Hi

I’m considering converting my good old Kona Caldera to a 1×9 or 10 set up.
I think there is a shimno ES30 Octalink bb on it, so I guess I’ll be needing both a new bb and a new crankset.
Or are there any single ring cranksets out there that will fit this type of bottom bracket?

Just fit the new chainring to the middle of the triple chainset you currently have. No need for new. Unless of course you need an excuse…

Yes should work alright.
I was considering giving the bike the big overhaul, but looking at the state of it just now, I get second thoughts.
Will be rather expensive before I’m done. So I think I’ll just strip the extra rings and fit the new one to the middle as you suggest.

Cheers

You should be able to remove the outer and inner ring, leaving the middle on there. Need shorter chainring bolts or a bash guard

Charlie the bikemonger does a pack of short chainring bolts.