After I hit a dog, went over the handlebars and injured my ribs...I decided a chest protector would be a good investment. I’m 5’10” 170lbs and the medium fits well. Under my race suit I don’t use the straps; the texture of the protector and the suit hold it in place. I do use the straps with my larger jacket I wear on my cruiser bike. Either way, it fits well and becomes almost unnoticeable after it warms up a bit. Weight is not noticeable to me and it feels substantial enough it would really protect me in a fall.