Help on Tightening a Maincap

After 70km’s of riding, one of the maincap bolts has loosened and the maincap is making noises on our KH 24 MUni. We have the tools, but I am worried about over tightening the bolts and possibly crushing the bearings. How tight should the maincap bolts be? Thanks…

Just tighten it a few turns, then spin the wheel. If the wheel goes for a long time, tighten it a little more, then check again. If the wheel seens to stop abruptly or doesn’t spin very long, the bearings are clamped on too tight. Make sure you don’t overtighten one though. For every turn on one bolt, try to turn the other one. Eventually you will get a feel for it.

people always say you shouldn’t over tighten them, but I cinch them right up and don’t have problems with them.

I use hardware 1/4" bolts (1.5" long i think) with a lock washer (you would now need 2 11mm socket/wrenches)

they don’t come undone, and will bend slightly instead of snapping off. I have replaced all seat bolts and main bolts on all my unicycles, and them loosening on any no longer crosses my mind.

I highly recommend doing this

Thanks… Normally how long should the wheel spin freely?

It’s really a judgement thing. For me if it spins long enough to piss me off and have me stop it with my hand (I am impatient), then it is too loose. Like Brian said though, I have never killed any bearings just by running the clamps too tight.

i dont think ive ever actually killed any bearings doing this, but you can feel the difference.

Now i just do them up as tightly as posible as I can with my fingers, then nip them up a bit further with a spanner, I use lock washers which helps a lot

My rule of thumb is to tighten the bearing caps finger tight. I hold the allen key with my finger tips. If you make a fist around the allen key you are going to get it too tight. It just needs to be tight enough so that there is no slop.

For my unicycles that have nuts, rather than allen bolts, I use a nut driver and hold the nut driver with my finger tips. Again, I don’t make a fist around the nut driver. Just use my finger tips. A nut driver is like a screwdriver but it’s designed to turn nuts.

If you have problems with the main cap bolts coming loose you can use Loctite threadlocker on the threads. I haven’t needed to use Loctite on my main cap bolts. They stay tight enough without it.

Here’s a little exercise to see how tight the bearing caps need to be. Hold the unicycle upside down. Loosen the bearing caps so they are completely loose. Now spin the wheel and watch how long it spins, how smoothly it spins, and how smoothly it comes to a stop. Now tighten the bearing caps down really tight and spin the wheel again. It won’t spin as long. When it comes to a stop it will do so with a little bit of a jerk and may even snap back a little bit. That’s too tight. The correct tightness is when the wheel spins almost as freely as when the bearing caps are completely loose.

Having the bearing caps too tight won’t instantly ruin the bearings. It will cause the bearings to wear out faster than normal. It will also cause more drag on the wheel.

On a freestyle unicycle indoors in a gym it is easy to feel the extra drag on the bearings when the bearing caps are too tight. On a muni it is harder to feel that additional drag because the wheel is heavier and you’re not riding on a nice smooth surface. But the extra drag is there and if you’re real picky you can feel it as you’re riding.

I use an iteration of the John Childs and ObieOne methods. Start with all four bolts finger tight and the main cap bearing holders spaced equally. Tighten both bolts evenly on one side (left or right) until the wheel drag appears then back it off. Now you know that side is adjusted perfectly. Then, do the second side the same way as the first. This way both left and right sides get tightened properly and there is no confusion about which side is causing the wheel drag when tightening.

Good afternoon! Thanks for your pointers everyone…

I wish I saw this when I first got my unicycle. I tightened one of the nuts to the point of it snapping a bolt :open_mouth: . It came with two extras though, and I backed off the other nut I had put on already and its fine now.