Originally Posted by
CliffordK
The other issue with Octalink, of course, is that a standard extractor doesn't fit. I think I have a bolt that fits well down into the crank (loose fit). But, the perfect size to pull the crank.
Yeah, standard square taper crank extractors don't work but you can use a suitable plug or washer to blank-off the hole in the spindle and give the extractor something to push against. The bolt you found does the same thing.
Shimano used to include a small mushroom-shaped plug with their aftermarket Octalink crank sets and Park made a specific extractor tool for them.