What year is my bike? How to work out how old a bike is
For most bikes the frame number will not give you a year. The paperwork, the parts and the paint usually will, and one of those you can decode on this page.
The short answer
For most brands you cannot read a year from the frame number. Bicycle serials are internal manufacturer records, and most do not encode a date or a model. What dates a bike is the evidence around the frame: a receipt, warranty card or Cycle to Work paperwork, the two-letter date code stamped on many Shimano parts, the groupset series and the number of rear sprockets, and the paint scheme matched against the brand catalogue for that year. The manufacturer can look up its own serials, so contacting the brand or the shop that sold the bike with the frame number is the route that works when the rest runs out.
The short version
- Most bicycle frame numbers do not encode a year, so do not expect a decoder for your brand.
- Paperwork is the most direct evidence: a receipt, warranty card, Cycle to Work paperwork or a registration record.
- Many Shimano parts carry a two-letter date code: the first letter is the year, the second the month.
- A component date dates the part, not the frame, and only bounds the build year if the part is original.
- The brand or the shop that sold the bike can look up the frame number on its own records.
Why the frame number usually will not date the bike
It is the first place people look, and for most brands it is a dead end.
A bicycle frame number is a production record the manufacturer keeps for its own factory and warranty system. It is not a registration number, and there is no public register that turns one into a year.
Most brands do not publish what their numbering means, and most serials do not encode a date at all. So for the majority of bikes, no amount of staring at the number will produce a year, and the page you are reading will not pretend otherwise.
There are exceptions. Brompton says the first four digits of its 10-digit serial number show the year and month of manufacture, so a serial starting 1903 means March 2019. That serial is not always the same as the number stamped into the frame, and the Brompton guide covers where to find both.
For everything else, treat the frame number as the thing you give the manufacturer or the selling shop, who can look it up on their own records, and date the bike from the evidence below.
Brompton frame number guide · Where the frame number is, by brand
Decode a Shimano date code
Enter the two letters from the component. The first is the year, the second is the month.
The year letters run from A for 1976 to Z for 2001, then start again at A for 2002. So most codes give two candidate years 26 years apart, and you choose between them from the component model and the era of the bike.
The month letters run from A for January to L for December. A second letter from M to Z is not a valid month, so check you have read the right two letters.
For example, VI means September 1997 or September 2023.
How to date the bike, in order
Work down the list and cross-check. No single step settles it on its own.
- 1
Look for the paperwork
A dated document is the most direct evidence of when the bike was sold. It is worth ten minutes of searching before anything else, because nothing on the frame is as reliable.
- 1.Look for the original receipt or order confirmation, including in your email.
- 2.Check for a warranty card or a manual with a stamped sale date.
- 3.If the bike came through a Cycle to Work scheme, the scheme paperwork carries a date.
- 4.If the bike was ever registered on a bike register, the registration record shows when.
What this cannot settle
A receipt dates the sale, not the build. A bike can sit in a shop or a warehouse before it is sold, and a second-hand receipt only tells you when that owner bought it.
- 2
Read the Shimano date code
Many Shimano components carry a two-letter code: the first letter is the year and the second is the month. It is the one dating method on a bike that is mechanical, and you can decode it on this page.
- 1.Look near the serial number on the part, stamped into the metal or printed on a sticker or label.
- 2.Check the cranks, the rear derailleur and the hub bodies first, where the code is common.
- 3.Note the two letters and enter them in the decoder below.
- 4.Pick between the candidate years using the component model and how the bike looks.
What this cannot settle
Not every part carries a code, and the year letters repeat every 26 years, so most codes give two candidate years. It dates the part, not the frame, and a part fitted later will make the bike look newer than it is.
- 3
Note the groupset series and the sprocket count
The groupset series name on the derailleur and chainset, together with the number of sprockets on the rear wheel, narrows the era. Groupset series change over time, so the combination points to a range of years.
- 1.Read the series name next to the brand on the rear derailleur.
- 2.Check whether the chainset carries the same series or a different one.
- 3.Count the sprockets on the rear wheel.
- 4.Compare the combination against the groupsets that series offered over the years.
What this cannot settle
This gives an era, not a year, and replaced parts skew it. A bike that has had a new derailleur or cassette will read as newer than its frame.
- 4
Match the paint and decals to the catalogue
Brands change colour schemes and decal designs from one model year to the next. Once you know the brand and model, matching the paint against the catalogue for each year is often what settles it.
- 1.Identify the brand and model first, from the decals and badge.
- 2.Search for the brand catalogue or product pages for the years your other evidence points to.
- 3.Compare the colour, the decal layout and where the model name sits on the frame.
- 4.Check the cable routing and brake type against the same catalogue year.
What this cannot settle
Some schemes run for several years, older catalogues can be hard to find, and a respray removes the evidence entirely. Treat a paint match as a cross-check on the parts, not proof on its own.
- 5
Ask the brand or the selling shop
Manufacturers can look up their own serials, and a shop that sold the bike may still have the sale on its system. When the evidence on the bike runs out, this is the route that works.
- 1.Find the frame number, usually under the bottom bracket where the pedals meet the frame.
- 2.Photograph it clearly, along with the whole bike.
- 3.Contact the brand customer service or the shop, giving the frame number and the model if you know it.
- 4.Ask specifically for the build year or the model year the frame belongs to.
What this cannot settle
This depends on the brand still existing, keeping records that far back, and being willing to answer. Smaller and discontinued brands may not be able to help.
Dating a bike, questions answered
Can I find out what year my bike is from the serial number?
For most brands, no. Bicycle serials are internal manufacturer records and most do not encode a date. Brompton is an exception: the first four digits of its 10-digit serial number show the year and month of manufacture. For other brands, give the frame number to the manufacturer or the shop that sold the bike, who can look it up on their own records.
What does the two-letter code on my Shimano part mean?
It is a date code. The first letter is the year, running from A for 1976 to Z for 2001 and then starting again at A for 2002, and the second letter is the month, A for January to L for December. So VI is September 1997 or September 2023. It is usually near the serial number on the part.
Does a Shimano date code tell me when my bike was made?
It tells you when that part was made. If the part is original to the bike, the bike cannot have been built before that date, so the code gives you the earliest the bike could be. If the part has been replaced, it tells you nothing about the frame, so check more than one component.
How do I find out what model my bike is?
Start with the decals on the down tube and top tube, then the head tube badge, the type of bike and the components. Our guide to identifying a bike works through those checks in order. Knowing the model first makes dating it much easier, because you can compare it against that model in each year of the catalogue.
Once you know the year
Last reviewed 24 September 2026 by the Cyclesite editorial team.