You know I couldn't disagree with you more! Mine has been done correctly and comparing how it RIDES and HANDLES with a stock version of the same bike which I also had at the same time was a huge difference. It was a much rougher ride because there is not as much travel, a stiffer sidewall, and less tire and air to cushion the ride. It really shows up how bad it handles when you start to ride aggressively. If your theory were true why don't sport bikes put 21" on the front of there bikes. And by the way I rode a new CVO RG last week and then got off and rode an Ultra and my first thought was man that CVORG looks cool but it rides like a tank and handles worse. So that's my assessment.
BigLew
Worst Handling bike I ever owned out of the Harley Factory was my 15 CVO Road Glide Ultra. Felt like it would wash out in the corners especially when pushed. It as almost scary. I had traded a 12 CVO Road Glide for it, and still had my 13 CVO Road King.
With 100 Miles on the bike I took to the dealer and complained about the crappy handling. They explained it was the air shocks, needed to be dialed in for my weight and riding style. Tried for 1000 miles to get it to handle as good as my CVO King or the CVO Road Glide I traded. Hated the bike and its handling.
Put a set of Ohlin shocks on the rear and got them set up right. This greatly improved the handling, but not still quite as good as the pervious CVO's. At least after the upgrade I felt better in the hard corners, the bike did not feel like it would wash out. I still think some of it was the tall side walls of the tires, flexing when pushed hard in the curves.
I feel way better pushing this stock out of the Factory 18 CVO Road glide with the 21 wheel than I did that CVO Road Glide ultra when it was stock.
Performance cars use very low profile tires to improve handling. So I sure do not see how a big high profile tire on a motorcycle helps handling. Ride sure as more flex and give, handling, no for the same reason it improves ride.