Loose Pedals

Today my new nimbus trials uni came in the mail, and I assembled it correctly, but my pedals seem to be coming loose quite frequently, and I have only had the unicycle for one day. Other posts about loose pedals all suggested that the pedals/cranks and whatnot could be on the wrong side, but mine are all correct. Others suggested riding backwards can cause problems, but I don’t ride backwards nearly enough for the frequency at which the loosening occurs (unless a few backwards rotations are the problem). I’m using the venture cranks that came with it, and the pedals that came with it as well.

I did have problems attaching the pedals to the cranks, I used the correct wrench to screw them in, but the way the crank is shaped did not allow me to tighten it enough, so I used an allen wrench and screwed it in from the other side, and adequately tightened it. Am I missing something? What could be causing this, and any tips on fixing this?

You’ve probably oriented your seat towards the back of the uni, thus you are effectively riding backwards.

I don’t understand why there isn’t a special lockring for unicycle cranks/pedals. They are intended to be ridden backwards, are they not?


  • Make sure your right foot is on the right pedal, and left on left. The right pedals threads normally (clockwise to tighten) and the left one is reversed. Even if the pedals were tightened with an allen wrench from the back, they shouldn't come loose easily; they should tend to tighten themselves.
  • If you did much riding with the pedals loose, you may have damaged the threads, making them hard or impossible to keep tight anymore. Hopefully not, as this will mean you need new cranks.
  • Your second paragraph makes me wonder if you have the cranks on inside out? I don't know if that's possible or not. Did the unicycle come with the cranks already attached?
  • Take it to a bike shop, where they have proper pedal wrenches, and can check to see if it's set up correctly. [/LIST] Lockrings or similar are not necessary, If one is planning to do extensive amounts of backward riding, turn the seat around and you'll be fine. Otherwise, properly tightened pedals should remain tight.
  • The cranks were already attached, and I’ve made sure everything is on the right side. I do go backwards sometimes, but I’m just learning to go backwards so I cant go for more than a few rotations. I think a pedal wrench was supposed to come with my unicycle. The papers that came with it listed the parts that were supposed to come with it, and it said pedal wrench, but only for some models, so I assumed my model didn’t need one because it didn’t come with one, and the regular wrench couldn’t tighten it enough because it was too thick, so the cranks aren’t backwards or anything.

    I hope my cranks aren’t stripped, but sometimes I ride for a few minutes before realizing the pedals are loose (riding forward does seem to tighten them, so I guess it is going backwards that does it), so I tighten them before further riding, but there is some loose riding. How easy is it to strip the cranks?

    It’s pretty easy to strip Nimbus Venture cranks. It’s likely they’re stripped already and that’s why the pedals keep coming loose.

    That’s a bummer. Is there some sort of screw adhesive that could help?

    mabey you could retap them

    Except you’ll need a set of special taps used for pedals to do it… You need one for each side as they thread in opposite directions.

    Take it to a bike shop or go buy yourself a proper wrench before the cranks are wrecked!

    most bike shops would tap them for free.
    and +1 on the wrench

    What damage can a regular wrench do to the cranks? because I did use a regular one at first, but once I saw that it wouldn’t work, I used an allen wrench from the backside.

    When you say a “regular wrench” what do you mean? Any 15mm open end wrench should work for the majority of pedals out there. Some pedals, mostly old French ones and Trailmix’s, use a 17mm open end wrench. Using an allen wrench from the back side is fine. You really don’t need to tighten pedals on very much as they tighten in use. The reason they make special pedal wrenches that are really long isn’t to tighten them on, but to take them off after they have been ridden for a while. The harder/longer you ride, the tighter they get on the cranks.

    There are only two reasons that pedals would loosen under normal riding that I can think of. First that you have your uni backwards, and are in fact loosening them rather than tightening them as you ride. The other, which is highly unlikely, is that the bearings are so tight that the pedals don’t turn freely on their spindles.

    Beyond the stuff that everyone, including myself, has posted I would bring it to a bike shop and see what they think.

    The regular wrench will not do damage, it is riding with loose pedals that is likely to cause damage. Tightening with a fat adjustable wrench ends up pinching the wrench between the pedals and the crank. A narrow non adjustable pedal wrench or an allen key is more suited. If your allen key is short it will be hard to do them up tight I imagine. A 15mm wrench/spanner is what I use.

    Yeah, I used a 15mm wrench, but it was too thick so I couldn’t tighten the pedal enough without scraping the cranks or getting the wrench stuck. It wasn’t because of the pedals though, it was the way the crank is shaped, it has a little lip on one side of the screw hole. I used an allen wrench, but it was a pretty long one, so it’s tough to use too (spokes get in the way). Are pedal wrenches thinner or something? The pedals do tighten when I go forward, but riding backwards, not even a lot, they loosen, but I guess thats not to much of a problem.

    My pedal wrench is a standard non-adjustable wrench, a pedal wrench might be a tiny bit thinner and have a crank tool on the other end but it is basicly the same thing. Your one sounds like it is a fat one if it pinches. Take your uni in to a bike shop or a hardware store and compare wrenches that fit.

    You should not be able to tighten your pedals by riding forwards, because they should already be tight before you start riding! If your pedals are done up really tight they should not loosen in theory from riding backwards, especially if riding backwards is not your main direction. Loctite can be used for threads that have an annoying habit of undoing themselves, and is not normally needed for pedals but if all else fails you could consider it.

    If you ride with loose pedals the worst thing that can happen is the threads can be damaged and it is quite possible with the aluminium threads in ventures. Buying new cranks can cost a bit but the lesson about not riding too hard with loose pedals is a valuable one.

    Yeah, they are always tight when I start riding, but if i practice going backwards a bit, they get loose so I just ride forward and it tightens them, if they get really loose, I stop riding and tighten them. Also, my wrench isn’t fatter than any other wrench i’ve seen, its a pretty standard wrench, but the cranks have a lip on one side of the screw hole, that’s why it grinds or gets stuck.

    I’ve got a nimbus trials, and on the venture cranks there is no lip the holes are flush. It’s weird that your one would have a lip to get in the way, I wonder if it is the new venture cranks. The allen key should be enough to keep tightening them, and if you get sick of it you could stop riding backwards so much, or turn your seat backwards for any long backwards sessions.

    it’s not really a lip, it’s hardly noticeable, but it’s just tad thicker on the side where the crank ends making it hard to use my wrench without scraping and grinding at it or getting to tight and wedging the wrench.

    post a picture

    I just found that my 15mm doesn’t fit very well on the Nimbus pedals and it seems to prefer a 16mm one for me. On my one the pedals themselves have a lip so only the 6mm wide tip can contact then it gets wider and rounder closer to the pedal, making any wider than 6mm not suitable.

    I’ve never been completely satisfied with those Nimbus pedals, there is something about them that has not felt tight, even though the threads are done up well the whole body moves a bit like the bearings are loose, but only once in a while. Peter told me he threaded two sets of ventures before getting moments, but my riding is pretty weak so I don’t need to upgrade.

    I got similar effect when I was learning to ride backwards just after I’ve assembled my uni. I stopped riding backwards for some moment, and after a week or two of riding forwards my pedals were so tightened by just riding that they stopped getting loose while riding backwards.
    It should not be a problem, but if it is, then let them get really tight by riding only forward for some time after the assembly.