From the review in cycle world (1966):
At the end of one lap we knew we had a tiger by the tail. Sheer speed the Vincent has, but it is virtually without brakes and the handling was enough to make brave men blanch. Someone once told us that the Vincent felt as though it had a hinge in its middle, but in riding the beast we quickly discovered that the hinge to which they referred was a ball joint. No motorcycle we have ever tested has flexed in so many different directions at once. Get the bike into a fast turn and it sets p a really heart-stopping shudder and waggle. The Vincent would, fortunately, track quite nicely when running straight but sooner or later you have to turn and that's where the trouble starts.... The example we tested had to be shifted very deliberately and even then it sometimes popped out of gear. Its clutch slipped furiously too.
The Vincent motorcycle may be fast, but it is an evil handling beast, with simply awful brakes. Potentially (and by this we mean unless ridden with great restraint) it is the most dangerous motorcycle ever to come our way and we are not sorry in the least that it is no longer being made.
I remember that article. It also mentioned at one point that they thought it had a hinge in the middle. I don't know who wrote it but it is pure 100% Bull. I've never owned a Vincent and with my current financial status means i will never own one. The only thing I (and others who read the article) can conclude is the Vincent tested was one in very poor condition or the tester had been neutered a couple of days before he rode the bike. If they were that crappy abike they wouldn't be revered as they are or command the prices they do. Next time you go to a Vincent gathering bring that article with you and show the owners how bad their machines really are and you should be able to pick up a couple of them for $50-$100 bucks. Or you could get beaten to a pulp
P.S. I have a large poster somewhere out in the garage. Its a picture of a guy on a Vincent, cranked over, with his knee on the ground. I'll believe that photo over the words of some Cycle World hack.
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This was written by a dude who raced bikes so I think he knows what he's talking about.