GT was founded in 1979 by Gary Turner1) and Richard Long in Annaheim, CA, as a maker of BMX bikes. In 1984 they entered the more lucrative mountain bike market with their Timberline MTB and GT soon began making more MTBs than BMX bikes.
GT's standout design element has been their Triple Triangle™2) frames, where the seat stays attach to the top tube forward of the seat tube. Introduced by GT in 1987, GT wasn't the first or only maker whose seat stays miss the top. Other MTB makers include 3Rensho and perhaps the Mantis X-frames. The frame style is known as Hellenic as is occasionally found on older road bikes.
GT sold itself to Schwinn in 1997 and today the GT brand is alive and well and owned by Dorel Sports. Gary Turner retired from GT in 1999, a few years after business partner Richard Long died in a motorcycle accident. After 20 years of retirement, Gary Turner has returned to making “Gary Turner” BMX bicycles with his son Craig. See: GT1972.
Info from: wikipedia, facebook, orangecoast, mmbhof, and fundinguniverse.
Gary Turner and Richard Long, 1981
wikipedia
SunTour MounTech 4900 (1982-4).
1984 Timberline
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The drop frame seat tube gusset is a forerunner of the triple triangle to come later in 1987. Dia-Compe brakes a step backwards towards its BMX roots. 1985 as per serial number. SunTour MounTech GTL (1982-84).
1985 Timberline
ratrodbikes
From Dec 1986 Mountain Biking magazine review: $489, 28.5 pounds. SunTour MounTech II, SunTour rollercam brakes.
1986 Backwoods
mombat
The triple triangle makes its debut, along with a non-bmx stem and awkward rear brake cable routing which is both internal and rubbing against the seat tube. Later models used cable guides around the seat tube (or added a cable stop on the seat tube.) Straightforward rear cantilevers have not been seen on a GT since 1984. See the 1993 RTS-1 brake detail below.
SunTour XC 9010 (1987-88), 1987 as per serial #G7K00153.
1987 Avalanche
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SunTour XC 9000 (1987-88). 1988 as per serial #T8021.
1988 Avalanche
oldschoolracing
1989 Tequesta Catalog shot. SunTour XCD rear derailleur. 32.3 pounds, $440.
1989 Tequesta
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“Purple Haze” color scheme. Shimano Deore LX (1990-92)
1990 Karakoam
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Partial titanium frame with chromoly forks and bolt-on rear triangle. Internal cable routing. Available with either XT or XC-Pro gruppos. “Xizang” is Chinese for Tibet.
1991 Xizang
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Fully aluminum. Deore XT.
1992 Zaskar
retrobike
It's impossible to find pics of a 1993 model with the original Mag-21's on the front, as they steered like wet noodles and blew out seals on alternate rides.
Noleen coil-over rear. Shimano XTR throughout.
Most components have been swapped in this pic.
Tricky brake routing detail from a 1995 RTS.
1993 RTS-1
retrobike