Originally Posted by
Seanaus
sthurman ,the second photo is what Merckx were using on the Corsa Extra with under bb cabling at that time. I believe yours is actually this bb shell with the raised lugs ground off, I seem to see a faint witness mark in your photo of the bb shell on yours (see marked up photo). Likely it was done at the Merckx factory when the frame was made. Out of interest, have you a detail photo of the underside of the rear brake bridge?
I don't think that the cast in cable guides were ground off, they were never there. We're looking at 2 different time periods of BB shells.
My early 80's De Rosa has the same IC BB Shell as shown in the top picture in the post above. Ugo et all brazed on sheet metal cable guides.
NOTE, it only has 4 faux machined in reliefs vs. 6 on the De Rosa Professional Sammontana photo posted by sthurman.
Another NOTE, the holes in some of the BB shells were used to attach pressed in, screwed in or riveted plastic or screwed in metal cable guides that came into play when under the BB cable routing became popular... Around the Aero Fantasy Fad era!
Peugeot used these plastic guides in the late 80's. They worked very well.
Campy made several pretty much non-documented versions of these guides.
Steel... I've only seen them on a few Italian bikes.
Plastic... Never seen one... ???
Back in the mid 70's there was a notion that a single hole at the bottom of a BB would allow water to drain out when riding in the rain... something that I quickly disabused myself of (unless of course I got caught in a storm).
Several points: 1. Under the BB cable routing allows a of dirt and gunk to get into the cable runs increasing wear. 2. Most of those setups can drastically increase friction on the cables themselves. Unless well laid out, the cables rub against the BB shells.
verktyg NEVER A SLAVE TO FASHION!!!
.