I have a 39 low in front and a 27 in back - I do a lot of climbing when I ride; but I also own a Giant TCR which is like 16 pounds or something insanely light so it works for me. The only time it gets troublesome is on multi day i.e. 3-5 day rides with lots of mountain climbing, then on day 3 or 4, it can seem not enough. I don't do that much of that type of riding, so the gears work fine for me. I have, however, been riding for 20 plus years so that has something to do with it too.