Engagement Angle: what is it?
Engagement Angle (EA) is the degrees of movement required from your freehub body to engage the drive on your rear wheel.
We offer 36t and 54t options for our wheels and simply put, this is the number of teeth on the ratchet discs in our drive system.
36T vs 54T Ratchet disc example
Working out the EA is simple; it is the total degrees in a circle (360 degrees), divided by the amount of teeth.
- 36t example: 360 degree / 36t = 10 degree EA
- 54t example: 360 degree / 54t = 6.66 degree EA
Engagement angle advantages and disadvantages
Engagement angle for road riding is a topic up for debate as it is only when the rider is standing still and begins to accelerate (track standing at traffic lights for example) that the engagement angle is really noticeable; and even then, it is difficult to feel the variation in EA between a 36t version vs 54t (3.34 degrees: 10 DEG – 6.66 DEG).
When you are riding the bike, this is even harder to feel as the rider has to turn the freehub faster than the rear wheel is spinning to get engagement, so if you are soft pedalling for example, you are effectively reducing the engagement angle to the point of near instant engagement, regardless of the tooth count.
It is worth pointing out that due to the smaller teeth on the 54t option, this provides a softer coasting sound as the ratchet teeth have a lesser distance to close when coasting.
However, the smaller teeth are more suspectable to fatigue long-term as less material is used for the torque transfer between the ratchet discs and the hub. In contrast, the 36t have larger teeth and provide a more robust system overall.
Our advice is to use the 36t option as standard for all Scribe wheels and it is only those that want the quietest system possible that should consider the 54t option. Unless you are track standing a lot, most riders won’t truly feel the faster engagement EA with a 54t option, so having the more robust 36t option would be the go-to for most.