Crank bolt came loose after about 6 hours, what did I do wrong?

Was very unsettling to notice the right crank was loose during riding today. I changed (for the first time ever) cranks about 6 riding hours ago or so. I noticed it right away, and re-tightened it. This was the same topic I was asking about Blue Loctite for crank bolts. Why is mine coming loose? I used the exact wrench in the photo below. I gorilla’d the heck out of it. It’s as tight as anyone can get it with that wrench. And just in case - they are on the correct sides.

Thanks in advance for any insight!

Well this has been covered to heck n back,
Proper spacers installed?
Place a piece of wood over the bolt area and drive it home with a dead blow hammer?
Last, tighten as you have!
I have never had to use locktight, but many swear by it.

1 Like

Yeah, I did do a search, but it sorta was kitchen sink stuff. All over the place.

I installed spacers as instructed by, and even chatted with them as I did it actually. Bought the spacers new and bought calipers for this. I’m not new to using calipers either.

As far as a hammer, isn’t that for cotterless only?

I do appreciate the response and hints. Thank you.

A rubber mallet, dead blow hammer. Not to pound it/nail it together. To leave no spaces before you allen key it tight.

1 Like

I think I understand, but I also think it would be to pound it/nail it together. To close any minute gap between the spacers and crank and bearing.

I mean, it makes sense, I just haven’t heard that in any of the multitude of videos or threads I’ve read. I’ve seen that for cotterless, but never for ISIS.

Regardless, should I be seriously concerned? Would you suspect I should take it apart and start again? Or just tighten and watch it?

Thanks again.

Your allen key is very short. If you use a longer one you’ll have more torque.

1 Like

I wondered about that. Something I can get on Amazon I’d suspect.

This I can certainly try. Thank you.

EDIT: if anyone has any Amazon links to any sets they recommend, I’d love you for it :smiley:

Also you may need narrower spacers, I can’t tell by the pic.

1 Like

You can use a hollow metal pipe as a handle extender/add leverage. Very useful.

1 Like

Spacers were ~10mm on one side, ~12mm on the other. I left the instructed 2mm gap for both sides before tightening.

Good idea! Thank you.

Ugh! That’s unsettling news! :astonished: Now I know not to buy a Nimbus, or those cranks.

1 Like

Oh well I love Nimbus. I don’t instantly think this is a Nimbus thing. I think this is a ‘guy changes cranks for the first time’ thing.


Ooohhhh, that’s a relief. So, I just won’t change the cranks. Problem solved. :+1::slightly_smiling_face:

1 Like

Those spacers sound quite thick.

1 Like

I know. I agree. Thats originally why I contacted unicycle dot com when I was doing it.

I have found that after the first time changing things they loosen in a few rides. I suspect this is due to bedding in. After the first good hard tightening, the crank gets slowly pulled in more, even though there is a spacer, to the point the bolt is loose. Also seat bolts do this a lot for me. After I change out a saddle, I’ll check the bolts after each ride for two or three rides because they inevitably bed in and loosen up before finding their final sitting point. Just tighten it as hard as possible again and you should be fine.


Yeah, this could be the explanation too. Thank you. I’m going to extend the length of the wrench, and gorilla it even more. Hopefully that’ll do it. In the meantime I’ll keep watch.

If anyone thinks I should rebuild this thing, please just leave me a note. Otherwise I’ll just keep watching. I hope that makes sense.

Thanks everyone.

So I had some cranks come look for me too, it was a specific side of a crank on a specific set on multiple hubs and I found the solution was just to check it a bit more regularly.

Hopefully the issue does not reproduce on different crank sets

1 Like

Test 8 mm spacers! I also never used 10 mm spacers

1 Like