This is a canonical question that will hopefully encompass all of the questions we get asking us to determine what year a bicycle was manufactured (how old is my bike, how old is my frame, etc.). Each "answer" should address a different way to determine the manufacturing year of a bicycle. To some extent, these will also help you narrow down the model as well as it will tell you what distinguishing features to look at.

The span of answers would include things such as:

  • Literature (e.g. old catalogues, fan websites)

  • Cottered cranks vs square tapered or splined cranks and bottom brackets

  • Skiptooth cranks

  • Cartridge bottom brackets (BB30/90 etc)

  • Elliptical chainring

  • Quick releases versus contemporary through-axles

  • How the steerer attaches to the fork (quill vs. threadless)

  • Serial numbers

  • Braking system (especially with mountain bikes: v-brake, direct pull, etc.)

  • Indexed and electronic shifting

  • Style of shifters (brifters, triggers, etc.)

  • Shifting ramps and pins on cassettes/sprockets and chainrings (versus flat sprockets)

  • Frame material (e.g., shift from tubular steel to use of CF and hydroformed aluminium)

  • Frame tubing type (e.g. Reynolds 531 tubing introduced around 1934, still used today; Reynolds 501 tubing introduced around 1983). So a frame with an original 501 decal can't be from the 70', 531 decal doesn't help as much because of the range of years produced. Also, see Decals.

  • Decals: style/design, amount, placement, color, etc. can help not only determine models, but also year of manufacture. Many changed decal design for the same model bike often yearly, with special/limited editions even more specific. This applies only if decals are original or have been replaced with the identical design. Tubing decals (Reynolds, Columbus, etc.) also changed designs for same tubing made in different years, although the changes aren't made as often, and manufacturers didn't always put tubing Brand decals on every model. Earlier bikes tended to have less fancy, less colorful, less quantity of decals.

  • Headbadges: most early bikes had actual "badges," often quite detailed and fancy. These were first made of metal, then plastic, and finally just using decals on the headtube. Most bikes lost their metal badges in the 60's and early 70's, although some brands still have actual badges to this day. In general a real badge indicates an earlier model bike.

  • Dropout style (including the later inclusion of lawyers lips)

  • Presence or absence of CPSC reflectors (USA only)

  • Manufacturing method (shift from lugs to TIG welding, for example)

  • Cassette vs. freewheel sprockets in the rear

  • Number of gears (shift from 2x5 ten-speed to 3x8, 2x9, 1x11, etc.)

  • Ask the owner/seller

  • Inspection of lug design: pantographs, cut-out, stampings, custom brazing/filing, chrome, fork crow n sweep, etc.

  • Frame/Fork Braze-ons. Race bikes tended have less braze-ons the earlier the year of manufacture. Most 60's racers and earlier had few or none with cable guides/stops, shifters, bidons, etc. being clamp-on. By the 80's if it was clamp-on, it was a sign of very cheap models and most frames had braze-ons for all cables, with multiple bottle and accessory bosses depending on style and use.

and so forth. Please edit this question if you have an answer that isn't in the index above.

A couple of caveats:

  1. A previous owner could have replaced or upgraded components on a bicycle, so this guide only applies to original equipment

  2. There is a delay between the introduction of a technology (such as indexed shifting) and when manufacturers start selling products that use it. Low-end manufacturers may continue using technology that is severely outdated (such as one-piece cranks, freewheels, or quill stems) because it is cheaper to do so.

  3. A number of bikes are built in a Retro style, but with modern components. Dutch bikes, trendy coffee cruisers, and beach cruisers may be modern but appear to be 1950s styling. These tend to have modern rims and brakes as a giveaway.

Trek serial number date of manufacture google

Note that bicycles.stackexchange does not do valuations of bicycles. How much your bicycle is worth depends on the location of the buyer and seller, how much the buyer wants the bike, etc. etc. etc.

  • 1
    I feel like there ought to be something about dropouts on derailleur bikes, but don't know enough myself.
    – Chris H
    Commented Jun 2, 2017 at 14:47
  • 2
    Related to drop-outs, I think the presence of lawyer's lips (retention tabs) would also help dating bikes. They weren't present in the early 1990s, I believe, but I don't have a date of introduction.
    – RoboKaren
    Commented Jun 3, 2017 at 5:22
  • good point. They're certainly not present on my '92 bike. I believe I had them on a BSO from about 2001 but have never done much work on a bike built in between these years.
    – Chris H
    Commented Jun 3, 2017 at 6:43
  • 1
    @RoboKaren: I bought a Scott MTB in 1988. It had lawyer lips.
    – Carel
    Commented Jun 4, 2017 at 8:53
  • It should be noted that the presence/absence of reflectors is a poor indicator of age. Reflectors often get removed when damaged (which often happens within days of purchase), while sometimes people add reflectors to old bikes. Commented Jul 24, 2017 at 21:20

9 Answers 9


Serial Numbers

Bicycles (except children's bicycles) are almost always required to have a frame or serial number. Some manufacturers use a date-code as part of the serial number.

For example, a Brompton uses YYMMXXX as their serial code, so a Brompton with a serial number of 1306123456 was manufactured in 2013.06 or June 2013

Surly is another manufacturer who uses date codes, this time in their stamped frame numbers.

Manufacturers who don't use date codes

However, many bicycle manufacturers don't use date codes and so you can't easily decode their serial numbers. Some of these manufacturers will provide their own serial number lookups on their websites. Some of the other ones have been reverse-engineered by their rider communities. The best way to find out is to google "manufacturername bicycle serial number date of manufacturer."

Trek serial number date of manufacture google

See also the Mongoose answer is below


  • 1
    Should we have a CW question showing all the "serial name lookup sites" ? Or is that something better left to google ?
    – Criggie
    Commented Jul 26, 2018 at 11:37
  • Why not just edit it into this answer or a community wiki answer?
    – RoboKaren
    Commented Jul 26, 2018 at 11:39
  • 1
    Could grow too long and cluttered an answer if it was all in this one.
    – Criggie
    Commented Jul 26, 2018 at 11:43
  • I say go for it then. Happy to link to that q&a from here. We certainly get enough serial number questions.
    – RoboKaren
    Commented Jul 26, 2018 at 11:44
  • Mongoose - see answer bicycles.stackexchange.com/a/57901/19705 further down.
    – Criggie
    Commented Nov 5, 2018 at 12:01

Literature (old catalogues, fan websites, etc.)

I managed to date my old Raleigh by finding scans of old catalogues online. That model was only sold in one particular year, but more often you'd get it to within a few years this way. There are many old cycling documents at Veteran-Cycle Club Online Library, including plenty that can be accessed for free. Searching for a brand and plausible year with "catalogue" can often turn up sites dedicated to scans of that brand's literature; you may need to check more than one such site for good coverage.

This will only really work for a major brand that has a bit of a following, as it relies on someone uploading the catalogues. You also need a rough idea (e.g. from the components) to know which catalogues to look in.

Bikepedia is also useful, but mainly for confirming when you think you know a year, and only goes back to 1993.

This would also include fan websites, such as for:

  • Mongoose - uses design features and serial numbers to date
  • 1
    I just visited Bikepedia and found it to be uniquely useless. Commented Nov 24, 2018 at 7:29

Indexed and Electronic Shifting

Shimano introduced Shimano Indexed Shifting (SIS) in 1984. If a bicycle has indexed shifters, then it is model year 1985 or later -- assuming that the shifters and derailleurs haven't been replaced.

The first Shimano Di2 electronic shifters were introduced on a production bicycle by Giant in 2009.


Ask the Seller/Owner

A simple thing if you're receiving a bike is to ask the person selling it. Take their info with a grain of salt though - some sellers may lie to increase the perceived value of a bike.

However if someone gives you a bike, they might say "I remember my dad riding this to work in the 80s while I was at school"

So this information may be authoritative, or it may be an indicator to be combined with other factors.


Style of Shifter (friction shifter, brifter, grip shifter)

Downtube or handlebar mounted friction shifters were common on bicycles until the early 1980s when indexed shifting was introduced by Shimano in 1984 (see Indexed Shifting).

Mountain bike trigger shifters were introduced by ... in ...

The first Grip Shifters were introduced by SRAM in 1989 for mountain bikes.

Brifters (combination brakes and shifters on road bikes) were introduced in 1990 with the Shimano Total Integration (STI) system.

  • Stem shifters were common on bikes in the 70s, but downtube took over in the 80s. One generally only saw handlebar shifters on really cheap bikes. Commented Nov 4, 2018 at 13:51

Freewheel or Cassette (Freehub)

If your bicycle uses a cassette freehub for the rear sprockets, then it was likely made in the late 1980s or later. Shimano came out with the first commercial freehub in 1978 in the Dura-Ace series, but it took about a decade for it to make significant inroads.

Like many other technologies, cheaper bicycles (and notably, many e-bikes) have continued to use freewheels even today so only the presence of a freehub/cassette can be used as a positive indication of date:

  • Freehub-cassette present as original equipment: the bike was likely made in the late 1980s or later
  • Freewheel present as original equipment: you can't determine anything about its age just from this
  • I'll note that it's sometimes difficult to distinguish between freewheel and freehub without disassembling the hub. Commented Jul 24, 2017 at 21:22
  • 1
    In some cases, the number speeds the freehub supports can give some information. Shimano road freehubs for 9/10 speeds were likely manufactured in the early 2010s. When Shimano debuted its 11s road groups in 2012, they introduced a new freehub design. For Campagnolo, I believe that a similar disjuncture occurred when they introduced 9s freehubs in the late 1990s. The presence of a SRAM XD driver may date the wheelset's earliest manufacture at 2015 or so.
    – Weiwen Ng
    Commented Oct 27, 2019 at 21:06
  • @WeiwenNg this is great info. You should spin it off as a separate answer.
    – RoboKaren
    Commented Oct 27, 2019 at 21:24
  • Karen, thanks. I think I may do so. I'm trying to find some objective sources for the statements.
    – Weiwen Ng
    Commented Oct 27, 2019 at 21:36

Cottered Cranks

The use of cottered cranks was popular on bikes until the mid to late 1970s until they were replaced by square taper and splined bottom bracket designs.

Raleigh, for example, introduced square tapers on some models in 1973 and phased cotters out on all their models around 1978. Like many things, the shift to square tapered and splined brackets took some time so there were still some mainstream bike companies still using them in the early 1980s. However, a cottered crank is generally a good sign your bike is pre-1980.

In some factories in China and India that are still working off old blueprints, cottered spindles may still be in use in the manufacture of new bikes.


Mongoose specific

if you have mongoose this may be if some help..


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:

HFGB00000 – 4 letters, GB are the dates. G is the year (1997), B is the month (Feb)

HFBH00000 – 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 few serial number examples are:

HAMME00000 – 5 letters, ME are the dates. M is the year (2003), E is the month (May)

SAJPJ00706 – 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.


Freehub Speeds

Component manufacturers have steadily increased the number of cassette cogs at the rear. At times, they needed to change the freehub body and/or free hub spline pattern to accommodate things. Thus, the number of speeds the freehub can support can provide some information on the wheels' date of manufacture. This can be a proxy for the frame’s age. But note that A road frame with 130mm rear spacing could have been manufactured in the early 1990s, but it could conceivably accept wheels made in 2021.

As required background information, there are three current types of freehub bodies. Freehubs can be splined for Shimano or Campagnolo cogs, or they can accept a SRAM XD or XDR driver. This article is focused on road bike freehubs; I believe the dates should be similar for MTB freehubs. If anyone knows otherwise, please comment!

This answer focuses only on the number of speeds in the freehub. Knowing the component group's model number or identifier (e.g. Shimano Dura Ace 7800, 7900, 9000, 9100, or Campagnolo Record 11s from 2008, Record 11s from 2015, or Record 12s) can also provide dating information. Knowing a wheel's model can also provide some information. I'm not covering that here. I also omit the number of speeds in the freewheel, because I'm not familiar with the technology. As previously observed, the mere presence of a freewheel does provide some general date information also.


SRAM introduced the XD and XDR drivers in 2015. The latter is for road bike wheels. Standard road or MTB freehub bodies cannot otherwise take a 10t cog. 10t cogs are helpful for 1x drivetrains (pronounced "one-by", refers to a single front chainring) to achieve a sufficient high gear. Thus, if a wheel has an XD/XDR driver, it was made in 2015 or later. However, do note that SRAM do still make double drivetrains with 11t starting cogs. Not all SRAM-specced bikes made after 2015 have XD/XDR drivers.

At the time of writing in late 2019, cassettes with 10t cogs do not appear to be commonly used with standard sized road chainring combinations (i.e. 50/34, 52/36, or 53/39). SRAM's 12-speed road groups have smaller chainrings and use XDR cassettes, so this may change. My understanding is that current XDR drivers will work with 12s cassettes.

SRAM is a relatively new entrant to road bikes. I believe they entered the market in the late 2000s. They used Shimano’s spline pattern until they introduced the XD/XDR system.


8s hubs mean 1996 or thereabouts: Some of this article relies on my memory. Wikipedia confirms that Campagnolo debuted 9s shifting in 1997. This would have started with Record, their then-top groupset, and then trickled down. This article from Branford Bike confirms that the spline pattern for their 8s and earlier hubs is slightly different from the 9s hubs.

Thus, if a Campagnolo hub has an 8s freehub body, it was likely made before 1996. Given that 9s probably took a couple years to trickle down, 8s Campagnolo hubs could have been in production up to maybe 1998 or 1999.

Take note that at least some 8s Campagnolo hubs might have been able to accept 9s freehub bodies. Sheldon Brown's site (first link) says that the parts might not have been available. The discussion on the Paceline Forum (second link) says that 9s freehub bodies might not have fit all 8s hubs.

9s, 10s, 11s, and 12s hubs: as I recall, a Campagnolo hub originally made for 9s cassettes can also fit 10s, 11s, and 12s cassettes, and vice versa. Thus, I don't believe that after 9 speeds, merely knowing the number of speeds is that helpful in dating a Campagnolo freehub. As shown at the Branford Bike site, the 9s hub may have had a slightly different spline pattern from subsequent hubs. I suspect most sellers would describe the freehubs as compatible with 9-12s cogs.

Note that Campagnolo doesn't have groupset model numbers like Shimano. Sometimes, Campagnolo users will use the number of speeds as a reference to the model year. This can provide some information as well, but do be aware that there are two versions of the 10s systems and two versions of the 11s systems that I am aware of. If someone advertises a wheel with a 9s Campagnolo hub, it was probably made in the late 1990s, but it can take 9-12s cogs.


9s and 10s compatible freehubs: In 1997, Dura Ace went to 9 speeds, and Ultegra and 105 followed. I believe 9s freehubs are also compatible with 10s cassettes. Hence, most 9/10s freehubs mean the hub was made prior to 2012.

However, for Dura Ace only, a 10s-only freehub body was introduced in 2004. It had taller splines (this was meant to provide more surface area for the cassette cogs, which should reduce gouging on the freehub). This particular freehub body should place a wheel or wheelset from 2004 to about 2008. Shimano did not trickle this design down to their groupsets below Dura Ace or to their MTB groupsets.

11s freehubs: In 2012, Shimano released its 11s Dura Ace group. This reverted to the old spline pattern, but had a slightly wider freehub. 11s freehubs can take 10s cassettes with a spacer. 10s freehubs cannot fit most 11s cassettes (note: they can fit MTB cassettes and HG700 or HG800 cassettes), and will be advertised as being specific to 10s. 11s compatibility means your freehub is made after about 2012.

12s or Microspline freehubs should mean 2020 or later for MTB wheels: For its 12s mountain bike groups, Shimano is moving to a new spline pattern.

At the time of writing in 2019, DT Swiss, i9, and White Industries have either licensed the micro spline design or come up with a workaround.

Shimano’s own Dura Ace 12s wheels, announced in late 2021, have freehub bodies with more splines than the Hyperglide hubs. I am not sure what the official name is yet. However, 12s cassettes can fit on previous Hyperglide hubs (but DA wheels can’t fit 11s cassettes). It’s possible Shimano may gradually shift to the new spline pattern, since the Hyperglide hubs were prone to getting notches on the splines. That remains to be seen.

  • 2
    This is a great post and super helpful for dating newer bikes.
    – RoboKaren
    Commented Oct 28, 2019 at 20:27
  • @RoboKaren Concur - we tend to focus on the older stuff because it is what we're more familiar with. The newer stuff is less well known to us. I should point out that the groupset/wheel could have been replaced so its another data point and not a hard and fast sign (I had a 9 speed shimano 105 groupset on a 1981 Raleigh which would have suggested 1998 onwards)
    – Criggie
    Commented Feb 5, 2020 at 0:31
  • 1
    There are two 9-speed Campagnolo systems too, known as "pointy ergo" and "round ergo". The derailleur actuation ratio changes between these so they are not compatible, but the hub may be the same.
    – ojs
    Commented Feb 5, 2020 at 8:50

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