Bike Frame Materials Explained: Titanium vs Carbon vs Alloy vs Steel
Compare titanium, carbon, alloy and steel bike frames. Discover the pros, cons, ride feel and environmental impact of each – and which suits your terrain.
Choosing a bike frame material isn’t just about weight and stiffness. It’s about how your bike feels to ride, how long it lasts - and increasingly, how it impacts the planet and people along the way.
At Sonder, we make bikes in titanium, alloy and steel because each has unique strengths. Whether you're heading into the hills, racing gravel, or riding round the world, this guide will help you choose the right frame for the job - and feel good about the choice too.
We’ve answered some of the most common questions below, including real-world ride feel and environmental impact. If you're still deciding what kind of bike you need, start with our guide to gravel bikes.
In a rush? Here's the gist:
- Titanium - Light, durable, corrosion-proof and comfy. Higher cost but built to last a lifetime.
- Carbon - Fast and light with excellent stiffness. Tricky to recycle and less crash-resistant. Very labour intensive to make.
- Alloy - Great value and weight. Stiff ride feel. Made with recycled content and easier to recycle than carbon.
- Steel - Smooth, strong, repairable. Heavy but low impact and long-lasting. Very high recycled content and recyclable.
Questions answered:
- Choosing titanium for a bike frame
- Carbon frames: weighing up the cost
- Alloy frames: the pros and cons
- Steel frames: how they compare
- Reynolds 520, 631 and 853 explained
- The most planet-friendly bike frame material
- Frame material's effect on ride feel
Choosing titanium for a bike frame
Titanium is the dream frame material for many riders. It’s light, incredibly strong, naturally corrosion-resistant and doesn’t fatigue like alloy. The ride feel is often described as springy and forgiving - perfect for long days in the saddle or rough terrain.
We use aerospace-grade 3Al-2.5V titanium on our Camino Ti, Broken Road Ti and Colibri Ti. These frames are built to last a lifetime (and then some).
Pros: Tough, lightweight, doesn’t rust, superb ride comfort.
Cons: Expensive to produce and weld. We buy recycled titanium however it is not yet generally widely recyclable at scale.
Carbon frames: weighing up the cost
Carbon fibre is the lightest frame material. It offers excellent stiffness-to-weight and lets makers fine-tune frame flex - which is why it's the go-to for racing bikes.
But carbon’s not without compromise. It doesn’t like crashes. It’s difficult to repair. And unlike metal frames, most carbon frames can't be recycled - yet.
Pros: Featherweight, aerodynamic, can be tuned for comfort or stiffness.
Cons: Difficult to repair or recycle. Can crack under impact.
Alloy frames: the pros and cons
Alloy - or aluminium - is strong, relatively light and affordable. We use both 6061 and higher-grade 6066 alloy in frames like the Camino AL and Colibri AL.
It’s less forgiving than steel or titanium, but frame design and fork choice make a big difference to ride comfort. Most importantly, aluminium is widely recyclable - a big tick if you’re looking for a lower-impact build.
Pros: Affordable, lightweight, stiff. Easy to recycle.
Cons: Harsher ride feel. Shorter fatigue life than steel or titanium.
Steel frames: how they compare
Steel has soul. It’s strong, easy to repair, and delivers a smooth, supple ride. Heavier than other materials, yes - but the comfort, durability and simplicity make it a top pick for touring, bikepacking and all-day gravel adventures.
We use 4130 chromoly and Reynolds tubing in bikes like the Broken Road ST. These are bikes for big journeys and big loads.
Pros: Smooth ride feel, long lifespan, repairable. Often locally sourced and lower energy to produce.
Cons: Heavier. Can rust if not looked after.
Reynolds 520, 631 and 853 explained
Reynolds 520 is a high-quality chromoly steel - ideal for robust, affordable frames.
Reynolds 631 is heat-treated for extra strength and fatigue resistance - you’ll find it on classic steel touring frames.
Reynolds 853 is the top-end stuff: heat-treated, air-hardened, and stiffer at a lower weight. Perfect for performance builds.
These British-made tubes are a nod to tradition, but with modern metallurgy behind them.
The most planet-friendly bike frame material
There’s no perfect material - each has trade-offs. But here’s a rough guide:
- Steel - Lower energy to produce, recyclable, often made in the UK (Reynolds). Lasts decades.
- Aluminium - Energy-intensive to mine and smelt, but widely and efficiently recycled.
- Titanium - Very durable, but high environmental cost to extract and process. Not yet commonly recycled.
- Carbon fibre - High energy to make. Not recyclable at scale. Shorter lifespan if damaged.
The most sustainable frame is the one you ride for years. That’s why we build for durability first - not disposability.
Frame material's effect on ride feel
Material choice affects:
- Comfort - Titanium and steel soak up vibration. Alloy can feel stiff. Carbon can be tuned.
- Weight - Carbon is lightest. Titanium and alloy close behind. Steel is heavier but strong.
- Responsiveness - Alloy and carbon feel zippy. Steel and titanium are more compliant.
But geometry and tyre choice often matter more. The right frame material should match your priorities - whether that’s racing, roaming, or just getting to work with a grin.
Final thoughts
There’s no wrong choice - just what’s right for you. Whether you go for lifetime titanium, trusty steel or value-packed alloy, we build bikes that go the distance - for riders and the planet.
Browse Sonder frames or get in touch for a chat about which is right for you.