I had someone ask about how this compares to other wheel sizes so I’ve expanded upon the charts.
Rising Distance: The horizontal distance the axle is traveling while the wheel/tire climbs onto the top of a square edge.
Initial Angle of Deflection: The angle the axle is pushed upwards at when a wheel first hits a square edge.
Based on those charts, I suspect 29 to 32 would be more dramatic than 27.5 to 29 but not as dramatic as 26 to 29.
After looking at this data some, I was also wondering if 90 degrees minus the “Angle of Deflection” gets you close to the ideal head tube angle for the wheel size. The table below has those angles for 35, 40, and 45mm edges, which probably are similar to most of the edges you’d want your bike to soak up on a trail. I’m not a mechanical engineer so I don’t understand if aligning these angles would result in all the force being directed along the axis of the fork, but it’s interesting to think about. It does seem like the difference in these angles between wheel sizes might align with the kind of HTA you’d want for each of them.
Angle Perpendicular to Angle of Deflection
| Square Edge Height | 26 | 27.5 | 29 | 32 | 36 |
|---|---|---|---|---|---|
| 35mm | 65.8 | 66.2 | 66.8 | 67.8 | 69.1 |
| 40mm | 63.8 | 64.3 | 64.9 | 66.0 | 67.4 |
| 45mm | 61.9 | 62.5 | 63.2 | 64.3 | 65.8 |