ahoy in there

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L.A.B.

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I can't see the video??

<They were also the first machine to use rear suspension (from 1926 on) and held a patent on this setup for many years.>

The Vincent HRD company were not the first company to fit rear suspension to a motorcycle.
 

ntst8

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Worked fine for me as well, although i won't win the prize for knowing who it was.
 

worntorn

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I only just learned that the prize in this contest is a new Rocket Three, so I'll fess up, it's me in the clip.
On the question of who had rear suspension first, my comments are taken from the video "Chasing Shadows", a history of the Vincent.
Philip Vincent's Daughter, Diedre Vincent-Day gives much of the commentary. She explains how her father had just graduated from Engineering studies in 1925 and approached his father for financial help to launch a new Motorcycle Manufacturing business. Mr. Vincent Sr. told Philip that if he could come up with a patentable design for motorcycles he would believe Philip was serious about the venture. Philip Vincent then designed "Triangulated Rear Suspension" for motorcycles and was able to patent this idea. All Vincent motorcycles from the 1920s onward used it, as did Yamaha (Monshock) years later after the patent had expired.

According to Deidre Day this was the first use of rear suspension on a motorcycle, but she could be wrong. I have searched, but I have been unable to find any other motorcycle that had rear suspension at that time, although the Broughs did have rear suspension on at least one of the late 30s models.
Most Britsh bikes were still rigid even in the late forties. Harley got rear suspension in 1959 according to my internet search.
 

L.A.B.

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worntorn said:
According to Deidre Day this was the first use of rear suspension on a motorcycle, but she could be wrong. I have searched, but I have been unable to find any other motorcycle that had rear suspension at that time, although the Broughs did have rear suspension on at least one of the late 30s models.
Most Britsh bikes were still rigid even in the late forties. Harley got rear suspension in 1959 according to my internet search.

Does Deidre Vincent-Day actually say that?

She does say: "...he [Philip Vincent] lodged his first patent for the *triangulated spring frame* which was granted to him...." (actually in 1927 not 1926) which isn't exactly the same thing as *first use of rear suspension on a motorcycle*.

In the video Bob Culver actually says: "...his idea was patented in 1927....the spring frame around which was the basis of his bike was quite unusual in those days......there had been spring frame bikes before...."

What about the (UK) ABC 1919-22?

And that may not have been the first -just the first one I could think of!

http://en.wikipedia.org/wiki/ABC_Motorcycle

http://www.cybermotorcycle.com/gallery/ ... Museum.htm

(Chasing Shadows is a good video.)
 
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About 1967, Phil Vincent published a piece in the weekly mag (Motor Cycle, I think) claiming wondrous properties for his trangulated rear swing-arm and single damper. Other manufacturers have done a good job with the concept in more recent times.

He reckoned that the twisting moment on a swing arm could get up to the equivalent of hanging a London bus off a 2-ft moment arm throught the rear wheel spindle. He'd calculated something on the order of 50g acceleration (1500 ft/sec/sec)

My boss at N-V said "see if you can shoot this down". When I looked into it, it turned out that Phil had assumed an infinitely stiff tyre, and infinfitely stiff spoked wheel and infinite mass of the bike against which the forces were being reacted.

I took a more reasonable premise, assuming a very low spring rate for the tire, a realistic spring rate for the wheel and a reasonable pitch moment of intertia, based on the Commando. I got an acceleration of about 4 g, a good bit of which went into pitching the bike tail-up, if the force was only on the rear wheel. If you assumed the front wheel had hit the same bump shortly earlier, the overall pitch variation was quite reasonable.

The Stormer , whose frame was based on the Commando, had a pretty wild ride in bumpy conditions, with very violent pitch-up at the rear. Malcolm Davis was very critical of the characteristic, saying he was often winded when the seat hit him in the backside.

We did some high-speed filming, trying to find out why. One segment I filmed at a race meeting up in Cumberland showed some very vicious pitch activity, going from fully extended off a jump, with about 20 degrees nose-up, to hitting the rider in the backside, 10 degrees nose down, in less than 2 frames, at 64 frames/second.

Because the frame was so stiff in the pitch axis, a lot of the small displacement rear suspension motions that were absorbed in frame deflections on other bikes had to be absorbed by the shocks. It wasn't unusual to see the paint blistered off the rear shocks and they were often too hot to touch an hour after the race.

I remember on post-race discussion where Dave Bickers was invited to take the AJS 250 for some laps. He reported "very good handling" and expressed interest in a works ride. When we got back to the factory, we found that the top tube on the bike Dave had ridden was broken clean through. just at the point where the gusset that stiffened the joint with the headstock was attached.

I later determined that there was a major stress concentration at that point and suggested a redesign where the top tube started out as two semi-circular sections with a filler plate welded between, tapering off to a circular section at the seat tube. I believe this was adopted and was part of the design sold to Bombardier.

I tried to get some decent test instrumentation to try and sort the problems out, but the decline of the company in early 1968 dried up the funds.
 

worntorn

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I stand corrected on the "first to have rear suspension" quote. It's Deidre Vincent-Day's fault, and I want my money back for the video.
Actually, I watched the video again, and her quote was "the first to have the Triangulated Rear Sprung Frame", so I got it wrong.
The setup on the ABC looks like it would only have a very small amount of total movement, and no dampening that I could see, but it is rear suspension.

Having done a couple of three thousand mile trips two up and fully laden with approximatley 100 litres of luggage on the Rapide, I can confirm that the Vincent rear suspension does work very well. They used friction dampening in the early years and hydraulic dampening from 49 on. The suspension gives a good amount of travel when set up with correct springs. My bikes give about 7" of travel thru the arc. The early Vincents used essentially the same geometery so even back in the twenties they would have given this same 7" of travel. The swing armed framed Nortons Truimphs and BSAs(or 70s) of the fifties gave less than this amount of travel so this was a real plus for his design.

One negative is that the rear of the seat pivots upward when the suspension moves. Seat movement is one half the amount of wheel movement, so the passenger can get a 3.5 inch jolt. This was changed in 1955 so that the seat was made fully suspended. One of my Vincents has the fully suspended conversion, the other does not. This doesn't make a lot of difference to the rider, but it makes a huge difference to the passenger.
 
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The Ariel Leader I had also gave the back-seater a hard time. I guess it wasn't too bad, since we're still married 42 years later!

Because there was no lower frame section - the frame was a steel monococque beam from which everything was hung - the back-seater's foot pegs were attached to the swing arm. Even average road undulations resulted in upwards jolts to the feet. My wife reckoned I sought out bumps on purpose. She like my BSA A7 a lot better.
 
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