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When I emailed Onyx to find out:

Hi Tim,

That hub has the following bearings

6902

6805

6804 – center bearing, replaceable here at Onyx only.



On the non-drive side there are two different variations. The 6804 version has be serviced here – that’s the red hub in the attached picture. The 6902 version is field replaceable – that’s the Antifreeze Green hub in the attached picture.

Thank you,



Dan Peterson

Sent from my moto g(7) power using Tapatalk
 
I'm still on original bearings from 2016. I would just ride it unless the bearings feel really rough. I think that middle one is a pita to replace but I have no experience. My hubs still spins super smoothly. I've never serviced the sprag bearings either. I've checked it multiple times but it still looks perfect. I love how the classic is basically a service free hub assuming no major contamination. Sucks that onyx's rep has been tarnished by the vesper. If they only sold the classic people wouldn't be talking about the 350 as being the most set and forget hub.
 
Bumping this thread as I would like to convert a classic hub to micro spline.

As I understand it, there is no need to regrease the sprag clutch? Bearings appear to still be in good condition.
When I did the conversion, I just put a light bit of fresh grease on the new driver, everything came apart looking good so I didn't touch the sprags. It's been a while but as I recall the only tricky part was setting the preload, I think it needed to be done under full installed axle clamping load.
 
When I did the conversion, I just put a light bit of fresh grease on the new driver, everything came apart looking good so I didn't touch the sprags. It's been a while but as I recall the only tricky part was setting the preload, I think it needed to be done under full installed axle clamping load.
What kind of grease did you use on the driver?
 
What kind of grease did you use on the driver?
I should have specified, I used the Kluber Isoflex LDS 18 Special A grease as required by Onyx. I believe they include some with the kit, but I bought a tube of it years ago when I got my first pair of Onyx hubs. It's pricy but that tube will probably last me forever. The sprags need a pure grease with no added friction modifiers to function correctly.
 
Bumping this thread as I would like to convert a classic hub to micro spline.

As I understand it, there is no need to regrease the sprag clutch? Bearings appear to still be in good condition.
I have a classic that's been in use since 2016 and I've never needed to service the sprags. My hub still spins super smooth. It's pretty amazing how long the sprag bearings can go without needing anything.
 
When I emailed Onyx to find out:

Hi Tim,

That hub has the following bearings

6902

6805

6804 – center bearing, replaceable here at Onyx only.



On the non-drive side there are two different variations. The 6804 version has be serviced here – that’s the red hub in the attached picture. The 6902 version is field replaceable – that’s the Antifreeze Green hub in the attached picture.

Thank you,



Dan Peterson

Sent from my moto g(7) power using Tapatalk
Just come across this post.
I don't know why Onyx say only they or a machine shop can replace the centre bearings, i've done several myself no problem. I have a park tool bearing spacer / bushing set and some other bits and pieces to use as spacers etc. It is not as simple as a conventional hub with 1 bearing either side that I agree, the only issue is that the NDS bearing and the centre bearing are the same size, so once the outer bearing and its locating circlip are removed, you remove the inner bearings circlip and use the puller to pull the bearing out and with a rejig of spacers etc to then pull it out through the outer bearings bore and a reverse to pull the new inner bearing through the outer bearing bore then pull into its central location. Its a bit of messing about to set it up right but perfectly doable.
 
Discussion starter · #52 ·
Just come across this post.
I don't know why Onyx say only they or a machine shop can replace the centre bearings, i've done several myself no problem. I have a park tool bearing spacer / bushing set and some other bits and pieces to use as spacers etc. It is not as simple as a conventional hub with 1 bearing either side that I agree, the only issue is that the NDS bearing and the centre bearing are the same size, so once the outer bearing and its locating circlip are removed, you remove the inner bearings circlip and use the puller to pull the bearing out and with a rejig of spacers etc to then pull it out through the outer bearings bore and a reverse to pull the new inner bearing through the outer bearing bore then pull into its central location. Its a bit of messing about to set it up right but perfectly doable.
Can you get the inner bearing out with a slide hammer? What size drifts do you need to press in the various bearings?
 
Just come across this post.
I don't know why Onyx say only they or a machine shop can replace the centre bearings, i've done several myself no problem. I have a park tool bearing spacer / bushing set and some other bits and pieces to use as spacers etc. It is not as simple as a conventional hub with 1 bearing either side that I agree, the only issue is that the NDS bearing and the centre bearing are the same size, so once the outer bearing and its locating circlip are removed, you remove the inner bearings circlip and use the puller to pull the bearing out and with a rejig of spacers etc to then pull it out through the outer bearings bore and a reverse to pull the new inner bearing through the outer bearing bore then pull into its central location. Its a bit of messing about to set it up right but perfectly doable.
This does sound a little complicated. It would be nice if there was a service video.

How often does the center bearing need to be serviced? Unless it's almost never, the idea of asking riders to send their rear wheel to Oynx to service the center bearings seems ridiculous. Shipping alone would cost more than getting bearings serviced at my LBS. Plus there's the added week+ of downtime waiting for the wheel.
 
How often do the center bearing need to be serviced?
Pretty rare to never. It's the most well protected and lightest loaded bearing in the hub. I've had a couple of sets for years and I have never had to touch the center bearings. But I would definitely figure out how to replace it myself before sending it away if I ever have one go bad.
 
My classic has been in use since 2016 on all original bearings other than the free hub bearings which were replaced not because the bearings were shot, I just needed a new free hub body. I don't think there's a need to worry about that middle bearing. That said, it would be nice if they could design their hubs so all bearings are easily accessed.
 
Discussion starter · #56 · (Edited)
I've got a Classic Boost rear hub:


and according to the parts listed for that hub, the required bearings are:

6804
6805
6902

I looked at the Tech figures of the hubs here:


and it looks like the rear hub may require 4, 5, or 6 bearings. The video on that page shows 4 bearings. Does anyone know how many bearings are in the rear hub, and how many of each I need? Thanks.
 
and it looks like the rear hub may require 4, 5, or 6 bearings. The video on that page shows 4 bearings. Does anyone know how many bearings are in the rear hub, and how many of each I need? Thanks.
2x6804, 1x6805, 1x6802 for ISO 6-bolt hub. In addition to that, the driver requires its own bearings that are model-specific. The older axle design might use different driver bearings than the new, and currently used MFU axle design.

To make sure, email Onyx directly. They're super helpful.
 
Discussion starter · #58 · (Edited)
I finally l located an email address for Onyx:

sales@onyxrp.com

I asked them which bearings are in my 2018 Classic Boost 6 bolt rear hub with a Shimano freehub (i.e. I use Shimano cassettes). Here was their response:

Maintenance on the hub can vary depending on usage.
At this time frame (2/2023 with no service ever), we would suggest cleaning and regreasing the clutch mechanism. This uses a specific grease and should be done every few years as it will absorb condensation.

On the classic hubs from ~2018. The brake side bearing is a 6804. The drive side bearing is a 6902. These are the two most common bearings to wear out.
The clutch area has a support bearing on each side. 6804 and 6805 size.

All the stock bearings in the hub are ceramic hybrids. They can typically be cleaned and greased rather than replacement. We have video walk throughs on our youtube channel for reference on the process.
On the classic pre MFU, the shimano freehub has a single 6902.
On the current classic with MFU, the shimano freehub uses a 6802 and 6902 stacked over a spacer.
So, if you want to have replacements on hand for all the bearings in an Onyx Classic 6-bolt Boost hub with a Shimano freehub, and the hub was made before the current MFU design, you need the following bearings:

2x 6804
1x 6805
2x 6902
 
Discussion starter · #59 · (Edited)
I pulled apart my Onyx Classic 6-bolt rear hub to service it. There was no grease under the end caps, and there was dirt on both outer faces of the bearings, which I cleaned off.

I pushed the axle out, then I pulled the freehub out of the hub body just like in the service videos. The extension protruding inward from the freehub had a lot of grease on it, and the grease was wet, clean, and tinged dark brown (Kuber Isoflex?). The service videos don't show any grease on there.

None of the collets for my slide hammer would fit the drive side bearing--one was about half a millimeter too big, and the next smaller collet was way too small, so I used an expanding type bearing puller, which only grips the inside of the bearing, and you tap it out from the other side of the hub. I purchased the tool from bearingprotools.com. Confoundingly, the drive side bearing was a 6805 bearing--not the 6902 claimed by Onyx.
Wheel Bicycle tire Bicycle wheel rim Automotive tire Bicycle hub


Automotive lighting Gas Nickel Jewellery Auto part

(6805 bearing puller on the left, press on the right)

The DS bearing has an orange seal that faces outwards, which says:
Verinent


6805 RH
And on the edge of the inner race facing outwards it says:

Onyx Racing Ceramic Balls
On the inside face of the bearing, there is a black seal, which says:
Verinent

6805 RS
I removed the orange seal with a pick to service the ball bearings, but the grease was wet, clean, and plentiful; so I put the seal back on without doing anything.

After tapping out the DS bearing, I removed the cir-clip, which allowed the spragues to slide out. Both of them were wet with clean grease, and they didn't need servicing. I serviced them anyway. I didn't want to use the toxic mineral spirits shown in the service video, then have to take the used portion to a hazardous waste dump, so I soaked the spragues in isopropyl alcohol, and I used an old toothbrush to clean them. I ordered the special Kuber Isoflex grease about 6 months after buying my hubs, and now 4-5 years later, I noticed it's not the right kind. I don't know if I ordered the wrong item, or the vendor shipped the wrong item, but I've got Kuber Isoflex NBU 15, so I went online and I ordered the correct Kuber Isoflex LDS 18 Special A. Expensive mistake.
Household hardware Font Rectangle Cylinder Auto part


Automotive tire Wheel Rim Bicycle part Automotive wheel system

On the NDS, the bearing has an orange seal facing outwards, which says:
Verinent

6804 RH
The bearing in the middle of the hub has a snap ring holding it in place, which you access from the NDS. On the black bearing seal, it says:
Verinent

6804 RS
The black seal faces the DS, and there is an orange seal that faces the NDS. If you were to remove the snap ring, I don't see any reason way you couldn't pull that bearing out the DS.
Bicycle wheel rim Bicycle hub Bicycle tire Automotive tire Bicycle

The Shimano compatible freehub has a bearing with an orange seal facing outwards, which says:
Verinent

6902 RH
I stuck my finger through the middle of each bearing, and they all felt smooth when I rotated my finger.

Once the special Kuber Isoflex grease arrived, I put some on the spragues. I tried putting a glob of the Kuber Isoflex on top of the inner bearing, but it was hard to apply anything but a thin layer of grease. Then I reinstalled the spragues (teeth facing counter-clockwise), but I had a little trouble getting the cir-clip back in--eventually I got it to seat in its shallow groove above the spragues.

Then I pressed the DS bearing back in. I didn't have anything to brace against the opposite side of the hub. Everything I had was too small in diameter, and therefore I would have been bracing against the inner race of the bearing or the ball bearings themselves. I finally managed to jam a female cup for a bearing extractor into the opening on the NDS, so that I was bracing against the outer race of the bearing, and after pressing in the bearing on the DS, I had a hard time getting the cup back out. I will have to order a 6804 bearing extractor and press.

Unlike in the service video, I waited until after I inserted the axle through the hub body to apply loctite to the threads at the end of the axle. Then I carefully applied some sticky marine grease under both end caps, and I reinstalled the end caps. The axle felt a little tight when I spun it with my fingers, which I expected might be the case after reinstalling the bearing, so I set about to adjust the bearing preload.

I removed the NDS end cap, and I loosened the screw on the preload collar, but the sticky marine grease seemed to prevent me from setting the preload correctly and getting the axle to spin easily. So I removed both end caps, and I removed the axle, and I cleaned off all the sticky marine grease I had applied. Then I reinstalled the axle, and I applied loctite to the threads at the end of the axle. I think I could have gone ahead and installed the end caps without any grease under them--they don't say to apply grease in the service video--but I decided to apply some Slick Honey, a much lighter, thinner grease than the sticky marine grease I used previously. That seemed to work well, and I eventually got the preload collar adjusted: I tightened the preload collar by hand, and as soon as it met any resistance, I found I had to back off the preload collar about 1/4-1/3 of a turn to get the axle to spin smoothly--more than they show in the service video.
 
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