Here's an easy question for someone out there, though I suspect I'm not the only one that's been caught off-guard so maybe this question will help others too.
Back in the 70's I'd installed a sealed bearing bottom bracket set-up (unmarked, maybe Edco?) in my 1975 Masi Gran Criterium & chunked the original Campy BB. I'd completely forgotten about doing this until recently. I wanted to go back to original specs so I bought a replacement Campy BB set-up. But, I was having trouble getting everything assembled. The spindle appeared to be too narrow causing me to just barely run out of thread to install the lock ring on the adjustable cup. The spindle was correctly marked for a 70mm Italian BB shell and of course both cups were marked for Italian thread. I started looking at the cups and come to find out, the fixed cup I installed was a "thin cup". I subsequently installed a "thick cup" I had on-hand and now all is well. About 2mm difference.
My question is why do two different width cups exist (thin cups & thick cups)? Is the thin cup simply an earlier version? From what time period and for what use? Is it just the fixed cup that appears in two varieties or is there supposed to be a matching "thin" adjustible cup?
I haven't had to mess with the fixed cups on my bikes very much over the years so this experience was a new one for me (and VERY frustrating until I figured out what was going on!). Can someone shed some light on this thin cup/thick cup subject? Thanks
Mark Winkelman
Dallas, Texas USA