Calculations for Understanding Standards
1. Drop Heights vs Joules
Calculated with a 5 kg drop mass.Drop Height Energy Falling Speed* =============== ====== ================ Meters Feet Joules KPH MPH 0.8 2.6 39 14.3 8.9 1.0 3.3 49 15.9 9.9 1.2 4.0 59 17.5 10.9 1.4 4.7 69 18.9 11.7 1.5 4.9 74 19.3 12.1 1.6 5.2 78 20.2 12.5 1.8 5.9 88 21.4 13.3 2.0 6.6 98 22.5 14.0 2.2 7.2 108 23.7 14.7 2.4 7.9 118 24.7 15.3 2.5 8.2 123 25.2 15.7
2. Joules vs Drop Heights
Calculated with a 5 kg drop mass.
Energy Drop Heights Velocity Falling Speed*
============== ============= ============= ================
Joules Ft-lb. Meters Feet M/Sec Ft/Sec KPH MPH
40 29.5 0.8 2.7 4.0 13.1 14.3 8.9
50 36.9 1.0 3.3 4.5 14.7 16.1 10.0
60 44.2 1.2 4.0 4.9 16.1 17.6 11.0
70 51.6 1.4 4.7 5.3 17.4 19.0 11.8
80 59.0 1.6 5.3 5.6 18.6 20.4 12.6
90 66.4 1.8 6.0 6.0 19.7 21.6 13.4
100 73.7 2.0 6.7 6.3 20.7 22.8 14.1
110 81.1 2.2 7.4 6.6 21.8 23.9 14.8
120 88.5 2.4 8.0 6.9 22.7 24.9 15.5
130 95.9 2.6 8.7 7.2 23.7 25.9 16.1
* Note that KPH and MPH relate primarily to the speed of the helmet hitting the pavement, not to the forward speed of the bicycle or rider, unless the rider hits a concrete abutment. The typical bicycle crash impact occurs at a force level equating to about 1 meter (3 feet) of drop, or a falling speed of 10 MPH. The rider's forward speed before the crash may be considerably higher, but the speed of the head moving toward the ground, plus a component of the forward speed, less any energy "scrubbed off" in other ways, normally average about 10 MPH.
We are indebted to Jim Sundahl for the Excel spreadsheet to calculate these numbers.
This page was revised or reformatted on: February 22, 2019.
