So, OK, this might be a little late to be useful to Ryan but I have put a lot of effort into making these wheels work so some good should come of it.
These 'durable Carbon Fiber impregnated composite wheels' come with the current Blue Sky Design kit. 16" means less frontal area than the 20" for less wind drag. Where the tire itself sits is smooth with smooth flanges. This works well for DIY tubeless and tubes.
Unfortunately 'durable' is less than accurate. I have found that side loads cause the plastic wheels to flex and eventually fail. They form a ripple on the outside of the spokes and the inside of the spoke cracks.
We tried reinforcing the spokes with carbon fiber. The wheels are plastic and normal epoxy will not stick well. We tried G-flex epoxy from West Systems and tried various methods of prepping the wheel surface. West Systems recommended roughening the surface and then passing an open flame to blacken the plastic to help the epoxy to adhere.
We started with just reinforcing the spokes but that just moved the cracking to next to the hub. We then wrapped the hub with carbon cloth as well. This was good for a race or two but the plastic continued to flex under the carbon fiber overlay. It was impossible to see the cracks underneath and then the wheel would fail completely (video here of front wheel failing: https://youtu.be/_H7O-ydRXqs )
At $100 a wheel, plus carbon fiber, plus labor, running them one race then tossing them seems a little extravagant.
I have been looking for a replacement 16 inch wheel with 1/2 hole and 6 holes to mount a brake disc. Our 20 inch wheel hubs have 32 spokes and I have not been able to find a 32 hole 16 inch rim.
I found this as a replacement wheel: https://www.amazon.com/Razor-MX500-MX650-Front-Assembly/dp/B001RMNMGE/ref=sr_1_3?s=sporting-goods&ie=UTF8&qid=1516047861&sr=1-3&keywords=Razor+front+wheel
It comes with the correct diameter brake disc and it is from an electric motorcycle so it should be stronger. The sealed bearings are metric. We ordered metric bearings with a larger inside diameter and then turned down 1/2 ID aluminium tubing on a lathe to create a bushing.
The 6 hole brake discs were a different 6 hole pattern from bicycles but same diameter. They are thicker which also means heavier but stay flat so it is easier to set the brake calipers not to rub.
Unfortunately with 28 spokes of less than ideal quality, we are breaking spokes pretty regularly. This is despite trueing the wheels and tightening the spokes after each session.
I have ordered 10 gauge spokes and will see if that will solve the problem.
Good info Cliff.
It would be interesting to hear how much you have invested in each wheel when you get done.
Budgetary concerns being important to most Electrathon teams.
Each wheel seems to be selling for around $65 each. They come with brake disc, bearings, tube and tire. The tire is for off road and pretty useless.
The bearing needs to be replaced to fit the 1/2 inch shaft. We used 6902ZZ-1 from VXB.com. metric 15x28x7. Need 2 per wheel at $7.77 each. We passed on the ceramic at around $50 each. We might try removing the shields, washing out the grease, replacing the shields and just oiling the bearings before the race. This is common in Go Kart racing.
3.25 inch of 1/2 inch ID aluminium tube <$1.00. Both ends need to be turned down to 15 mm on a lathe with a width of 7mm.
10 gauge bicycle spokes $28 for 36 spokes. https://www.amazon.com/Kingstar-Electric-Bicycle-Nipples-Dia-3-0mm/dp/B01I6Y0HZO?th=1&psc=1
So around $110 per wheel plus the time to replace bearings, replace spokes, true wheels.
I do not have the spokes yet (literally on a slow boat from China) but will report how they work.
I have put the 10 guage spokes in and none have failed. They keep coming loose, so I am now trying 45 inch pounds torque. I will see next race how well it works.
We ran the wheels I mentioned in my last post with the 10 gauge spokes. I used a motorcycle spoke torque wrench to set torque. It was easy to accidentally distort the rim. Even at higher torque settings, the spokes would need to be retorqued ever few sessions. The rims are fairly flimsy and do not have a good run out. The folded metal lip and flexing of the rim does not allow DIY tubeless to stay sealed. We sent two wheels to a motorcycle mechanic who torqued and trued them. We ran these with tubes. This was the best solution but fairly expensive and still requires regular maintenance.
Not completely satisfied with our motorcycle wheels, we purchased the wheels Steve Archer had discovered. They are solid aluminum and have more consistent run out than the motorcycle wheels. They mount a standard bicycle disc brake.
Since Steve only had two wheels, I did a Google image search and found more for sale: https://www.aliexpress.com/item/33014018955.html
They ship with a 30 MM OD and a 10 MM ID bearing. Steve kindly pointed to where he found 30 MM OD 1/2 inch ID bearings: https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F142904371709
So at a cost of around $66 per wheel, they are cheaper than any other option. They are about half a pound lighter than the modified motorcycle rims but heavier than the plastic rims.
We ran them tubeless at 70 psi at the first race of the season at HCC and had zero problems. The track had just been resealed so there was not much grip or tire wear, so it was not a very stressful test. I will post more as we get more experience with them.
We have run the aluminium wheels at three other races. On smooth tracks, they are great. This includes running the 20 minute races on a 1/4 mile oval running track. The lateral G`s were around 1.7 most of the way around the corners with about 5 degrees of negative camber on the outside wheel.
I do have concerns on rougher tracks. We ran on an airport runway that has lots of divots and holes. When I checked the car after the race, I discovered a crack in one of the spokes on the right front. We are running tubeless 100 psi Hookworm and a solid suspension, so there was a lot of stress on the wheel.
It could just be a flaw in one of the wheels. When I get a chance, I will weld it and see if it is still usable.
The wheel saga continues. My rear wheel broke 4 out of 5 spokes during testing. This was the same wheel that I ran on the rear on the Lee County but I inspected it carefully after discovering the broken front wheel and did not find any sign of cracks. On the other hand, the metal is covered by a flat black paint that might hide beginning cracks.
My test track is very tight and we see higher side loads than are normal in most electrathon races. I ran my spare wheels at the last race and the tire wore out without any problem with the wheel.
We tried welding the first wheel but the aluminum casting did not respond well. We ended up with a bit of a blob and the wheel well out of true.
It turns out they also have a six spoke model. The spokes look slightly thinner but a simpler design. I have ordered a set to try.
im not sure if you are dead set on using single piece (no spokes) wheels, but you may try contacting a dirt bike shop, before i left, i was very close to ordering a dirt bike wheel with some really heavy duty spokes, and the one i was looking at ( i no longer had the specs on this as i lost my notebook that had this info ) had the same fittings to run a bike chain, you might want to give those a look, i know for the kid size bikes, they did sell the smaller wheels, although you may have to look at different tire options for the rear.
Somewhere near the start of this thread, I tried an electric motorcycle spoked wheel. I had to replace the spokes with heavier gauge. The rims themselves were poorly made. I could either not tighten the spokes enough and constantly have to retighten them or distort the rim. If I have to go back to this route, I will try and find a better quality rim and use the spokes and hubs that I have.
