Background: Bike safety in older subjects is a major concern in multiple countries given the strong increase in the number of cyclists that are admitted to the hospital due to single-sided bicycle accidents in older populations. The increase in single-sided accident rate in older subjects suggests that older adults have more difficulty controlling balance while bicycling in traffic, which has been related to various age-related changes in the sensorimotor system. Yet, the impact of these age-related sensorimotor deficits on the ability of older people to remain stable on their bike during traffic situations such as turning their upper body to check on potential road users, remains unknown. Methods: We instructed a group of 40 young (22.86, SD:1.53 years) and 41 older participants (62.73 SD:1.57 years) to bike in a straight line while performing a shoulder check movement in order to identify the color of an object presented behind them. We recorded the task-errors (lost balance, errors in identifying the color, cycling outside the lane) and computed the steering angle and rotation of the frame, pelvis and torso from IMU recordings. Results: We observed that older adults made task-errors (one third of the older participants failed at the task by making errors such as cone-identification errors, loss of balance and cycling outside the lane). In the successful trials, we observed an increase in steering angle and rotation of the pelvis with respect to the frame in the older subjects compared to the young subjects. Significance: Older cyclists lose balance while turning their head, which might contribute to the increased number of single sided bike accidents in older subjects. The use of simple devices, such as using a mirror, should be encouraged in older subjects to replace the shoulder check maneuver.