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Discussion Starter · #1 ·
Suspension Turners,

My next mission is to install Ohlins fork springs on top of Race Tech cartriges. The springs are 281mm long vs 261mm for the stockers. Stock '03 oil level is 100mm down from top of tubes. Race Tech recommends 130mm, but their springs click, so what do they know.

Additionally, spacer length is a question to me. Stock is 149mm resulting in installed length of 246mm or 15mm of compression with the adjuster all the way out. With longer aftermarket springs, what is a guy to do?

So, suspension tuners please share your experience on rules of thumb or just thumb your nose, your choice.

Thanks.
BAGSTR in San Diego
 

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Not a "tuner", but based on my experience 100mms sounds about right for sport riding; springs out, slider fully compressed, fork tube out of bike, ie level. Probably close to 750mms in an FJR 48mm slider, so make sure you have at least 2 litres available.
 

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He's almost exactly right on the amount of fork oil. I didn't measure any closer than that. And the level is pretty standard at 100mm. Less gap there will result in more progressive fork action, just as higher gap will result in LESS progressive fork action, which COULD increase the perception of diving on braking. I'm sure you could 'season to taste' within that range.

The aftermarket Wilbers springs were about that much longer than the stockers, resulting in a strangley high amount of tension on the spring, just to re-install the fork caps. I wasn't really tickled with that, but it IS fairly common in many suspension upgrades I've done over the years on different bikes.

The only things that matter on the fork springs, theoretically, are rate and preload. AFAIK, if the rate is correct for your weight, and the weight of the motorcycle, and the static and race sag settings are correct, the spring is just right. Any other upgrades need to happen somewhere in the valving.

I'm not a suspension guru, when it comes to messing with the stacks or cartridges, they either go to Curtiss at CSW - or my local guy.

This will be your third set of springs? Sounds like you're trying to make that last 100 pounds disappear... I'm not sure you'll ever get there, but if your search is earnest, perhaps it's time for the phone call to Curtiss - California Suspension Works. I've never heard anyone with anything but high praise for his intuition, skills and value.

Cheers.


:)
 

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Discussion Starter · #4 ·
Ohlins Oil Level & Spacer Length

Liquid and ST,

Thanks for the input gents.

No, these will be the fourth set of springs. Stock '03, stock '04(+10%stiffer), RaceTech because I thought they would match their cartriges, and now, and I hope finally, the straight wound Ohlins.

The '04s where $30, so that was cheap help. The RT should of been the deal, but RT did not give our kit suitable attention. I mean really, they try to give everyone 37mm springs. My wrench had the forsight to get 40mm (their largest diameter), but those still click on compression. I'm sorry, $650 dollars and the system clicks. They need to get their head out of their ass.

I hope Ohlins (42.5mm x 281mm) will provide installation instructions as to spacer and oil level. But, I am not hopefull. The suppliers seem to generally not not give the FJR much thought. In the back of my mind there is the idea that they simply throw a kit from another bike that is close to what they think will work.

Back to the point. I read that straight wound springs compress at a constant rate. Our fork travel is 135mm. If the longer than stock Ohlins are used with the original spacer, they may run the risk of reaching full compression prematurely. I'm thinking a similar percentage of preload as found on the stock spring is all that is needed. Short of a recommendation from Ohlins, this will be my first attempt. The installed length of the '03 spring is 246mm, which is about 5% comprssion from free length of 261mm. It will be interesting to see if this results in proper rider sag of about 30-35mm. 281mm x .95 = 266.95mm. This would be a spacer measuring 130mm. as the stock was 149mm.

Liquid, Did Wilbers give a spacer and oil level recommendation? If you used the original spacer on a longer spring, that could explain the increased tension during the install.

Finally, Oil level is measured with the spring out. If a longer spring is installed, i.e. more volume, the level of oil with the spring installed will be higher in the tube and therefore affect action.

All a fair number of issues to sort through for an electrician. Thanks for your input.

In San Diego,
BAGSTR
 

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No indication on changing the spacer... oil level recommended at 100mm. No worries on the max compression, it won't get there.

The Wilbers springs setup and 7.5 wt fork oil DID work very well.

"All a fair number of issues to sort through for an electrician."

I hear ya brother... moreso for an advertising guy ;) but some advice from Curtiss could be definitely worth the phone call.



:)
 

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The length of the spring will not effect fluid displacement; the thickness of the coils and the number of coils submersed in the fluid will.

Some folks like to place progressively wound springs with the more widely spaced coils down, so not to effect oil levels too much. Linearly wound won't matter, as no difference in spacing between coil windings. If the spring rate is "stiffer", this is acheived by thicker wire, not longer spring. The total dispalcement effect is probably neglible for ST riding.

AFAIK, Linear spring compression is more predicatable, ie less initial/sudden dive, but they should not bottom out more than progressive, just compress more smoothly, ie what they make up for in initial dive is not lost on full compression. That's determined by the spring rate, which could be the same for either; therefore, spacer length might be less on linear, as less pre-load may be required to give desired dive.

I'm not a big fan of any pre-fixed sag figures. I don't like "across the board"/"one size fits all" solutions/problem solving. I dial my suspension in to my liking, so it's smooth and responsive at the bike's optimal level according to my style/preferences. The so called "proper" sags are for race bikes, for race track racing. I prefer "top 1/3" sag settings, which are relevant to the individual bike. Why set your frt sag at 32mms when you have 135mms of travel? 38-40 would be more like it IMO. I think a bike with that much travel available, is designed for a greater variety of road surfaces than a race track. Not enough pro-dive can be just as negative as too much. ST suspension is always a compromise IMO.

YMMV.
 

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I installed Ohlins front springs on my 04 that is now deceased. I picked the Ohlins springs because I had already installed an Ohlins rear shock and was very pleased with the improved suspension performance. I did pull the Ohlins springs out of the forks and dropped the stockers back in before it was sent to salvage. I can provide measurements if needed. Here is what I found out when I ordered mine.

The 04 FJR had two spring rates available. A .9 was available and the police version 1.0. After some discussion about riding style they (Traxxion Dynamics) suggested the 1.0 spring rate. The length was the same as the stock spring but was heavier when held side by side. Traxxion Dynamics said run 7 weight oil, 100 mm below top of fork with springs out and fully compressed.

The improvement was noticable but still required a good bit of preload to get sag correct.
 

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st ryder said:
The so called "proper" sags are for race bikes, for race track racing.
Not really. Sag settings are more about total control of the motorcycle, especially important in variable and potentially dangerous situations in traffic. Emergency braking maneuvers, alone, can be made or broken by a correctly or incorrectly tuned suspension.

As you suggest, 40mms is not unreasonable as a percentage of the total you listed... but a good suspension guy will suggest race sag (no, that doesn't mean 'going racing,' it means the sag with the geared up rider on the bike) as part of a ratio between free sag (bike unladen) and race sag. He's supposed to understand why he recommends the number, too. For one person that is good with suspension, I'd guess there are 99 that are completely clueless.

Theoretically you could get ANY spring to the desired race sag, but if the spring requires too much preload to get to the desired race sag... there'd be almost no free sag, resulting in an ill-handling machine. Conversely, if the springs are over-rated, the correct race sag would result in too large of free sag. This also changes handling. Only correct spring rate will allow recommended free sag, and race sag at the same time. ;)

Most tuners insist on straight rate springs in forks, because the progressiveness should really be controlled by oil level. The weight of the oil will change some of the characteristics of the dampening. I'm told it's better to have correct fork valving, than to be correcting harshness with lighter fluid. (though I didn't do that on the FJR)

I always used to think suspension stuff was window dressing, as long as you weren't bottoming the suspension... but measuring those millimeters really does make a huge difference... resulting in vastly improved handling and rider confidence in turns and over bumps.

:)
 

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@Liquid

Yes, I pretty much agree with much of your post, and what I was trying to say was that it seems to me that there's a "myth" developing "out there" about , (please refer to the part of my post your quoted) "so-called proper sag", which is said to be "X" amount of mm's, rather than an expression of an individual bike's travel. I was referring specifically to bagster's comments about his new spring/spacer arrangement:

"It will be interesting to see if this results in proper rider sag of about 30-35mm."

I'm sure bagster knows what he wants from his ride, and perhaps this is the proper sag for his style, body weight etc, but I hear this same, or very close to the same figure bandied about for just about every bike/rider combo out there, without contextualisation, and I'm of the opinion that this approach is not right though I do understand the value of having a "target" or "goal" sag when dialing in your suspenders.

IIRC, 30mm - 26mm frt sag is into the "race" or superbike settings, (according to Ohlins) and good for an R1, but, I'm wondering if this would make the ride unecessarily harsh on an FJR considering the girders you'd have to use to get it, FJR being a 600lbs bike. :shock:

Oh, BTW, I'm wondering if your suspension tuning buddies who refer to "race" sag as, (ahem) "rider" sag, use 30mms frt sag as a target. Sorry, but anybody who refers to rider sag as race sag and who then states it's not for racing, has about as much legitimacy as a young man, who when picking up his date and having a condom pac fall out of his jacket, explains to her father that it's a "masturbation condom", and not what it looks like. :lol:
 

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Discussion Starter · #10 ·
Sag

ST, Liquid et all,

30mm = 1.18"
35mm = 1.38"

My take on sag:
Static Sag = difference between fork position with no weight on wheel and bike weight on wheel.
Rider Sag = difference between static sag and sag with rider aboard

There should be some static sag, at least a 5mms
I want to use all the travel available during spirited riding. Tie wraps are a good method of checking travel used.
Springs merely establish a ride height, Valving controls dive and rebound.

RaceTech claims their valves provide firm control and plush action. They do this with several washers in the stack which deflect at different pressure points.

With 90kg springs, 5wt oil and rider weight of 180lbs, I'm using all the fork travel. In conjunction with the Wilbers shock, the suspension is excellent! Once I stop the spring from deflecting (clicking), my work will be done.

In San Diego,
BAGSTR
 

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st ryder said:
IIRC, 30mm - 26mm frt sag is into the "race" or superbike settings, (according to Ohlins) and good for an R1, but, I'm wondering if this would make the ride unecessarily harsh on an FJR considering the girders you'd have to use to get it, FJR being a 600lbs bike.
No. That's my point. The individual suspension designer should have a race sag assigned to the suspension he designs, whether it's a RoadKing or an RC211V, designed for the purposes the rider chooses. Harshness, generally, does NOT come from improper spring rate, but poor valving/settings.

Theoretically, a suspension designer could design a non-traditional, plush, sport-touring suspension model that was plush and proper... with 25mm of race sag, and if so, at 40mm, his model wouldn't work right.

Those little rings that go with bearings are also called races, it doesn't mean they're exclusively for racing. 'Race sag' is a term you'll see frequently in old motorcycle literature, as well... it's just the term I've heard most, among people that understand suspension setup. Perhaps they're not stigmatized by the word, "race." (It seems to me, the term is coined to remind - the number takes into account rider AND all of his gear, ready to ride... not simply just the rider's weight. Whatever. :roll:)

BAGSTR said:
With 90kg springs, 5wt oil and rider weight of 180lbs, I'm using all the fork travel. In conjunction with the Wilbers shock, the suspension is excellent! Once I stop the spring from deflecting (clicking), my work will be done.
It sounds like you have the combination you like, with regard to spring rate. Many folks I've talked to, and read from... don't subscribe to using the entire fork travel, unless you're encountering heavy bumps... but if it feels right...

Most suspension guys make most of their gravy on revalving. Stock suspensions often leave a lot of room for better valving which can result in more plushness, without losing feel.

:)
 

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"Theoretically, a suspension designer could design a non-traditional, plush, sport-touring suspension model that was plush and proper... with 25mm of race sag, and if so, at 40mm, his model wouldn't work right."

That would be a trick as it would top out after what? 35mms of rebound, so the travel would be fairly limited no? Plush equals lots of travel with both wheels on the ground regardless of weight, yes? If that 25mms race sag represented even the top 1/4 of travel, I can't see it being plush(?), but what do I know, right? :lol:

I guess we're getting our information from different sources, but a harsh as in stiff ride from what I understand could most certainly come from a too-stiff-for-the-bike/rider spring, regardless of valving/dampening, as a set-up can reach a point where one aspect overrides the other, ie a soft spring with improper dampening/fluid viscosity could also ride harshly, and a too stiff spring could make the ride harsh even with "soft" dampening.

Only time I've seen in print the term "race sag" was in a book called something like "Building Racing Motorcycles" written by a John somebody who I'm assuming is a pro, and it most definitly was used in the context of "race bike set-up." I didn't know it was also used in place of the more generic term for measuring sag with a fully clad rider.

I'm enjoying my set-up on my ST3, (took 2500 miles and 5 or 6 tweakings to get it right, new srpings and all) though it's outside the "recommedned"/"proper" sag , but feels spot on for me. I could only have arrived at the "right for me setting" by ignoring "recommended/proper" sags, and that was my simple point.
 

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"Race Sag"

... these guys all use the term as well, just for your edification ... :wink:

http://old.bemsee.net/tech/setup.html

http://www.racetech.com/SubMenu.asp?cMenu=4&c=Yes&cSubMenu=11&showPag#3

http://www.works-suspension.com/new_page_4.htm

http://cycledoctor.com/suspension101.htm

http://www.proracingsuspension.com/tips.shtml

http://inline4.motorrijden.nl/susp/susp1.htm

http://www.mx-tech.com/tuning_dtx.asp

http://www.faultlinesuspension.com/tipsshock.html

http://www.district5ama.org/techtips/proaction/sagtip.html

http://www.eric-gorr.com/techarticles/suspension_terminology.html

Oh, and NTNOA's Dean Baker, writing the following;

"Do not read too much into the word "race". Race sag does not strictly mean the correct sag for racing purposes. Rather, the terms "race" or "static" sag refer to the suspension travel achieved when the motorcycle is laden with rider(s), riding apparel, and any luggage and/or gear. Let me mention at this point that, depending on the source, these terms are not absolute and are sometimes interchanged. The term used is not as important as the concept."

quoted from here ---> http://www.ntnoa.org/suspension_preload.htm

Ooops, Max McAllister of Traxxion Dynamics, uses it, too.

quoted here ----> http://wiki.bcsportbikes.com/index.php?title=Suspension_101

Strangely, there are several writings that use the term "static sag" for laden sag, race sag, or rider sag... and some that use the term "static sag" as unladen, on the ground with no rider. They all seem to use the term "race sag" with only one meaning. Off-road suspension people seem to use the term, unanimously. (which indicates what part of motorcycling I came from)

Also, almost unanimously stated among suspension guys, spring rate should only be about maintaining a motorcycle's correct ride height for various situations. Harshness or wallowy-ness are not supposed to be a matter of spring rate, but dampening. You could be riding with extremely stiff springs, and have a very plush ride, but the ride height characteristics would probably be all wrong.

California Suspension Works and Traxxion Dynamics may not agree on everything, but there is much to be learned from their insights, even if you're flopping around the asphalt on a Dyna LoRider XYZPDQ.

:)
 

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Hey, thanks for all those links. Winter's here and they will make for good reading. I agree with much if not most of what you're saying, like I said before, and agree spring rate/sag is for ride height, (primarily) and a race bike needs much less sag than a touring bike so it won't grind hard bits when cornering due to higher centrifigal forces at work.

I'll peruse those above links in the hope of reading something new, but as far as I'm concerned, sag should always be a proportion of travel specific to the bike, not an across the board # expressed in mm's or inches that is sought after like some holy grail to the possible detriment of comfort and safety.

I appreciate that there are a variety of different terms to describe what's derived the same way, the laden/rider/race etc sag, however, and here's my simple point, if a term *can* be confused, with another term, avoid using it when possible. There are some suspension tuners who differentiate between a *race* sag, for the track, and a *street* sag.

I didn't see this one on your list, but here's an example of what I mean.

http://www.ansusa.com/SuspensionGuide.htm

OTOH, here is a link to that constructor's guide to building a motorcycle I mentioned above, and if you go to the sample sections for volume 1, you will see the author referes to laden, not race oddly enough, sag in the suspension preview. :shock:

http://www.eurospares.com/samplepages/index.htm

Speaking of books on sportbike tuning, IIRC Kevin Cameron not once mentions a specific sag # in his Performance Tuning for Sportbike book, but refers to 1/4 1/3 of travel for track and street respectively. So, in the end I guess it's a more a matter of preference rather than correctness if even experts use different terms, but I, a non-expert, try use terms which are les likely to get confused, if you can belive that. :lol:

Tuning the suspenders on a Harley FXDL is very easy. When the going gets tough, twist the loud handle and loose the bi&^%!! :D
 

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I've never heard of Mr. Hodges, and I've never heard anyone use the term race sag versus street sag as he has.

Ya learn something new everyday? :?

I'm now going to walk away from this riveting discussion over one word, with a minimum of belly sag. Surely, you must know that's not strictly a racing term. :wink:

st ryder said:
Tuning the suspenders on a Harley FXDL is very easy. When the going gets tough, twist the loud handle and loose the bi&^%!! :D
I'll leave that field of expertise to you. :p 8)

As it's written on another board you and I often frequent:
Harley-Davidson: The most efficient way to convert gasoline into noise without the adverse side effect of horsepower.

Hee hee. :lol:

:)
 

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Discussion Starter · #16 ·
Race Tech Recommends:

15-35mm (.59-1.3mm) of spring compression.

With the forks fully extended, and the top of the springs level with the top of the tubes, the distance of the cap threads would be equal to spring preload.

In San Diego,
BAGSTR
 

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Discussion Starter · #17 ·
Ohlins Fork Springs

Finally received the springs after 4 weeks wait. They were out of stock in Conneticut and had to come from Sweden during the holidays.

Length was almost exactly that of Yam stock. Ohlins=263mm, stock =261mm. So, I was able to use the stock spacer. They are dot 90 kg/mm.

The outside diameter is 42.5mm, and they do not click on compression as the 40mm RaceTech.

The action is excellent at speed with the RT cartriges. Well balanced with the dot 90kg/mm Wilbers springs and my 180lb weight.

Well then, the suspension is complete. Anyone want a pair of RaceTech springs?

BAGSTR
 

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Liquidsilver said:
Most tuners insist on straight rate springs in forks, because the progressiveness should really be controlled by oil level. The weight of the oil will change some of the characteristics of the dampening. I'm told it's better to have correct fork valving, than to be correcting harshness with lighter fluid. (though I didn't do that on the FJR)
Actually, most tuners are racetrack tuners that also do 'normal' customers. On the track progressive springs are a pita to correctly calculate an optimum setup. On the road however, they provide a wider compromise between the ever changing road conditions, speed and style of the rider.
 
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