This post compares the advantages and disadvantages of 65° and 67° head tube angles.
Definitions
Head Tube Angle (HTA). The head tube angle is formed by the head tube and the ground (or a horizontal line passing through the bottom bracket). [image above]
The Advantages of a 65° Head Tube Angle
The 65° head tube angle is 2 degrees slacker (smaller) and thus has the following advantages/features:
- Better for descending
As the aggressiveness of an MTB increases, the slacker the head tube angle becomes.
XC bikes have the steepest head tube angle averaging about 67.59°. Meanwhile, the standard head tube angles of trail and downhill bikes are respectively 65° and 63°.
A slacker head tube angle positions the front wheel further in front of the rider and reduces the chances of going over the handlebars by shifting the center of mass toward the rear end.
As a result, the front wheel acts as a “shield” and makes it much easier to overcome obstacles when descending on off-road terrain.
A rider who is used to a slack HTA will have a hard time riding on the same terrain with a bike that has a steeper HTA. The experience will be a bit scarier due to the feeling that you are about to flip over the handlebars.
In different, someone used to a steeper HTA will be able to conquer much more dangerous off-road terrain after switching to a slacker machine.
In other words, if you plan on covering aggressive trails, a 65° head tube angle is your friend.
- Compatible with long travel forks
When a suspension fork compresses, the head tube angle gets steeper. The slacker the initial head tube angle is, the longer the fork’s travel can be (provided that the head tube can take the stress).
If a fork with a lot of travel is installed on a frame with a steep head tube angle, the angle will get dangerously steep when the fork closes.
The Disadvantages of a 65° Head Tube Angle
- Not ideal for climbing
A 65° head tube angle is a bit too slack for climbing. It reduces front-wheel traction and positions the rider closer to the rear wheel.
As a consequence, it’s a bit more difficult to pedal efficiently uphill. The chances of accidental lifting of the front wheel are higher too.
- Drag
A 65° HTA makes the rider’s back angle more vertical and thus increases the drag created by the torso. The higher the drag, the less efficient the bike becomes.
- Reduced maneuverability at slow speeds
A slacker head tube angle makes the bike less maneuverable at slow speeds. For that reason, XC bikes have steeper HTAs than enduro and downhill models.
The Advantages of a 67° Head Tube Angle
- Efficient Climbing
As mentioned, the average head tube angle of XC bikes is about 67°. Out of all MTBs, XC units make the best off-road climbers as they’re engineered for the discipline.
A 67° HTA positions the rider closer to the front wheel and consequently reduces the weight on the rear wheel while improving front-wheel traction. Those properties make uphill climbing easier.
- Responsive Steering
Steeper head tube angles make the bike’s steering more responsive and thus more suitable for technical maneuvers.
- Aerodynamic
A steeper head tube angle makes the rider’s back more vertical and thus results in a more aerodynamic stance.
The Disadvantages of a 67° Head Tube Angle
- Not ideal for aggressive descents
By modern standards, a 67° head tube angle is slightly too steep for enduro and downhill.
Of course, an XC bike with a 67° HTA and descent suspension is very capable, especially when the rider has a lot of skills, but if maximum performance on off-road downhill is the goal, a bike with a slacker HTA will produce better results.
What should I choose?
It’s important to note that selecting a bicycle based on a single angle is not a correct procedure as many other factors should be taken into consideration. Those would be:
- The discipline that the bicycle is designed for
- The manufacturing quality
- The condition of the bicycle (if you’re buying one second-hand)
- The skill of the rider
- The terrain that the bicycle is going to be used on
Ultimately, a 65-degree HTA works best when it’s on an aggressive hardtail or a trail bike. However, if you don’t plan on covering difficult terrain you wouldn’t need such aggressive MTBs, to begin with. In that case, it’s wiser to look into XC bikes.
And if you plan on using your bike simply as a commuter that would have to pass through some off-road sections, consider a gravel bike – it will be faster overall and still plenty capable.
If you plan on doing serious XC climbs, a 65-degree HTA could be too slack if the rest of the bike’s geometry and components are equally as aggressive.
