Need a screw

I bought a Qu-Ax 29" and I was riding halfway then my crank fell off. Now I’m not too sure whether the screw came together in the box or whether it slipped out while riding.

Does anyone know where to get such a screw? Circled in red. Click link for big picture.

any bike shop, it’s a standard part

and incidently that’s a bolt

Apparently not, going by the way my engineer wife keeps correcting me when I call things bolts…
Apparently if the thread goes all the way up to the head it’s a set screw. If there is a plain shaft with the thread just at the end, it’s a bolt.

Or so I’ve been told.

But anyway, to stay on topic… yes, they’re easy to get from any decent bike shop.


Amusing thread title, by the way. Yak yak.

Hohohohoho, agreed.

Here’s a catalog page with what you need. That is the US name, not necessarily the UK name. I would suggest going to a bike shop and asking for a self extracting crank bolt with dust cover and 8mm allen head. They’ll have a variety of them for a couple of bucks US.

question: is it your left crank that got unscrewed?

Yeah. It dropped off somewhere, the one in the photo is the right screw with the left crank+pedal.

That’ll be understood here as well. Everybody calls them bolts anyway, even if they are technically set screws.

There does seem to be a difference between British and American usage of “set screw” however. If you Google “set screw”, the American references are for what we would call a “grub screw” (no head).

Just call your thing a crank bolt and you’ll be fine.


Edit: FWIW, I think the one in your picture is a normal allen(or hex)-headed crank bolt with an integrated plastic dust cap, not a self-extracting one. The self-extracting ones have a thread on the (usually metal) dust cap bit that screws into the extractor thread on the crank, so when you undo the bolt it pushes against the fixed dust cap and pulls the crank off without having to use a separate puller. If yours has a thread on the outside of the dust cap bit, it’s self-extracting.

Yeah, I’ll need the French translation. lol

I have a set of allen keys, which is what I used to take out the right screw you see in the picture.

You are correct here. I used a normal allen key to remove that particular screw. I should have taken a more complete picture. I have no idea how the “self-extracting” ones look like. =/

Wait, I’m confused now.

“Self-extracting” refers to the tool or the screw/bolt? Cos’ the link harper showed is the exact same thing which I’m lacking on my left crank.

I went to a unicycle shop where I am and they couldn’t find a screw of the correct length (correct size though). I’ll try a bike shop as suggested.

Even better is to take the one you have into the bike shop and say, “give me one of these.” Here’s one of the standard types.

You can find one on most street corners after 8pm.

A self extracting bolt is one that is designed to pull the crank off as it is undone, thus negating the need for a crank puller tool. It comprises a bolt and a seperate threaded ring. The bolt goes in first as normal, then the ring screws in to the crank. WHen the bolt is undone, it preses on the inside of the ring, pulling the crank off as it unscrews.

But the one you pictured isn’t self extracting, it just has a black plastic dust cap.

Wow, never saw those self-extracting bolts (/set screws) before. They look like they could be really handy in times when you have to switch back and forth. Too bad my Coker doesn’t use bolts. I almost ordered a pair from that catalog, but the shipping was $9.50 for the $15 item. I’ll find them somewhere closer…

They were standard issue on the KH/Onza cranks. Two issues with them:

  1. the rings come undone and fall out unexpectedly sometime
    2.doing up the rings to ensure they dont come lose and fall out requires a special tool that will fit in the two small holes. A pair of circlip pliers can be used, but not ideal.

I went to a few bicycle shops the past week, some had the screw, some didn’t.


The screw is the wrong length, the ones at the bicycle shops is longer.

Any ideas? Other than cutting it? (Which is rather difficult where I am)

were they actually bottoming out in the hub thread, or just longer than the bolt you have currently?

They’re just longer.

i.e. If I did indeed cut it to the correct length, they “should” work just fine.

It only takes a hacksaw to cut it to the same length as your other one; can’t you borrow one? FWIW, when I need to cut a bolt/screw, I put a nut on the screw first, and tighten it up so that its end lines up with the place I want to cut. Then, the nut acts as a little guide for your hacksaw as you cut. When it’s cut to length, you unscrew the nut, and it re-cuts the threads into the end of the bolt (which sometimes get messed up when you cut it).