How Do I Know What Material My Bike Is Made Of: An easy to follow flowchart


Titanium, Aluminum, Steel, and Carbon Fiber are the four most commonly used materials for bike frames and forks, but how do I know what material my bike is made from? With so many types of materials being used to make bikes, it can be very challenging to work out for certain what your bike is made from, especially when they all look so similar. It can be very useful to know what your bike frame is made from as it can determine the value of the bike that you have, or if you want to know the best way to look after your current bike (different materials have different maintenance needs).

There are 5 key steps to working out what material your bike frame is made from.

  • See if the frame is magnetic
  • Look down into the seat tube
  • Tap it with a screwdriver
  • Make a small scratch
  • Look at the tube diameter

Below we go through this series of steps in more detail and have simplified them all into one easy-to-follow flowchart. We will also take a look at how to distinguish the two most common types of steel bikes, Chromoly steel vs high tensile steel.

A flowchart showing you how to work out which material your bike frame is made of: Aluminium, Steel, TItanium or Carbon Fibre

Before you start: Check the bike model online

While it may seem obvious, the easiest way to find out what material your bike frame is made from is to check the model online. This doesn’t help in all cases though, as sometimes you do not know the model of the bike you have, or in other cases the same bike can have manufacturing runs with a variety of different frame materials, making it hard to work out exactly what material the bike in front of you is made of.

Either way, this step can help to rule out some frame materials, for example, if you know that this bike only came in Aluminium or Carbon fiber versions, then it makes it much easier, as you only need to decide which of those two materials the bike in front of you is made of.

See if the frame is magnetic

How do I know if my bike is made from steel?

The first step to working out what material your bike is made of is seeing if it is magnetic. Steel bikes are magnetic whereas other types of bikes aren’t.

You can use any magnetic object you have in your house already, or buy a small magnet such as this. Simply touch the magnet to the frame of the bike and see if it attracts. If it isn’t magnetic, then you know your frame is not made from steel and you can move on to the next step.

If it is magnetic, there are a few more things you need to do to work out what type of steel it is, as there are many different types of steel bikes (high-tensile, Chromoly, etc.). There are a few key ways to differentiate between these types of steel, which we go into more detail in the last section of this article on, “How do I know which type of steel my bike is made from (Chromoly or High tensile)?”

Look down into the seat tube

How do I know if my bike is made from Carbon Fibre?

A good way to tell if a bike is made from Carbon FIber or another metal is to look down into the seat tube and look at the color of the material inside.

To look down the seat tube remove the saddle from the frame itself. The seat tube is the hollow part of the frame that the saddle slots into. When looking down into the inside of the seat tube, look at the color of the material it is made of.

If it looks metallic inside, it could be made from aluminum or titanium, if the inside of the seat tube looks black or plastic-looking, then it is probably made from carbon fiber.

Tap it with a screwdriver

Confirming whether or not your bike is made from Carbon Fibre

For extra confirmation on whether a frame is made of carbon fiber, you can use the ‘Tap test’. Simply tap the frame with a screwdriver or other metal object.

Aluminum and titanium bikes will have a definite metallic ‘tink’ when tapped with another metal, whereas carbon fiber frames have more of a hollow plastic sounding ‘thunk’.

While both steps 2 and 3 could be quite subjective, using both together can help you feel confident in whether the frame is carbon fiber or another metal.

Make a small scratch

How do I know if my bike is made from aluminum or titanium

To tell the difference between Titanium and aluminum frames, you need to go back again into the seat tube. In the tube itself make a very small scratch (don’t worry, both Aluminium and Titanium have good anti-corrosion properties and so this should not damage the frame itself).

If the exposed metal is dark or dull silver, it’s more likely to be titanium, if light silver it’s aluminum. If you’ve gotten to this stage and still don’t know what material your bike is made from, it’s more likely to be aluminum than titanium. Titanium frames are expensive and rarer, so you are not as likely to come across one unless you had been looking for it specifically.

Look at the tube diameter

How do I know if my bike is made from Aluminum or steel?

Another step you can take to help you decide on the material of your bike frame is to look at the diameter of the tubes making up the bike frame itself. This step helps to differentiate aluminum bikes from steel (particularly Chromoly) bikes.

In general, an aluminum bike will have larger tube diameters due to the properties of the material. On most steel bikes, the seat tube is 28.6mm in diameter, while aluminum usually comes in at 31.8mm or 34.9mm. This can be another way to help confirm if the other tests have led you to the right conclusion.

How do I know which type of steel my bike is made from (Chromoly or high tensile)?

There is a significant difference between the two main types of steel, Chromoly and High tensile steel. Chromoly is a stronger and lighter (high carbon) steel and is generally found on mid to high-end bikes.

There are a few ways to try and differentiate Chromoly steel bikes from high tensile steel bikes. Firstly, during the magnet test, if the magnet attracts strongly to the frame, then it is more likely that it is a softer type of steel such as high-tensile. If the magnet sticks and then slowly slides off, then it’s likely that Chromoly steel has been used.

The next step is to check the tube diameter of the frame. Presuming the bike is reasonably modern, a bike made from Chromoly steel is more likely to have smaller diameter tubes and possibly a smaller diameter seat post than its high tensile alternatives. Bear in mind that this isn’t as good an indicator as it used to be – new steel frames are being produced with smaller diameter tubes that can fit dropper seat posts.

Another clue to the material that your bike is made from may be found on the seat tube. Some manufacturers, particularly those who work with Chromoly may have a sticker on the seat tube from the tube manufacturer (Reynolds, Tange, or Columbus, etc). This will either give you the material the frame is made from or may give you the serial number of the bike, allowing you to search it online.

Overall

As you can see, by following the easy steps set out in our flowchart, you can have a good indication of the material your bike is made from. Whether you’re looking to sell your bike, or simply want to properly check over a second-hand bike you are buying, working out the material your frame is made from is an important skill that all riders should know.

Mark Holmes

30-year-old doctor with an interest in cycling, bikepacking, and statistics.

Related Articles