Effects of sticking for varying population density and chemoattractant slope. (a) Mean velocity difference versus race duration for various population densities. For each race duration, the mean velocity difference is given by taking the mean velocity in a simulation where stickiness is set to zero, minus the mean velocity in a simulation where stickiness is set to one. A positive mean velocity difference then corresponds to a lower mean velocity due to stickiness. The velocity difference peaks at intermediate race durations where slow microbes dominate due to sticking. For long races, there is a small velocity difference from fast microbes co‐operating to lower their mean velocity to a new optimum. As the population density decreases, the effect of sticking diminishes, and the race duration region where stickiness benefits slow microbes shrinks. (b) As we vary the slope, the position of the peak shifts. A larger slope shifts the position of the peak to shorter race durations. The width of race durations where sticking makes a difference also shrinks with larger slope. The effect of varying slope can essentially be understood from a rescaling of space