My wife and I have a 2007 cannondale with an ultegra front deraillier. It will up shift ( to a larger chain ring) using shifting cable tension, and downshift ( to a smaller chain ring) with derailier spring pressure. Our problem, it won't downshift into granny gear with any pressure on the pedals. If we're on a 3% grade and then round a corner and face a steeper pitch, we are unable to down shift. Our older burley did not have this problem. Any possible solutions? Is there a triple that downshifts under pressure (tension) and up shifts with a spring. Our local pro level bike shop hasn't been able to help.