The Passenger rides on a rigid frame

[hadronuk]

You can see why the passenger's bum gets such a paddling on a rough road . Bad passenger!!;-)
Looks like about 4" total movement in both the front and rear.When fiddling about with measurements before building the Glenli rfm, I measured 4.5 inches non progressive movement on the rear of my Rapide. Perhaps the Thornton hits the stops a little bit earlier.
The relationship between spring movement and axle movement in the front end is ideal, to my way of thinking. As Rob mentions, there is progression in the movement, which gives the front end the ability to soak up the millions of small irregularities like a softly sprung setup while retaining the ability to handle a big jarring bump like a firmly sprung setup.

Glen

Very true about the passenger! You can see the rider does not entirely escape either. I went from the standard rear set up to a fully sprung set up with Girling 135 lb/inch springs and my short length/long travel AVO damper in more or less one go. The improvement was therefore massive, but perhaps I am judging the semi sprung seat too harshly, as I have never tried it with the other mods. I shall have to give it a go some time, out of interest.
I agree progressive springing can be good (and I have them on my T160), but the Girdraulics have far, far too much, especially when combined with the steeply rising friction in the link bearings. Modern bikes have gone in the opposite direction, specifically to improve handling, as have I. It is much more comfortable and behaves better under braking.
Rob

 

[Monkeypants]

Things have moved on a lot in sixty years, for sure.The Thornton and your AVO sound like good options.
Handling of a Vincent isn't ever going to equal a modern sportbike, but it is surprisingly good for the Vintage of the bikes. Last time out in the Mountains riding two up, we were motoring along a fairly long straight stretch at 70mph when two modern sportbikes went by at nearly double our speed. I recall the blast of air pushed us sideways as they went by.
About a half hour later we were in the Monashee Mountains on a very twisty section of road. For the most part the same speed could be retained, but there were also some hairpins that required slower speeds. About a half hour into the really twisty stuff, we caught up to the two sportbikes. They weren't about to have some heavily laden ancient bike on skinny tires go past, so they cranked their cornering speed up some. I had great fun pressing them for the next 20 miles or so until they finally pulled off and we went by.
You can cover a lot of ground on a Vincent.

 

[vibrac]

I know when we had a track day at Snetterton to run the racing Comet in and have some rides out on our track bike I was out on the Comet with some intermediate riders on crutch rockets.
They blasted past down the straights but if encountered on the twisters sometimes the bikes close in front would suddenly heel over with arms and elbows scratching the tarmac while the Comet would majestically sail past with what seemed a much less extreme angle and power away for a distance before the inevitable happened and they came past again.
Ignored in the pits before the sessions the Comet had lots of visitors later.
I did not mention it was a lot more to do with rolling radius of their tyres compared to 400X18 AM23 and the fact it takes a good man to regulate the harsh amount of raw power on a modern bike when heeled over rather than the skill of the Comet rider or the fine Stevenage product