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I have a Specialized Tarmac SL6 which comes with "Specialized full sealed bearing thru axle hub". I tried searching for the hub specifically but cannot find any number or series on the back hub, the front hub states SCS-722.

I want to service or replace the bearings and also service the freehub. Where can I find an instruction PDF on how the bearings are is disassembled from the hub and how the freehub comes apart from the hub and which bearings are needed? I would also like to know, if any, which other freehubs are compatible.

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    Have you tried contacting Specialized? It's probably an OEM part that they put their label on. As for bearings specifically, assuming they are cartridge bearings, they are standardized, and once you know you've got a "6802" bearing or whatever, you can order a replacement from whoever you like. Loose bearings are also standardized parts, of course.
    – Adam Rice
    Feb 9, 2022 at 16:39
  • it appeared that there was a perfect video showing a complete overhaul of the specialized OEM hubs (Formula hubs indeed) for those wondering. If the freehub does not come off you have to press or hammer out the axle from drive side to non drive side with the axle in place. youtube.com/watch?v=1ZhK-95HO8o
    – Turan
    Mar 12, 2023 at 18:58

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Hubs have enough standard features that anyone generally familiar with hubs can usually determine how to service them.

Cartridge bearings come in standard sizes, and these are generally printed on the rubber seals. Once you expose the bearings, you should only need to look closely at the seal to find a numeric code, e.g. 6802. Each code corresponds to a set of measurements - external diameter, internal diameter, and depth. (Admittedly, proprietary cartridge bearings do exist, but these should be rare, and manufacturers using them are going to provide the service manuals.)

To get the end caps off, you usually can use a pair of Allen wrenches. Hold one endcap with one wrench, and unscrew with the other. Some endcaps are friction fit, i.e. you simply pull them off.

Freehub bodies are often held on by screwed-on endcaps. Some freehub bodies are pulled off without unscrewing the endcap - remember that your thru axle or quick release holds the system together, so there's no risk of the freehub body coming off while riding.

You do need bearing extractors and presses to remove the bearings from the hub or the freehub body and to refit new bearings. If you want to do your own work, you can find general purpose extractors and presses that fit a variety of parts. Bike stores will also have these items.

As Adam stated in a comment, many hubs with anonymous branding are made by third party companies like Novatec, Bitex, and others. These OEM manufacturers tend to be based in Taiwan. DT Swiss often supplies hub internals on an OEM basis to other manufacturers, and it makes its own branded line of hubs. Even if you can't determine who made the hub, you can still service it. If you need to replace the freehub body wholesale, it's best to contact a Specialized dealer or distributor. They should be able to look up the part in their system. Riders who come across an old OEM wheelset where the manufacturer can't locate spares may be out of luck if they need to replace a freehub body, a bent axle, endcaps, or parts other than the bearings.

As I alluded to above, some hubs have proprietary parts. Generally, these are rare. For example, I had a pair of Alchemy hubs. These were lightweight, high-performance hubs. Wheels Manufacturing later bought the designs to Alchemy, and supported existing hubs that they had parts for, but they later discontinued the hub. While they did this, they did send out a replacement front axle, as I had somehow managed to bend the lightweight axle while doing general road rides at 135-140 lbs. Later on, when I needed the bearings changed in the rear hub, the shop discovered that one of the bearings needed a proprietary tool to remove, which was no longer available as Alchemy itself had gone out of business and Wheels didn't provide that tool. I digress, as I often do, but we can derive a lesson from this: most cyclists should avoid proprietary parts. If you feel you must go this route, you might want to consider an established manufacturer with a long presence, e.g. I'd happily consider Campagnolo's factory wheels if I ever went back to using Campagnolo. With cheaper OEM wheels, the proprietary parts issue should only strike you if you need to replace something other than a bearing, and the hub is unlikely to need proprietary tools to service anyway. In any case, you may be ready to upgrade by then.

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Specialized hubs are often called "Axis" though there is very little markings on them to determine a maker. Google "specialized Axis hubs" will give you many hits to look through. This link in particular describes an Axis rear hub from Specialized. Generally once you've figured out the removal process (see Weiwen's answer for those tips), it's an exercise in cartridge bearing hub maintenance, where the process is very similar across brands.

One thing I will add is to use care when removing en caps on the drive side. The Freehub body can come off and spill the internals. It's important to know the order and direction the pieces go and careful disassembly will allow you to keep track of the order and direction.

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