Front light aerodynamics
The goal of this test was to evaluate the aerodynamic performance of different shapes of front light, as well as their location on aerobars and base bars.
We used four different types of lights for this test:
1. A silicon light which sits either above or below a handlebar.
2. A cylindrical light which sits inline with a handlebar.
3. A longer light which sits either above or below a handlebar.
4. A rectangular light which sits inline with a handlebar.
We also manufactured a few different mounts for the lights to test their efficiency:
1. A 31.8mm round section which sits below a computer mount.
2. A 31.8mm round section wich sits in front of/inline with a computer mount.
3. A 31.8mm round section which sits off to the side of a 22.2mm round pole.
WIND TUNNEL
We tested these lights in a wind tunnel at 45kph across a range of yaw angles to represent real world changes in wind direction.
We tested the aerodynamics of the lights and locations at our typical test speed of 45kph. This allows us to get good clean data (compared with testing at lower speeds, where the resolution isn't as good) which can then be applied to lower speed calculations later. As an example, a 10w aerodynamic drag saving at 45kph is equivalent to 4.7w at 35kph.
Lights were tested both with a rider aboard and without, and the data collated across the two conditions. We found no difference between bike only and rider on data in this instance, but in other scenarios differences can occur.
The results of the front light wind tunnel testing are shown below.
Mounting a light below the bike computer was slower in all cases than having no light at all, around 1-1.5w worse than no light (blue bars on the chart).
Mounting the rectangular light on the base as pictured was around 1w worse than no light, but this was similar to mounting it below the bike computer.
The inline computer mount with an inline light (in this case the circular light) resulted in no significant penalty, and so we offer this for sale as the best solution. You can find this light bracket in the webshop (integrated TT light mount).
The round pole adapter which attaches to the side of a 22.2mm pole (or the bottom section of our Angles extensions) was also 1w worse than no light/the AeroCoach integrated light, but is a nice simple solution and so we also offer this for sale (standalone TT light mount).
From these results there is only a small penalty from mounting lights of different shapes and sizes in various locations on aerobars, and in some cases no penalty at all.
These data were presented at 45kph, at lower speeds the differences will be even smaller (and at higher speeds the differences will be greater).
