So what happens next?

UcR said: "Fear not Pittsy, I have just the system for you. The rear suspension as found on a Mobylette, fully height adjustable too!"

Hee Hee. I'm looking for suspension, but I can only see a saddle. Is there a spring in there?

Controlled riding height

Quote:
“P.S. Another reason it took so long to answer your good question regarding damping is that, in this very simple example of a hydro/pneumatic suspension system, we have a potential challenge.”

How much force does it take to hold up say a 15 lbs. object 36 inches above the surface?

How much force does it take to hold up the same 15 lbs. object 40 inches above the surface?

Would not the forces be the same?

So in our simple basic suspension system, how would it know when the desired or normal riding set height is correct?

One solution may be a bias spring so that different riding heights would result in slightly different system pressures to overcome the bias spring compression.

That way the suspension system would be able to control and maintain the desired or programed riding height as long as the pump is running.

The desired riding height would be set prior to moving the loaded bike but with the hydraulic pump working.

Some type of vertical measuring system would be required when the desired riding height is set.

As mentioned earlier, the bias spring would only be strong enough to just begin to lift the bike’s sprung weight plus maybe a 100 lbs. load.

This bias spring would also significantly lower system pressures and accumulator pre-charge pressure at the required riding height.

One of the goals of this hydro/pneumatic suspension system was to try to separate the sprung mass and its inertia and turning forces from road shock as much as practically possible.

One system handles maintaining the correct programmed riding height and another system mainly controls road shock.

A system that only has to mainly deal with road shock can potentially respond quicker/easier because it doesn’t have to deal as much with the inertia of the sprung mass.

Sprung mass inertia is a major factor in excessive spring bounce.

In my opinion, a suspension system that can tell the difference between road shock and sprung inertia loads would be a major advancement.

Regards,

JAG

No spring. The French wisely spotted that spring failure could cause a catastrophic effect on handling leading to loss of rider control. The solution was simple, a rubber block! Cheap and ultra reliable, it's only draw-back is a slight lack of movement.

Ahh, but think of the weight dear boy! If there's anything I've learned from this forum it's to keep the old weight down.

And as for the lack of movement, the French though of that too. Just limit the performance. It's so simple it's brilliant!

No. Only real ale, proper bitter, should be at ambient temperature so one can enjoy the subtle mix of flavours. All other such drinks should be cold because the flavour is nasty or non-existant or just sugar, and the cold disguises this. The colder it is the less one can taste it which is a good thing IMO. :-)

I once read that all things act as a fluid, given a long enough timescale?

I still like the hyrolik idea, but how about air suspension? Seems to work well on commercial vehicles and Range Rovers? Air is lighter than fluid too!

How about this for a solution, whereby the coil spring and hydraulic cylinder both get to play a leading role.

Variable spring rate.

This has to be the next big step forward for the real world rider. The ESA II elastogran goes some way towards giving a very workable solution, but I'm still not convinced it is the definitive incarnation.

I'm not talking about preload or ride height here, that's a different thing in my eyes and one more easily (and already) solved.

Take a look at a cross section of the top end of an ESA II shock absorber, showing the elastogran mechanism. Basically they have placed two springs on top of each other and come up with an ingenious way of altering the rate of the top one, to the point of actually making it effectively solid when required. How else can we achieve the same end? Hydraulic locking and unlocking.

If we convert the annular chamber presently occupied by the elastogran into an hydraulic cylinder on top of the existing spring and then connect that chamber to a couple of separate chambers. These other chambers would each contain a coil spring, of different rates (we could substitute these springs for bladders containing pressurised gas). Let's say we had two extra coil springs. That would give us three spring rate modes. If we shut off the cavity above the shock, that would hydraulically lock the chamber, making it effectively solid. Alternatively, by opening it up to one or the other of the bladders we would change the spring rate.

Madness, I know.

Bit weighty too.

Back to the drawing board?

Hey pittsy,

That’s a lot of springs.

You have some artistic talents, maybe you could post some simple drawing of your ideas.

I agree with you pittsy. The coil spring is a very elegant and beautiful thing. It’s simple, reliable, compact and very cost effective. One could say it’s almost perfect.

If it was perfect, though, you wouldn’t need so many in your proposed system.

Even in my system it would be difficult to eliminate the spring completely. It’s such a darn handy little thing.

Part of the problem I suspect is that we expect it to do too much.

The present spring, shock systems have been around for a very long time because under most conditions for most riders it works well. A modern well designed system that is correctly set up for one specific rider for a specific type of riding would be a very tough act to beat.

From Captain Scarlet and others I suspect, for now at least, in the handling/comfort department a really comfortable seat and handle bars could be higher on their list.

Regards,

JOK

P.S. What about a set of adjustable handle bars you could raise or lower a couple of inches? The higher setting for cruising and then lower them when you want to take the twisties or run at higher speeds.

Jag said: "maybe you could post some simple drawing of your ideas"

Doing the drawings is not a problem. I have tried to get photos and text files from my i pad to this site in the past, but it won't seem to work. If anyone can advise the best way to do that, mit would be appreciated. My drawings, by the way, would be on paper, with a pencil! I'd then have to photo them. I told you I am a Luddite!

Jag said: "If it was perfect, though, you wouldn’t need so many in your proposed system."

The coil spring is perfect for one job at a time. We are asking it to turn its hand to three jobs. We need 3 springs. The elastogran is a simple, elegant, light(ish) and cost effective way of giving you 3 springs.

My idea is none of those! Hah!

WOW CAPTAIN SCARLET !

I just viewed you GREAT video of your runin on the Triumph.

That was an amazing video. Loved it. Fabulious road and senery. Great riding skill.

That old road was on a 45 degree angle a lot.

The thing went on for 10 minutes!

You have to do more.

I am almost lost for words.

The last shot was perfect.

Thank you!

Now I understand why you place so much importance on good handling and light weight.

JOP

Thank you Captain Scarlet,

Honestly, you have a talent for this type of video.

I like that you didn't add music or a song. You let the engine and wind do the singing. You kept it honest and true.

I have added it to my small collection of bike videos.

Now during those long gray winter months whem I am dying for a ride I can go for one.

My favourite before was the video titled "Sleepy ride through Atlanta". Your's is better.

Your video was a bit of an eye opener for me. No where in that ten minutes did I get the impression you wanted another 50 HP. Maybe I have placed too much importance on top gear straight line acceleration.

I hope Triumph gets a hold of you and offers you a big lump of cash to use the video in their advertising of what the Tiger really is all about and what it can do.

Respectfully

JAG

I am now! Old trucks used cart springs (leaf) which as you say were set up for a full load, and ridged when empty! With a bit of experience you knew how much weight was on board simply by looking at the ride height. All newer trucks run on air suspension, big bellows on each end of the axles, these are so much smoother as they adjust themselves. No idea how they work though. :-)

That praise is well deserved Cap'n!

Hey pittsy,

If you go with a recirculation ball and screw system you may need to add some type of simple electrically controlled lockout to stop the worm screw from turning on its own when the DC motor is off or not in use.

I can see there would be times when constant loading and unloading of the spring would not be required such as highway cruising on smooth roads.

The Captain of course would not need a lockout. He works the suspension all the time. Might have to add a bigger alternator though on his bike to handle the extra activity of his suspension.

The lockout would only release when electrically activated. Some like of simple electic DC coil and rod and spring. The rod could have a simple cone that goes into the end of the worm screw.

JEZ

Jag said: "You are correct, locking out sections of the coil spring will stiffen up the spring. On a constant rated spring (where the wire diameter and the space between the coils are constant) your idea will stiffen up the spring."

Actually I had in mind a dual (or even multi) rate spring! I can't see how locking out coils of a single rate spring will change its rate?