The Bike List

The quick guide to aluminium alloy

With over 60% of adult bike frames being made from various grades of aluminium alloy it's by far the most common material currently in use on all types of bike including commuter, road, mountain and children's bikes. As well as being a relatively cheap material for manufacturers to purchase, aluminium is also straight forward to work with, lightweight and has a high strength to weight ratio.

Aluminium framed hybrid / commuter bikes and hardtail mountain bikes start at around £300, aluminium framed road bikes at around £500 and aluminium framed full suspension mountain bikes at around £1000. Although aluminium frames feature on many entry level bikes they also frequently feature on mid and high end bikes too, particularly on high end downhill /freeride mountain bikes that are more likely to be subjected to greater stresses and strains and the odd crash.

Aluminium is about 1/3 the density of steel but by using wide diameter tubes with thin walls, and thanks to it's high strength to weight ratio, aluminium alloy frames can be lighter, stonger and stiffer than their steel equivalents.

Hydroformed tubes

As manufacturing methods have improved so have the shapes that can be achieved with aluminium alloy and an increasing number of tubes are hydroformed. This process involves using fluid under high pressure to shape aluminium and has allowed frame designers to produce more imaginative and less traditional tube shapes.

As with carbon fibre there are numerous grades of aluminium alloy, each with slightly different properties and some being more expensive than others.

Double and Triple butted frames:

To make frames lighter manufacturers will often use double or even triple butted tubing. The process of butting involves making the middle sections of tubes thinner than the ends to reduce the amount of material being used and is almost always internal which is why you won't see it. As the names suggest double butting means that a tube has two thicknesses and triple butting means it has three. The lightest aluminium alloy frames will be triple butted as this saves the most weight by using the least amount of material.

The advantages and disadvantages of aluminium alloy as a frame material.

Advantages

  • Aluminium is relatively cheap for manufacturers to buy and work with.
  • Aluminium allows manufacturers to produce stiff, strong and lightweight frames
  • Aluminium can corrode over time but doesn't rust.
  • Aluminium has a long life span and a good aluminium frame should easily keep going for 10-20 years if not more.
  • Modern manufacturing processes have allowed for some super lightweight aluminium frames to be produced. The most advanced, such as the Cannondale CAAD10 road fame, are as light and stiff as their carbon equivalents.
  • Aluminium frames can often be repaired if one of the joining welds cracks or breaks.
  • Aluminium can be manufactured (hydroformed) into shapes that steel and titanium can't.

Disadvantages

  • Aluminium offers a harsher or rougher ride than most other frame materials as the material is very stiff and does not naturally absorb vibrations as well as carbon fibre, titanium or steel.
  • Aluminium welds are much larger than steel or titanium welds and can in some instances be a bit unsightly.
  • Aluminium's breaking, bending and stretching strength are far less than high strength steel and titanium alloys.

Top Tip 1: Some manufacturers such as Boardman fill in some or all of the welds to create clean lines more similar to those found on carbon frames.

Top Tip 2: When buying a new aluminium framed road or commuter bike look for one that has been paired with a carbon fibre fork to help dampen vibrations from the road. This is less of an issue with mountain bikes which typically come with suspension forks.

Want to know more about other frame materials?

Read our quick guide to carbon fibre.

 

Click below to see all aluminium alloy framed bikes by family.

Cyclocross Bikes

Road Bikes - Sportive / Performance / Endurance

Road Bikes - Racing / Aero

Triathlon / TT Bikes

Hybrid/ Town / Commuter Bikes

Hardtail Mountain / Cross Country Bikes

Full Suspension Mountain / Cross Country Bikes

Downhill / Freeride Mountain Bikes