Mountain bike geometry has changed dramatically in recent years. The trend? Longer reach, lower bottom brackets, and slacker head angles – often referred to as “longer, lower, slacker.” But while this progressive geometry is great for some riders, is it the right fit for you?
Here’s a breakdown of what geometry numbers matter and what you should be paying attention to when choosing your next bike.
1. Head angle
A bike’s head angle, or steering axis angle, is the angle between the fork and the ground. Mountain bikes typically have a head angle between 62° and 73°.
A slacker head angle (a lower number, like 64°) makes the bike more stable on steep descents but less agile in tight corners. A steeper head angle (a higher number, such as 67°) offers quicker handling, making it better for technical climbs and twisty trails.
2. Reach & wheelbase
A bike’s reach is the horizontal distance from the centre of the bottom bracket to the top of the head tube and measures how far forward your hands will be when riding.
- Longer reach provides a more stable feel at high speeds but requires a more aggressive riding position.
- Shorter reach makes a bike feel more playful and easier to manoeuvre.
The wheelbase is the distance between the front and rear axles, it grows as reach and head angle change, which will in turn, affect stability and turning ability.
3. Bottom bracket height
This is the vertical distance measured from the ground to the centre of the bottom bracket axle. It measures how high the pedals are positioned when the bike is standing upright and helps determine how stable and easy to handle a bike will be, depending on riding style and terrain.
- Lower bottom bracket: Helps with cornering stability but increases the chance of pedal strikes on rough terrain.
- Higher bottom bracket: Offers more pedal clearance, which is helpful especially on rough terrain.
4. Seat tube angle
A seat tube angle is between the horizontal plane and the seat tube. It measures how tilted the vertical seat tube is relative to the ground. Steeper angles position the saddle further forward, while slacker angles move it backward, both of which have a large impact on a rider’s position on the bike.
- Steeper angle: This places you in a more efficient climbing position, leaning forwards more.
- Slacker angle: Pushes the saddle further back for a more upright posture, which is more efficient for cycling on flat terrain.
Do you need progressive geometry?
Progressive geometry is designed for aggressive riding and high-speed descents. But does that mean every rider needs it?
- For enduro & aggressive riders: Longer and slacker geometry is the best choice for you. Added stability will help at speed, and you’ll appreciate offers more confidence on tough terrain.
- For trail riders & all-rounders: If you want one bike for all disciplines, a trail bike with balanced geometry is the best option. It gives you a mix of agility, climbing efficiency, and stability – perfect for UK trails.
Sizing: stick to manufacturer recommendations
With modern geometry, some riders consider sizing up for extra stability. But it’s best to follow the manufacturer’s size chart for the best fit. A bike that’s too long can feel sluggish, while one that’s too small can feel cramped and unstable.
You Can’t Go Wrong with Uprise
No matter what you focus on, the most important part of mountain bike geometry is how the bike feels. At Uprise Bikes, we ensure every model is built for a great experience – whether you’re an enduro racer or a weekend warrior.
Check out our range at Uprise Bikes and find the right geometry for you!
