Hi there, I recently bought a road bike kitted out with Shimano 105 drivetrain. My lowest gear is a 39x25, which i'm finding ok in general, but on rides with sustained 18-30% gradients, really hard work! I've thought about fitting a compact, but was told by a friend that compacts cannot be fitted to bikes with Shimano 105. Is this true, and are there other ways I can stick some lower gears on? Thanks!