COFSTA

I can't get my head around this concept so one of you guys who know more than I edumacate me.

Today I found that my RT handles *way* better in the "2-riders" preload setting (than the rider plus luggage) but its quite a harsh ride, since theres only one rider plus I don't even ride with the sidecases--so I guess its operating in the upper extreme of the shock travel....maybe always very close to "topping out"? (is there such a thing?) I'm not sure if the handling is so much better because the suspension is so taught or if its because the front rake angle is decreased by jacking it up like this. Maybe its both--but that harsh ride is bone-jarring when I hit a bump.

So my question is this: am I getting the same results from cranking up the preload as I would from replacing the spring with a higher rate to produce the same amount of sag as cranking the preload? Or would the ride be plusher/less harsher with a new spring as opposed to using extra preload? If so, why? If not, why?

Though people sometimes use preload instead of getting a spring with the proper rate it's not the same thing.

What you do is set preload for correct front and rear sag at your typical riding weight with gear and whatever you usually carry. That's your baseline then you can increase preload for heavier loads. Many bikes are sold undersprung so if you're having to dial in excessive preload for correct sag then you need heavier springs.

Once you get the springs sorted out then you can make the ride more or less sporty with compression and rebound adjustment. I like tight settings because I can't stand for the bike to wallow and while it locks into curves like a champ it's too harsh for some. Ferinstance, Brick has his FJ-09 set up softer because he likes it smooth and is a BIG PUSSY!!

LeeDavis wrote:Though people sometimes use preload instead of getting a spring with the proper rate it's not the same thing.

OK, thats the whole premise of my question--WHY isn't it the same thing if the end result is the same? It raises the ride height and firms up the ride?

Thats the part I'm trying to get my head around.

Spring rate is usually measured at Kg/mm - X number of Kg will compress the spring by 1 mm. If you add preload you change the initial weight required to further compress the spring but you're not changing the spring's rate. If it was bottoming out because it's rate was too low, it'll still bottom out. You haven't done anything to change that.

Bob wrote:

LeeDavis wrote:Though people sometimes use preload instead of getting a spring with the proper rate it's not the same thing.

OK, thats the whole premise of my question--WHY isn't it the same thing if the end result is the same? It raises the ride height and firms up the ride?

Thats the part I'm trying to get my head around.

Hey I resemble that!


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Bob wrote:I can't get my head around this concept so one of you guys who know more than I edumacate me.

Today I found that my RT handles *way* better in the "2-riders" preload setting (than the rider plus luggage) but its quite a harsh ride, since theres only one rider plus I don't even ride with the sidecases--so I guess its operating in the upper extreme of the shock travel....maybe always very close to "topping out"? (is there such a thing?) I'm not sure if the handling is so much better because the suspension is so taught or if its because the front rake angle is decreased by jacking it up like this. Maybe its both--but that harsh ride is bone-jarring when I hit a bump.

So my question is this: am I getting the same results from cranking up the preload as I would from replacing the spring with a higher rate to produce the same amount of sag as cranking the preload? Or would the ride be plusher/less harsher with a new spring as opposed to using extra preload? If so, why? If not, why?

Suspension shouldn't really be hard or soft. The tires should track the ground imperfections while maintaining consistent pressure on the contact patch to optimize grip. It may also "feel" harsh if you have a death grip on the bars. You may also want to lower tire pressures a tad. You will probably get more out of a few track days with coaching for improved technique (the best part to change is the nut behind the wheel). As already discussed, I would imagine the 2 riders setting jacks preload in the rear, which probably increases your ride height in the rear (to adjust to the passenger you don't carry). This will sharpen your rake and trail so it probably turns in more quickly. To discuss BMW ESA in more detail would be akin to contemplating the latest NASA space shuttle's electronics. The system is not designed to be end user modified... I know people do modify it, but it's probably not worth it. For that matter, all good suspension discussions end with "Ohlins."

007 wrote: Suspension shouldn't really be hard or soft. The tires should track the ground imperfections while maintaining consistent pressure on the contact patch to optimize grip. It may also "feel" harsh if you have a death grip on the bars. You may also want to lower tire pressures a tad. You will probably get more out of a few track days with coaching for improved technique (the best part to change is the nut behind the wheel). As already discussed, I would imagine the 2 riders setting jacks preload in the rear, which probably increases your ride height in the rear (to adjust to the passenger you don't carry). This will sharpen your rake and trail so it probably turns in more quickly. To discuss BMW ESA in more detail would be akin to contemplating the latest NASA space shuttle's electronics. The system is not designed to be end user modified... I know people do modify it, but it's probably not worth it. For that matter, all good suspension discussions end with "Ohlins."

Thanks for your input. After thinking more about this, I think that increasing the preload creates a harsher ride than would a new spring of the correct weight because (as Jeff once pointed out to me) there is no such thing as a linear rate spring---every spring made is "progressive" to a degree since the the "rate" increases as it is compressed---so compressing the spring using preload is using up that initial softer compression and putting me into the tighter-harder range for the spring. Gonna check with Ohlins about a spring swap, just gotta determine what rate to go with. I want the ride height to be the same as it is in the 2-up mode now, when its in the 1-up mode with a new spring.

I'm looking at Wilbers so I can keep the ESA functionality. Ted Ports Beemershop unless y'all know a local dealer.

Marc K wrote:I'm looking at Wilbers so I can keep the ESA functionality. Ted Ports Beemershop unless y'all know a local dealer.

Ted Porter has a great reputation. There are some others closer than him but dunno if they have an ESA compatible shock. I think Touratech has one, not sure who else. Or you could do as many other Hexhead/Camhead owners have done, switch to a good non-ESA shock like Ohlins or one of the others. Since yours doesn't have the "dynamic ESA" the only loss is the push-button change of preload settings and damping settings. I did this on an '07 RT and once I had the standard Ohlins dialed in, never felt the need to touch the rebound damping setting.

Lots of $$$ to be saved by unplugging the ESA ! Whenever you sell or trade the bike, you can reinstall the OEM ESA unit and hang onto (or sell) the new(er) shock.

I like the current ESA choices. The change in rebound/damping make a big difference in what riding I'm doing specifically when I'm 2 up. "Soft" is way to soft except for even interstates. The bike just bounces along. "Normal" is good for around town and "Sport" is really good when pushing it. With 2 up I run in sport mode all the time. I test rode an RT at Eurosport with ESA Wilbers front and rear - what a difference ! I would have the set up the non-esa shock with a one up design and would suffer somewhat in 2 up.

Marc K wrote:I like the current ESA choices. The change in rebound/damping make a big difference in what riding I'm doing specifically when I'm 2 up. "Soft" is way to soft except for even interstates. The bike just bounces along. "Normal" is good for around town and "Sport" is really good when pushing it. With 2 up I run in sport mode all the time. I test rode an RT at Eurosport with ESA Wilbers front and rear - what a difference ! I would have the set up the non-esa shock with a one up design and would suffer somewhat in 2 up.

No doubt that Wilbers ESA is the cats pajamas. Where the hell did that saying come from?

But if you go to BMWST.com there are lots of older threads re. unplugging the ESA for a standard Ohlins/etc and the general consensus is that once you get it dialed in all those Soft-Normal-Hard settings are a joke, just marketing hype from BMW. That the "optimal" damping setting will be plush, compliant, yet firm, without the need to change it on the fly. That was also my experience on my '07 RT. YMMV. But the ability to change pre-load with a button is still nice if you go from 1-up to 2-up often. I never needed that.

Edit: and to be honest I rarely change the damping on my '17 RT, it stays in the middle range mostly---as you said, SOFT is too bouncy for really ANYTHING. And HARD is usually overkill.

Edit 2: BTW I'm not trying to talk you into cheaping out on this, just offering some alternative thinking re. the RT's/etc .

Bob wrote:
those Soft-Normal-Hard settings are a joke, just marketing hype from BMW.

I'm perplexed by the money spent on BMW hype followed by cheaping out on suspension "upgrades." Leave it to BMW to over-engineer a bad idea to an obsessive degree of perfection and then charge more for it. I learned the hard way, myself. I stopped drinking the Kool Aid after disconnecting the non-serviceable ESA on my K1200S in exchange for Ohlins. Even still, the Telelever took away feel from the front end.

Spend about $2K on the good stuff and pay an expert to set it up to get you in the ballpark (at least set your sag with fairly neutral rebound and compression settings). You won't be disappointed and will refuse to go back to poorly designed or old parts! There's a reason I own a$5K my bike with $2300 suspension. Not for everyone, but it's way more fun around a corner than a $10K bike with stock suspension. Even worse: a used $10K bike with lots of miles on the suspension.

Suspension is undoubtedly the most important part of the motorcycle other than good tires, which are the least expensive way to upgrade cornering (even more baffling is cheaping out on tires). You can't fight physics around a corner...

Leave it to BMW to over-engineer a bad idea to an obsessive degree of perfection and then charge more for it.

Hah--thats a good one Steve, pretty damn accurate too, when I think about some of the "innovations" from them over the years. But I'd disagree with you about the tele-lever front end. You either like it or hate it--and I like it's anti-dive properties. Plus the bike doesn't want to stand right up when braking while leaned over (yeah I know, don't do that). So it has some nice features to compensate for a "lack of feel". And it sure is easier to replace a shock than rebuild conventional forks.

Bob wrote:

Leave it to BMW to over-engineer a bad idea to an obsessive degree of perfection and then charge more for it.

Hah--thats a good one Steve, pretty damn accurate too, when I think about some of the "innovations" from them over the years. But I'd disagree with you about the tele-lever front end. You either like it or hate it--and I like it's anti-dive properties. Plus the bike doesn't want to stand right up when braking while leaned over (yeah I know, don't do that). So it has some nice features to compensate for a "lack of feel". And it sure is easier to replace a shock than rebuild conventional forks.

I can't say I hate it overall. As a touring set-up, it is no doubt a much more efficient setup to manage with just replacing a shock, and they have no doubt refined the Telelever ad nauseam. The numb feeling serves to isolate the rider from the harsh road conditions that make a touring rider weary. In that regard it is very well done as it was designed for that purpose. However, all of the characteristics you mention for suspension (good and bad) are managed with properly set up forks, including anti-dive. Don't drink the Kool Aid!

When moving to an emphasis of sport riding, you will find that a touring Telelever setup will only be so good. A conversion van with Ohlins suspension will certainly handle the curves much better than one without. Sublime even, by conversion van standards, but good luck chasing my Cogent Dynamics CB500X up or down the mountain. While no one here is expected to reach MotoGP level lean angles on the street (or track) at any time, it is very nice to have a similar margin of safety built into the design of the bike to go beyond the technical skill of the rider. Numerous fork alternatives have been tried and failed in racing and that is really all that needs to be said. I'll be glad to switch when a new design is more competitive.

Whether or not I drink the koolaid is my choice. I think I have plenty of suspension experience dating all the way back when we ran the Greensboro shop TZ350 in club racing at VIR in the late '70s. I have been able to take a stock bike, like my R1, and set up a suspension just fine using damping/rebound settings, oil weight, raising or lower the triple crown and tire pressure. I'm not looking for a race bike for the street. What I'm looking for is a shock system that will retain the versatility of the RT. By the way the ESA OEM shocks are rebuildable look at EPM Performance Imports. My 2cents and I'm done.

You may also want to lower tire pressures a tad.

Something I've never tried on the street--is this for better traction or a more supple ride? How much do you lower yours?

Bob wrote:

You may also want to lower tire pressures a tad.

Something I've never tried on the street--is this for better traction or a more supple ride? How much do you lower yours?

Depends on the bike, tires, suspension setup, and feel. Usually 33/38 to 32/36 on the T30 EVOs or S21s. I usually run a couple pounds lower pressure in cold temperature to help them warm up a bit faster. The lower overall speed limits overheating. I didn't like lower pressures on PR4s because the side walls are flimsy with hard rubber and they felt unstable so I ran 34/40 on the VFR this Fall. The weight of the bike may have played a factor. I was on 32/36 on S21s on the VFR this Summer at the Snake because they handled the heat well. S21s are just mental on the CB500X. Nobody should go that fast.

Good simple article on BMW suspension setup http://www.eilenberger.net/Suspension/suspension.htm

Thanks, thats helpful, I'll be measuring my sag today and sending the numbers to Ted Porter to analyze. Looks like the rear shock on my RT is way more complex than I ever imagined. For preload, it has an internal "elastomer" that provides the soft setting, and some kind of metal cup that moves to firm that elastomer up to provide the medium setting, and then for 2-rider setting it cuts the elastomer out and goes straight to a 450 lb spring in one big jump, thats why the 2-rider setting is so damn harsh. Ted says the shock was designed for a touring bike and does a great job when switching between 1-rider and 2-riders, but doesn't have the abilty to fine tune the preload because of the design. He is going to try adding some shims to increase the "initial preload" and get the rear up some.

Hmm... in BMW talk I assume that The T in RT stands for Touring. Right?
Seems you got just what you bought. I wonder how the RS would be in comparison?




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Brick wrote:Hmm... in BMW talk I assume that The T in RT stands for Touring. Right?
Seems you got just what you bought. I wonder how the RS would be in comparison?
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RS is even sportier riding position which is worse for my aching neck/shoulders/etc. The OEM spring has just settled a little, combined with it being undersprung right from the factory of course. I can definitely feel the difference after 6K miles, it handled better when brand new.

Bob wrote:

Brick wrote:Hmm... in BMW talk I assume that The T in RT stands for Touring. Right?
Seems you got just what you bought. I wonder how the RS would be in comparison?
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RS is even sportier riding position which is worse for my aching neck/shoulders/etc. The OEM spring has just settled a little, combined with it being undersprung right from the factory of course. I can definitely feel the difference after 6K miles, it handled better when brand new.

You do realize it's easier to find a light, good handling bike and make it more comfortable than try to make a tourer into a sportbike. Right? Even if it feels right and you get it moving quickly at lean, you're playing with fire where the rubber meets the road. I've considered buying the SV650 and making it into a sport tourer.

007 wrote:You do realize it's easier to find a light, good handling bike and make it more comfortable than try to make a tourer into a sportbike.....I've considered buying the SV650 and making it into a sport tourer.

Wait--you just said I shouldn't try to turn a sport-tourer into a sport bike and now you're wanting to turn a sport bike into a sport-tourer??

You do realize its easier to find a dedicated sport-touring bike than hanging a bunch of weight all over a light little SV650 sport bike and flirting with catastrophe. Right?

But seriously, I don't want a sport bike, I just want my RT to handle as well now as it did when it was new. Thats all.

Yea I knew the riding position was more aggressive on the RS. BMW offers lots of options too bad they don’t allow the RT with the RS suspense. [SMILING FACE WITH SMILING EYES]


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The other issue with expensive suspension is that it needs to be refreshed often. You buy Ohlins and the service interval is ridiculous depending on how much abuse it is going to take. You may not be happy with it after 10K miles and probably hate it after 20K.

007 wrote:The other issue with expensive suspension is that it needs to be refreshed often. You buy Ohlins and the service interval is ridiculous depending on how much abuse it is going to take. You may not be happy with it after 10K miles and probably hate it after 20K.

Any shock's performance is going to decrease with use, thats not confined to Ohlins or any other "high-end" solutions, but at least those are re-buildable, as opposed to the oem's which are disposable. Plus, the Ohlins recommended rebuild interval is just that----a recommendation. The Ohins on my old RT and 2010 GS were still doing well at 20K miles, damping had decreased some but turning the rebound screw a little further compensated. Of course at some point the fluid has lost viscosity and needs to be replaced. But that point varies depending on riding style.