drafting

jeffgordon73

Hello,
I can feel the difference with someone in front of me. Dose it make a difference if you have someone behind you in a group ride? I am not sure if it is a mental thing or if the rider behind me is helping with an aero push?

Bike_Tyson

I'm not too sure,

but if it's a fierce dog drafting behind me, I'll surely feel the "turbo boost" on my bike.

dhk2

I've noticed the same effect. Have read that it really does help reduce your aero drag to have someone behind closely, but of course not nearly as much as the 20-25% gain you get from sitting on a rider in front. Considering how important aero effects are on the rear of a race car, suppose it's not far-fetched to see how a rider in back would help.

taricha

Having a rider follow closely can help lessen the effect of the low pressure area immediately behind the leader. The effect is real, but totally insignificant.
Sort of like the fact that gravity is slightly weaker near the top of a big climb than at the bottom because you are further from the center of the earth and gravity is proportional to 1/r^2. (Yes you are slowly, slightly breaking free of earth's gravity!) :p
It's real, but likely most useful as as a positive thought to concentrate on through the pain.

frenchyge

The effect is real, but totally insignificant.

Pretty much. It's also possible to hurt the aerodynamics of the leading rider by following closely, depending upon the speed and shapes involved.

Unlike race cars, cyclists don't always leave a large turbulent wake, and a following rider which causes the laminar air flow to separate from the leader sooner could actually increase drag.

In either case, the effect would be imperceptibly small. The benefit I feel having a rider on my wheel is the mental boost of knowing that I will get a rest when they pull through. :)

Veloblue

Here's my take - if I know someone is behind me, it keeps me a little more honest maintaining speed - and maybe pushing a little more. Kinda like the effect of a rider ahead in the distance and whatever that force is that makes you want to catch them.

Pretty much. It's also possible to hurt the aerodynamics of the leading rider by following closely, depending upon the speed and shapes involved.

Unlike race cars, cyclists don't always leave a large turbulent wake, and a following rider which causes the laminar air flow to separate from the leader sooner could actually increase drag.

In either case, the effect would be imperceptibly small. The benefit I feel having a rider on my wheel is the mental boost of knowing that I will get a rest when they pull through. :)

dhk2

Yes, have to agree the effect is nil after checking my little reference book "Bicycling Science". There's a graph showing the drag reduction on the first of two cylinders as a function of the diameter of the cylinders and the spacing between them, based on wind-tunnel testing.

There is a noticeable reduction in drag on the first cylinder at a separation of two-diameters, but it disappears rapidly as the spacing between them increases. Some rough measurements indicate that the closest two riders could get (following directly behind) is 6 feet, which is at least three diameters even for big guys. So, now I'm convinced there is virtually no gain to the first rider.....except knowing someone is right behind and ready to take the lead.

roadhouse

Yes, have to agree the effect is nil after checking my little reference book "Bicycling Science". There's a graph showing the drag reduction on the first of two cylinders as a function of the diameter of the cylinders and the spacing between them, based on wind-tunnel testing.

There is a noticeable reduction in drag on the first cylinder at a separation of two-diameters, but it disappears rapidly as the spacing between them increases. Some rough measurements indicate that the closest two riders could get (following directly behind) is 6 feet, which is at least three diameters even for big guys. So, now I'm convinced there is virtually no gain to the first rider.....except knowing someone is right behind and ready to take the lead.

i'll agree with you on the last sentence.

Amazon.com: Bicycling Science, 3rd Edition (9780262731546): David Gordon Wilson: Books

i thought you were joking at first about the name of the book. another must read.

RHR38

Old trick in TT competition DS drives 1 inch behind athlete with support car (beware marshalls..). Next stage: DS may lean heavy to car horn button. 1-2 mph more average speed easy, but better leave athlete alone for a while after race is finished ;)

SourDieseL

i've rode all 3 positions of a group ride, I somehow prefer to pace lead and drop, sweep in my eyes is the worst since you're pulling the tail end. There is no aero benefit from being in the drop position with a line behind you, but I tell you this much, to sweep a line is much more difficult then staying in drop or even pace leading.