When was it a good idea to do a hilly century in 53/12? Well, last year just as we were heading out on a century ride (albeit much flatter course) one of my deraileur cables broke and I ended riding the entire ride in my 53/12. So as tradition would have it this was my yearly ride in my toughest gear only. No shifting- only pushing the cranks in some cases at a VERY low cadence. It was a tough day but certainly one that went into the "strength training" category.