Yeah, single sided swing arms are old school now. The factory braced one is a lot stronger. I got a friend who races a 1997 Honda RS250GP with the "Pro-Arm" and he tells me that if he takes it hard on the corners, the swing arm will flex so much that the tire wall will rub against the arm. After the race, you can see where the tire contaced the swing arm.
Here is my NSR250 with the "Gull Arm" I think it's overkill for a 250cc bike, but that's Honda!!
It is not that a traditional swingarm is stronger than a single sided arm.... But that equal weight swingarms single and traditional are not of equal strength. Triumph uses a single sided swingarm on their 955 Daytona and Speed Triple. The swingarm holds up fine to the 140hp. Die hard fans of Triumph were screaming for a lighter bike, so Triumph released the Daytona with a traditional swingarm (significant weight savings for the total weight). People then bitched they wanted the styling of the single sided arm, so they went back to it and accepted the weight penalty.
Hi all, apologies in advance for the negative 1st post but i have a 2003 RR which wouldn't start although fuel pump was ok etc just span really fast on the button but wouldn't fire. Turns out cylinders 1 and 4 had 40 psi and 2 and 3 20 psi so engine pretty well toast although was running fine...