It seems to fit as slim as it can. A rainy day going about 6 miles on muddy/boggy trails crossing a few streams, steeply up and downhill. I was skeptical when reading the reviews, but its true, these headphones have very good sound quality. Don?t bother, there are plenty of other cute waist belts on this website. That said, it is super warm and cozy and if it fits you, then I think you?re fine. In other words, they are flexible and adaptable enough to acclimate to any foot between those sizes. HOWEVER, if you are going to put this up in a garage or other room with hard floors and sturdy ceiling, this will work wonderfully. I feel w a few months of training imma need to get a new hexbar that holds more weight. I also recommend getting one of these for each bike you may use with a trailer. I was very wrong because it fits my coats very nicely.