Zipp first developed the service course sl stem for the fit and performance needs of pros that goal of being pro grade has proven out over the past several seasons as the stem became a mainstay in the pro peloton and cyclocross circuit being ridden to victory in paris roubaix and the vuelta a espa now we take that pro proven legacy and build on it with the redesigned service course sl stem the service course sl stem crafted from 7075 aluminum features a redesigned shape thats strong and