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Over Axle vs. Open Bore Adapters
What do I need, Over Axle or Open Bore Adapters?
This is a question we get a lot in our tech calls. And the short answer is it depends on the type of axle your hubs use: shouldered or non-shouldered. A non-shouldered axle is smooth across the length of the axle, allowing for it to slide completely thru the bearings. If you can remove the axle from the hub or pivot completely without removing the bearing, you will use open bore adapters to press new bearings back in.
Non-Shouldered Axle
A shouldered axle has a shoulder, or a stop, that prevents the axle from sliding completely thru the bearings. When disassembling the hub or pivot, if you have to push the bearing out of its bore using the axle, you will need an over axle adapter to press in the new bearing.
Shouldered Axle
Open Bore Adapters
Wheels Mfg open bore adapters work by pressing on the outer race of the bearing, without an axle yet thru the bearing. The outer diameter of the adapter matches the outer diameter of the bearing you are pressing. The adapter will have a step down to match the inner diameter of the bearing. This step is critical to keep the bearing aligned properly while pressing.
For pretty much all hub applications, you will need at least one open bore adapter. Bearing replacement with a non-shouldered axle is a fairly simple and straight-forward process, and should require the use of two open bore adapters. Both bearings are pressed into the hub shell before the axle is installed.
The first step for either axle type is to remove the old bearings from the hub shell using a good quality bearing extractor. Next, you'll want to clean the bearing bore of any dirt or grease. Then you will want to choose the appropriate open bore adapter for your bearing size. Wheels Mfg bearing adapters are labeled by bearing size (6802, 6903, etc.). Make sure you accurately identify your bearing! Using the wrong size adapter for a bearing is a quick way to damage a bearing and possibly the hub or frame pivot.
Always press one bearing at a time. Use one adapter in the bearing you are pushing, and one adapter on the opposite side directly against the shell or frame. You will probably need an adapter slightly larger than the OD of the bearing that goes into the opposite side. Or, use an adapter with a step that matches the bearing bore in the shell to keep everything centered and in alignment.
For the second bearing, you leave the first adapter in the previously installed bearing and add the second adapter to the second bearing. Again, use adapters that match the bearing size exactly to keep the bearings straight and true while pressing. With the bearings now installed, you can slide your axle through the bearings and attach any seals, spacers, end caps and/or lock nuts.
Over Axle Adapters
Wheels Mfg over axle adapters are meant to be used with shouldered axles, or where the bearing slides over the axle first before it is pressed in. Over axle adapters will press on both the inner and outer races of the bearing. With a shouldered axle you'll follow the procedure above using an open bore adapter to press your first bearing into one side of the hub or frame, then from the opposite side of the hub you'll insert your axle into the bearing bore as seen in the photo below.
Looking at the photo you're probably thinking "Great, now what do I do? I still have to press the other bearing in, but the axle is in the way." That's where the over axle adapter comes in. From here you'll use two over axle adapters matching your bearing size. One adapter will be placed over the axle and bearing you've already pressed in. The second will be used to press in the other bearing.
For hubs or pivots where the axle is longer than the adapters you are using, you would need to use our Speed Spacers to extend the length of the adapter setup beyond the end of the axle, allowing the press to push the bearing in completely. Use a Speed Spacer with the same inside diameter as the outside diameter of your axle.
If your axle has a hole thru it that is 10mm or larger, you can use our PRESS-1 handles to press in the bearing. If the axle is for a quick release skewer or smaller than 10mm, you can use the PRESS-2 skewer as your press, or any QR skewer. The PRESS-1 rod is also drilled and tapped on one end so you can use a skewer thru the axle and threaded into the rod as your pressing mechanism.
So, there you have it. Replacing bearings isn’t as complicated as it looks and with the proper tools such as the Wheels Mfg. Large Sealed Bearing Press (PRESS-1), Small Sealed Bearing Press (PRESS-2) and our Over Axle Adapter Kit (PRESS-3) it makes the job even easier. It beats a hammer and a socket any day!
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