H). I guess it comes down to whether it's more work to make a new custom fork or a solid rim. But I already have the 205 hub, so I'm leaning toward making the rim.
MadRhino wrote:
Apr 22 2018 11:31pm
I believe this motor is available 14 inch cast wheel for 360$ at QS motor factory. They also offer smaller and bigger motors in cast wheels, 12 inch to 16 inch.

Might be simpler to just sell yours and buy one in a cast wheel.

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haulincolin   10 W

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Re: Building a solid rim for my QS205

Post by haulincolin » Oct 09 2018 5:49pm

Well, I did it. It was interesting to discover that the spoke holes were very much not in a perfect circle. I ended up filing out our beautifully precise CNC-machined rim holes every which way to match the wonky spoke hole drilling on the motor.

Photo 1: Spoke holes threaded to M5
qs205work1.jpg
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Photo 2: Two halves and 90/90-14 tire
qs205work2.jpg
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Photo 3: First rim half installed
qs205work3.jpg
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Photo 4: Fully assembled
qs205work4.jpg
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haulincolin   10 W

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Re: Building a solid rim for my QS205

Post by haulincolin » Oct 09 2018 5:56pm

You may notice that I've also ditched the stock QS axle for a custom one to match my custom-built fork. I did this operation for my first QS motor, so this one needs to match. I took some photos this time.

Photo 1: Stock and custom axle side-by-side
qs205work5.jpg
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Photo 2: Test fit in my fork
qs205work6.jpg
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Photo 3: Threading wires. This is the most pain in the ass part of the whole operation.
qs205work7.jpg
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Photo 4: Pressing the new axle into place in the hydraulic press
qs205work8.jpg
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Re: Building a solid rim for my QS205

Post by biggy » Oct 09 2018 6:39pm

wow, that looks awesome. i was going to say have you ever tried titanium spokes. Alex rims also makes a triple wall called the Super E. But I totally get where you're coming from The Hub Motors don't lace well with rims because they're so big in diameter that the spokes don't really tension against themselves like they're supposed to.. I used to ride freestyle BMX in my younger years and I would order all my parts from Dan's competition they have everything. but your wheel looks really good.. very nice. let us know how it rides. I heard a couple people complain of unbalanced Wheels when they get to high top speeds I don't know if you guys know but they make these BB's that go inside your tire that balance the wheel as it spins. Also you have plenty of surface area for sticky weights.

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Re: Building a solid rim for my QS205

Post by amberwolf » Nov 02 2018 10:45pm

Those look like an interesting solution for heavy-cargo haulers like my trike or trailer, especially since it would allow any size rim to be made, in any width or diameter.

I"m gonna guess it was fairly expensive to have those made, though.

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haulincolin   10 W

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Re: Building a solid rim for my QS205

Post by haulincolin » Nov 05 2018 8:54pm

amberwolf wrote:
Nov 02 2018 10:45pm
Those look like an interesting solution for heavy-cargo haulers like my trike or trailer, especially since it would allow any size rim to be made, in any width or diameter.

I"m gonna guess it was fairly expensive to have those made, though.
Well it's my shop so I get to waste my time as I see fit. :D
But yeah, you're right, it would be very expensive if I were doing it for a customer.

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Re: Building a solid rim for my QS205

Post by amberwolf » Nov 05 2018 11:20pm

Ah; somehow I got the impression you'd had them made elsewhere.

I doubt I could afford it, but what wild-ass-guesstimate would you think something like this:
https://endless-sphere.com/forums/viewt ... 30&t=96354
would cost to make?

ATM my plan is to make it myself as I have time, but no real idea on how long that will take, given the number of more critical things I have to do around here. :oops: (and I expect mine will be significantly cruder than your work)

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