I've come across this interesting frameset on my regional CL and am perplexed as to its origin. The Suntour dropouts seem to indicate Japanese manufacture, but the BB shell and lugs have me scratching my head.
I came across this listing while searching for potential L'Eroica candidates.

I'd appreciate any expertise from our resident experts. Thanks!!!!!

Maybe a Windsor? Just a wild, partially-informed guess.

I think you nailed it. Clearly not a Professional....... more interwebs research seems to be pointing at the "Carrera" model, which appears to be lower end bike boom material.

Thanks for the tip!!

Yeah, the seat cluster kind of screams "Windsor," but I agree that the other lugs and the fork crown say "not a Windsor Pro." This is another partially-informed opinion, and it's worth exactly what you are paying for it.

Maybe a Super Carrera? Late 70's ones appear to have less ornate lugs, but they have the Suntour GS dropouts and the fastback seat cluster. Also, Tange double butted...

That's my vote^, juvela always has something to say re: Acer Mex products. This looks to me nicer than most in the Carrera range: some chrome, Cinelli-clone fastback, nicer flat(ish) fork crown too. Can't beat an orange frame but kind or weird black lug in-fills

Or Carabela?

Link: Help me ID this frame?

Edit: Disregard, the Carabela in the linked thread does not have the fastback treatment nor the same fork crown.

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always wise to keep in mind the Carabela marque

it is much scarcer in the U.S. market than the Windsor one but we did receive some

California had at least three different ACER-MEX importers at one time or another

ACER-MEX did some contract manufacture as well; two recalled are C.Itoh and Centurion. there are likely to be others...

lug pattern of subject frame is an Agrati one which enthusiasts oftimes refer to as "Bozzi" as it appears in the notorious Bozzi parts catalogue of 1950

my guess for model, and it is only a guess, is International

for a time frame thinking 1973-75

you might wish to check the steerer to see if it is an .833

is shell 68mm but Italian threaded?

w/b mount clearly an add-on; looks to have been achieved with rivnuts

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Oh my, I can't believe what I am about to type. I'm going to contradict juvela .

I don't think it is a Windsor International because I had an International and from my memory, which may not be that great, it did not have fast back seat stays, it had the serial number on the seat tube rather than the lug, it did not have holes in the bottom bracket and the lugs don't look the same.

I will say that I got the same Windsor/Acer Mex vibe but, if it is it is a Windsor/ Acer-Mex then it would be up a model or two from the bottom end International. Carrara maybe?

Agreed, it's definitely an Acer-Mex product based on the seat cluster and serial number. With the exception of the eyelets on the SunTour GS dropouts, ir reminds me of the Falck tubed Carabela Semi-Pro,

Doesn't look like the Carabela Semi-Pro I owned from the 70's.

i fell for the chrome head lugs and shorty chromed socks. i fell-out with the ride/handling characteristics

We've been through this in the past. The extant Bicycling! road test shows that the Carabela Semi-Pro was available with the Cinelli style fastback seat stay and binder bolt arrangement, as seen on the OP's bicycle.