sthurman 

Hi. I picked this up today as a frameset. It has a strange mix of features that I've never seen together on a Merckx. Any insight from our resident Merckx experts appreciated! Serial is left: Y, right: A 2107
features:
single downtube shifter boss for aero-style mounted shifters
Columbus SLX tubing (helical ridges in seat tube and downtube near bottom bracket)
eddy merckx brake bridge
top tube internal cable guides
top mounted cable guides on the bottom bracket
a sticker with a person's name (probably the racer this was made custom for?)
possibly others to a discerning eye (see photos)

merziac

@sthurman,

Good pic of the bottom of the BB with all #'s and build tag on the steerer if present plz.

Paging @CyclesMakaron

sthurman 

I'll get photos of steerer tube when I get home

merziac

Hopefully the real expert will chime in, he would ask for these so we'll already be there.

juvela

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certainly looks like mcmlxxxiv


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jet sanchEz

Did you google the name?

sthurman 

yes I did! It's 1984

sthurman 

it has a D and a 3

Jeff Wills

Shift lever mount is for top-mount shifters similar to Shimano AX stuff. I’m trying to remember if there was a top-mount gadget for Nuovo/Super Record.

CyclesMakaron

Corsa Extra 1987. Mounting of 'aero' style manettes(on top of DT) required 'old' slides on top of BB cover. This was a paid option.

merziac

Duragrouch

The helical ridges on the tubing, I don't see, are those on the inside of the tubing near the bottom bracket?

The large cutouts on the bottom of the BB shell, don't make sense to me. Highly stressed area and the shapes don't make sense.

Otherwise it seems like a desirable frame.

oneclick 

I'd replace "The large" with "Any".
For any BB's versions of Any.

sthurman 

there is one little hole that is cutout. The paint is flaking on the BB shell, so maybe it's a visual illusion?

sthurman 

Yes, inside tubing. You can feel them in the seat and down tubes through BB, and see them clearly if you shine a light in there and peer through the top of the seat tube.

gearbasher

Is that a pump peg on the seat tube?

sthurman 

Yes it appears to be so

Duragrouch

Nope, it's definitely big cutouts there. My only guess is, there appears to be another tube on the inside... perhaps this is kind of like a "tailor blank"; from wiki:

seagrade 

https://www.velobase.com/ViewFramePa...a-b1c095f7aa90

seagrade 

Photo credit VeloBase user wiel

Duragrouch

(above and link) Interesting. The FEA part of my brain needs to digest in terms of BB loading. Nomad: "Must a-nal-lyze."

OK. So in terms of torsional loading on the BB shell, the partial-depth slots don't make sense. However the BB shell is loaded mostly in bending, due to pedal forces transmitted through the shell to the seat tube and down tube. The stability of the shell in bending depends on the wall stability of the cylinder; For example, a filled and pressurized soda can is very stable, the pressure from a mostly incompressible liquid under pressure, pushing out on the can walls, prevents them from easily buckling. But empty that can, and the sides are very vulnerable to localized buckling and the can collapses. But if you were able to stiffen the can walls, like with vertical ribs, it would be stronger. The BB shell curvature gives some form stiffness. But at a smaller scale, the partial depth slots may help. Plate stiffness, IIRC, is proportional to the thickness cubed (t^3). This is how aluminum frames can be lighter, aluminum is 1/3 the density and 1/3 the elastic stiffness; Making the frame tubes much larger diameter greatly improves bending and torsional strength, but with steel, you run into limitations on how thin the walls can be on a bigger tube before you can distort the walls just by squeezing with your hand. Aluminum, for the same weight, can make the tube wall 3X the thickness, thus 3^3 = 27X the geometric stiffness but times 1/3 the material stiffness = 9X local stiffness, or go 1.5X thickness so half the weight and still 1.5^3 = 3.375X better geometric local stiffness but times 1/3 the material stiffness = 1.125X local stiffness, about the same as steel but at half the weight.

So getting back to the BB shell, they were still in the steel frame era, but need to make the shell stiffer; By reducing thickness in some places, while adding thickness in others, the shell walls may be stiffer in localized bending for the same weight, and thus more stable in global bending strength, or less weight for the same stiffness. At least on paper. How well this worked in practice is another question, both in performance, and manufacturing; That BB shell looks to be investment cast, a lot more expensive than just cutting off lengths of drawn tubing. Anyway, that's my theory on the partial depth slots. Then again, they might just have thought it looks cool.

Choke 

In my best Paul Hogan voice.....That's not a cutout, this is a cutout....

jdawginsc 

What’s that one? That’s cool!

Choke 

Here you go https://www.bikeforums.net/classic-v...arly-losa.html

unworthy1

the IC (investment-cast) BB shell on the OP's Merckx frame MIGHT be a Roto product, but details differ from the example on Velobase, most glaring besides the pattern of the (NOT) "cutouts" on the shell body and the style of all 3 sockets is lack of a Roto logo. Might be made by one of the other casting/forging operations in Italy.
Kind of doubt Merckx would have sourced a Japanese shell, but there were popular Hitachi-branded IC units that also shared the "bas-relief" treatment of the shell body, but yet another pattern from these two.

some pix of the typical "Hitachi" branded shell from other C&V threads, and per Mark Bulgier this may have been cast by sold as a Takahashi or Eisho shell but cast by and branded with Hitachi's mark:
"The Hitachi mark does mean it was cast there, but that's not the "brand". I think it's an Eisho shell, and they used Hitachi as their casting partner. Takahashi also made shells and crowns with the Hitachi mark."