which one?
http://www.amazon.com/gp/product/B001VS1M20/ref=pd_luc_rh_sbs_02_02_t_img_lh?ie=UTF8&psc=1
http://www.amazon.com/gp/product/B006UMFUES?psc=1&redirect=true&ref_=ox_sc_act_title_1&smid=AOOJRST9WE1AB
i want to upgrade the crank with shorter arms and need to know of some that will work for this bike with out spending a arm and a leg for it thanks in advance