CASE CLOSED ..... PROBLEM NOW SORTED THANKS.
Hi - I wonder if anybody can help me here.
I bought a bike almost new off Ebay. It's expensive - hand built. The guy who had it sold it because his circumstances had changed.
The bike had done about twenty miles when I got it and now it's done 140.
Today, in the middle of a forty mile spin, the Sugino direct drive cranks started coming adrift. I'd heard creaking for about fifteen miles and had tried tightening various hex bolts on the chain wheels, seat post and so on to eliminate the sounds, but as it got worse and interfered with gear changing, I spotted what was going on.
This crank set goes right through a hollow bottom bracket and has a kind of disk nut that pulls the main spider piece hard up to the left side (see black threaded disk at bottom right of picture) where a cottered left hand crank arm seems to bolt the whole lot up tight. Just using common sense, it looks like the black disk nut pulls the right hand crank up against the Bottom Bracket and pre-loads it, and the tightening of the two hex bolt cotter pins holds it all together. I've never seen a crank set like this, and though I think I have it about right now, I wonder if any of you bike mechanics can confirm how tight I should have it all pulled together. This picture below is a crankset like the one I've got, but I can't fully confirm that this is the exact one, because mine has three chain wheels.