i was riding and looked down and…gasp! here is the crank with the missing piece. its not the side i crank grab with so i dont know how i lost it. i think its just a dust cap but if not…darn.
That’s more than a dust cap, it’s the self extractor for the crank. With that thing in, unscrewing the bolt in the centre will pull the crank off. Without it it’ll just remove the bolt but leave the crank there.
I think they’re threaded the same on both sides, so you should be okay; just don’t lose the other one…
I haven’t worked out a really satisfactory way of tightening the things. I use the end of a screwdriver (or key, if I’m in the middle of nowhere) to push them tight. Presumably you can get a special gadget to tighten them properly…
Phil
Incidentally, IrfanView is a very nice little program that will shrink pictures down so you don’t end up with almost 2MBs of pictures in a thread… 
Phil
I put a piece of spoke in each hole (as they fit well), then lever them round while holding the ends of the spoke offcuts.
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the link doesn’t work:(
Ferko
if i have a crank extracter tool then i should still be good right? just unscrew bolt, then use crank extractor as i normally would with a square tapered crank…
I can’t really tell. Can you post a larger photo?
oh ho ho ho!!
Nope. I have the old onza, and I lost the dust cap on my non-crankgrabbing crank, too. The dust caps are reverse threaded, so a normal crank-extractor will strip out your cranks. Also, the tool for removing the dust caps is called a spanner wrench. I don’t have one, so I use a hemostat (aka roach-clip for you stoners out there), or small scissors.
A note for all you onza owners: I have the old Onza, and when I took apart the cranksert, I found the bolts were tightening on the splines. I put a washer in there to rectify the problem. I reccomend you do too. It only makes the bolt stick out an extra 1/8". Also, the hub works like the profiles. Don’t fully tighten the right crank, alternate. 1/2 turn right, 1/2 turn left… That way the axle stays centered in the hub. If you do one side completely first, you can pull the axle out of the hub (I’m not saying this from observation, but sadly, experience).
I did the same with one of my Profile hubs.
Threaded bolts can create a lot of force with just a little bit of twisting and can easily pull the axle through the hub.
so how do i take the cranks off?
Erm… does this lose something in the translation?
Phil
Well then, how about a pin spanner?
Park Tool makes one.
Park Pin Spanner SPA-2
Picture of it in use
Aaah, 'tis all clear now. Why on earth is it called a spanner wrench (UK: “Spanner spanner”)?
Phil
That’s easy. Just leave the dustcap on and unscrew the bolt. The dustcap is reverse threaded, so when you unscrew the bolt, it pulls the crank off with it. Then, remove the only dustcap, put it on the other crank, and repeat. Check the tightness of the dustcap after putting the cranks back on. Also, leave the dustcap on your pedalgrabbing side, so that if you land hard on the crank, it’ll have less of a chance of ovalizing tha ring on the outside.
Unicycle.uk.com sells spare Onza hub bolts that come with the extraction washers I think they’re £9 though…
Yes, spanner wrench is redundant in the UK. Here in the USA we don’t call wrenches spanners so spanner wrench doesn’t sound at all odd over here. Generally, things like the pin spanner are what we call spanners.