Bike Frame Aerodynamic Details

Triathlon Forum
1

I noticed with one of the Planet X posts yesterday some debate over internal vs. external cable routing where someone indicated that they would buy a P2C over a Planet X due to the cable routing.

Companies such as Cannondale, Kuota, and Planet-X run external cables while Cervelo, Trek, Felt, and Quintana Roo and the Blue that I ride run the internal cables. X-Lab even has a different routiing through the seat stay that claims to improve the shifting. Any aero gurus with some data about how much difference this really makes? I find to hard to believe that someone would pass on a bike (the Cannondale and Kuota seemed to be ridden effectively in Hawaii the past 3 years) due to some exposed wire on the downtube when I see people with super aero frames and their number flopping around on their back as it hangs off their race belt. Maybe it is a comfort feeling with the overall attention to detail in the frame design?

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how much difference? not huge, not even big, but it is something. round cables create more drag than you might imagine because they are round, just like round spokes. round is not a very slippery shape. and when you are counting every watt, no detail should be ignored.

along this line, i give some guidance to racers i have advise as what to do with their hair and their bike numbers. both can easily kill the drag saving of $1000 set of wheels. details do matter. and stadler did fine on his external-cabled kuota. but imagine if he had *not *won in HI and, say, lost to macca by 15 seconds. then, he might have wondered whether such details would have won him the race. i sure as hell would have.

ps. the revised version of stadler’s winning bike now has internal cable routing …