There are so many frames that bear the similarities. The main difference with Bontrager and Cotic, apart from the decade they were born, is Cotic are made in the Far east.
Again a familiar story.(in Brief).
Paul Sadoff honed his craft with both Keith Bontrager and Ross Shafer, after a time leaving to make his own mark on this thing of ours and created Rock Lobster.
Handbuilt Steel, with a similar philosophy.
With such a demand here in the UK for good quality well put together frames, NTI Imports approached Paul Sadoff with a view to add more frames to there portfolio, a deal was struck, and Paul oversaw his hardtail steel frame design which was to be manufactured in the far east and sold here in the UK as ROCK LOBSTER, A well gusseted Cro-Mo frame, at a lower cost but retaining all the traits of the proven California design.
A really great frame that always seemed to be sold out, hardly surprising when the cost to buy one was £250-£295, and the nearest Salsa Al La Carte or Bontrager OR was £695 (all at retail Prices here in the UK.)
The Rest as they say is History, relatively short lived, as the rights to the Rock Lobster Name found its way to Merlin Mail Order as there Flagship Brand sitting above there own Far East Imported frames/bikes under the Merlin Name. Obviously Some of the Frame details remained, Gussets etc, and the range was expanded to other materials too and all were made for Merlin cycles in the Far East.
NTI, still continued to supply there hardtail Steel Frames only from this point forward they were renamed "Amazon" with the model name of "Bladerunner".
I guess, when something is a Good Design, that solves problems, and is "Strong Light and Cheap". Frame builders/Engineers from all over will draw the same conclusions
.