All Mongoose frames, every model and every frame prior to the new numbering style was sequential. They started at 1 or 100 or 1,000. By 1980 or so, they were up around 450,000. The bottom brackets were stamped with serial numbers prior to being even attached to a frame. The guy welding frames up would reach in the box and grab a BB shell. Jun 25, 2012 - Based on my knowledge of serial numbers it doesn't look at all like a Mongoose frame unless it is from a departmant store. If the frame has a.
The first thing everyone wants to know when the buy a second hand GT BMX is ‘how old is it?’ Reading the GT serial number and finding out the build date is an important part of any BMX restoration. Once you now when the old GT BMX bike was built it’s much easier to find out what model it is and also look at the original parts lists and colours from the bike makers catalogues. A while back I spend some time investigating how to read mid-school and new school serial numbers on Mongoose BMX bikes.
After buying and restoring a number of older mid-school and new school GT BMX bikes I also need to to figure out how to crack the GT serial numbers to get the same build date information. It didn’t take long to realise there were many similarities when looking at GT serial numbers and Mongoose serial numbers. The placement and sequence of the numbers is stamped in the same place under the bottom bracket. Many of the GT serial numbers start with the same letter sequence.
After a bit of digging around online I soon realised that GT BMX bikes and Mongoose BMX bikes were owned by the same company and also made in the same factories in Taiwan. In fact look closely at many Mongoose and GT BMX’s from the around 2000 to 2010 and you’ll see many similarities in frame design and geometry. This is probably not true for all of the bikes in either range, but there were a number of bikes that were identical apart from the logo stamping. Anyway that’s a post for another time. As with the Mongoose serial numbers there are many posts from forum members around the world on old-school GT serial numbers, but very little on mid-school or new school.
Of course there are also many variations in GT serial numbers and I have focussed mainly on cracking the new-school numbers for now. That is bikes made between 2000 and 2010, and those bikes made in the Taiwan factories with specific serial number sequences.
There will be bikes that are different, if you have any examples of where this crack doesn’t work, add a comment below. GT serial numbers are usually found stamped on the bottom of the bottom bracket of your BMX. This is not always the case and there will be some bikes that do not fit into this formula. For mid-school GT BMX bikes built in Taiwan through most of the 90’s with a serial number that begins with 4 letters before the series of numbers. The 3rd letter corresponds to the year of manufacture. 1991-2000 – 4 letters at beginning, 3rd is year A B C D E F G H I J 91 92 93 94 95 96 97 98 99 00 The 4th letter indicates the Month A B C D E F G H I J K L Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec A few examples are: HF GB00000 – 4 letters, GB are the dates.
G is the year (1997), B is the month (Feb) HF BH00000 – 4 letters, BH are the dates. B is the year (1992), H is the month (Aug) For new-school GT BMX bikes built through most of the 2000’s with a serial number that begins with 5 letters. The 4th letter corresponds to the year of manufacture and follows on from the mid-school serial numbers. 2001-2010 – 5 letters at beginning, 4th is year K L M N O P Q R S T 01 02 03 04 05 06 07 08 09 10 The 5th letter indicates the Month A B C D E F G H I J K L Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec A few examples are: HAM RF00000 – 5 letters, RF are the dates. R is the year (2008), F is the month (Jun) HAM OI00000 – 5 letters, OI are the dates. O is the year (2005), I is the month (Sept) Please note: The GT serial number will give you the build date of your GT BMX. Frames were normally manufactured the year before being sold in bike shops.
So a build date on a frame of 2003 usually means the bike was sold in stores in 2004. If you have a GT BMX that doesn’t fit into the code style above, here is how I can help. If you think your bike was made between 1991 and 2000 go to and post a couple photos of your bike and make sure you include the serial number in your post. I will look into all the numbers listed. Thanks for reading. If you liked this post, sign up to the blog via email on the home page and get all our news direct to your inbox.
Your guide to old Mongoose serial numbers. Find our what year your BMX was built and sold and date mid school and new-school bikes made between the mid 90’s to mid 2000’s.
The guide covers many serial numbers but not all. There were many different factories making Mongoose BMX bikes and all had different serial number codes. Mongoose serial number information has never really been properly documented, possibly lost as the company changed hands and moved production. However, there are a few BMX restorers who have painstakingly attempted to decipher these multi-digit mysteries. A big part of buying, rebuilding and restoring old BMX bikes, is knowing exactly how old they are. When I started looking into finding out how to read Mongoose serial numbers I found plenty of information on Mongoose BMX bikes made in the 80’s and early nineties through google and BMX forums. The problem was there was no information helping to date Mongoose BMX bikes built from 2000 onwards. It seemed nobody figured out how to read the serial numbers.
Older Mongoose bikes made through the 1980’s had pretty easy serial numbers. Generally the year and month of build was stamped as the first part of the serial number. For example my 1986 Mongoose Expert has a serial number M6EG0652. The first number (6) relates to the year – 1986. The next letter relates to the month (E) is May based on the convention January (A), February (B), March (C), April (D), May (E), June (F), July (G), August (H), September (I), October (J), November (K), December (L). It is assumed that the G0652 is the production number. There were a few variations on this type of serial number, but usually they were pretty easy to work out.
There are much more difficulties when looking at Mongoose serial numbers through the 1990’s and 2000’s. I spent quite a bit of time looking into these numbers on a few of my bikes as well as checking against other Mongoose BMX owners to see if my serial number crack was right. It seems to hold up and here it is. Mongoose serial numbers are usually found stamped on the bottom of the bottom bracket. This is not always the case and there will be some bikes that do not fit into this formula.
Mid-school Mongoose BMX bikes built through most of the 90’s have a serial number that begins with 4 letters. The 3rd letter corresponds to the year of manufacture. A B C D E F G H I 91 92 93 94 95 96 97 98 99 The 4th letter indicates the Month A B C D E F G H I J K L Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec A few serial number examples are: HF GB00000 – 4 letters, GB are the dates. G is the year (1997), B is the month (Feb) HF BH00000 – 4 letters, BH are the dates. B is the year (1992), H is the month (Aug) New-school Mongoose BMX bikes built through most of the 2000’s have a serial number that begins with 5 letters.
The 4th letter corresponds to the year of manufacture and follows on from the mid-school serial numbers. J K L M N O P Q R S 00 01 02 03 04 05 06 07 08 09 A B C D E F G H I J K L Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec A few serial number examples are: HAM ME00000 – 5 letters, ME are the dates.
M is the year (2003), E is the month (May) SAJ PJ00706 – 5 letters, PJ are the dates. P is the year (2006), J is the month (Oct) Please note: The Mongoose serial number will give you the build date of your BMX. Frames were normally manufactured the year before being sold in bike shops. So a build date on a frame of 2003 usually means the bike was sold in stores in 2004.
This is the case with the 2003 Mongoose Brawler 24 below. The Serial has a build date of 2003, the 2004/004 on the stickers indicate this was a 2004 model. I have confirmed this Mongoose serial number crack many times against bikes that have been known to be purchased that year, bikes with distinct graphics and colours and checked them against Mongoose BMX catalogues. If you have a Mongoose BMX that doesn’t fit into the serial number style above, go to and post a couple photos of your bike and make sure you include the serial number in your post.
I will look into all the numbers listed. Thanks for reading. If you liked this post, sign up to the blog via email on the home page and get all our news direct to your inbox.