JIS vs ISO headset size -- have I wrecked my frame?
I stripped down & rebuilt an old hybrid bike earlier this summer, and ran into some confusion buying a new headset for it. The first one I bought was JIS and the 27mm fork crown race seemed too big -- it just slipped right onto the crown, so I took it back and bought an ISO one which was too small (race wouldn't sit straight enough to be hammered down.) Then when I tried putting the original crown race that I removed back on, it slipped right down too -- must have been held on with loctite or something originally. So I guess the frame/fork must have been supposed to be JIS size (the frame was labeled Roland -- anyone heard of this?? -- and "made in taiwan". I think it's from around 1991).
Anyway, on the advice of the friendly LBS mechanic I ground the inside of the new crown race down enough them to install it on the fork, and it all seems to work now. What I'm kinda worried about is the OD of the head tube cups (30.2mm instead of 30mm). Is that enough of a difference to crack the head tube or cause other problems? this sad story
makes me wonder...
thanks for reading a long question! any advice appreciated...