I have 2010 rkc with standard windshield with lot of extra unwanted air. Riding in the rain is like not having a shield to begin with. Are there larger windshields that fit the rkc and where do I find one. Need help.

 

Try these guys.
http://www.longrideshields.com/index.html

 

Your stock RKC windshield should measure about 18'' from top of headlight to top radius of windshield. H-D has a 22'' for Road Kings and Road King Classics (both bikes use the same windshield). Part # 57995-96. Page 326 of the 2012 parts catalog.

Memphis Shades is another supplier of Road King windshields.

 

I get a lot of wind (haven't had any rain to ride in yet) from under the shield. I'm waiting for my fork wind deflectors and the fork baffle from Kury to arrive. Those two items should stop the wind. Maybe it will help with rain.

 

I just purchased a nib 20" std H-D Windshield for my '05 RC,,,I bought the bike last month and first thing I noticed was not really much air hit me without a windshield figured it was because of the Nacelle, Passing lamps etc...but I put this windshield on yesterday and it's like throwing out an anchor, I can't believe the amount of resistance it creates at 35+mph... I had a windshield for my Softail, and I really couldn't tell it was on until around 55mph...
The RC to me seems really stable as far as wind and turbulence, unless there is a cross wind blowing, with or without a windshield...

 

I bought a slightly larger windshield from a company called Clearview, who make replacement windshields for many brands of bikes - including Harleys. It was only about $120 for a unit that was listed as blemished. I couldn't see any defects when I got it.

One reason it's so inexpensive is because you reuse the original chrome hardware. The only new piece is the windshield itself. I got one that's called "recurved". The very top of the shield is slightly curved to flip the air higher and over your head.

The Harley front fork air deflectors combined with the larger windshield (I'm 6'3") make a nice calm spot with minimal buffeting. The air deflectors are ugly and make the ride too hot in hot weather but they work pretty good at stopping the buffeting.