I ride alone on my commute so carrying a cellphone makes sense to me. I was hit by a car last summer so called my husband to take me to the ER. It was also useful to call my work to let them know I wasn't going to make it in the next few days (let them know sooner the better). Also, it had saved me from schlepping my bike home on a few occasions. I called my hubby concerning the mechanical breakdowns and he was able to talk me through it so I can get my bike back on the road.