Bicycle Frames — Materials, Geometry, and What to Look For

The frame is the heart of any bicycle. Everything else bolts on and can be upgraded, but the frame determines the bike's character, weight, ride quality, and fit. Choosing the right frame material and geometry is the foundation of a great build.

Frame Materials

• Aluminium — the most common material for modern bikes. Light, stiff, affordable, and corrosion-resistant. Can feel harsh on rough roads compared to steel or titanium, but quality aluminium frames with good geometry ride very well.
• Steel — the traditional choice. Heavier than aluminium but renowned for its smooth, compliant ride quality and durability. Chromoly (CrMo) steel is the premium option — lighter and stronger than hi-ten steel. Steel frames are also easier to repair.
• Carbon fibre — the lightest and most performance-oriented option. Excellent stiffness-to-weight ratio and can be shaped to optimise aerodynamics and vibration damping. More expensive and harder to repair if damaged.
• Titanium — the premium all-rounder. Light, strong, corrosion-proof, and with a ride quality comparable to steel. Expensive but potentially a lifetime frame.

Geometry — How a Frame Rides

Frame geometry determines your riding position and handling characteristics:

• Stack and reach — the two most important fit measurements. Stack is the vertical height from bottom bracket to head tube; reach is the horizontal distance. Higher stack = more upright position.
• Head tube angle — steeper angles (73°+) make steering quicker; slacker angles (68°–70°) are more stable at speed, common on MTB.
• Chainstay length — shorter chainstays make the bike more agile; longer chainstays improve stability and heel clearance with panniers.

Standards to Check

Before buying a frame for a custom build, verify compatibility with your components: bottom bracket shell standard, headset standard, axle standards (front and rear), brake mount type, and seatpost diameter.

Browse our frames collection to find the right foundation for your build.