Aerodynamics of naked bike buffeting

[yjleesvrr]

When I got my RF1000 helmet, I noticed that placing my hand to block the opening near the chin reduced the wind noise considerably. Knowing that some R1150GS riders often put small saddle bags on both sides of their gas tank to prevent wind from this area of the bike from sweeping upward toward their heads, I fully realized that the primary reason we get buffeting on our Roadsters (if equipped with the touring shield) is not because of non-laminar flow coming off the top of the shield, but rather the wind sweeping upward from below the shield toward our helmets.

A week ago, I bought a HD touring shield for my Dyna Super Glide Sport. Riding down the highway at 75 mph, I was disappointed that there seemed to be rather severe buffeting despite the size of the shield. I tried blocking the gap again between my chin and helmet but doing so only cut down on the noise by about half. I then placed my left forearm horizontally across my abdomen to block the wind sweeping upward and sure enough, this reduced the wind noise completely! The only thing I could hear was the thrumming of the v-twin. Knowing also that there are optional lower deflector panels on Gold Wings, FJRs, and even the HD Road Glide, I did a search of the Internet. I found lower deflector panels from National Cycle for Harleys, but these are only compatible with the National Cycle touring shield. I’m continuing my search for lower deflector shields for my Dyna, and am looking for ones that are compatible for R1150Rs.

The long and the short of it is that larger windshields create low pressure behind them. Air passing the edge of the shield then flows inward behind the shield due to the lower pressure. It is this airflow that creates buffeting and wind noise. The reason wind sweeps upward from the bottom rather than the top is because of the angle of the windshield, i.e. – the bottom part of the shield is further forward than the top part of the shield. We thus have to find a way to prevent this stream of air from coming toward our heads. Lower deflector shields seem to be the answer judging from the prevalence of these things. But I have not been able to find any for the R1150R.

[iowabeakster]

i think this is what you are looking for. check out these. Some people also claim the addition of a tank bag to help.

http://r1150r.org/board/viewtopic.php?t ... tank+wings

[Sit]

Check Wunderlich too. They sell several different kinds of shields that go by the cylinders that are supposed to help with air coming from down low and helping with buffeting

[Sunbeemer]

I wonder if cutting a relief hole in the windshield would allow enough air to fill/reduce the low pressure to eliminate the updraft? I have a friend who cut a triangle about 3" on a side at the base of his GS windscreen and he claimed it helped, but I never rode it. Just a thought...

[Biff's R]

I think smaller screens, and a tankbag are the best option, but I have also looked at the Cee Baileys sport shield, too.

[yjleesvrr]

Duh. I forgot about this thread. I'm going to have to purchase a pair and try 'em out. I guess the question is whether or not they can fit under a touring shield and clear handguards.

[telliott]

Very interesting thread. I just got my RR about a month ago and have only taken one trip with a tank bag, stock short shield.

Buffetting wasn't too bad but I did notice "hot" air coming thru the oil coolers and back toward my legs. Weather was cool and it felt good but it got me to thinking about how bad this gets in summer. Anyone had problems with this? Is there a solution? I thought about a small black piece of plastic inside to divert air out away from the tank. Do the "tank wings" help with this as they appear to direct air down and away from the tank?

[ProductUser]

Very interesting thread. I just got my RR about a month ago and have only taken one trip with a tank bag, stock short shield.

Buffetting wasn't too bad but I did notice "hot" air coming thru the oil coolers and back toward my legs. Weather was cool and it felt good but it got me to thinking about how bad this gets in summer. Anyone had problems with this? Is there a solution? I thought about a small black piece of plastic inside to divert air out away from the tank. Do the "tank wings" help with this as they appear to direct air down and away from the tank?

There is no concern about the air coming from the oil coolers during the summer. I ride in 100+ degree heat all of the time with no issues at all; the ambient heat radiating from the street will make the hot air from the coolers feel refreshing.

ProductUser

[Buckster]

I have the tank wings and the hand gaurds. They do not interfere with each other. I will take the wings off in the summer to let more air through.

[yjleesvrr]

Well here is something interesting I discovered about my Harley touring shield. I rode down to Blacksburg on it Wednesday to swap it for my Roadster for the return trip on Thursday.

When I opened the helmet visor while riding my Dyna, the wind noise reduced by quite a bit. The wind sweeping upward and hitting the bottom opening of the helmet was allowed to sweep upward through the front interior of the helmet and exit through the top of the opening, whereby pressure was reduced and less sound generated. I guess Harley shields - whether intentionally by design or not, are better suited for open face and half helmets!

This same action on the Roadster did not seem to apply.

[Ed K]

yjleesvr,

Every considered trying a chin curtain to reduce wind noise?

Shoei provided one for my RF1000, for free... and it works great reducing wind noise! (My bike is completely naked... and I like it that way!)