I've seen it before, but have forgotten its use and name.

It holds a tire pump in position when placed horizontally beneath the top tube.

That was my first thought as well, but I'm not convinced. Those tend to be a little higher up (closer to the top tube) and shaped differently. Also, I'm not familiar with them on such an old bike; they're an 80's-90's thing, while this bike is early 60's.

Other possibilities... holding a race number? Or is it an oil port for the headset? I'm not convinced by those ideas either.

Does the bottom bracket have a similar fitting?

Your bike? It's been a very long time since I've seen a Bianchi with that style head set. A beauty for certain. I vote lubrication.





Dad's Frejus.



I'm certain it has a screw in the bottom bracket where the Frejus has the zerk-type fitting, too.

This is strictly a guess, but it might be to secure the fork steerer tube to prevent the fork/front wheel from swinging from side to side when it's being carried. That could prevent the handlebar from hitting the top tube, for example. Check the steerer tube to see if it has a small indentation where that bolt would match up.

Not a pump peg, it IS for lubrication, how well that might work, who knows.

Kind of a throwback to the old days. Guess the theory was you could "refresh" the lube in the headset bearings, and keep them flushed in lube, by injecting some oil in there every now and again. My Frejus also has one on the BB shell. Seems to have become an obsolete idea by the late sixties.

Well, now that I've seen different angles to get a NICE VIEW of it, I agree with the lube theory. However, it had to have been applied with some sort of hand/squeeze pump in order to get it in there. Similar to one I used on my cars back in the early 70's to apply grease to areas otherwise impossible to get to.

Actually, though some do look like grease zerks, I believe they were meant for oil. At first I thought they squeezed the head tubes full of grease, but read differently several years ago, somewhere. It may have old ties to racing as you mostly see these on vintage 40's to 60's racing bikes, I think. Old grease may not have had the properties we're used to today, so they had to "doctor " it occasionally to keep it working.
That's my theory anyway. Probably misguided BS.

I agree with lubing and the zerk fitting or whatever missing. The position seems wrong for a pumpeg.

Looks like a great bike any other pics?

A zerk fitting for grease? Sounds like grease everywhere, and a big mess, to me. On frames I've inspected, there are holes that allow the head tube to communicate with the top and down tubes, so the grease or other lube would not be constrained to remain within the head tube. Maybe the frames with such a fitting do not have these communication holes.

Not buying the zerk fitting idea, at all... that would take a lot of grease and application is extremely indirect. Filling the headtube with grease? Really?

Grease hasn't changed that much in the last 50 years. Even if you go to an extreme, before lithium grease was common, what they used wouldn't be all that different from what is being used for general lubrication today. Grease has gotten better for high temps, extremely high loads, longevity, and wider spectrum of use... but the fundamental properties for a non-disc wheel bearing type of grease hasn't changed much.

As said it's for dripping oil into the head-tube. The version on the Frejus is not a zerk fitting for grease. Just spring loaded ball-check. You use a oil can with those. Grease would dry out. You could revitalize it with some oil. Same for hubs and bottom brackets.

This. It's an oiler. It would have been standard equipment on a lot of mechanical devices from that era. Quite often the spring ball would break and a screw would replace the device.

The img is linked to Flickr. It's not my bike. Here is a direct link to the gallery:
https://www.flickr.com/photos/604281...57626240964030
Similar here, but without the oil port:
Museum bikes from 1945 to 1965 | Classic Cycle Bainbridge Island Kitsap County

No knowledge about exactly what the port is for, or the screw fitted, but that is one seriously beautiful Bianchi in the pictures.

Bill