I would really appreciate any information that could help to identify this bike frame. I bought the frame at a garage sale and was told the frame was a "specialized" possibly s works but never had anything to back that up. I have done as much research as I can and I now doubt it to be made by specialized. But still have no idea which manufacturer made the frame. I believe it to be roughly early 2000's period bike from geometry, style and hardware compatability. It is a aluminium alloy frame that looks to be hydroformed. It has been tig welded by hand and is a 21" frame that weighs only 1.955 kg or 4lb 3oz. Which seems lightweight to me for a older frame? The serial number is stamped on the bb outer shell parallel to the frame and the number is : SW0401833 please check your bike serial number if anyone has one starting "SW" I would love to know the manufacturer name. The frame has capability to run rim brakes (post mount) or disk calipers. The head tube is semi integrated 50mm outside diameter 44mm inside. The cables are routed on top of the top tube in a cluster of three made of alloy and part of the frame, there are two of these "3 clusters" on the top tube positioned near the headtube and seat post. As far as I know the frame was never painted so possibly came from the factory in bare metal or lacquered finish although that's only an assumption I made from not being able to find a trace of paint or over spray anywhere on the frame including inside of the headtube, bb, or seat tube. I can add any measurements or specific pictures if that would help to narrow it down at all. Please comment if you know anything at all that could help identify this frame. Thanks for looking! (https://i.stack.imgur.com/B591a.jpg)
I can't identify it, but in the interests of progress, my observations:
It is not a fancy frame sold new and blank. I've never heard of a cycling manufacturer that would ship a bare metal bike. So I think this is an existing bike that has been stripped of its paint. Check the bearing races for any wear.
As for lightness - all bare frames feel ridiculously lightweight when they're bare frames. ~2 kilograms is probably medium weight, so neither a clunker nor a top-end bike.
As observed, it has provision for a rear disk brake caliper, as well as a rim brake in canti, V brake, or similar format. It also has a brake bridge for a caliper brake. So it is a "multipurpose" design.
The gear cables are routed above the top tube. This keeps them away from any muck thrown by the front wheel. So the front derailleur will be "top pull" design, not "bottom pull" as traditional on road bikes.
The head tube is quite wide - this suggests a relatively large fork steerer tube and likely a threadless headset.
That you have no fork is disappointing - I suspect it would have been a suspension fork, and the bike has the proportions for a 26" wheel. Finding a good fork to use might be difficult.
The bottom bracket standard might tell you something too, but it would be a lot of work to figure out when Specialised changed each model line from threaded to press fit and which style. And that presumes it really was specialised.
There is no rear derailleur hanger. Either its been removed and lost, or was broken and removed. You might have difficulty finding exactly the right one if its not already in your possession. It definitely had gears in the past - otherwise there's no obvious way to tension a singlespeed chain which would have trackends or similar.
RESULT I think its a late 2000 hardtail MTB, looks well made, but someone has stripped all the parts off for a paint job or possibly chroming. It might have been to build a 26" BMX which is a single speed.
One path forward is to put a photo of the right-side view on screen, and then search google images with something like https://www.google.com/search?q=specialized+sworks+MTB+hardtail&tbm=isch and just keep looking.
You could also attempt to register the frame to yourself at https://www.specialized.com/us/en/support/bike-registration however if the serial is rejected that doesn't prove its not just old.
Another option is trying their "contact us" links and see if customer services can help at all. It's worth a shot.
Lastly, as per the first comment, it doesn't really matter what it is. You will need a bunch of parts to make it an effective bicycle again, and they have to fit the frame. If you're going for a factory-original rebuild then identification is important, but if you want to build a bike to ride, just do it well.
For the finishing touch, purchase or get some decals cut that say whatever you want. A nice small logo that discreetly says "David Surname" or some gaudy wording saying "SPECCYBIKE!!!" its all your preference.
Do please let us know what you do - post your own answer with progress and eventually final pictures.