right, let me get into all of this!
first of all when i click on the link i get an 'sta' lookin frame. but from whats been posted up was a trail boss/trls250 / bicycle motocross/r125 frame.
to clear up a couple of your questions on this. my 99 trls250 weighs in at 6lbs 7ozs. don't forget that custom frames are made so brake lugs could be anywhere but generally on the chainstays until about 3ish years ago
its been a fantastic study and what we have here is frame thats been designed with a mix of standard parts so its a kind of hybrid copy
if you look at this pic you'll see an ox sta i my living room and the 'sta' from the website. the gusset at the back of the of the bb is reminiscent of the old shorty and lengthy frames, not used on the sta. check harris's chrome sta frame from about 94/95 in the midschool. they've always had a tube instead.
next are the dropouts. wrong shape! the sta has always had slightly squarer dropouts, these are more like the trls250 look but still with the wrong curvature
to be era correct with this frame. the droputs aren't true to the bb either. euro bb's didn't start appearing on bmx frames until about 2002 ish. and standard were the first to do it. at this point i can't recall any street/burly frame being produced to take a 10mm dropout.
the only conclusion i can reach with this frame is that it possibly is made by waterford as the quality of the build is fantastic, the dropouts are capped really nice and it screams standard all over. if it is a waterford then i'd say these frames are part of a prototype batch that never appeared in production so we never saw the evolution process. if they're not waterford frames then someone has picked they're favourite parts from all the standard frames and have made a nice copy.
for the price though, if they're 4130 and the quality of the build would make up into a nice bike
if someone has got a pic of these trail boss/ r125 looking frames can you post it up for me to have a look at as i've had a 97 trailboss, a 98 trls250, a 99 trls250, a 2002 0x trls250, 2005 250l