Paceline Aerodynamic Question
- Thread starter skammer
- Start date
Yes, the rider behind you breaks up the low pressure region behind you much like the duck tail on an aero helmet. Decreasing the low pressure region results in a lower fore-aft pressure differential or IOW less drag. The second rider obviously gets the most benefit from drafting, but both riders benefit to some degree.skammer said:
-Dave
Not sure that's exactly the reason, but I agree that the lead rider could experience a small benefit.daveryanwyoming said:
The low-pressure effect results from the flow boundary layer changing from laminar to turbulent as it passes over a body. Whether or not that happens depends on the speed of the body relative to the Reynolds number of the fluid (air) and shape of the body. At cycling speeds it's not a given that there really is a low-pressure suction region behind the lead rider.
However, the trailing rider also directs the airstream away from the trailing edges of the lead rider, effectively smoothing the shape of the leading body, which also reduces the drag somewhat. In any case, the effect is small.
I know that works with cars at high speed and in theory it should work with anything... Maybe it's time to dig out someone's 24" front wheeled time trial bike from the late 80's!daveryanwyoming said:
I surprised that someone didn't invent the team time trial tricycle - two "moser sized" monster disk wheels 18" apart at the back that the rider behind with his 24" front wheel could sneak inbetween!
You could just see the headlines - UFO's spotted in TdF team time trail
daveryanwyoming said:
That's the theory, but there are some who dispute whether two cyclists are close enough to each other for the effect to be significant. Last summer I (accidentally, really) collected some power data on the indoor track in Los Angeles that suggests that it is, but because these weren't formal experiments I'm hesitant to draw any firm conclusions.
Yes, it is worth noting that the drag reducing effect on the front rider shows a very strong dependence on distance, to the point that the drag on the front rider can, in fact, increase in certain configurations. The only published data I know of are either for generic blunt-body configurations (circular cylinders and such), or for race cars, but they indicate that the distance for effective reduction of drag on the front rider is really close to the minimum (meaning, wheels touching, not really practical...)acoggan said:
In any case, the effect would be of the order of a few percent at best; two minutes off of a 7-mile split cannot be explained by such a small effect.
You could take the lead and have a prototype in the market. We all look forward to seeing the Swampy TTT bike.swampy1970 said:I know that works with cars at high speed and in theory it should work with anything... Maybe it's time to dig out someone's 24" front wheeled time trial bike from the late 80's!
I surprised that someone didn't invent the team time trial tricycle - two "moser sized" monster disk wheels 18" apart at the back that the rider behind with his 24" front wheel could sneak inbetween!
You could just see the headlines - UFO's spotted in TdF team time trail
