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So, I have a stuck lock nut on one side of my front axle, and I can't seem to get the axle out pushing on the other side. I need some pointers on diagnosing and repairing this.

The bike is a Merida Speeder 300, and the product page lists the hub as "Bearing disc". The bearings are cartridge bearings, which means this answer doesn't help.

Here's a shot of the stuck nut:

The offending nut

I believe the cause of my troubles is that those outward-facing ruffles have been tightening the nut.

The other side looks like this:

A cartridge bearing with a threaded axle sticking out

There's nothing on the axle where a wrench could find purchase.

The nut and assorted washers that came off are these:

A nut, two washers and a thicker washer with a rubber collar

The other side of the nut is flat. Only the nut is threaded, and it's the only one that has flat sides for a wrench to grip.

What I have tried so far is to grip the free end with a pair of pliers, but I didn't get a good enough grip to get the other nut loose. I have tried to push the axle out from the free end, including whacking it with a rubber mallet a few times, and I even tried to put my weight on the hub with the free end resting against the ground. The axle hasn't budged at all, as far as I can tell, and I'd at least like to have a second opinion before I try to hammer the axis harder than I already have.

  • Maybe it is obvious: on each side, there are two nuts - inner and outer, which are tightened against each other such that they can't move on the axle. To open them, you need two wrenches - a slime one (called "pedal wrench") to hold the inner nut, and a regular one for the outer nut, which you will turn. – Christian Lindig Feb 10 '18 at 18:42
  • @ChristianLindig am I missing something here? Can you point out where this part is on the side I managed to dismantle? – HAEM Feb 10 '18 at 19:01
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    I don't think it should be a pedal wrench, rather than a cone wrench. – Grigory Rechistov Feb 10 '18 at 19:01
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As this hub has pressed-in cartridge bearings, it means that the axle sits pressed into the inner races of both bearings and cannot be extracted without some sort of smashing process. This is meant to be done when your are about to change both bearings as they are not designed to be reused after extraction. All in all, it is expected that you are unable to extract the axle at this point.

The lock nut is unrelated to axle being "stuck". If you screw on two locknuts on another side of the axle again, you can use them to place a counter-action wrench and thus be able to unscrew the thing from the other side.

  • I see. That would explain the locking pattern facing outwards, too. – HAEM Feb 10 '18 at 19:20
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    I was going to add a comment to the question that a hammer is generally the wrong tool, it takes things from PROBLEM to REPLACEMENT-NEEDED. But I've never owned a bike with cartridge bearings, so based on my rollerblades this sounds plausible. – Criggie Feb 10 '18 at 21:02
  • You don't usually remove cartridge bearings unless you are planning to replace them. – ojs Feb 10 '18 at 21:29
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If you tap on the side of the axle that has the nut removed it should push the axle and bearing out. Use a rubber or plastic hammer. You could also place a block of wood on the axle end and tap it with a regular hammer. Once the axle is sticking out of the hub you can grab the non bearing seat surface with a small pipe wrench or vice grips to loosen the nuts.

  • Is a pipe-wrench rather drastic and desperate measure? It damages whatever it clamps, especially soft aluminum. – Grigory Rechistov Feb 10 '18 at 19:12
  • A small pipe wrench say 6 or 8 inches long will do less damage then pliers if used correctly. Small scratches from the jaws on the non bearing seat surfaces will be of little or no consequence. – mikes Feb 10 '18 at 21:23
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    You know, there are tools designed exactly for this job. They are called cone wrenches. – ojs Feb 10 '18 at 21:28
  • Taking the other set of nuts off will not make getting the axle out easier. The bearings are pressed into the hub and onto the axle.. – mikes Feb 10 '18 at 22:02
  • I'd just like to point out that my problem is that my wheel doesn't have cone nuts and I can't knock the axle through with a rubber hammer. – HAEM Feb 11 '18 at 18:11

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