Noobie assembly question

I bought my first unicycle. A Sun 24" classic

I am assembling and I am trying to attach the frame to the wheel section. But the screw doesn’t tighten all the way. So, it seems loose. Does this look right?


If you’re referring to that gap that I can see, then it’s perfectly normal. (All unicycles are made this way.) Make the two gaps (on each side of the bearing) equal by screwing the two screws equally. Be careful not to over-tighten them!! (It de-forms the outer bearing race.) If you loosen them so that the outer bearing race has a little play, you’ll notice that the wheel will spin with very little friction. (The wheel may have a tendency to turn on its own since they are usually a little out of balance, which is ok.) Now gently tighten the screws until notice a little drag when you turn the wheel. This is how much the should be tightened. You might want to put some blue lock tight on the screws since they won’t be tightened down like a normal screw.

Make sure your pedals are nice and tight, and check them often. They may tend to loosen on their own. Pedaling on loose pedals will wear out the threads.

I just watched your a video (it’s not a still photo!) I assume that you screwed the nuts down as until they hit the end of the screw’s threads. Maybe the manufacturer designed them that way on purpose so that the bearing races can’t be de-formed by over-tightening!. Sounds like it would work - but you will notice some slop in the wheel when riding it. I would find some thin washers and use them to eliminate the slop.

1 Like

OK, great thank you! I guess it is correct then :slight_smile:

The screws are designed so that you can only tighten them to a certain extent, so I assume they are probably just right.

I wanted to make sure before I jumped on and started practicing again for the first time after almost 20 years :slight_smile:


Nope, it’s loose. It needs tightening. The nuts have silicone inside which makes it harder to tighten. Did you use a wrench/spanner to tighten? Looks like you need a spanner to hold the hex head, and an Allen key to tighten the other side. Keep turning till tight, and I like to keep the gap at both sides the same size (often it’s about 2mm)

edit: in your video it might end up as 1mm.

1 Like

I just watched the video. It’s too loose. It shouldn’t move when you touch it like that. I think you need a wrench to hold the nut on the other side still as you tighten it further, as @Gockie said.

That is definetely too loose. Looks like the washer is on the wrong side, should be between the nut and the bearing holder, not on the bolthead. Normally, on this style frame, the bolthead has a little fin that indexes in a slot in the frame (which allows you to tighten it without an allen key), the washer would prevent that.

Are you 100% sure that you bottomed out the threads? Because it looks like you just got to the nyloc part, at which it will feel tighter, but still can be tightened more.

Agree. Anyway, it should all be tight, no play at all and usually there is a little “key slot” for the screw to fit into so only the nut is tightened and the other side usually stays in place by itself using that slot as @finnspin says. But that washer is definitely in the wrong place. (I didn’t see it the first time I watched the video)

Thank you, everyone, appreciate the help. I did put the washer on the right side.
The problem is that the bolt is designed to only screw up until it reaches the tip of one end. I don’t see any other way to tighten.

Here is another video.


That tip of the end must be a black nyloc end.(usually the nyloc is white)
Try screwing it right through the end with force and see if it pushes through.

If the cap is metal then go to the automotive store and grab some regular nuts along with lock washers.


Agree with this. @benjifunk, have you tried a wrench to tighten? The nylon inside the nut is meant to make it very hard to loosen so you cannot tighten by hand.

Thanks, everyone. I really don’t think I can screw it any further. I sent another message to Sun, but so far, they haven’t responded.

Maybe I’ll just return it and buy a better brand. Nimbus, KH, and Impact are recommended brands?

What are you using to tighten the nut? Nyloc nuts can offer a decent amount of resistance the first time they are used.

As a beginner, I found a club completely fine. You can use that for learning on and it’s very solid. Those other brands you mentioned are good as well. You might be able to put a nimbus together on a reasonable budget.

As stated above your nuts are nylon insert lock nuts. It will take a little force to deform the nylon insert. That is normal.

Hold the bolt into the fitting with one hand and use a wrench to tighten the nut. If that does not work, get a bigger wrench.


Yes! That did it. I just had to hold the top part tightly with pliars and force the bolt to turn. What a hassle, but glad, I can start riding now.

This is a very helpful forum, I’m glad I joined.

Thank you everyone who chimed in!