I've gone and done it now!

not sure if it was over-enthusiasm or the plastic cap had just UV ray degradation, but I've managed to remove the entire outside of the cap but left the threaded part inside the crank. so i'm not getting a socket or crank puller in there now!

anyone suggest a way to dig this out? could I dissolve it was acetone or something equally nasty?

thanks.

oh, yeah - I need two "Sugino" dust caps, too!

A chisel or pick of some sorts, some elbow grease, and a little careful determination.

...at least that's been the consensus when the topic's come up before:
https://www.bikeforums.net/bicycle-me...eck-frame.html

I'm thinking a small metal tool, perhaps a sharpend paper clip, a pick of some sort (or the right dental tool). Keep it small so damage to threads stays very local and the odds are the crank remover will sort all the damage out when it is used. (Damaging the threads until the remover cannot be started or wrecks th threads is a big problem. With force, you can still get the crank off but its life as a useful bike part is over.

Ben

Get an exacto keyhole saw. Or, if you can't easily find that, a knife with a blade edge that is parallel to the axis of the knife handle (like the pic below). Take that knife and place its sharp edge against the face of a sharp file. Whack it with a hammer. The file should cut little "teeth" in the blade. But a keyhole saw is better.

Saw several radial cuts in the remaining plastic cap, almost to the crank arm threads. Then use a chisel to break off part of the cap. The rest of the cap should then easily be removed using an awl, or a dental pic.

I think i'll end up using all of the above!

thanks for the encouragement; will report back when "mission accomplished".

Usually you can just use a punch to unthread the remains. If the plastic shatters more, big deal. If enough shatters, it will just fall out without unthreading.

N.B. ther caps aren't strictly necessary, but they do help keep the extractor threads clean. If your bottom bracket has a "female" type axle, you can get Allen head bolts with integral caps to keep the threads clean.

those are what my Surly LHT has. if they would work, it will save me the hassle searching for covers. right now, the penetrating oil is earning its keep so it might be a couple of days before I summon the courage to attack the crank bolts.

as easy as the rest of the bike fell apart, I think the crank bolts will make up for gained time.

++++ X-acto bladed hobby knife.

Or hit the plastic with dry ice or liquid nitrogen, followed by a tap with a punch or screwdriver and the plastic will shatter.