It looks as though that may well be a 1988 Cascade Lava Dome. It is certainly noticeable that although the Lava Dome name pre-dated the first Kona range, there was no 1988 Kona Lava Dome (at least not in the UK catalogue). So maybe TBG retained the Lava Dome name for a final Cascade, sold alongside the new Konas.
The T88etc serial number is exactly in the format of the early Kona bikes, and indicates that the frame was built in Taiwan in 1988. Aside from the location of the U-brakes, your bike looks very much like the 1988/89 Kona frames - and the fork appears to be the same as the one on the 1988/89 Kona Fire Mountain - see below.
The second page of the '88' Kona brochure gives all the history I'm aware of. It says Joe Murray had been with TBG for 'many years' at that time. He certainly raced for TBG, latterly on Brodie bikes (which were at that stage distributed by TBG), but I don't know whether he ever raced on Cascade-branded bikes.
The T88etc serial number is exactly in the format of the early Kona bikes, and indicates that the frame was built in Taiwan in 1988. Aside from the location of the U-brakes, your bike looks very much like the 1988/89 Kona frames - and the fork appears to be the same as the one on the 1988/89 Kona Fire Mountain - see below.
The second page of the '88' Kona brochure gives all the history I'm aware of. It says Joe Murray had been with TBG for 'many years' at that time. He certainly raced for TBG, latterly on Brodie bikes (which were at that stage distributed by TBG), but I don't know whether he ever raced on Cascade-branded bikes.