Would you prefer turbulent flow or laminar flow around a racing bicycle?

Answer 1

As regards the movement of air around an object, laminar flow would present the least drag and allow more speed or a more efficient operation. But getting air to move around a bike in a laminar flow just isn't going to happen. There are waaaaay too many irregularities, like around the front wheel and the front suspension and braking system. And there are rapid changes of cross sectional area, like with the fairing. At speed, all the problems suffer algebraic or geometric increases. It gets ugly. Laminar air flow? Around something like a superbike or a Café racer? Keep dreamin'. Now what? Here's a primer on what some call "the big three" in aerodynamics. One is the shape of the leading edges of the machine. Sharp is good. Picture a high velocity rifle bullet for long range shooting. Second is the transitition and shape of the trailing edges. Sharp is good here, too. You recall the "silly" helmets used by cyclists on time trials where they have a fin coming off them in the back. Now you know why. Third is the cross sectional area. Less it better, of course. A streamlined arrow will have better aerodynamics than a streamlined broom handle (all things being equal) because it has a smaller cross sectional area. The less air something has to move out of the way to get through it, the better. Since you're going to have to eat the turbulent air flow, it is important to look at the machine to see where you can "help" the turbulence so it is more "controlled". You'll have to do the best you can to "streamline" the leading edges of the machine and anything sticking off of it into the air stream. This is already being done, and there will be severe limits as to what you can do to accomplish any improvement in it. At the trailing edges where fairing or other aerodynamic skirting "end" or curve back in toward the body of the bike, there may be some little things that might help create turbulence that will actually decrease drag. This may not be something you can visualize, or something that makes any sense. But when air comes off the trailing edge of a surface, particularly if its at a place like the back edge of the fairing where there is "nothing" behind it, there will be a lot of turbulence. If you can break up the air stream just a little bit as it approaches this point, create a little turbulence, you may be able to reduce drag due to turbulence. You're fighting fire with fire, but it can be and is done in some applications. Be advised that these gains will be minimal, tiny. Trailing edges are killers. Look at some of the many short YouTube video posts on wind tunnel tests and see what trailing edge turbulence is. The thing is, the new superbikes are so powerful and the skill of the rider so extreme in competition that any "tiny" gains created in streamlining will not "matter" in the big picture. Nor will the minute improvement in fuel or other efficiency. You just can't get that much more out of the machine by tinkering with the aerodynamics beyond the "standard" setups. There may be some windows to improve ground effects, but don't count on a lot of other gains. All the money is in the performance of the bike and the performance of the rider. Given the nature of the courses these machines fly around, adapting fairing for the front wheel isn't worth it. The reduction in performance due to the "bulk" of the fairing standing out around the wheel would easily offset any gains in aerodynamics. Plus it's a pain to have to set that up. There is still some work to be done improving the aerodynamics of a big crotch rocket, but the point of diminishing returns is all around us right now on this one. Some links are provided to pictures and vids to get you started. Note that these sorta show you why things cannot be improved. Fee free to ignore them and find ways to actually improve motorcycle aerodynamics and make a fortune doing it. Then come back and carve up this post. This is notsarcasm. It is the way things are advanced. There will always be people telling you why you can't improve something. That is not the case here. All that is being offered is some insight into the problems, and they are problems which you will have to understand in order to find any success in overcoming them. Please jump in and show the industry what it is missing. And best of luck in your efforts.