ok so im new at the fixie side of things... today i put clips and straps on a fixie that had only cheap plastic clips.. that did nothing... anyway im riding and i go to push down and pull up ... using the new straps... and i felt the crank or something slip... now this is not my bike its my friends who "doesnt have time to ride any more" so he let me borrow it... so what the heck is going on???? should i stop riding his bike to prevent breaking something.. i love these bikes and i bought a entry level fuji track just to get my feet wet.... so should i just wait till it gets here and give his bike back... he gave it t me as a loner till my bike gets here... what should i do and what is going on with his bike? thanks sorry if i sound hella newb.