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enter image description hereMy rear wheel was wobbly so I tightened the hub bearing which removed the play but caused the wheel to stop rotating freely. Stupid question I suppose, but is the adjustment just a matter of trial and error?

the adjusting nut is cone shaped with no flats for a spanner!

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Yes - bearing adjustment is very much trial-and-error.

The bearing balls must be located so they are restrained from moving in any direction except around the race.

Do do this, the mechanic must "preload" the bearing so there is slight compression all the time, but not so much that the bearings cannot spin freely.

This process is hard to describe but can be felt directly.

TOO LOOSE: detectable play in the bearing in the left/right or up/down direction.

TOO TIGHT: bearing is hard to turn and resists correct operation.

Make it easier on yourself by:

  1. Disassemble and clean the cups, cones, and all balls before assembly.
  2. Inspect after cleaning - if there's pitting on the cone or cup consider your options. If the balls are not shiny and round then simply replace them. Bearing balls are cheap.
  3. Use grease to hold the balls in place while reassembling
  4. Use the right spanners - cone spanners exist and are especially thin to make this task accessible. If you're using normal spanners, or pliers then it becomes harder.

Ideally you'd tighten the cone nut till it's perfect, then put the locknut on . But the locknut always interferes with the placement of the cone. At this point its a matter of adjusting things by an eighth of a turn.

If you can't find the sweet spot between tight and loose, its okay to have a very small amount of play more than having resistance that fights you and chews up the bearing races over time.

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    If you have the above described loose ball bearing system AND a quick release axle, be aware that the act of closing a properly tightened QR skewer deforms the hollow axle ever so slightly causing the preload. To be tighter. Thus what seems to be good when the wheel is off may be too tight when installed. A QR axle system should have a tiny bit of play when set and out of the bike.
    – Jeff
    Commented Mar 25, 2023 at 21:48
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    Tips: You can utilize the tightness of the skewer within a narrow range to adjust preload. If you detect some play after install, open the skewer and tighten the acorn nut a ¼ to ½ turn then close it back up. Check if the play is now gone. Similarly if the wheel is too tight after install, can the skewer be loosened a bit while still ending up. This direction should be used more discerningly.
    – Jeff
    Commented Mar 25, 2023 at 21:51
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    I love the art of adjusting a loose ball hub. Especially QR hollow axle ones. I'm not satisfied until the installed wheel has zero play but will pendulum at least twice each way as it comes to rest.
    – Jeff
    Commented Mar 25, 2023 at 21:57
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    Clarification of some aspects of my comments above: In the first above regarding preload. It's more correct to state, closing the skewer results in ADDITIONAL preload. In the second, I'm simply stating that that effect can be leveraged to finish with a more perfect preload. And a secure wheel.
    – Jeff
    Commented Mar 26, 2023 at 2:15
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    @jeff all those comments together can be a great standalone answer.
    – Criggie ♦
    Commented Mar 26, 2023 at 4:32
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I find that the parktool approach removes the uncertainty (HUB ADJUSTMENT - CARTRIDGE BEARING HUBS, step 9) https://www.parktool.com/en-int/blog/repair-help/hub-overhaul-and-adjustment

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