What's this hole for?
 

I'm sure this must have been asked here before, probably even by me, but I couldn't find an answer. What's the hole at the top of this dropout for? There's one of these on each side.

https://live.staticflickr.com/65535/...a77ed3b7_b.jpg

For going faster? For a Pletscher rack? Is it threaded?

Looks like a Gippieme dropout Bianchi would use, and would be for attaching a rear rack.

That's where you keep your corn.

If it didn't have that embossed ring around the hole I would have thought that it might be for a rack, but with the ring, perhaps it is a lightening hole. It doesn't lighten it much. At least as a mounting hole it can be used for fenders or a rack. It looks like it is ready for a M5 tap.

Maybe a good place to put the lead for plating?

Interesting ponder.

It’s a deer whistle. Air rushes through the hole and creates a high pitched tone that the deer don’t like. Keeps the critters off the road so you can enjoy a fast decent with no fear of sudden impacts. It may attract dogs though.

Provocative question.

Boring answer is a question: Does an M5 screw thread in there?

Yes, it's a Bianchi. It's on the frame that was used in 1989 for the Mondiale, Giro, and Superleggera, so I don't think it's for a rack.

I've always assumed that such holes serve the same function as eyelets on Campy dropouts (for fenders and/or racks) but I have never put that to the test.

You mission, whether or not you choose to accept it, is to find out. If you are captured, C&V will deny any knowledge of your activities. This post will self-destruct in 10 seconds.

I was about to say that it isn't threaded, and with powder coating it effectively isn't. I don't see any clear indication of threads, but new evidence has come to light that suggests that it is.

https://i.ebayimg.com/images/g/rOQAA...D5/s-l1600.jpg

https://www.ebay.co.uk/itm/254075368019

Serious plot twist: the 1989 Bianchi Krono also has these:

https://cdn.finqu.com/users/38150/th..._1920_1080.jpg

It’s for a bike flag!

I imagine it was for flexibility without committing to eyelets...or so Gipiemme could easily source both racers and sport tourers without retooling the basic design?

I got holes too! Same dropouts. ‘86/‘87 Vittoria.

https://cimg0.ibsrv.net/gimg/bikefor...d49e7a985.jpeg
Proof a Campa derailleur can shift a 30 tooth freewheel. Mirage 9sp.
https://cimg1.ibsrv.net/gimg/bikefor...2d7a4e088.jpeg

Those holes are for mounting the Wheelie Bar! :p
https://cimg6.ibsrv.net/gimg/bikefor...79da2e9f20.jpg

It’s just to let the air in.*



*cue somewhat obscure literary reference.

Yes, for rack or mudguard mounting. They also made a version without the eyelet:
https://cimg8.ibsrv.net/gimg/bikefor...5a9478e813.jpg

That's what she said.

It's a simplification by Gipiemme. Only one dropout needed for both racers and tourists. Tourist - mask those threads before painting. Racer - save the labor and skip the masking. And the odd part - the tourist version is lighter!

The tourist version whistles much better. They need it. No preceding caravan to scare the deer off.

I don't plan to use a rack or fenders with this bike. That means I can cut this off, right?

Looking through my catalogs from '89 to '91, I see the threaded holes in all Mondial, Superleggera and Giro frames. I also think I see them with the Campione D'Italia models. I had one from this era and seem to recall it had the eyelets.

Looking back, it's surprising to me that Bianchi was using Gipiemme dropouts and didn't ssem to ever use Campagnolo.

Whatever its purpose, the crew at Bianchi were that committed to it as the frames came with a sticker to cover it up. From my ‘89 Giro

https://cimg8.ibsrv.net/gimg/bikefor...3b5078148.jpeg

Perhaps a little large, but I would try to use it for a portacatena.
https://cimg0.ibsrv.net/gimg/bikefor...0b2667f7b8.png

A hole that small on the rear dropouts means its most likely for mounting racks and/or fenders. It not for weight reduction because of it's very small size.
Other bikes with bigger round holes on their dropouts for weight reduction would be the ALANs, as evident on their Carbonio race bikes.
https://cimg6.ibsrv.net/gimg/bikefor...1ace6e80be.jpg