Well, the project turned into something a bit more than expected after we determined that Red Locktite on the rotors to the 21" wheel doesn't want to move real easy without some heat. A blow torch wasn't an option due to the custom (re: expensive matching RC Czar rotors), so finally a soldering iron right on the bolt did the trick, one bolt at a time. Here's what we did:

-Replaced the Metzeler 120/70-21x3.5 with a Metzeler 140/70-18x3.5.
-Added one inch back to the Race Tech with dual emulators that was removed to keep rake and trail in line with the 21/18 combo.
-Softend the preload a hair for just a bit softer rider.
-Used same fork oil as with the 21".
-Rear tire remained the same at 150/70-18x4.25.

I rode about 250 miles over the long weekend, highway cruising, backroads, and city streets. Here is my initial assessment:

-For whatever reason the ride with the 18", softer Race-Tech setting, and increased 1" shock travel feels considerably firmer and even harsh.
-The 1" increase in front end travel now feels kind of sloppy vs nailed to the ground 21" feel when cornering at higher speeds.
-The tires somehow make the bike feel not nearly as nimble or quick as the 21's, and worse the ride feels harsher and not as pliant.
-Where the 21" tended to really absorb the road imperfections with the Race-Tech set firmer, and almost provide a floating sensation, (unless I took a direct hit at a raised ridge in off an intersection or pothole, which wasn't often), the 18" tire feels coarse and and more sluggish. It's fully inflated at 42psi.
-When the bike was equipped with the 21", even lowered an inch, it was easier to ride with a shorter windshield and seemingly not feel as much wind turbulence. Now that I'm back to very close to stock ride height, I'm feeling the need to have to adjust the windshield to a higher one again, which I hate to do.
-I like the way the bike sits lower overall, but kind of miss the 21" raked feeling it provided.
-The bike looks great with the 18" but it's hard to draw comparisons since it's really what look you like. I like both looks, but have to say I'm thinking the 21/18 looked a bit better, and cleaner. If the dual 18's gave me what I was going for-a much improved ride and handling over the 21x18 I'd be very happy cause it still looks bad ***, but it's almost the contrary.

It's just odd to me cause almost everyone I've talked to said the dual 18's would almost always provide a better ride than the 21/18 setup. I'm just not finding that to be the case at this point. Maybe it's the way the Suspension was dialed in. Maybe it's adding the inch travel back to the front end after being used to having it lowered. I'm not sure, but I do know that going back in and tearing down the forks to adjust the Race-Tech setup is far too involved to do it often, and not be able to try it out without tearing it back down again.

Hey at the end of the day, I'm always tinkering with something, and sometimes this is the price you pay---literally Some would say the second you start removing stock front end suspension on the newer bikes, changing wheel and tire size, etc., you're setting yourself up for more frustration than it's worth, but there's no use telling myself that, cause I no matter how hard I try I tend to what to "try" something.

So anyway...if you read all this, guess there was some interest in the topic. At this point, I'm not sure what the next step is. The Race-Tech installer suggested it might have as much to do with adding the inch travel back into the front end as anything in the way it "feel"s. He suggests we could lower the front end with dual 18's a half an inch, but seems like trial and error to me, and again too hard to know if what you're doing is right. I do know that my old 21x18 setup was never a bad ride, as I've stated numerous times. In fact nowhere close to something I would discourage anyone inclined to go that route in doing. So, about the only thing I'm considering now is either:

-Go back and soften the Race Tech suspension more yet and lower the front end a bit. I always understood there wasn't a need to lower with dual 18's.
-Reintall the stock HD 2008 suspension and keep the 18's.
-Put it back together with 21x18's, lowered an inch and preload etc set up the way it was prior to the swap.

Any comments, first hand experience or opinions are welcome.
I think I needed to get this all down in print to get it clear in my own head

 

after that long post you convinced me to stay with the 16's Thanks

 

Well that's certainly always an option BTW you sent me a PM during the days of the broken forum and I could never respond. I don't remember what it was but if you think of it, send me another and I'll reply.

 

GliderXXX, thanks for the update and sorry to hear the 18/18 did not improve the ride. Your bike and the original gangster 21/18 is one of the best looking rides I have seen. I read where you were swapping to an 18 right after I ordered a 21 and was really worried I made the wrong choice. Unfortunately it sounds like you have to go back in and adjust things. I know you will get it figured out.

Can I ask where you set the emulators to turn wise?
What weight fork oil?
How much fork oil?
Which spring rate race tech kit do you have?

 

RJ you didnt say if you were happy with your 21"/18"combo.

 

Good poop. I think you saved me about $3,000. So thanks. I love the look of the 18x18 setup, but the ride is really the most important thing to me. I appreciate your candor, and it's refreshing to hear you tell like it is, instead of how you wished it was. Many thanks. I was wrestling with this being a winter project. I'm now going a different direction.

 

No complaints with my 18/18 setup. Never rode with a 21 front though. I love the looks but finding 18" tires on hand on the road is challenging. Sometimes wonder if I should have stayed with 16"s.

 

It's too bad you made so many changes at the same time. It makes it harder to figure out where the problem is coming from. IMHO, I'd fiddle with the suspension some more before reverting to the 21".

And, you have also convinced me to keep the 16"s.

 

All my comments are within the text of your comments.

 

Bigsky...ain't nothing wrong with the way that Road King of yours looks! Very nice. I also don't want to be someone who discourages folks from going a custom wheel/tire route. There are LOT's of folks who swear everything got better or is just as good. There are also a LOT of dealers who know there ain't much demand for baggers for $3000 set's of wheels and tires for 16's Couple that with all the latest Bagger rage and customization and one might just be lead into thinking that 16" tires are far inferior to anything else...another on that one. That said, I love function and the ride of a good bagger, but I also LOVE what can be done with the look of these beasts so I'll likely keep working to dial it in. If I were betting I'd bet the 21" will go back on but I'm going to give the 18" another 500 miles or so before I even touch the emulators for more suspension tuning.