Duragrouch

This is all geekily interesting.

Thalia949

The local group of "experts" will be meeting at the Velo retro ride tomorrow in Pasadena. A suggestion is to bring it along to see what expertise, if any, is available before the ride.

The ride meets at the aquatic center at 10:30am.

Cheers
Warren

CyclesMakaron

Roto products were not used in the Merckx cycling frames

Fredo76

Somebody knew what they wanted and paid to get it. Probably a relatively rare example of a truly custom '80s steel frame, actually built to order, unlike the ones rush-built in standard sizes, with machined cutouts, pre-manufactured 'craftmanship', and pantogragh silliness.

sthurman 

It looks similar to me to BB that De Rosa used in the era. The white photos are from a frame I owned, blue is another variant of De Rosa I found online. The Merckx example lacks the underside cable guides likely because it needed topside cable guides for the single aero shifter mount.

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?

verktyg 

I've don't recall ever seeing a "modern" investment cast BB shell fail. Back in the mid 70's we got in some Guerciottis with sharp pointed star cutouts in the BBs. A number of them cracked at the points because they were "stress risers". Eventually a new importer started bringing in Guerciottis to the US that had rounded points... Problem solved.

BB shell on my 1985 Eddy Merckx. Same as some posted above. It's a 56 cm Corsa with a Z Date Code.



I have seen a few welded design BB shells crack at seams. Poorly welded??? The welded seam on this BB shell was pretty well done, maybe on some kind of automatic setup. A lot of cheap Italian 1970's bikes had really bad welding but they were pretty thick so that helped.



Can't speak for any cutout BB shells done by weight weenies who got carried away.

verktyg

sthurman 

I think you're right. Here is another angle of the BB and the underside of brake bridge.

verktyg 

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!!!


.

Seanaus

Merckx did use the earlier style of bb shell with brazed on straps, but, as you say this is a different, later, time period. You can see in the marked up image vestiges of the cast in grooves that remain after the wings / ribs you see in the picture of my unmodified bb shell are ground off. As a side note, some Merckx frames used the Vitus bb guide for a short period. I believe most of the reason for changing to under bb cabling have been just cost saving. A small cost saving per frame adds up over a year's production. Thanks sthurman for the brake bridge picture, that's the unmodified Silva bridge, some around that era had a lightweight version of that bridge.