Welcome to the early GT technical site for mainly 1980 through 1983 models.

As an avid early GT collector in search of all colors and sizes of 80-83 GT's, I have researched extensively what was available back in that time, plus some 70s. I will provide what I have found, and ask for what I don't have.

This site will be a constant work in progress. Going to start with the size guide. I have most sizes in my collection, and measured using the crude 'Crescent wrench over the tubes and measuring the jaw's spread' since I do not have caliper gages. Most length mesures are done from center to center in inches.

Here is the spec diagram for the following measures:

They started actually stamping the size on the dropout with the serial number in mid 82.

Frame Stamp / Size Top Tube Down Tube Height Rear Stay Top Tube Diameter Down Tube Diameter
16 - Pit bike 16.25 16.75 7.25 15 1.25 1.25
JR - Junior / Mini (mostly Euro bb's) 17 17.5 8.5 16 1.125 .875
1 - Standard/Expert w/ Euro bb 17 17.5 8.5 16.5 1.25 Pre 82 -1.00 / Late 82 - 1.25
2 - Standard/Expert w/ American bb 17 17.5 8.5 16.5 1.25 Pre 82 -1.00 / Late 82 - 1.25
3 - Pro w/ Euro bb 18.5 19.25 8.5 16 1.25 Pre 82 -1.125 / Late 82 - 1.25
4 - Pro w/ American bb 18.5 19.25 8.5 16 1.25 Pre 82 -1.125 / Late 82 - 1.25
4L - Pro XL w/ American bb (late 83ish)* 19.5 20.50 8.5 16 1.25 1.25
24 - Cruiser 20.25 22.125 13.00 19.5 1.25 1.25
26 - Cruiser 22.125 24 13.25 19.5 1.25 1.25
*Actual measures not validated. Best Guess            
Forks            
Mini     10.5   .875  
Pro     11   1.00  

Here are some early advertisements showing colors and sizes. Standard colors were Red, Blue, Black and Chrome (most common).

I had a question about what a GT-3 was in the ad on the left. So, I asked the man himself.

 

I have since found and acquired two GT-3s, shown below in the bikes section and know of another in Plymouth, Massachusets.

 

The rear of all models 83 and earlier have a flat, unstamped end of the top tube, like this.

 

The Nora Cup designation

In November of 82, GT won the Nora Cup for best manufacturer. So, for 83, they could run the Nora Cup decal on all frames as the 82 winner. Decal says 82.

There was never a Nora Cup model. Stating you have a Nora Cup bike is an incorrect description. If you have to mention it, just say Nora Cup winner year/era!

Correct decal

 

Serial Number Info

The standard serial number, found on the inner drive side dropout, will be as follows: Month, Year, Production number, and from four to eight numbers.

August 81                                                                                       January 81

May 82 (about the time size stamps started as well)

October 83                                                                January 82 (rare 4 digit)

There are some oddities, as seen on this 80 Pro, 0 at the beginning

One of the most rare frames is the 83 Pro Long. Has a 19.5" top tube and a L4 stamp

 

Here's a partial group shot of some of my bikes.

 

  List of bikes in my personal collection by year.  
1980 Standard/Expert w/ Euro bb (GT-1) - OG Red
1980 Pro W/ American bb (GT-4) - OG Red
1981 Pro w/ Euro bb (GT-3) - Chrome
1981 Pro w/ American bb (GT-4) - OG Blue
1981 Cruiser 24
1981 Cruiser 26
1982 Pro w/ Euro bb (GT-3) - Custom white
83 GT Jr / Mini
83 Pro (GT-4) - Black Chrome
83 Pit bike - 16"
83 Expert (GT-2) - Black Chrome

   
     
     
  I am also a Skyway Tuff Wheel enthusiast.  
   
     
     
     
     
     

This is an individual website. Some pictures sourced from images found on the internet.

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