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Bianchi Professional: Chainstay Indentation?

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Bianchi Professional: Chainstay Indentation?

Old 12-29-22, 09:07 AM
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Bianchi Professional: Chainstay Indentation?

I recently picked up this incomplete Bianchi Professional (no wheels or saddle/seat post) and while cleaning noticed drive side chain stay is different than the non-drive side.

Anyone know what the thought process was behind this? Also any guess as to the year? 1985?

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Old 12-29-22, 09:09 AM
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Creates freewheel cog clearance. Not uncommon.

P.S.: That's one drop dead beautiful frame.

-Kurt
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Old 12-29-22, 10:16 AM
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Originally Posted by cudak888
Creates freewheel cog clearance. Not uncommon.

P.S.: That's one drop dead beautiful frame.

-Kurt
Interesting and thanks. Was there a wide range of freewheel widths? The rear is spaced 126 so I am curious why the extra space was needed?
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Old 12-29-22, 10:20 AM
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Originally Posted by fender1
Interesting and thanks. Was there a wide range of freewheel widths? The rear is spaced 126 so I am curious why the extra space was needed?
It's less for space in operation and more for clearance during installation of the rear wheel. The freewheel needs space against the frame when the wheel pulls forward.

I've seen this 3/4" long recess on many brands (always executed slightly differently, of course), and while it's probably overkill, it also cuts down on "oops, gotta move a washer and redish the rear wheel again" scenarios.

-Kurt
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Old 12-29-22, 10:23 AM
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Is it an optical illusion or is that one steep headtube angle?
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Old 12-29-22, 10:24 AM
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Originally Posted by gearbasher
Is it an optical illusion or is that one steep headtube angle?
The entire top right of the frame seems to bend towards the camera, so I'd definitely say lens distortion for this one.

-Kurt
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Old 12-29-22, 10:34 AM
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Originally Posted by gearbasher
Is it an optical illusion or is that one steep headtube angle?
Assuming that is a 58/23 it's 74 head and 73 seat about normal for a performance oriented Bianchi. Interesting the Profession came in that stunning Amethyst and of course Celeste as complete bikes, with SuperBee, but was offered as a frame only apparently in black.
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Old 12-29-22, 07:24 PM
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It looks later to me. I had an '86 'Pro', black, chrome sox, different crown but all 022. 6 speed Sprint, friction. Nicest ride ever. Congrats, lovely frame.
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Old 12-29-22, 07:55 PM
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Best crown I have seen on a non Italian Bianchi.

actually surprised the seat stay is not flattened above the dropout- that is where the extra room really helps
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Old 12-29-22, 09:37 PM
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...believe it or not, for a long time this was one of my favorite bicycles. I don't know who made them for Bianchi, but they did a nice job on them. Pretty sure this one is an '85.

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Old 12-30-22, 10:18 PM
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Originally Posted by cudak888
Creates freewheel cog clearance. Not uncommon.

P.S.: That's one drop dead beautiful frame.

-Kurt
Thanks. It will be sold in the classifieds here in short order. (Hopefully)
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Old 12-30-22, 10:19 PM
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Originally Posted by fender1
Thanks. It will be sold in the classifieds here in short order. (Hopefully)
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Old 12-30-22, 10:39 PM
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Interesting. Bianchi kept horizontal dropouts and over the BB/chainstay RD cable run to the mid '80s. Also just single WB bosses.
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Old 12-31-22, 05:09 AM
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Originally Posted by 79pmooney
Interesting. Bianchi kept horizontal dropouts and over the BB/chainstay RD cable run to the mid '80s. Also just single WB bosses.
According to me catalogs (US market) cable routing seems to differ by model but mostly under in '84/85 but by '86 is under the BB. Dual bottle bosses as well as pump pegs appeared on most models in "86.

What I find more interesting here is that while I believe this is a Japanese production bike it is drilled for a Portacatena


fender1 I wish I had known this was for sale, I mean not that I have room for it but....
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Old 12-31-22, 09:54 AM
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Originally Posted by Bianchigirll
According to me catalogs (US market) cable routing seems to differ by model but mostly under in '84/85 but by '86 is under the BB. Dual bottle bosses as well as pump pegs appeared on most models in "86.

What I find more interesting here is that while I believe this is a Japanese production bike it is drilled for a Portacatena


fender1 I wish I had known this was for sale, I mean not that I have room for it but....
send them Italian parts to support the Italian-ness. I think Bianchi was vulnerable to criticism that they were not all being made in Italy anymore.
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Old 12-31-22, 09:58 AM
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repechage It's all about money, they were having lower level bikes contract built in Europe already so what's wrong with Japan?
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Old 12-31-22, 10:40 AM
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very nice frame
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Old 01-01-23, 01:33 AM
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Originally Posted by Bianchigirll
repechage It's all about money, they were having lower level bikes contract built in Europe already so what's wrong with Japan?
True people forget that Panasonic and Rensho made high end bikes that hold a candle to anyof the most prestigious italian bike brands.It is kinda like Shimano until they are appeared with Dura Ace in 1973,none knwew them and they became one of the most admired and the best selling high end road racing group group in the late 80's early 90's. Shimano is the biggest bike transmission manufacturer way ahead of Sram and even Campagnolo. Campagnolo lives on exclusivity and only road racing,their Euclid MTB range of transmission was short lived and a no match for the Shimano XT and XTR transmissions.
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Old 01-01-23, 02:22 AM
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Originally Posted by repechage
Best crown I have seen on a non Italian Bianchi.
That's a Takahashi HNR, which stands for Hitachi Nagasawa Road.
Casting by Hitachi
Design by legendary Keirin framebuilder Nagasawa, who apprenticed at De Rosa. The crown is definitly an "homage" (knock-off) of a De Rosa, with a couple refinements.

Richard Sachs favored this crown, used a lot of them, then designed his own knock-off (with help from Kirk Pacenti). So the current RS crown is a sort of a descendent of this Takahashi and the De Rosa is the grandpa.

It's a sentimental fave of mine also. I made my favorite road bike, in about 1989, with an HNR crown that I milled and drilled to make it lighter.



There was a HNT too, a track crown, also designed by Nagasawa and cast by Hitachi.

They have a Hitachi hallmark, but you have to saw up the fork to see it, because it's down inside the socket for the forkblade, hidden after the fork is assembled. How cool is that?
I'm told the symbol is a combination of the characters for “hi” (“sun”) and tachi (“rise”).


The other hallmark shown in the pic is on a BB shell from Eisho.

Both are superb quality castings, unsurpassed by anything ever used on bike frames, that I know of. A pleasure to work with.

Mark B
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Old 01-01-23, 02:46 AM
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Originally Posted by repechage
actually surprised the seat stay is not flattened above the dropout- that is where the extra room really helps
Yes, the chainstay can be allowed to have some "meat" inboard of the dropout, for strength, but the seatstay should be trimmed down pretty much flush with the dropout because (1) it needs less strength than a chainstay, and (2) it has to clear the chain, where the chainstay only needs to clear the sprocket with no chain on it, which is that little bit narrower.

Optimizing those stay clearances lets you make the wheel with less axle stick-out on the right for greater strength, less chance of bending an axle, and a stronger wheel due to less dish. The only reason to not do that is cheapness for mass-production.

Couple examples on frames I made. Both frames were 20-30 years old when these pics were taken. Lack of severe chain gouges shows that it worked, despite tight clearances. (OK, there's a little gouging, but not too bad considering!)




The chainstay indent needs to be long enough to clear the sprocket teeth when the wheel is being knocked out of the frame, sometimes violently, as in a wheel-change during a race.
So it needs to be longer for a horizontal dropout than for a vertical. One more nice advantage of verticals.

These clearances can be made simply by filling the joint with brass while brazing, then grinding away metal as necessary for clearance. But that weakens the stay, and stays do break there sometimes so it's not just a theoretical concept. The bikes pictured above had the stays forged into that shape before they were slotted for the dropout, so they are not weakened by removing metal at the crucial spot right where chainstays break sometimes.

The left stays were not formed like that, because there is no reason to. Symmetry is overrated!

Mark B

Last edited by bulgie; 01-01-23 at 02:58 AM.
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Old 01-01-23, 02:58 AM
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Here's another Bianchi, a 1960-61 Specialissima. Sorry it's not a great photo but I think you can see that the chainstay and seatstay are both flattened on the inside for clearance. The seatstay is taken down closer to the dropout than the chainstay is.



French and English framebuilders took another 20 years to figure out that this was worth doing on high-end frames. Even many top quality French and English frames continued to have big ol' doned ends protruding into the space where the chain should have been, requiring you to add a spacer on the right side of the hub axle. More tendency to bend/break axles, and more wheel dish, just so the framebuilder could save the few minutes it takes to do it right.

This '60-ish Bianchi is by no means the first frame to have this feature. The better Italian bulders knew to do this maybe 10 years earlier than that. I think, I'm not an expert, but someone here will know when these flattened stays first appeared.
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