This post compares the advantages and disadvantages of 69.5° and 67° head tube angles.
The Advantages Of a 69.5° Head Tube Angle
- Better for Climbing
A 69.5° head tube angle (HTA) is too slack for road and gravel bikes, but a similar angle can be seen on some “progressive” touring bikes (e.g., Panorama Taiga EXP) and less aggressive cross-country MTBs.
The main advantage of a 69.5° HTA is that it makes climbing easier.
A steeper HTA positions the front wheel closer to the rider. As a result, there’s more weight on the front end resulting in better traction and lower chances of accidentally lifting the front wheel.
Steeper head tube angles are snappier, especially at slow speeds. Hence the ultra-steep HTAs on freestyle BMX bikes despite the short stems.
If you plan on climbing technical terrain, a 69.5° HTA could help with the handling thanks to the increased responsiveness.
- Less Stress On The Head Tube
Slacker HTAs place additional stress on the head tube and increase the chances of a cracked frame. Of course, when the frame is strong enough, the additional load doesn’t matter.
The Disadvantages of a 69.5° Head Tube Angle
- Too Steep for Aggressive Downhill
A 69.5° HTA is considered too steep for fast descending on off-road terrain. A steep head tube angle makes it more difficult for the front wheel to overcome irregularities and increases the chances of going over the handlebars.
- Shorter Fork Travel
When a suspension fork compresses, the head tube angle gets steeper. Consequently, forks with more travel require slacker HTAs. If that condition isn’t met, the HTA can become dangerously steep when the fork is in the compressed stage.
The slacker the HTA, the more travel the fork can have safely.
The Advantages of a 67° Head Tube Angle
- The best of both worlds
А 67° head tube angle is quite common for XC models as it’s neither extremely steep nor too slack.
If you want a bike that’s a decent technical climber and yet still capable on off-road descents of moderate difficulty, a 67° HTA can work just fine.
- Compatible with more aggressive forks
As explained above, a slacker head tube angle allows the usage of forks with a longer travel.
The Disadvantages of a 67° Head Tube Angle
- Too slack for road cycling
A 67° HTA is too slack for bicycles that are going to be used primarily on paved roads. The main goal of a slacker head tube angle is to make the machine more potent on off-road descents.
And when that isn’t part of a bike’s description/usage, it makes more sense to go for a steeper angle that offers agility and better climbing properties.
- Slower Cornering
A slacker HTA is more stable downhill, but it isn’t as responsive and doesn’t offer snappy cornering.
- Not slack enough for difficult off-road
A 67° HTA is notably slacker than 69.5°, but it’s still not as slack as what we see on enduro and downhill bikes. Consequently, the difference in terms of off-road capabilities between 67° and 69.5° is not enormous and whether the switch is worth it depends on the rest of the geometry and bike components.
What Should I Choose?
It’s not wise to make a big decision on the basis of a single angle. 2.5 degrees could be important but there are other factors that should also be taken into consideration. Those would be:
- The bike type and model
- The rest of the bike’s geometry
- The quality of the frame and the class of the components
- The suspension travel
- The condition of the frame and the components when buying second-hand
- The possible future upgrades
If the above conditions are acceptable and it comes down to choosing between the head tube angles, then the most important factor will be the terrain on which the bike will be used.
If you plan on covering fairly difficult off-road, a 67° HTA will show its benefits.
If most of the terrain isn’t very aggressive, however, 69.7° will offer satisfactory performance too without hurting the climbing capabilities of the bike.