I was swapping between 8mm and 10mm bearings and found it more work than it could have been. Although I suppose I wouldn’t have wanted to take the wheels apart to do that anyway.
The other thing I was thinking about was when Stan’s bearing exploded and the race was stuck in the hub. A two piece design would potentially make that easier to fix. Teddy had the smart idea to semi reassemble the bearing with only 5 balls and press it out.
A two piece design might make that easier to recover from, but I think what would make more difference is the shoulder on the bearing seat being thin enough that it doesn’t obscure the entire outer race.
That way once you have one bearing out, you can use a flathead or something to hammer against the partially exposed back of the outer race to get the exploded bearing out.
I’m not sure if companies don’t do this for strength reasons or what, but it would make a ton of difference for maintainability.
Yeah, it’s a strength issue. Hubs are generally aluminum or plastic, bearing races are hardened steel. If there’s minimal engagement between the outer race and the wheel, then it could start digging into the wheel over time. Lateral forces from turning/carving would put a lot of force on that bearing race surface. Safer to make it beefy.
Both of those scenarios are going to be largely dependent on the bearing fitment in the hub. If the bearing fitment is not “just right” then you’ll have issues, no matter if the hub is split or not.
If the bearing fitment is loose, the bearings just fall right out which makes removing bearings easier obviously, but can make owning the wheel annoying if your bearings are constantly falling out. It can also lead to clicking noises and wobble from the wheel as you’re riding, if the bearing is not snug in the seat.
If the bearing fitment is tight then you have to press the bearings in with a lot of force, and getting them out is a huge ass-pain. However, the bearings will be very securely captured in the wheel, which can improve bearing longevity and eliminates the possibility of bearing wobble/clicking.
Getting a bearing seat “just right” in an aluminum hub is actually very challenging, from a machining and engineering perspective. You have to call out a very accurate dimension (which might be perfect for one bearing, but slightly off for a different bearing, because skate bearings are not precision at all), and then the machinist has to machine that feature extremely precisely to your dimensions. People think that CNC machining is automatically high precision, and in general it is, but for something extremely precise like a bearing seat, normal machining operations have little tiny variations that would cause issues. So you have to call out that high precision dimension in your engineering documents, and the machinist has to do a separate operation to make that high precision feature.
All that to say, it’s non-trivial to make a metal hub with a bearing seat that is “just right.” Stan’s hub was one of the v1 Hoyt 5" hubs (silver), and those had an extremely tight bearing seat. So tight that we had to install the bearings with an arbor press. That made removing bearings a big problem, as he experienced. The new v2 Hoyt 5" hubs (black) have a muuuuuch better bearing fitment. They are a perfect press fit with your thumb, and then you can knock them out by tapping the wheel against your hand or the table or whatever. Extremely satisfying, and non-trivial to get them “just right.”
I know they’re designed for it, but there’s a lizart-part of my brain that stays awake at night thinking about how the only thing that keeps a bearing seated are down-forces / radial load and friction. I start thinking of nightmare scenarios where a wheel just casually slides off its bearings on a turn after being subject to repeated axial-loading.
Have you considered adding a nylock nut to the end of your axles ?
That sounds like a loose slide fit.
Retaining fluid makes it so precise metal machining isn’t necessary.
Retaining compound does not absolve the requirement for a precise fit. Its a band aid solution and does not let you ignore tolerances.
If u can knock it out by tapping that’s not tight enough.
In some situations retaining fluid is preferred. On aluminum if it’s not tight it’s going to wear.
Ahh yeah I owned these same hubs. Loved them but the bearing fit was a challenge.
Good to know it was addressed for the v2’s 
Our mechanical engineer disagrees
But even if you’re techincally correct in some applications, for this specific application a designer has to balance usability vs other factors like this. If arbor pressing all bearings is the technically correct install method, it doesnt mean its the right solution for an esk8 wheel where the end user needs to be able to service their bearings and do not have bearing pullers and arbor presses in their home.
That’s the advantage to using retaining fluid and u don’t need an arbor press. To remove the glued bearing put the aluminum hub in the oven then can knock it out. Beats wearing down the fit in the hub with a slide fit bearing. A bit more work then tapping it but beats wearing the wheel down. Or maybe run it slide fit and add thicker retaining fluid later after it’s gotten noticeably loose
I’m not a“mechanical engineer” but I have installed at least 1000 bearings with an interference or close to interference fit. I use retaining fluid on all fitments (tighter or looser)and even both shaft and housing. It’s more work to take them apart but they don’t get sloppy.
Getting a manufacturer to do like .02mm or .01mm tolerance is hard. They will not get them all exactly right and trying to get refunded for their lack of precision is work.
I think you would be hard pressed to find anyone who feels this is preferable for an esk8 wheel vs a snug press fit.
Good thing we use a high quality manufactuer who nails it then
I will say for the v2 hubs it’s incredibly annoying when the bearings fall out of the hub as you’re trying to install or remove them, especially while juggling getting the pulley on the already tensioned belt.
all 8 bearings on my hubs just fall out from laying them down on a table (no taps required).
I personally would prefer a slightly tighter fit, but I understand the tradeoffs and the decision to go with the loose fit.
I mean that keeps the bearing on, but the hub and wheel basically sit on the bearing for dear life.
The bearings are sandwiched in the spacing stack of the axle and the geometry of the wheel locks that within that sandwich as well
Right, I get it logically. My lizard brain however still sees that without a thrust bearing, the only mechanical connection between the wheel hub and the OD of the bearing is a friction mount.
Oh I see what you mean now yeah I guess that is a A valid concern. Maybe you can add a big washer at the end of the axle that is bigger than the bearing outer diameter as some kind of emergency system lol
Gets flash backs to first day of being in Vegas 
What numbers ended up being just right?
A press fit sounds ideal. A moment ago u were saying ideal to be able to just tap them out with ur hand. That’s not ideal unless they’re gluing them in w retaining fluid.