Here is an email I got from an actual employee of GT:

  1. Specialized Bike Serial Number Lookup

If the bike frame was manufactured at the Santa Ana CA facility, the first three or four digits of the serial number should be letters abbreviating the model or size of the frame such as 'XL', 'XXL', CR24, or something like that.

The next part of the serial number is eight numeric digits. The first four numbers should be a two digit month followed by a two digit year.

The last four digits are the serialization digits 0000 to 9999 depending on what number the frame was of the years production.

Search this site. Specialized Bike Serial Number. Specialized Bike Serial Number. Serial number A serial number is a unique number assigned for identification which varies from its successor or predecessor by a fixed discrete integer value. The unique code that identifies your bicycle, also referred to as a frame number. The majority of serial numbers are located under the bottom bracket where the two pedal cranks meet. Simply turn your bike upside down and record the number. If there is no serial number there then check places like the headset at the front of the bike or the rear stays. The diagram below indicates the five most common serial number locations. Search Bicycles by Serial Number Please enter the bicycle serial number using only letters and numbers without spaces or other special characters.

This tool searches a database of Schwinn serial numbers and if it finds a match to your serial number then it will display the information available for your bike. Notes: This tool works for Schwinn bikes from 1948 to 1982. All serial number records before 1948 were lost in a factory fire. Serial Number Location.

If the frame was made overseas in Taiwan, it gets more complicated. If the number starts with a K, the frame was made by Kinesis.

That's the only one I remember off the top of my head.

There were at least four companies in Taiwan that made the GT lines :

Robinson, Dyno, Powerlite and Auburn included)

The first digit would be a letter designating the factory that made the frame. There might also be a second letter digit specifying the factory that assembled the bike, if applicable. The model and year of production was also coded by a letter, so you won't be able to spot a two digit month and two digit year.
Before I left, I was writing a specification to standardize all of the serial numbers because GT was starting to send most of its US production to other US fabrication shops.
The information might also come in handy for deciphering other makes because the factories in Taiwan make bikes for a lot of different companies.
I am tinkering around with the idea of starting to make my own frames, kind of on a 'one-off' basis. I am also teaching welding at a local community college.
By the way, did I tell you that the guy ran GT's in house fabrication for the last ten years (he recently retired) was none other than Gilbert Axt. Who? Do you remember Race, Inc.? That was Gilbert.
He also did the original PK Ripper for SE Racing. History, man.
It might be a really cool thing if I can track down Gilbert now and interview him for you.
THAT is the kind of stuff that belongs in the BMX Museum!

Later. I'll write you when I get a chance. Dan Garcia

and here is the updates, thanks to love thegoose! (Michael S)
well we get a good bit of gt serials that could be identified by the owner, if they only had the tips that some of us have learned, so i will post what i know, and anyone with more knowledge can add to it..so here we go.
here is an example to go by. on the dropout you have 'M1' followed by '08922198'..this one is simple.
M1 stands for 'mach one' that is your model gt.
it can also be a 'I' for interceptor and so on.
next on the serial is '0892' this is easy to decode too,
08 means 8th month, which would be august.
then you have '92' next in the lineup, this would be 1992
the last 4 digits, are your build number, this one would be the 2,198th one built.
Here is another example. if your serial is KGCG2297 this one gets a little complicated. but still easy once you learn the code to it.
the first letter is who made the frame itself, in this case it would be 'Kenisis', an overseas company.this could be replaced by another letter but at least we know what that one is there for.
next is the letter 'G'..this isnt always there, but if so, this is where it was assembled, (ever notice the built in usa sticker on your gt or dyno?) this is what that letter is there for. it wasnt made here, but was built here.
next is the letter 'C'..C is the 3rd letter in the alphabet, and march is the 3rd month, so march is the build month.
next is the letter 'G' this is the year. G is the 7th letter in the alphabet,
so this would be a 1987.
here is one more..your serial resembles this:f6030578.
to start, if you have a 'baseball' looking stamp behind your serial, this frame was made overseas...no its not a pacific, so dont cry, or get mad...and lets continue.
on this serial, the first number is the last digit of the year, so 6 stands for 1986
next is '03'....this is the third month..which is march.
so you have a gt built in march of 1986.
but still use the museum as a guide to id the frame, cause sometimes you can find the year, but getting a posotive id on the model isnt possible without knowing which style frame you have.
this doesnt apply to new gt's, but hopefully some people with info on those will chime in. this isnt always going to match your serial, you may have a 'fake'..its not likely but it happens. also on earlier models this can differ. this is for the 2 most popular style serial's i see on here. also, common sense tells you that if you have a suspected 'gt' frame, look it up and compare it in the musuem, knowing which style frame you have will help with the process of id'ing your bike with the serial, especially if the serial has some damage that prevents you from getting the full number.
hopefully this bit of info can be used for everyone, and this will save you from those late nights sitting around waiting for a response to your post looking for an answer to the idendity to your gt...although i do feel smart and proud when i can answer these posts. well, thats it for me, if anyone else has info on serials or if you see a mistake in this guide, tell me so i can edit it. happy holidays people.

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Posted: Thu Nov 26, 2015 3:47 pm
Dirt Disciple

Joined: Wed Apr 08, 2015 4:10 am
Posts: 13
Hi all. Im hoping someone may be able to throw some light on a steel mtb frame i picked up cheap at car boot. Its light, just under 5 pounds, been poorly resprayed but original colour under rattle can finish is light green. Seller said it was a rockhopper. But looking at the serial no which is 94M2403, im thinking it may actually be a 94 Stumpjumper M2 FS. frame. Seat post size is about 30-31mm which i think was on stumpjumper of the time but not rockhopper. Colour given in 94 catalogue for M2 FS was silver-green which also points to that conclusion. Any info would be greatly appreciated.


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Posted: Thu Nov 26, 2015 5:58 pm
Retro Guru

Joined: Wed Aug 07, 2013 7:24 pm
Posts: 307
Location: New Brunswick, Canada
If it's steel, it's not an M2. M2 is an aluminum alloy with a ceramic component, non-magnetic... Looks very aluminum-y Frames weighed about 4.4# IIRC.... mine's not been weighed frame-only. Check out the photos of my bike (link in sig), and compare to yours. Downtube gussets and the like... Mine's a '95, but substantially similar to the '94 M2.
Without seeing it, it is possible that it's a steel Stumpjumper. Weight is close. Steel is magnetic, check. I have a light metallic green steel stumpy frame (95) in my basement right now...
Check the catalogue for that year:
http://www.retrobike.co.uk/gallery2/d/1 ... 4_Mini.pdf
J

_________________
My '95 Stumpjumper M2 FS http://www.retrobike.co.uk/forum/viewto ... p;t=267744
My wife's '97 Hardrock AX retro-mod http://www.retrobike.co.uk/forum/viewto ... p;t=344385


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Posted: Thu Nov 26, 2015 6:40 pm
Dirt Disciple

Joined: Wed Apr 08, 2015 4:10 am
Posts: 13
Hi, thanks for that info. It's definitely steel, no extra gussets or anything. I want to make use of a set of carbon forks I already have, which are 445mm crown to centre, which I think equates to an 80mm suspended fork. Assuming it is either the Stumpjumper or Sj FS in the catalogue. Is it likely the actual frames are exactly the same, ie suspension corrected? Headtube is standard 1&1/8'.


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Posted: Thu Nov 26, 2015 6:52 pm
Retro Guru

Joined: Wed Aug 07, 2013 7:24 pm
Posts: 307
Location: New Brunswick, Canada
Spesh frames were suspension corrected, AFAIK, by 1994. Especially likely on those with 1.125' steerers.
I wouldn't worry a bit.
J

_________________
My '95 Stumpjumper M2 FS http://www.retrobike.co.uk/forum/viewto ... p;t=267744
My wife's '97 Hardrock AX retro-mod http://www.retrobike.co.uk/forum/viewto ... p;t=344385


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Posted: Thu Nov 26, 2015 6:59 pm
Dirt Disciple

Joined: Wed Apr 08, 2015 4:10 am
Posts: 13


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Post subject:Re: Specialized model
Old School Grand Master

Joined: Wed Feb 20, 2008 12:21 pm
Posts: 3607
Location: Lost in Translation
Hi, thanks for that info. It's definitely steel, no extra gussets or anything. I want to make use of a set of carbon forks I already have, which are 445mm crown to centre, which I think equates to an 80mm suspended fork. Assuming it is either the Stumpjumper or Sj FS in the catalogue. Is it likely the actual frames are exactly the same, ie suspension corrected?

The correct rigid fork for a Stumpjumper of that age measures about 412mm axle-to-crown, so the carbon fork you have is a fair bit longer than ideal. A classic Kona P2 is a good alternative at 410mm.
Oversized steel Stumpjumpers and Rockhoppers of the period (assuming a frame built in 1994 for the '95 model year) both used a 30.4mm seatpost in a 31.8mm seat tube.

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Posted: Thu Nov 26, 2015 9:04 pm
Dirt Disciple

Joined: Wed Apr 08, 2015 4:10 am
Posts: 13
Ah, that's a pity. I do actually have a pair of Specialized rigid forks from a later model stumpy, think a 95 rigid. They are 425mm, as well as another chromo set around 415mm so will have to play with them and see how it goes.
Many thanks for the advice.


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Posted: Fri Nov 27, 2015 3:11 pm
Retro Guru

Joined: Wed Aug 07, 2013 7:24 pm
Posts: 307
Location: New Brunswick, Canada
Ultimately, I guess it depends on what you want from the bike... BITD, and still now, people regularly modify their bicycles with upgraded forks, often pushing the A-C measurement beyond what the original rigid forks had. IMHO, it doesn't affect a bicycle's handling nearly as much as some would have us believe.
As a more extreme example than what you're contemplating, over the last couple years as my wife's MTB skills progressed, I've upgraded her once rigid Hardrock AX ('97) from the OEM rigid chromo fork to a crap Judy J1 80mm, to a Magura Asgard 100. The Asgard's AC length is a whopping 476mm. That slackened the head angle a couple degrees. She came back from her first hard riding experience with the upgraded bike (on trails she's very familiar with) commenting only on the better suspension and surer handling (no doubt due to the stiffer Magura fork over the crap J1). Her head angle has been slackened by some 3 degrees, from something near 69 to more like 66 (neglecting sag, which adds a degree back in). Actually, it's put the bike's geometry largely in line with more relaxed modern offerings...
Adding 30mm to a fork on a bike with a wheelbase of about 44' changes the head angle less than 1.5 degrees. At worst, it'll remove some of the mid'90's nervousness from the bike's handling on fast downhills, IMHO.
J

_________________
My '95 Stumpjumper M2 FS http://www.retrobike.co.uk/forum/viewto ... p;t=267744
My wife's '97 Hardrock AX retro-mod http://www.retrobike.co.uk/forum/viewto ... p;t=344385


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Posted: Fri Nov 27, 2015 9:02 pm
Dirt Disciple

Joined: Wed Apr 08, 2015 4:10 am
Posts: 13


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Specialized Bike Serial Number Lookup

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