Age-related balance difficulties during shoulder checks increase cycling risk in older adults

Older adults are more often involved in bike accidents than other age groups, especially in single-sided accidents (crashes without another road user). This suggests that older adults have more difficulty maintaining balance while cycling, likely due to age-related sensorimotor decline. A particularly challenging maneuver in traffic is the shoulder check (turning the upper body to look behind while maintaining balance and direction). This study investigates how age-related sensorimotor deficits impact this skill. 40 young (22.86 {+/-} 1.53 years) and 41 older participants (62.73 {+/-} 1.57 years) cycled in a straight lane while performing a shoulder check to identify the color of an object behind them. We recorded the task-errors (interrupted cycling, incorrect color identification, cycling outside the lane) and computed the steering angle, rotation of the frame, pelvis and torso, and task duration from inertial measurement unit data. Older adults made more task-errors than young participants; one-third failed the task due to mistakes such as misidentifying the color, losing balance, or leaving the lane. In the successful trials, older adults showed greater steering variability, increased pelvic rotation relative to the frame, and took longer to complete the task than the young participants. These findings suggest that age-related difficulties in maintaining balance while head-turning may contribute to the higher rate of single-sided bike accidents among older cyclists. Infrastructure adaptations (e.g., wider bike lanes) and individual-level interventions (e.g., mirrors) that alleviate the difficulties older adults experience when performing a shoulder check could improve safety for people from this age group.