Profile 3/8 Mini Cassette Hub Overhaul

Remove the wheel from the bike with the Allen wrenches and then loosen the drive side (DS) axle bolt about halfway out. Then take a mallet or hammer and strike the back of the bolt. This should pop the non-drive side (NDS) bearing out after a couple of good whacks. You don’t need to hit it as hard as you can.

This is the result of step one. Remove the DS axle bolt, and slide the cone spacer, driver, and driver spacer off the aluminium centre axle. The axle in these photos is pretty old, don’t worry if yours looks different. Remove the NDS axle bolt, cone spacer, and bearing from the centre axle.

Thread an axle bolt about halfway into one end of the centre axle - it doesn’t matter which end at this point. Place the centre axle back in the hub shell through the DS hub body bearing (the end without the bolt on it). Again use the hammer to hit the bolt to remove the DS bearing.

Use a rag to clean all the parts you’re re-using. Inspect all of the parts for signs of damage or wear. This particular wheel is off the shop’s errand bike, and it’s been around for a long time. This is probably one of the first mini hubs we ever built, so it dates from around the year 2000 or so. That ratchet ring still looks new. It is possible to wear them out, but you need to ride an awful lot to do it.

Once you have the hub completely apart, clean the bearing seats, axle, bearings (externally only, if you’re keeping the old ones,) and inspect all components for damage. If you see any cracks, crushing, distortion, or deformation then you should replace that part. Inspect your bearings for side to side play. Then, slide your bearing (c) onto the axle (d). If you are installing shims, they should go on the axle, followed by the bearings. After the bearing, slide on a cone spacer (b) and tighten the axle bolt (a) all the way down, finger tight is fine.

Insert the axle assembly through the NDS of the hub shell.

For re-assembly, I recommend actually doing a bit of disassembly first. Since we’re using the driver to help us press the bearings back in, it’s easier if the pawls and springs are out of the way. To do this, lay a light coloured rag down flat on a table, and set the driver down in the middle of it, pawls and springs side up. We’re doing this to reduce the chances of losing one of these tiny but crucial (and expensive) parts of your hub. Note the direction the pawls are facing. Slide them straight up to remove them, and the spring will more or less fall out.

Back on the DS, insert the shim (if needed), the bearing, the driver spacer, the driver, and the cone spacer, and use the axle bolt to hold it all together.

The bearings should not slide into the hub shell at this point - if they do, or if you can slide them in and out of the hub shell with your bare hands, there is an issue with your hub shell.

You will ideally have 2 8mm Allen wrenches for this step. Use the bolt on the far side to hold the axle steady. Make sure that the bearings and cone spacers are lined up square to the hub. As you tighten the bolts the bearings should be drawn into the hub. It shouldn’t take a great deal of force or pressure.

You will feel a definite stop when the bearings are completely inserted. The edges of the cone spacers should also be more or less flush with the curve of the hub shell as well. Loosen the drive side axle bolt.

Slide the drive side axle bolt into the dropout of your frame. Tighten the bolt down again. This should seat the bearings completely. Loosen the bolt, remove the wheel from the frame, and then remove the axle bolt and driver from the hub. Make sure that the drive side hub body bearing is flush with the hub shell. If it’s not, find a deep socket which is as close as possible in size to the bearing itself, and CAREFULLY strike the socket with a hammer so that the bearing is flush in the hub body. The socket should be about a 21mm or 7/8″, the outside diameter of the bearing should be as close as possible to the outside diameter of the socket.

Re-install the pawls and springs into the driver. If you have questions about how to do that, click here. Slide the driver back onto the axle, making sure that the driver spacer is still located next to the drive side hub body bearing. Slowly rotate the driver backwards while pressing the cassette driver towards the centre of the hub. If the pawls prove difficult to slip into the ratchet ring, you can use a slim flat-bladed screwdriver to press the pawls down towards the axle. This should allow the driver to be fully inserted into the hub. It should have a definite “click” when you spin the driver backwards, and it should not spin freely when you spin it forwards. If it does not do these things, the pawls are installed backwards.

Replace the drive side cone spacer, and put the wheel back on your bike. Tighten the bolts as you normally would, and check the wheel for side to side play and smoothness. If you have some side to side play, then you should start over, paying special attention to the inspection stage. If you still can’t get rid of the side play, contact us, and we’ll get it fixed.