Originally Posted by
Duragrouch
You may be correct. I don't know: Crowd, do they make adaptors to convert press-fit to threaded BB, and is there still space then to use a 24mm(?) hollow-spindle crank with external bearings?
EDIT: Maybe; They make adaptors to convert 42mm BB30 or 46mm PF30 press-fit BBs to BSA threaded to take 24mm hollow-spindle cranks. I don't know if your "pressed-in ISO square taper" is in one of the above BB shells.
Originally Posted by
mphey
This is all really useful info, thank you! The guy sold me the frame with a ISO square taper BB already in there, but since I'm building the bike up from scratch, my thought was to prioritize finding a quality square taper crankset first, then replace the spindle to fit whatever that crank is. I know Phil Wood sells both ISO and JIS taper spindles, so I'm ok to make the switch to JIS if that's ultimately the best option... but the existing ISO square taper spindle planted the idea seed of of putting a Campy group on the bike. The previous owner told me it previously had a Campy group, but he wasn't sure which.
I missed the part about this being a Merlin with a pressed BB. No: There are no adapters for this particular BB because the diameter is on the small side. There are adapter BBs for pressed in Kleins, but they are larger diameter.
Given the production dates of the pressed BB Merlins, this is almost certainly the 111mm spindle for the 1980s/early '90s C-Record/Croce/Chorus/Athena/Xenon cranks. The wrinkle is that Phil Wood doesn't believe '80s Campy cranks were ISO, so they would spec JIS for those cranks. I have no idea what Merlin did at that time. In my experiments '80s Campy
was ISO, but who knows how Phil shapes their tapers. Here's how you can tell them apart:
So measure the spindle length and look at the tapers to guess what kind of spindle it is. You don't have the ability to just use any crank, because the Merlin BB shell is (I recall) wider than a BSA 68mm shell, so the later Campy, Dura Ace 7410 and Speedlight cranks that take 102/103mm spindles would bottom out in the frame.
Any decent '80s crank will work fine with 10 or even 11 speed - especially if you upgrade the rings - but there isn't a real compatibility issue (though 11 speed chains, with some chainrings, can get caught between the chainrings. Try it and see.)
Personally, if this is indeed a spindle for that era of Campy, I'd find an old Chorus or Athena crank. They were beautiful and not expensive used. Campagnolo continued using 111mm spindles with their lower level groups like Mirage/Daytona/Centaur after Record and Chorus went to 102mm. So there are a lot of choices for a compatible crankset.