I built it but im having a problem with the crank, i had my bmx crank on it but we had to add spacers so the crank are wouldnt hit the frame which made the pinch bolt not pinch the spindle good enough, is my spindle to short? now i have a mountain bike crank on it and i cant get it to tighten up? any solutions? i have an fsa headset and bars and a mavic 321 front wheel and the sherman dirt jumper, the rest is just old parts