Not all bikes are made the same, and in an effort to manufacture a quality tail light with multiple mounting options, we've intentionally given the Vis 180 a longer strap.
These straps can be cut down to a shorter length if needed, they are designed to be cut to length at any of the grooves. We do recommend leaving 2-3 extra notches in the strap so that you have some flexibility if you ever need to transfer it to a different bike or position.