So what happens next?
I've been thinking about sexy suspenders (get mind the of your out gutter: anag)
Firstly BMW had a go with ESA. Then they tweaked it's nipples (greased them too) and fitted a diaphragm, to enable it to calculate laden preload, calling it the catchy 'II'.
My best guestimate is that they release (a ZX10R style) manga-tronic Ohlins TTX EC as an option on the new (R1150-ST screened, by the look of it!) R12GS-LC.
This will provide semi-auto stepper-motor cranking to effectively move between ESA modes automatically. E.g. Comfort to 50 mph, Normal to 75 mph, Sport above?
I think this will be their trumping (sic) USP over the Hinkley chaps. In turn, Triumph may well release an XC (GSA peer) with mechatronic TTX EC too?
So how will BMW then top-trump that? I guess they have to then move to full ES. The so-called DDC (Dynamic Damping Control) connected to the bike's ECU via the CAN bus, to provide electronic actuation of the adjustors.
That could potentially alter damping rates not only based on compression and rebound movements (length, speed and pressure), but also make dependency adjustments for gyro-measured lean angles too.
I need the likes of Pitts, Jag, Navy Boy, Shuggs, RIC, Kev, etc, to feedback their views on what they think will happen next in the world of suspension ... how long before we have to accept 'the shame of it' - having to adjust our existing fully-adjustable suspension 'by hand'! ;-D
Yes, another point over which I have often pondered though that still hasn't seemed to get me any nearer the answer I'm afraid!
ESA - Yes it's good and (Surprisingly so on my 1200RT that I had) rather useful. I reckon further developments like this will happen with other manufacturers getting in on the act.
However I reckon that fully active suspension will be the next big challenge/opportunity for the early adopters out there. Engineering-wise this is still a huge challenge for a bike and, if it could be made to work properly, would be something that your average rider would still notice (That's perhaps the important bit).
Just my 2p's worth. Doubtless more to come on this one! I look forward to it.
Captain, excellent choice of subject, must admit I miss ESA, I guess the question that needs to be asked is just how far should the NextGen suspension go.
If using CAN Bus, then should the suspension be linked to GPS / SatNav so it can update road information and receive road quality info to preset the suspension for the road ahead.
Most of the technology exists electronically, the issue is cost. With the power of control in ECU's limited only by the processor/memory combination used and most only use a small portion of the computing resource available so much more could be done for little hardware cost once the suspension control hardware is in place.
Dependent on the speed of the suspensions adjustment, the ECU could also link up with the ABS and traction control to optimise suspension under braking and acceleration as well as the suggested giro control based on lean angle.
Like with ABS there will/would be many who "prefer" to use their skill as they can outperform the early variants, much like happened with ABS; ABS now having reached the point where even top ex GP class riders in reviews admit they would prefer ABS on the road though perhaps not on track yet!
Even Harley have gone down the ABS route even though it has been done pretty discreetly, so while it may create a have / have not class of rider for a while, once the cost of the technology drops with economies of scale there will probably be a new "Smooth Rider" option. Maybe it could even link to an active seat, soft for motorways, hard in "sport" mode?
Given the current state of many UK roads , some form of adjustment on the move is almost a must for non Adventure bikes to soften the suspension when not on the "interesting" sections of road!
Considering the technology now being deployed elsewhere, how about a BMW GSA which lowers when stationary or at a button press like a Range Rover to allow vertically challenged riders to get their feet down instead of looking for a kerb or performing strange contortions?
Hi there Mr. Scarlet,
Some basic questions come to mind.
Do you still want to use springs?
Do you want to be able to set or adjust the suspension yourself while riding or have the bike set it up automatically based on riding conditions?
In other words, have the bike read the road and make the adjustments as required?
What we have now is pretty good.
Finally, what's it worth to you?
Semi active suspension system:
This type does not read the road ahead. It simply reacts as the tire runs over the road surface. This is what we have now. Simply put, when you hit a bump or hole and then the suspension system reacts.
Active suspension system.
This type reads the road ahead and adjusts the suspension as you come to the bump or hole. It does not wait for you to actually hit the hole or bump. It responds as you hit the hole or bump.
One advantage of an active suspension system is that the bike would always be level or at the same riding height regardless of road or riding conditions.
I only know of one proto-type active suspension system. It is very expensive and it doesn't use springs at all. It is all done with hydraulics and is controlled electronically. It actually reads the road or surface conditions ahead of the vehicle and adjusts each wheel independantly (lifts it up or down as the wheel travels over the surface) as required to keep the vehicle level.
Rekrab said: " how about a BMW GSA which lowers when stationary or at a button press like a Range Rover to allow vertically challenged riders to get their feet down instead of looking for a kerb or performing strange contortions?"
That sounds like a genuinely useful suggestion and a damn good marketing ploy. There is the other side of the argument which asks why you need to be up there in the first place?
Semi active suspension system
Right now I think I would prefer a semi-active suspension system but do away with the springs. It would be a hydraulic system using a small pump at low pressures and an accumulator (for the very fast reaction times requred) with adjustable valving. The rider would control the riding height and shock characterics or the bike would have built in riding mode choices.
The cylinders (front forks or rear shock) would not need internal piston seals. This and the low pressures would help with keeping seal stiction low.
Did some quick math.
With 43 mm front forks with a 450 lb bike and 200 lb rider you would need about 72 PSI pressure in each front fork. Raising the pressure would lift the bike and lowering the pressure would lower the riding height. Flow through the forks supplied by the pump would be low, maybe a couple of GPM. About the same size as your oil pump.
The accumulator would react very quickly to the road surface and allow the pressure and flow to increase or decrease rapidly for short periods of time. Variable valving would control the shock characteristics.
Nice topic Captain.
That sounds like a genuinely useful suggestion and a damn good marketing ploy. There is the other side of the argument which asks why you need to be up there in the first place?
I think tyres are much better nowadays, which allows cornering angles that previous generations only saw on the race track. This demands high footrests, which is fine on a racer where comfort means nothing.
On a roadbike comfort demands a certain relationship between footrest and seat, so the seat has to be high.
Also, men's average height is more now than before. Better nutrition, I think.
Semi active suspension system - power requirements
The front suspension at 2 GPM at 100 PSI with a pump with an overall efficency of 80% and a DC electric motor at 90% overall effficiency you would need about a 121 watt 12 VDC motor. A variable speed DC servo motor would be a good choice.
The rear suspension would be about the same.
The suspension system (both front and rear) would cost about 240 watts. The alternator size may have to be increased.
In terms of HP this type of suspension would cost about 1/3 of a HP.
To put it more simply, about 10 amps at 12 VDC for the front and about the same for the rear for a total of 20 amps at 12 VDC.
The system would have a fail safe feature so if for some reason either the front or rear suspesion pump/motor failed or you blew a fuse a check valve at the pump's outlet and return line would lock in the pressure and fluid in the system. You would loose the static height control, (it would remain at the last setting) but the rest would still perform well.
Of course if you are happy with the static height you could turn the pump/motor off to save energy.
This would also insure that the riding height does not change when the bike is turned off.
Ooh excellent point Rekrab, GPS tracking to feedback info on the state of the roads, adjusting incrementally to suit. I suspect the more likely use of that technology will be two-fold. Firstly so that insurance companies can monitor driving habits and reward 'safe' (read: low mileage, slow accelerating/decelerating, minimal turns) drivers by offering to let them pay reduced (read: existing rates) premiums, whilst penalizing the erm, handy drivers for their anti-social frenetic-ness.
And of course the government will be pro pay-per-use mileage based taxation, to help bail the economy out of the mire that they could have stepped in earlier to stop the fallout of. I've actually worked with teams developing the kit to fit to OBD ports on cars to measure just that, which is now available with insurers like State Farm for instance.
Once GPS is mature enough, combined with (existing) radar cruise control, days of 'manually' driving cars are numbered. If they still 'let us' ride, that could actually be the best thing ever. I.e. Cars that can't speed and can't crash into you. Think of the fun we'll have forcing them to emergency brake by deliberately cutting them up whilst lane swapping! :-0
I like your idea about a slammed GSA too. Makes perfect sense to have a tall-rounder quickly auto-lower (a few inches) when speeds reduce below ten mph. You'd need an override for off-road or a dedicated mode, in same. But it'd probably double-sales, as I know lots of shortish folk who really want a full sized Adventure bike, love them on the move, but are petrified of dropping them when doing u-turns or pushing them on the drive. Build it and they will come...
Jag, I think springs or not, matter not to the average rider, only the end result. A linear movement, lightness, affordability and reliability would perhaps be more of interest to them? I do like the low stiction theory though, saves on the nitride :-D
I do believe gold-obsessed Ohlins do have a fully-active suspension prototype, so like Emmanuelle, it's coming! Puter power and economies of scale aside, I think it'll be the next big thing. So many (ever aging) riders are constantly complaining about comfort, irrelevant of bike they ride nowadays, that in theory it could be a bit of a holy grail in terms of riding enjoyment?
I've owned bikes with ESA (indifferent) and ESA II (noticeably better) and tried DES (in theory better than ESA II, but not convinced by the practice) a few times. But they still feel a bit, well Microsoft Beta. If Ohlins can make full-active a reality at a stomach accepting price, it'll be more Apple Lion. This said I agree that good quality suspension does work well over a wide range at present. A good example is KTM's SMT WP items. They work very well from docile to seriously?, riding styles.
Pitts, tall bikes give you two potential key advantages: longer travel suspension to soak up the pot holes and the ability to see over obstacles (we'll call those cars) giving a further line of site, highlighting both potential dangers or opportunities to open the throttle sooner. I read it, so it must be true! ;-D
Your ability to number crunch never ceases to amaze me and always impresses me Jag. BTW, there's an 'S' in maths! ;-D
Yes Dean, sizes have increased, which as you highlight is directly down to nutrition. Does that explain my middle-aged spread then? :-D
'GPM'? Gurning Putrid Manticles? Have you always had a brain the size of a planet?!?! :-D I'm glad I started this thread.
P.s. Do you think, when full-active ES comes on song, the way to go will be forks and shock, or shocks with tubes (telelever) front ends? In theory ride-height could remain the same, negating one advantage of telelever, however the setup is still heavier than USD forks, and with regards to both would it rob rider of confidence inspiring feedback?
Hi Captain Scarlet,
GREAT response! You have still got it, even if you do live in the US.
GPM = American gallons per minute.
1 American gallon equals 231 cubic inches.
MATHS or MATH ?
I was only doing one calculation at a time.
We really need Kevin's thoughts and inputs. He is really good at this stuff.
GREAT thread, well done !
I had a Citroen once with brilliant hydraulic suspension, is that what we're talking about?
It reacted to weight automatically which would be nice on a bike, and firmed up the corner under load in corners too (fore & aft on a bike?).
It also went up and down, if you jammed a brick in the opposite wheel arch then lowered the suspension the wheel would come off the ground to change it easily. Fit a low, easy roll on centre stand then drop the rear suspension and hey presto! Easy chain lubing and wheel changing!
Another thought. Had a Scania once with air suspension, you could lower/raise the rear of the tractor unit to fit under trailors. You could also use this to aid traction temporarily by lowering the rear thereby putting more load on it. Could work on a bike too?
Hi unconventional rebel,
"I had a Citroen once with brilliant hydraulic suspension, is that what we're talking about?
It reacted to weight automatically which would be nice on a bike, and firmed up the corner under load in corners too (fore & aft on a bike?)."
GOOD JOB !
I believe it had an accumulator above each wheel.
The accumulator in a sense replaces the spring.
You are pretty sharp, didn't think anyone would connect the dots.
Now I can't take credit for being original.
Best of regards,
P.S. Tell us some more stories about your Ural.
"P.s. Do you think, when full-active ES comes on song, the way to go will be forks and shock, or shocks with tubes (telelever) front ends? In theory ride-height could remain the same, negating one advantage of telelever, however the setup is still heavier than USD forks, and with regards to both would it rob rider of confidence inspiring feedback?"
With engines approaching 200 RWHP I say the heck with it. Who needs suspension anyway. Why do we need to touch the ground at all?
Think Star Wars - that's the kind of bike I want!
HEE HA !
BLASTER BIKES !
Hydraulic suspension system with bias springs
Further to our discussion I was thinking maybe we would still need, for want of a better word, a bias spring.
One of the biggest challenges is what will this type of system cost in weight.
Secondly, where are you going to put the motor/pump and reservoir.
If we used a bias spring with just enough spring compression to take the static weight of the bike plus a minimum weight value of the lightest typical rider we could get away with a much smaller, lighter less powerful DC motor. Hydraulic pressures would also be much lower.
Motor current draw would be much lower so we probably won't need a larger capacity alternator.
Basically, the bias spring tension would be just enough for the suspension to just start to lift with the lightest typical rider on board.
Maybe the lightest/smallest pump/motor setup would be a single DC motor driving a tandem pump (one pump connected to the other). Total current draw could be under 4 amps (about 48 watts).
I like the thinking!
Not knowing how it's done, is that similar the the way say a RangeRover works, I seem to recall it checks the status of the suspension 500 times a second and adjusts accordingly.
Would that sort of frequency be OK on a bike? Knowing the weight of a Range Rover I would expect that the system used is not light but there are plenty out there working so maybe some info would be relevant to this threads progress.
With its adjustable ride height and pretty good ride quality a car like that shows what can be done but some serious thinking outside the box would be required to make it fit a useable motorcycle!
I am not familiar with the RangeRover suspension system.
What we have now is pretty good. As Captain Scarlet indicated, companies like Ohlin’s are doing great work.
Whichever system we use first has to overcome or minimize the basic disadvantages of the present telescope front suspension system. It’s been around for a long time and under normal street riding conditions for most of us it does a pretty good job.
Ohlin and others have spent lots of time and money trying to get it right.
One basic problem with any semi active system is that it only responds to events. It reacts to the bump or hole or centrifugal weight change or when turning and braking.
Another basic problem is the weight difference between the unstrung weight (weight of the wheel and brake assembly and the bottom of the fork) and the sprung weight (everything on top of the spring).
The greater the weight differences between those two the easier/quicker the wheel will react the bump or hole.
In other words, if you hit a bump the wheel will move more and quicker than the rest of the bike.
It’s basically an inertia issue.
That’s one of the reasons Captain Scarlet likes carbon fiber wheels so much. They are so light which increases or improves that sprung and unsprung ratio weight difference.
Another problem is the forks themselves. When you hit a bump or hole there is a force that compresses or extends the spring. There are also other forces that try to bend or twist the forks . This is bad.
Throw in heavy braking and hard cornering and a pot hole and it’s amazing the front suspension works at all.
Jag, what are your thoughts on non telescopic front suspension systems, where the wheel spindle travels vertically, (or perhaps more precisely, perpendicular)? I think this will lower the acceleration of the wheel as it has less distance to travel in a given time, for a given bump. How will this help or hinder the electronics and/or hydraulics?
Thanks for the pat on the back Jag, means a lot from a clever chap like yourself!
Modern Range Rovers use air suspension, and it has had it's problems regarding expense and reliability. To the point where people sometimes retro-fit the old coil springs when the system starts causing problems. Having said that most artic lorries have used air suspension for years and do huge milages without problems (did 500,ooo miles in my Scania without the suspension being touched) but then weight isn't such an issue on them.
Regarding a hydraulic resovoir tank, you could use the frame? Maybe even incorporate some mechanical bits in the headstock and rear frame next to the shocks?
I think a hydraulic system would be a little bit heavier, but the real world everyday advantages of not having to mess with the suspension when carrying a pillion/luggage ect..., effectivly a self leveling headlamp, or indeed bike, variable seat height and having a really easy use centre stand could be enough even without the ride quality benefits.
As for the Ural, well my 1st outfit had a right hand chair. Being new to piloting a rig I took it easy without problems until confidence was gained. Then I met an 'expert' after buying a squashed Reliant off him. He looked at it, tut tutted and set it up 'properly' for me. Shortly after I was rounding a sweeping right hander when the chair started to lift, and carry on lifting... I bailed out when if got past 45 degrees and skidded down the road on my backside while watching it complete the arc and come to rest in the middle of the road upside down. Having turned it the right way up I noticed that while most of the outfit was pretty undamaged the parallel twin was now a parallel single, the nearside pot complete with piston and half a con rod was under the bike, though still attached by the throttle cable.
The search for an engine became a sizable collection of Dnepr & Ural parts (and a couple of semi-complete bikes I rebuilt), once word got round I emptied most of the sheds in Yorkshire of old Russian bike parts. As for the 'expert', it turns out you set up a right hand chair quite differently to a left hand chair, you live and learn.
There are good reasons to disdain the common telescopic fork. Under heavy braking it compresses (obviously) and this reduces rake & trail. These give stability, so you are sacrificing straight line stability at the very moment when you need this property the most.
Earles forks, leading link, trailing link, BMW Telelever are all better in this respect, I believe. I think cosmetic and marketing considerations are at fault here. A telescopic fork looks neat; a bike with an Earles fork looks like it's pushing a wheelbarrow!
Hi Dean 15,
"Earles forks, leading link, trailing link, BMW Telelever are all better in this respect, I believe. I think cosmetic and marketing considerations are at fault here. A telescopic fork looks neat; a bike with an Earles fork looks like it's pushing a wheelbarrow!"
I think this is true. I know it is in my case. It looks like what I am used to seeing. Big telescope front forks with nice big stainless steel brake discs and polished fork tubes look so nice.
I still don't like black rims or engines painted black. I'm not crazy about a lot of chrome, but I really like polished metal engine parts.
The first time I saw a single sided rear swing arm drove me crazy. I hated it. It took a couple of years to come around. The same thing with rear suspension without two shocks attached to the back swing arms. It just didn't look right.
Right now I can't stand really wide rear tires. 190's or 200's are ok but those 240's are just too much.
Seems like the 240 rider is saying, "mine's bigger than yours."
What is it with cruisers with very low seat heights? Why is it so important to have both feet flat on the ground when you stop? I'd rather have another 1 or 2 inches of rear suspension travel.
Thanks for letting me get this off my chest.
"Jag, what are your thoughts on non telescopic front suspension systems, where the wheel spindle travels vertically, (or perhaps more precisely, perpendicular)? I think this will lower the acceleration of the wheel as it has less distance to travel in a given time, for a given bump. How will this help or hinder the electronics and/or hydraulics?"
Very good question !
I think what we need is input from other members who have had a lot more experience than I riding a lot of different bikes with different suspensions.
Obviously Kevin would be a great source of information and there are many others.
Who else (are you listening Captain?) could we impose on who has ridden almost everything under the sun at one time or other? What we need is someone with a fine gift for words and real life biking experience.
Maybe a summary of the advantages and disadvantages of various suspension systems or types they have encountered.
"GREAT response! You have still got it, even if you do live in the US."
... the Doodles haven't quite, yet, sucked my will to live! ;-D
"MATHS or MATH ?"
... you say Abacus, I say Babbage, lets call the whole thi... Agreed Mista Kev is good at 'stuff'.
"I had a Citroen once with brilliant hydraulic suspension, is that what we're talking about?"
... yip. Like a sports-car wing rising over 50 mph, why can't suspension rise a couple of inches once speed hits 15 mph or something, it's almost too obvious a USP isn't it? Imagine doing this (towards the end of vid) as you wait for the lights to go red: http://youtu.be/wZh5vRhFeZY :-D
"Secondly, where are you going to put the motor/pump and reservoir"
... we'll just reduce tank capacity from 15L to 10L, we know how popular that will be don't we!
"That’s one of the reasons Captain Scarlet likes carbon fiber wheels so much"
... yes, the other being that they are sssooooohhhh pretty, ha! :-D
I've had BMW bikes with telelever and paralever and on the whole I like the way that they reduce rebound movements through the bars. My titanium filled wrists particularly appreciate it. And of course the harder you ride, the greater that individual benefit, but also the greater the difference in feedback/feel grows. It means you have to trust the BMW front end more, which on the road is relatively easy to acclimitise to, but not so much on the track. However, IMPO front ends in recent years have become phenomenally good. My last three bikes (K13S, SRR, Diavel) all had fantastic front ends, that glide well over potholes, whilst being nice and firm when using their awesome mono-bloc radials. The weak link (sic) for me, still, is getting a good rear. Perhaps we should ask J-Lo's advise?
"What is it with cruisers with very low seat heights?"
... it's two USP's are that sitting lower to the ground, you get a faster sensation of speed, despite traveling at a more modest rate of knots. And secondly the genre, perhaps very genuinely, does appeal to the short of leg. My brother is a good six inches shorter than me (probably explains why we don't look like each other!) and I remember him sitting on an Africa Twin at a bike show many years ago. And if I can recall correctly, his feet couldn't even touch the pegs, never mind the ground! He's thinking about buying a Hardley Movingson. He'll need one with a 240 section rear hoop, just so as everyone can think of him as a tripod ;-D
Jag said: "I think what we need is input from other members who have had a lot more experience than I riding a lot of different bikes with different suspensions."
Nicely dodged Jag! : D
I wasn't trying to start another Telelever bun fight (although, if you're having one, count me in) but offer reasonable questions relating to topic. Since someone mentioned Telelever, how would this type lend itself to building in your various rams/balloons etc, when compared to teles? The Telelever shock is already tucked away and there's no reason why, with links, it couldn't be tucked away even more.
Captain scarlet said: "IMPO front ends in recent years have become phenomenally good"
Agreed. Having taken out my r100 "project" a couple of times I can see how, with the world seen by BMW in the 70s, they embraced Telelever so strongly. It would have been difficult to imagine that a lot of the problems with telescopics would diminish to such a degree with steady development. As a solution for a road going machine though, Telelever is a very, very good option.
I've been thinking about the front suspension designed by Claude Fior. As featured in the latest issue of MSL.
Is this geometrically the same as the Girdraulic fork that P C Vincent drew for his Rapide/Black Shadow?
Claude fior will have done a few different designs I guess, but the one you're probably talking about looks more like the hossack (duo lever) to me. Can't see any telescoping legs on the pictures I've seen, but the suspension element is separate from the steering.
To my eyes the girdraulic is a sophisticated girder, using hydraulic damping instead of friction. But the girder forks don't separate suspension from steering. Although girders do offer an opportunity to do something different with wheel travel and therefore anti dive, I would have thought.
Maybe girder style forks are the answer to combining anti dive and feel? You could certainly play around with lateral flex. Was the Britten fork a girder or hossack type?
We should really conduct this aspect of suspension discussion on a separate thread I suppose!
C'mon, get yer slide rule flexed, do the mathz and give us your thoughts. You don't have to have ridden the things to give us your interpretation of the theory.
Going back to what I said earlier, with regard to front suspension types which have a fixed shock, as opposed to two swinging around in/on fork legs, it mut be easier to buid in all the gadgets you've been talking about? No?
Back to basics
The purpose of the spring is to hold up the sprung weight and allow the wheel to move up and down independently of the vehicle so the wheel/tire can follow the road surface to maintain tire traction.
The only purpose of the shock is to absorb the energy of the spring as it is compressed and de-compressed to prevent spring bouncing. It does this by changing the spring excessive movement or kinetic energy into heat energy.
All the suspension system types mentioned so far have these two basic features in common.
Another thing suspension systems have in common is sprung weight and unsprung weight as mentioned earlier.
So we have two obvious choices to maintain the biggest weight difference between them.
#1 Make the wheel and tire and brakes and lower suspension (unsprung weight) as light as possible.
#2 Increase the weight of the sprung mass. Make everything else a lot heavier. Not such a good idea.
Do we have a third option?
Maybe we do.
How can we increase the sprung force pushing the bike down as if it was heavier without increasing its weight?
I believe racing cars have been doing it for years. Maybe what we need is some kind of upside down adjustable wing surface to create a down thrust.
Thought I’d throw it out there and see how it flies.
Crash and burn !
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