I see no reason to go past a compact gear unless you frequently cycle in groups, have little elevation gains or rarely spin past 90rpm for any extended period of time.
My most commonly used gears are 50/21 and 50/19. Spinning between 90-100 rpm on solo rides, I can maintain 21-25mph with these two gears depending on elevation and wind. On TT rides where cadence is emphasized, I can get up to 21-23mph on 50/21 at 110-120rpm. When wind or hills hit, I drop down to my 34 and a 34/15 or 34/14 can do 17-20mph within that range. If a long climb hits, I simply don't run out of gears to keep high cadence. I can spin up to 42 mph on my biggest gear. There's really no need to go past 40mph whilst training, ever, in my opinion.
Seeing people with 53/39 tells me that they misunderstand the importance of cadence with respect to aerobic power and efficiency. A high cadence on a lower gear has greater ability to produce more power with less fatigue over a period of time. It's just part of the new ideology in cycling which has been producing successful results for over a decade now. Hence Froome's 'washing machine' cadence on climbs.
Theres a reason most new, top of the line bikes are being seated with compact gearing. Hell, the Madone, Trek's flagship aero road bike, comes stock with a 48/35 on all sizes.
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