Hubs came with 8mm spacers. Any 608 bearings would work.
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Better tight than loose 
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But there’s a twist!
Here is the motor with the adapter fully seated on the rear axle:
The thing to notice here is the stepdown from 10mm to 8mm, which is “outside” of the adapter.
After seating the adapter flush with the hub and then sliding both onto the axle we are left with a ~4.8mm gap:
So the way I see it, we’re left with (3) simple options, only (1) of which is probably tenable:
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Get a 22mm bearing with a 10mm internal diameter to fit the step down (6900 bearings). These Sovereign Speed Bearings seem to fit the bill. That said, the small gap between the adapter and the axle would likely prevent the inner ring of the bearing from contacting the adapter, which would mean the outer race would seat against the adapter (not good).
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Fully seat the adapter on the motor, crank down the hub, and just let there be a nearly 5mm gap between the adapter and the hub. This will likely put too must pressure on the pins, which will likely shorten their life.
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Pull the inner bearing and spacer. The motor itself has both an internal and external bearing, if the adapter is fully seated against the hub and the outer 608 bearing is locked in place with the axle nut and speed ring(s), then the entire “assembly” should have (3) bearings distributing the force across them. The adapter pins already have a very firm seating in the hub, so the axle nut shouldn’t need to be insanely tight to make this work. Also, since the hub is Aluminum, there should be no skew in the bearing if it’s fully seated in the hub.
Here’s shot of the rear axle with the inner bearings removed and everything fully seated (without being screwed down):
As a bonus, the distance between the outer rim of the hubs on the rear axle in this configuration is ~12.3125" whereas the outer rim of the hubs on the front axle is just a fraction over 12". This means the wheel separation for the axles (in this configuration) is nearly identical.
One item to note, however, is that the threading on the axle is just barely deep enough if you use a speed ring (I may use two just in case):
I’m going to go with option 3 here, unless someone can shoot holes in this approach. Thoughts?
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Why not make a washer shaped spacer to sit between the motor and the kegel adapter. Would 3/16 aluminum plate or ABS plastic sheet not do the trick? Two holesaw cuts would give you the interior and exterior circles. Then drill the five screw holes and use longer screws.
In otherwords, I’m saying to make the kegel adapter thicker by beefing up the back side. That would push your kegel teeth deeper into the wheel core.
Does that help?
Removing one of the four bearings seems like a really bad idea. You would be asking the kegel adapter to support the inside of the rim. That would make the adapter vulnerable to impact, fatigue and cracking. Plus you would make your motor bearings load bearing like a hub wheel. The direct drive hub motors might not be designed for that type of load.
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Thanks @pkasanda that’s a great idea. I pulled out the calipers and whipped up a quick design:
This should slot between the adapter and the motor. I’m thinking 3/16" (4.7625mm) aluminum would work quite well.
Looking at the hardware, the motor ships with Black Oxide M5 socket cap bolts @ 10mm. Since we’re looking at adding 4.7625mm, Black Oxide M5 socket cap bolts @ 15mm should be a great fit.
The only “challenge” here is the fact that the motor has a ring which acts as a fitment guide for the adapter to maintain tolerances compared the axle (as well as keeping the brunt of any force off the bolts):
Since the bolt holes in the adapter are 5.15mm, there is some slop and this may put the strain back on the bolts and not on the fitment ring.
One possible solution would be to add a fitment ring to the spacer. That said the motor fitment ring is ~3mm “high” so attempting to integrate a fitment ring onto the aluminum spacer would only allow for ~1.7625mm of material below it, which is probably not enough for it to be load bearing.
The real solution here would be to add the spacer between the motor cap and the can, which would push the entire motor cap out, although I’m reticent to start taking these motors apart (at least right now).
The alternate plan would be to add an adhesive material between the spacer and the adapter, which would likely hold everything in place just fine (the sheer holding force on this material, especially when bolted down, would be huge).
Next steps are:
- Cut these spacers out of aluminum
- Check for fit
- Find an ideal adhesive material
- Get everything bolted down
I think I have a solution for you that would require minimal effort.
Even if the adapter holes are sloppy, the torsional force will center the adapter holes on each of the bolts. The wheels will also keep the kegel pins centered on itself.
So my opinion is that that center ring is vestigial (serving no real purpose).
So doing nothing except using blue locktite on the thread holes might be the best solution.
If you are still concerned about the slop, then I woudl recommend adding a toothed lock washer between the bolt head and the adapter. I’ve done this to my Revel kit adapters with good results.
I recommend against any disassembly or tampering with the motor. It is not worth the risk and you would void your warantee for sure. Aluminum sheet is not going to be as consistent in thickness as the motor parts. Also, I suspect there would be a myriad of problems for the outer motor bearing which is likely supported by the part that you proposed moving.
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I’m having the spacers laser cut this week and will drop my results here once things are set up. I will keep the toothed lock washer in my back pocket- good idea.
My adapter is slightly different to yours, it has a piece that replaces the inner bearing. They seemed to have removed it in the newest iteration of the drives. I have one of your generation but chose the ABEC adapter this time.
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Really, the old version had you run on only one wheel bearing? That’s a bold modification.
I believe you. I’m just surprised they would decide to make the outer bearing of the motor responsible for carrying the weight of the rider (half of it). I always felt one of the benefits of a direct drive system was that the motor bearings only carried the weight of the motors and nothing else.
Anyway, it looks like the newer ones were redesigned to keep both wheel bearings. I’m basing that on what I understood from your posts. I don’t own any elofty motors.
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My early eLofty drivetrain uses a traditional two bearing setup. Maybe that’s why it’s still going strong, Shaft tolerances were always dogshit though. The inner bearing gets stuck when I swap wheels.
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Loctite 222 or 242 for the hub bolts do you think?
I have a different recommendation based on my experience. The non-permanent loctite does not seem strong enough to prevent the bolts from loosening off. I don’t think you want to mess with permanent loctite. The heating process to unlock the threads is tricky.
What I did was to insert a lock washer underneath the bolt head. I tiried conventional lock washers and external tooth lock washers. They both seem to work equally well. Conventional lock washers are easier to find.
In my experience, if you use the lock washer, then you don’t need any loctite.
Hey, you never posted pictures of your laser cut spacers.
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A little video of direct drive maintenance tips that includes the lock washer modification.
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Just picked them up Monday. I need to clean up a couple spots with some fine grit paper and will post shots soon. Thanks for the feedback on the Loctite.
eLofty Kegel Spacer for Janux Hubs
This appears to be a success! While I have not run these spacers yet, I have mounted them and things look good.
Just a review
- 3/16 Aluminum plate
- Laser cut to specifications
- 65mm OD
- 39mm ID
- 5.15mm holes
- 6mm between OD and outside of bolt hole
- 6 holes equidistant
- Finished product ~24g each
- 16mm M5 black oxide socket head bolts (up from the stock 10mm)
Fit and finish
Here are the adapters. The top one is finished while the bottom adapter is as the parts arrived from the laser cutter (actually slightly polished).
You should be able to see the difference in the grain of the screw holes, the surface, and the ID.
Here is the spacer fitted to the motor (it’s a nice tight fit after some time with fine grit sandpaper):
This shot shows both the adapter after having been lightly bolted down and (more importantly) shows the now flush fit of the axle step down:
Finally, we put the hub onto the adapter and viola!- a nice close fit between the adapter and the hub. The spacer therefore allows for use of both 608 bearings in the Janux hubs.
Points to consider
While my dimensions for the spacer were correct, I did not take the kerf of the cutting laser into account (which is slightly angled). As such, the dimensions of the cuts on one side of the spacer are ever so slightly wider than the other side of the part. This resulted in a fit which was slightly too tight on one side of the spacer. After some quality time with files and sandpaper, the spacer provided a nice tight fit to both the motor fitment ring and the adapter bolts.
My concern above about the motor fitment ring is now moot. The bolt hole tolerances in the adapter are tight enough to self align with the bolt holes, which means the motor fitment ring is indeed vestigial.
I thought about anodizing the spacer but I rather like the color of the raw aluminum and how it contrasts with the adjacent parts.
I also thought about sanding the OD, but the ribbed pattern left by the laser is also pretty attractive to me.
Pending Question
My question above about Loctite was meant for the hub bolts and not really the adapter bolts. Nonetheless, based on feedback from @pkasanda - I’ll be adding additional lock washers to the adapter bolts. Any word on what to use for the hub bolts? With the hubs being made out of aluminum, I’m concerned that lock washers would damage the surface.
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Nice Job.
So I guess you were wondering if you should put locktite on the four bolts that hold the split rim together.
While knowing nothing about a subject rarely stops me from giving advice 
…
I think the right thing to do in this case is to have you ask the rim manufacturer.