Suspension Modification Advice. Help!

[Baileyrock]

The problem is that with all the different approaches used it makes it much harder for us simpletons to understand and apply because you can't do it until you just choose theory and go with that concept. :fing02:

From an engineering standpoint, there's really only one correct concept for tuning with linear springs as there's one equation of motion. And it's close enough for the non-linear ones in my fork as well. It's the zillion and one mechanics, tuners, owners, and whoever who've come up with their own little way that "works" that muddy the water. The ones who are the most correct are one way or another coming up with damping settings that resemble close to critical damping for that spring and weight combination for each aspect of the circuit (high and low rebound or compression).

I knew a vibration analysis professor in grad school who used expensive accelerometers to tune motorcycle suspensions. And I know mechanics who have no idea what the linear equation of motion is but just kind of push up and down on your bike at different speeds until it feels right. Both are really coming to the same answer.

I've watched people who prefer over-damped and over-sprung harsh suspensions because they think it's better or sporty or whatever. On mountain bikes it's pretty obvious that it's craptacular as their wheels go everywhere and they slide out in berms and such, but...it's their bike and their saddle sores.

Kind of like engine oil and break in theories on VFRD...I've only ever found one and only one acceptable answer in engineering journals and textbooks for each, but as many anecdotal references as you'd like on here to prove whatever

Hey shipfixer, where you been? :rolleyes:

No doubt you are correct and with all the damn Engineers here on VFRD it should be pretty straight forward, but simple(none engineer )types like me don't have that wisdom! So have you gone through all the tuners and discovered which one or outfit best follows the equation of motion? :wub:

Inquiring minds what to know? Is it Ohlins, Penske, Race tech, etc. who has it most correct? :fing02:

[FotoMoto]

Ultra-cheeep: fresh fork fluid with a good cleaning and set your sag correctly on both ends. No hope I'm afraid for a 25k mile, 8+ year old stock shock except set the sag and rebound as best you can.

[ShipFixer]

Hey shipfixer, where you been? :goofy:

Hiding! There's a lot more pedalling road bikes going on in DC than motorcycling so far I've gone from riding like 10,000 miles a year and commuting to riding twice a month to keep the battery up. I'm only up to 22K on my '02 with no valve checks! :D

No doubt you are correct and with all the damn Engineers here on VFRD it should be pretty straight forward, but simple(none engineer )types like me don't have that wisdom! So have you gone through all the tuners and discovered which one or outfit best follows the equation of motion? :unsure:

Inquiring minds what to know? Is it Ohlins, Penske, Race tech, etc. who has it most correct? :fing02:

Haven't in depth, but from what I've seen they all come to the same place. I think Aftershocks and Traxxion use shock dynos to set up your gear before sending it back to you. Some of the other shops rely on the shock supplier to do that for them and do the final tune by the "bouncing up and down method," if it's revalved at all. A couple years ago when I got my WP 3-Way I talked to several of the bigger shops and kind of probed different people's knowledge...they came to the same kind of conclusions on settings with different methods, whether analytical or by feel or whatever.

None of them were "bad." Some of them had misconceptions about things, but nothing that would keep them from setting up a shock properly. I really think that most of the products and most of the installers are going to end up giving you a bike that feels about the same unless you're a racer or something.

I got great engineering feedback discussing Hyperpro springs with Race Tech valves from Hyperpro directly. But that's non-linear (progressive) springs. Never talked to the other shock companies, only the distributors.

After first reading and then installing and testing them, I totally agree with Race Tech and Traxxion about stock valving. It sucks, although it's going to be more correct for a wider variety of rider weights. It's "backwards" with stiff high speed damping and soft low speed damping. Totally wrong frequency response characteristics.

For the life of me I can't figure out from a manufacturing standpoint why we get such crappy stock suspensions, even in cheaper motorcycles. Maybe I'm missing something but there can't be that much of a cost difference.

[Guest]

The 929 while a slight improvement over the VFR shock is still a crappy stock shock. Do the springs and get an aftermarket shock! It's THAT much better!

[Baileyrock]

Haven't in depth, but from what I've seen they all come to the same place. I think Aftershocks and Traxxion use shock dynos to set up your gear before sending it back to you. Some of the other shops rely on the shock supplier to do that for them and do the final tune by the "bouncing up and down method," if it's revalved at all. probed different people's knowledge...they came to the same kind of conclusions on settings with different methods, whether analytical or by feel or whatever.

Well that is why I'm asking, so your saying all results are basically the same no matter the method ? :goofy:

None of them were "bad." Some of them had misconceptions about things, but nothing that would keep them from setting up a shock properly. I really think that most of the products and most of the installers are going to end up giving you a bike that feels about the same unless you're a racer or something.

I did 25 track days last year and never touched my suspension after paying $70 for one of those touchy feely set-ups by Superbike Ken(sets SAG then does the "bouncing up and down method,") on my F4i w/ Onlins/ Traxxion stuff. The bike seems to work great and I go faster and faster, but I'm sure I could gave more speed and confidence spending time on the set-up. It's just seems close enough not to mess with it. :fing02:

[Guest]

That's why Baskin Robbins sells 31 flavors.

:unsure:

I like 31 Flavors and more! :fing02:

The problem is that with all the different approaches used it makes it much harder for us simpletons to understand and apply because you can't do it until you just choose theory and go with that concept. :goofy:

BR:

That's exactly why I bought a copy of Trevitt's book and am going to try to follow/develop a logical/rational method for sorting the suspension out as opposed to "try this, try that" - "so and so recommends this, so and so recommends that". Right now I'm putting my efforts on getting together a somewhat precise baseline set of measurements and then go from there.

I will have to say this, Phil Douglas set up the triple Penske and my forks for my Duke II and it rocks! Phil's been sick a lot lately (had a bad accident) so I don't know how much work he is able to do now days.

But like you say, I want to find/subscribe to a school of thought and go through with it and see where the results lead. I'm an engineer by trade and I know there is seldom one unique solution to any given problem. There are usually 5 or 6 different ways to accomplish the same task. That's something you learn in the real world - not in college. You give the same problem to 10 different engineers and you will get 10 different solutions to the same problem.

Pete

[Guest]

For the life of me I can't figure out from a manufacturing standpoint why we get such crappy stock suspensions, even in cheaper motorcycles. Maybe I'm missing something but there can't be that much of a cost difference.

Because most of us engineers have to ultimately answer to a bean counter of some sort somewhere along the line. 99.99% of the people in the world (including a lot of members of this board) want cheap more than they want good.

You want a first class suspension for your VFR? Be willing to shell out some bucks, time, and aggravation.

You get what you pay for.

[Baileyrock]

That's why Baskin Robbins sells 31 flavors.

:fing02:

I like 31 Flavors and more! :rolleyes:

The problem is that with all the different approaches used it makes it much harder for us simpletons to understand and apply because you can't do it until you just choose theory and go with that concept. :unsure:

BR:

That's exactly why I bought a copy of Trevitt's book and am going to try to follow/develop a logical/rational method for sorting the suspension out as opposed to "try this, try that" - "so and so recommends this, so and so recommends that". Right now I'm putting my efforts on getting together a somewhat precise baseline set of measurements and then go from there.

I will have to say this, Phil Douglas set up the triple Penske and my forks for my Duke II and it rocks! Phil's been sick a lot lately (had a bad accident) so I don't know how much work he is able to do now days.

But like you say, I want to find/subscribe to a school of thought and go through with it and see where the results lead. I'm an engineer by trade and I know there is seldom one unique solution to any given problem. There are usually 5 or 6 different ways to accomplish the same task. That's something you learn in the real world - not in college. You give the same problem to 10 different engineers and you will get 10 different solutions to the same problem.

Pete

I like your plan Pete and I hope you share what you find out with the rest of use so that we may lear more about this Black Art while hanging on your coattails ! :fing02:

[Baileyrock]

For the life of me I can't figure out from a manufacturing standpoint why we get such crappy stock suspensions, even in cheaper motorcycles. Maybe I'm missing something but there can't be that much of a cost difference.

Because most of us engineers have to ultimately answer to a bean counter of some sort somewhere along the line. 99.99% of the people in the world (including a lot of members of this board) want cheap more than they want good.

You want a first class suspension for your VFR? Be willing to shell out some bucks, time, and aggravation.

You get what you pay for.

Yep, Honda found the cheapest way to cover as diverse a group of riders as possible with one set-up and it actually works well for many until you start to push the thresholds of it's limitations. :rolleyes:

[Guest]

For the life of me I can't figure out from a manufacturing standpoint why we get such crappy stock suspensions, even in cheaper motorcycles. Maybe I'm missing something but there can't be that much of a cost difference.

Because most of us engineers have to ultimately answer to a bean counter of some sort somewhere along the line. 99.99% of the people in the world (including a lot of members of this board) want cheap more than they want good.

You want a first class suspension for your VFR? Be willing to shell out some bucks, time, and aggravation.

You get what you pay for.

Yep, Honda found the cheapest way to cover as diverse a group of riders as possible with one set-up and it actually works well for many until you start to push the thresholds of it's limitations. :rolleyes:

Well put Bailey. :unsure:

Pete

[ShipFixer]

Because most of us engineers have to ultimately answer to a bean counter of some sort somewhere along the line. 99.99% of the people in the world (including a lot of members of this board) want cheap more than they want good.

I'm both a mechanical engineer and a bean counter. When I say I don't see why we can't get better from a manufacturing standpoint it's because the cost difference appears minimal to me when I disassemble the components, particularly in fork valving.

For the vast majority of things it's a drawing change and a few extra parts. It's not like, say, moving from cast to machined components. And even if it were, Race Tech's full set of gold valves with machined aluminum pistons costs what, $300 at full retail? Everything else (adding an orifice and control rod for adjustable rebound damping, or even another for compression) is minimal cost and manufacturing effort.

I really think it's more of a question of some kind of hide bound doctrine for one broad damping scheme rather than anything else.

[Baileyrock]

I really think it's more of a question of some kind of hide bound doctrine for one broad damping scheme rather than anything else.

I smell Conspiracy !!!

:fing02:

[ShipFixer]

Well that is why I'm asking, so your saying all results are basically the same no matter the method ? :goofy:

Sort of but not exactly I'm saying most of the high dollar ones will get you "to the same place" with different methods. Cheaper, less experienced shops that don't use analytical tools instead might not. There is one and only one correct engineering concept from an analytical point of view. But some people get to that same answer from just years of tinkering, and they become recognized as experts because whatever they do "works." (The math way is quicker and doesn't take years, I think!)

For instance, look at the different concepts of "damping" in this thread alone. Makes the spring easier or harder to compress? Not really accurate. At very, very low speed it won't hinder you whatsoever. At high speed it will. Unless you have a good shimmed damping cartridge of course, in which case it will be easier at high speed, harder at low speed, but still very easy at very low speed.

Clear as mud? Of course. But for tuning purposes, it's good enough to think that "damping will slow down or speed up the spring's reaction time." Does that totally capture the nuances of speed sensitive shimmed damping cartridges? That damping force is proportional to velocity, with caveats? The significance of how it shifts the bandwidth of the frequency response higher, allowing it to accept small bump inputs (high speed compression) while rejecting cornering and acceleration inputs (low speed compression)?

No, of course it doesn't. But you can tune your bike by feel using it, and that's what the vast majority of shops and riders do. It only screws you up in some instances where the low speed damping is really stiff and it tricks the "push up and down on it" guy into thinking it's overdamped.

I did 25 track days last year and never touched my suspension after paying $70 for one of those touchy feely set-ups by Superbike Ken(sets SAG then does the "bouncing up and down method,") on my F4i w/ Onlins/ Traxxion stuff. The bike seems to work great and I go faster and faster, but I'm sure I could gave more speed and confidence spending time on the set-up. It's just seems close enough not to mess with it. :goofy:

Pro'lly is...that accelerometer setup the professor had cost something like $18K. Pushing up and down is cheaper! I got really good Race Tech setup help in San Diego from a shop that way. A lot of pro teams get around the track that way anyhow.

[Guest]

Shipfixer:

Did you do you Master's thesis on Spring Harmonics/Dynamics?

I think you and I are thinking along the same lines and that's why I'm so excited about Trevitt's book. I'm looking for some sort of mathematical/empirical methodology to determining the correct spring rate and ball park damping for a bike. Tuning it to the fine edge is a matter of individual preference.

I'm still not convinced some of the racing suspension gurus have all the answers. I watch the Team Suzuki riders and the rear ends of their bikes are really pogoing coming out of turns. I think they need a tad more rebound damping.

I may be wrong, but I still think the first step in suspension tuning is determining the correct spring rate and then going to the next step. I think that should be first and foremost in suspension tuning.

Let's all of us also keep in mind in our bitching about suspensions the limited adjustability a motorcycle affords to begin with. Can you imagine how difficult it would be to sell cars/trucks if the seat position was not adjustable? If the factories set the seat in one position as a "fits all" solution. That's where the motorcycle industry is now. We'll see more adjustments available in the future. I just think we will see them in the area of ergonomics first.

I think BaileyRock put it best, the stock suspension serves 99% of the motorcycling public well. How many people do you know that ride reguarly even check their tire pressures? We're pushing the envelope here. It's interesting territory.

[V4 Rosso]

I may be wrong, but I still think the first step in suspension tuning is determining the correct spring rate and then going to the next step. I think that should be first and foremost in suspension tuning.

Don't rule out the tires themselves, they're both a damper and spring which characteristics that change with temperature. By how much varies with the kind of tire you use.

[Baileyrock]

I may be wrong, but I still think the first step in suspension tuning is determining the correct spring rate and then going to the next step. I think that should be first and foremost in suspension tuning.

Don't rule out the tires themselves, they're both a damper and spring which characteristics that change with temperature. By how much varies with the kind of tire you use.

Agreed, tires can make a huge difference in overall handling. Just throw on a set of Pilot Powers and it will enhance the VFR's ability 2 fold IMO. :fing02:

But once past that stuff, springs are the building blocks of the suspension system. :goofy:

[Guest]

Bailey:

What kind of pressures do you run in your Pilot Powers when doing the twisties we've talked about?

Pete

[V4 Rosso]

Agreed, tires can make a huge difference in overall handling. Just throw on a set of Pilot Powers and it will enhance the VFR's ability 2 fold IMO. :idea3:

But once past that stuff, springs are the building blocks of the suspension system. :fing02:

That's not what I meant. Springs and shock are not the building blocks of the supension, they're just part of it. A PP has a different springrate than a PR due to it's construction. The PP, or any other sport or track tire, being the softer "spring" when run with the same tire pressure. Also if there is a substantial weight difference between the two tires there will be a difference in damping. Same goes for the rims. Stock rims are havier then e.g. Marchesinis and will therefor offer more resistance to travel than lighter ones. What that means is that the choise of tires and rims affect the overall suspension characteristics. So if you have set up your suspension (springs and shock) of your track bike but than change to lighter wheels or different kind of tires you can start all over again.

[Baileyrock]

Agreed, tires can make a huge difference in overall handling. Just throw on a set of Pilot Powers and it will enhance the VFR's ability 2 fold IMO. :fing02:

But once past that stuff, springs are the building blocks of the suspension system. :idea3:

That's not what I meant. Springs and shock are not the building blocks of the supension, they're just part of it. A PP has a different springrate than a PR due to it's construction. The PP, or any other sport or track tire, being the softer "spring" when run with the same tire pressure. Also if there is a substantial weight difference between the two tires there will be a difference in damping. Same goes for the rims. Stock rims are havier then e.g. Marchesinis and will therefor offer more resistance to travel than lighter ones. What that means is that the choise of tires and rims affect the overall suspension characteristics. So if you have set up your suspension (springs and shock) of your track bike but than change to lighter wheels or different kind of tires you can start all over again.

Oh I agree completely, just think your going to a far more advanced degree then most here even think about and it only adds to the confusion. Were not talking about developing Race Bikes systems here, just a general and simplified way for the masses to better set-up their VFR's. :fing02: Sure, ideally designing the entire system with all aspects involved will provide the greatest results, but it's far to complicated to apply to street set-up IMO. :fing02:

PM I've always run 36/42 most of the time, but occasionally run 34/40 for grins. :blink:

[skuuter]

"SKUUTERPINION"...........it is only possible to "dial in" a street vehicle to a certain degree, because every day on every mile ridden, the "test track" varies. Unlike setting up a race bike or race car for a given track with very minimal varying conditions while there...."STREET" has to be survived daily. What is a very comfy set-up on my bikes for me in my local area is not always the "hot ticket" when I venture out to totally different types of roads in other areas. Sometimes it would be nice to have a different set of damping, spring rates, compression, etc.......not possible....."Street Set-Up" is a comfy shock / spring package that is "close" most of the time................... :fing02:

[Guest]

Very interesting discussion guys. I'm on an engineering path in school and have always enjoyed tinkering with systems looking for an ingenious way to improve them or at least to understand them. This thread proves that as usual, I am (and probably most of us here are) trying to improve a system that we have a very limited understanding of. Kind of like the guy with a huge spoiler on his '89 Ford Escort who swears he gets better handling. :fing02: (no I don't own an Escort)

This is why when dealing with systems not fully understood and trying to improve them, small adjustments and changes are best until the system dynamics are better understood.

Or you can just send you stuff to Racetech/GP/Noleen etc.

I'll take option 2

[Guest]

I've been looking and haven't found much info. Does anyone know of any threads that discuss using some of the F3 or F4 fork internals in a 5th gen? I've heard some reference to this but since I'm not finding much, I'm starting to think it's not a viable upgrade option.

[SEBSPEED]

I've been looking and haven't found much info. Does anyone know of any threads that discuss using some of the F3 or F4 fork internals in a 5th gen? I've heard some reference to this but since I'm not finding much, I'm starting to think it's not a viable upgrade option.

I think HispanicSlamer has a thread on it in the How-to section?? :fing02:

[Guest]

I've been looking and haven't found much info. Does anyone know of any threads that discuss using some of the F3 or F4 fork internals in a 5th gen? I've heard some reference to this but since I'm not finding much, I'm starting to think it's not a viable upgrade option.

I think HispanicSlamer has a thread on it in the How-to section?? :biggrin:

Sweet. Found it. Thanks Seb