The ideal head tube angle for climbing is about 73° for road bikes.
Modern XC MTBs operate with a 67.3º average head tube angle, but a steeper one will also be suitable for climbing.
How Does The Head Tube Angle Affect Climbing?
The head tube angle (HTA) is one of the properties that determine the distance between the front wheel and the head tube (and respectively the rider).
A slack (smaller) head tube angle positions the wheel further in front of the rider and makes climbing harder for the following reasons:
- Extra weight on the rear wheel
A slacker head tube angle shifts the rider’s center of mass closer to the rear wheel. As a result, spinning the rear wheel becomes harder when going uphill.
- Upright riding position
A slacker head tube angle makes the rider’s back more vertical. This position increases the drag and the involvement of the quadriceps at the expense of the glutes. Consequently, the rider has a harder time generating maximal torque.
- Reduced Front Wheel Traction
It’s very easy to lose front-wheel traction when going uphill because the steep gradient moves the rider’s center of mass closer to the rear wheel. A slacker head tube angle exaggerates this effect.
Additionally, generating a lot of torque during pedaling (as it often happens during climbing) helps lift the front wheel too, and is exactly what happens during the initial part of a wheelie.
When you combine all three factors, you get a recipe for unwanted front wheel lifting during climbing.
- Knees Hitting The Chest
During climbing riders instinctively move their torso closer to the handlebars to increase front-wheel traction and reduce the weight on the rear wheel. As a result, the back angle gets more horizontal.
When this is done on a bike with a slack head tube angle and a steep seat tube angle, the knees of the rider can sometimes come in contact with the chest, or at the very least the pedal strokes can become uncomfortable.
- Harder Steering at Slower Speeds
The elongated front end caused by the slacker HTA results in “boat-like” steering at slow speeds. And since climbing is naturally done at slow speeds, the front end can sometimes become floppy.
If the climb is technical, the negative effect will be even larger.
А steeper HTA, on the other hand, reverses all of the processes above by:
- Shifting the weight towards the front wheel and thus increasing the front-wheel traction.
- Increasing the bike’s maneuverability/snappiness at slow speeds.
- Keeping the riding position more aerodynamic.
What Are The Ultimate Climbing Bikes?
The ultimate climbing bike has the following characteristics:
- Steep (not necessarily super steep) head tube angle
- Balanced seat tube angle that isn’t extremely steep or slack
- Low gearing
The bicycles that satisfy these criteria the closest would be lightweight road models. Meanwhile, the bikes that are the furthest away from those requirements are MTBs in the following order – downhill bikes, trail bikes, and XC bikes.
The table below contains the head tube angles of popular lightweight road bikes that can serve well as climbing machines.
|Trek Madone SLR 9||73.5°|
|Canyon Aeroad CF SL 8||73.25°|
|Cube Attain Race||72.5°|
|Cannondale Synapse Disc Tiagra||72.1°|
|Specialized Allez 2019||73.5°|
|Cannondale SystemSix Carbon Ultegra||73°|
|BMC Timemachine SLR02||72.5°|
|Boardman SLR 8.9c Tiagra||72.5°|
|Moots Vamoots Disc RSL||73.5°|
|Niner RLT 9 RDO||71.5°|
Conclusion: The average head tube angle of lightweight road bikes is 72.78° – a number that falls in the steep category.
It’s also necessary to analyze the head tube angle of XC bikes as they’re the climbing machine of the MTB world and can cover terrain on which road bikes would have a hard time.
|Lapierre Prorace CF 9.9||68º|
|Specialized Epic Pro||67.5º|
|Vitus Rapide FS CRX||67º|
|YT Izzo Uncaged 7||66.5º|
|BMC Fourstroke 01 Two AXS||66.5º|
|Cannondale Scalpel HT Carbon 4||66.5º|
|Canyon Exceed CFR Team||69º|
|Giant Anthem Advanced Pro 29 1||67.5º|
|Intense Sniper XC Expert||67.5º|
Conclusion: The average head tube angle of modern XC bikes is 67.3º and is therefore on the slacker side. That said, it’s still steeper than what we see on trail bikes and downhill models.
How Can I Improve The Climbing Geometry Of My Bike?
If the bike isn’t designed for efficient climbing, to begin with, no amount of post-production hacks will help. For example, a downhill bike will never be a good climber no matter what.
That said, it’s still possible to improve the climbing capabilities of other models that aren’t a “lost cause”.
The following adjustments could help:
- Replace the tires with a model that has a low rolling resistance
- Get a lower gearing via a larger cassette and/or a smaller chainring
- If the effective seat tube angle is too slack, play with the saddle setback.
- If your bike has a suspension fork, lock it to minimize the energy losses that occur when pedaling outside of the saddle.
(Note: Some forks have a controller that will allow you to lock and unlock them via a lever installed on the bars.)
- Consider carrying less gear with you (don’t spare the essentials) to make the bike lighter. You can also switch from rear panniers which “suffocate” the rear wheel to bike-packing bags for a more even load distribution.