Bigger chain rings used by pros: 54 - 40, (I use 50 -34)

Wheels of Happiness Many pros are using bigger chain ring; 54 - 40, 56 - 44. Pros can ride at 60 kph

Advantages:   straighter chain line, less bending of chain and therefore less friction.  (But I guess this hard on the thighs and calf) Only for Iron men.!

They can handle steep mountain roads at 40 - 34.  My bikes have following chain rings:   50-34, 52 -36,  and 44 -34 - 24 (for MTB)    I am a mere mortal.