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I recently bought a second hand bike which was originally sold with a flip flop hub to fix up as a project. The person I bought it from gave me a rear wheel with a geared hub.

However, when I put the wheel onto the frame, the remaining axle that sticks out is quite small; when I put a locking nut on it, the axle doesn't go all the way through the locking nut. There are maybe one or two threads left. I can use a wrench to tighten it very tight, and it does seem to be quite strong; however I am no expert.

Essentially: Is this safe or am I in danger of the wheel falling off? Should I swap the wheel out?

Sidenote: I have never dealt with geared hubs before. Do they always make a sound when rotating? Because that could get annoying for me.

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    If you had to ride ten miles to save your life, you'd probably survive on that. But I wouldn't want to bet on twenty. – Daniel R Hicks Apr 18 at 1:50
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    There should be a washer between the nut and frame – ojs Apr 18 at 5:19
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    Its never going to be 'lawyer will sign it off safe', using a high tensile nut (which this does not appear to be, no marklings) would make it safer. By the time you add the washer, its probably less than a turn of thread, I would not use it. – mattnz Apr 18 at 8:39
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    Is there maybe a washer on the shaft, behind the dropout? – Daniel R Hicks Apr 18 at 12:12
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    Would you please add a photo showing the hub and bolt from the side? This might inform about the reasons the bolt is too short (which I find surprising). – gschenk Apr 18 at 15:14
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What kind of hub is this? That'll help answer this question.

However... you're installing a hub in a way that's non-standard. Even if, as Cedric's answer indicates, the first 3 to 5 threads take all the load, you're exposing threads to the elements and this will be, at best, only a temporary solution. The bolt is going to rust in time.

I can use a wrench to tighten the shit out of it

Bike parts have specific specs that indicate how tightly you should attach them, using a torque wrench. How tight you make this bolt is going to depend on what hub you have, but to use a common example: the Shimano Nexus inter-8 hub has a rating of 30-45 newton meters. (See page 18 of the Dealer's Manual PDF) There's also a specific set of non-turn washers you should be using. (See page 17, ibid.) All of this will change based on what hub you have, of course.

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Usually, only around three to five threads take all the load, so check if you have that many threads overlapping between the nut and the axle. If you do, make sure you put grease on the threads so that you can get the nut tight, and you should be ok. However, make sure there is no grease at all, or any contamination for that matter, at the interface of the nut and the dropout.

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    What about washers? – gschenk Apr 18 at 8:04
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    In this case, I advise against washers because they would reduce the amount of overlapping threads. Instead, I recommend one of these nuts: images-na.ssl-images-amazon.com/images/I/… – Cedric Eveleigh Apr 18 at 13:12
  • Would you be so kind to include these nuts in your answer? It might not be a good idea without. – gschenk Apr 18 at 15:11

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