Rear Spring Pre-load and loaded bike

[~TABASCO~]

We just installed new springs / oil in a customers bike not to long ago, he likes it...... I needed something a bit stiffer for the Colorado Mt passes..... ::008::

 

[Dallara]

I understand what your saying however my reference really was that Versys is designed as a sport bike not a touring bike but the S10 is designed to be a touring bike which implies loading it with gear. One would think that the bike designed for the load would handle better when loaded than one that doesn't. Obviously that's not the case,

I'll also add the suspension never bottomed out...so it wasn't over taxed and beleive me the roads around here can bottom out a suspension. My only real complaint was the low speed handling...turning off the road to parking lot...that kinda thing...didn't feel that stable.

I can certainly see your point, but again, let's not forget a couple of relative points... Like factory claimed weights (without side cases or gear):

Kawasaki Versys - 454.2 lbs

Yamaha Super Tenere - 575 lbs

That's a whopping 120.8 lbs difference, or over 21% heavier.

Then there's that wheelbase difference again of literally 5 inches (60.6 - 55.7 = 4.9"), or over 8%. Longer is more stable at speed, but harder to turn at low speeds.

Another important difference is the ground clearance of each bike, which is fairly indicative of how high off the ground their engines (the bike's heaviest single component) are... The Versys has 7.1 inches between the ground an it's underslung engine, while the big Yamaha has 8.7 inches of clearance for its similarly mounted motor. That's a difference of 1.6", or 18%. The Yamaha also carries one more gallon of fuel (6.0 gallons vs 5.0). Since gasoline weighs about 6 lbs per gallon you are potentially carrying another 6 lbs high up on the motorcycle some of the time when you turning into the parking lot.

Last but not least there is the steering geometry of each bike... The Kawasaki Versys has a rake of 25 degrees with 4.3 inches of trail. For the Yamaha the measurements are 28 degrees with trail of 4.96 inches. More rake and trail means slower, more ponderous steering, especially at low, parking lot speeds... and the Yamaha has 11% more rake and over 14% more trail.

So, here we have a bike that weighs 21% more, has an 8% longer wheelbase, has it's heaviest lump of metal 18% higher off the ground, has 11% more rake and 14% more trail...

It's no real surprise that it's going to handle a bit more ponderously at low speeds... Actually it should handle about 14.4% slower and more ponderously at low speeds if you run the numbers. That's a fairly significant amount, but that's the trade-off for more power, more stability, more off-road ground clearance, more wheel travel, more load capacity, more ergonomic room, etc.

Just FYI...

Dallara



~

 

[avc8130]

Spacer by Jaxon $65
Eibach 1000lb spring $65

If you're in the super heavy weight category, this setup works and is relatively inexpensive. So far I'm very happy as I went from max preload on a normal basis to 5 clicks with the new spring. I don't get flashed at night by oncoming traffic like I used to either. ::012:: I'm just starting non paved roads, so I don't require a full custom setup like some of the pilots do here.

Once again, I can't in good conscience recommend swapping a spring onto the already under-damped stock shock that is 67% stiffer than the stock rate.

1000lb is a crazy rate on a Tenere. Even the largest guys with the heaviest loads I have helped spring have never gotten a rate that stiff.

ac

 

[Rasher]

I never go mad on springs, I have followed Wilburs advice on last two bikes, this was a custom spec based on my (and the Mrs) weight, the amount of two-up work the bike does and our typical luggage load when touring.

On my GS it went from a 140 to a 150 (I don't understand these lb measurements y'all use ) and the Tenere is claimed at 137, and I now have a 150, in both cases an increase around the 10% mark, and in both cases two-up riding was transformed, whilst not ruining the compliant solo ride....

...probably helped by a much better quality shock with far better damping characteristics, and better adjustability (3-way damping adjustment)

When adjusting springing the damping should also be adjusted to match, and I think this will give a problem if just throwing a much bigger spring onto the OE shock, I believe the theory goes that the heavier spring will move less and therefore need heavier oil / stiffer damping (shim stack adjustment) - I believe damping works in a non linear fashion with the faster / greater movement of a softer spring amplifying the damping effect

I would have thought a much stiffer spring on the OE shock would maybe solve one problem and cause another.

 

[ejy712]

Also, I believe you'll need a spacer in the rear shock if you go with a Eibach or Hyperpro aftermarket spring. Call Jaxon and he can get you that spacer for $65.

The Hyperpro spring is a direct replacement. It is the same length as the OEM spring. It does not require a spacer...

 

[offcamber]

1000lb spring does seem a bit over kill for my situation.....I weigh in at 230lbs...not a lite weight but not a feather weight either....yeah I could lose a few pounds.

I guess what I really need to do is weigh all the gear and realy see what I'm dealing with. As I said it wasn't horrible. I could ride and maneuver just fine but I felt the weight in the corners. I guess I just notice it more on this bike than the Versys but that probably has to do with all the math Dallara was going on about....

Swapping in a $65 spring may be the short term easy solution and I'm not out that much cash if I don't like it....For the short term I'm just going to adjust my load and see if that helps.

 

[avc8130]

1000lb spring does seem a bit over kill for my situation.....I weigh in at 230lbs...not a lite weight but not a feather weight either....yeah I could lose a few pounds.

I guess what I really need to do is weigh all the gear and realy see what I'm dealing with. As I said it wasn't horrible. I could ride and maneuver just fine but I felt the weight in the corners. I guess I just notice it more on this bike than the Versys but that probably has to do with all the math Dallara was going on about....

Swapping in a $65 spring may be the short term easy solution and I'm not out that much cash if I don't like it....For the short term I'm just going to adjust my load and see if that helps.

Weigh your load and take the sag measurements. Without data the only thing we can say is "you need more spring". "How much" is impossible to determine without accurate data.


ac

 

[mcrider007]

When adjusting springing the damping should also be adjusted to match, and I think this will give a problem if just throwing a much bigger spring onto the OE shock, I believe the theory goes that the heavier spring will move less and therefore need heavier oil / stiffer damping (shim stack adjustment) - I believe damping works in a non linear fashion with the faster / greater movement of a softer spring amplifying the damping effect

I would have thought a much stiffer spring on the OE shock would maybe solve one problem and cause another.

The general rule of thumb is that if you have correct damping for a given spring and go to a heavier spring then you need more rebound damping and less compression damping. The standard configuration for a emulsion shock like the Tenere OEM shock is that a common valve is used to meter oil to both the compression and rebound damping shim stacks. The adjustment is called a rebound damping adjustment because rebound is considered to be more important but the adjustment actually increases/decreases the oil flow to both circuits. The damping change is always going to be in the same direction for both circuits and that is the problem when changing springs, especially when going to a heavier spring on the Tenere shock where the compression damping seems to be too strong to begin with. If independent adjustments were available if might be possible to have the correct damping on a heavier spring but the most likely outcome on the Tenere is less sag but a much stiffer ride.

 

[sumo64c]

Once again, I can't in good conscience recommend swapping a spring onto the already under-damped stock shock that is 67% stiffer than the stock rate.

1000lb is a crazy rate on a Tenere. Even the largest guys with the heaviest loads I have helped spring have never gotten a rate that stiff.

ac

It may be crazy, but it works fantastic for me on the road. When I start with the serious offroading, a full suspension upgrade will take me there.

 

[avc8130]

It may be crazy, but it works fantastic for me on the road. When I start with the serious offroading, a full suspension upgrade will take me there.

I think you'll be pleasantly amazed at how much better the rear of the bike works with a proper spring rate.

The reason you need such a stiff spring on the OEM shock is because the spacers guys are selling aren't long enough to get the extra SPRING preload you need to make a proper rate work on the OEM shock.

The problem with the OEM hydraulic adjuster is that its range of adjustment is actually quite small. Most aftermarket hydraulic units still have threaded bodies that let the tuners adjust the coarse starting point of the adjuster, then the hydraulic takes over from there. The stock shock has a fixed adjuster and the limited range doesn't let you get a proper preload on the spring to make a proper rate work.

ac

 

[Boondocker]

My wife and I ride 2-up with camping gear, which puts us pretty close to max GVWR. I've dialed up the dampening a couple of clicks from center and max the rear spring preload when luggaged up. No matter how great the suspension or tires, we're still pushing nearly 1000 lbs. We've ridden all over our neighborhood - southern Utah, southern Nevada, southern California, and central Sierras, just happy as clams that the bike goes down the highway, through the twisties, and over the dirt roads feeling comfortable and secure.

Thank goodness I don't know how good it could be, not that my numb butt could discern the improvement. Maybe the Ténéré just seems good because we rented an Electra Glide last year for a trip to Zion, NP. So please don't tell my wife that custom suspension would make the ride so much better or she will surely insist I pony up some large coin for it. I did have Go-Race rebuild my WR250R suspension for me, and it's good.

Nevertheless, we're going to enjoy the ride to the Colorado Gathering on a relatively stock bike (excepting the seats and tires), camping in some famous National Parks on the way. Maybe we'll wear out the OEM suspension, then even I can justify upgrading it. nudge, nudge, wink, wink

 

[Mzee]

Oh man! That's a serious load.

You probably don't want to hear it, but your stock suspension really can't handle that too well.

You know the rear is at full preload when the indicator points to the max line. That's all she's got. The stock spring rate is ~675...you need ~850.

ac

I don't think it is fair to say your bike cannot handle that load just from looking. It would be appropriate to know the actual weight of the load.

 

[avc8130]

mzee

just knowing he is 230 I can tell it would do better with a stiffer spring

ac

 

[Rasher]

The general rule of thumb is that if you have correct damping for a given spring and go to a heavier spring then you need more rebound damping and less compression damping. The standard configuration for a emulsion shock like the Tenere OEM shock is that a common valve is used to meter oil to both the compression and rebound damping shim stacks. The adjustment is called a rebound damping adjustment because rebound is considered to be more important but the adjustment actually increases/decreases the oil flow to both circuits. The damping change is always going to be in the same direction for both circuits and that is the problem when changing springs, especially when going to a heavier spring on the Tenere shock where the compression damping seems to be too strong to begin with. If independent adjustments were available if might be possible to have the correct damping on a heavier spring but the most likely outcome on the Tenere is less sag but a much stiffer ride.

Thanks, what I was alluding to in a clear and concise manner ::008::

Also a reason why I always buy aftermarket shocks with indpendant adjustment, the 100kg of Mrs + Luggage adds plenty of rebound damping, I need to control the spring on the way down, I have found on both sport and ADV bikes being able to pile on compression independently gives great results.

Most aftermarket hydraulic units still have threaded bodies that let the tuners adjust the coarse starting point of the adjuster,

My Wilburs sits about perfect with zero pre-load wound on, it then has a much bigger range than the OE adjuster, as well as being able to independantly control rebound and both Hi and Lo speed compression, works well across a huge range of loads, roads and riding styles, I think for anyone who regularly switches from solo to two-up the botom line is a good replacement shock is the only thing likely to get great results.

For those who maybe just need to shed "a pound or two" a slightly stiffer spring would probably help a lot.

 

[viewdvb]

I'll dispute that it needs a different spring. I ride two up with fully packed luggage though no camping gear. I guarantee that my all up load exceeds yours. It worked well enough on the max pre-load and never bottomed. Ok, steering is not as good as unloaded but you wouldn't expect it to be. I can still use all the rear tyre and throw it about in the mountains. Just to be safe, I made a spring spacer from 5mm alloy plate (cut out with a powered jig-saw) which gives even more preload on the hydraulic adjuster max and cost almost nothing. I'm weird. I quite like the stock damper which gives a very comfortable ride so that's my solution. In any case, I have a very British aversion to spending unnecessary cash that could be better used for travelling.

 

[Rasher]

I'll dispute that it needs a different spring. ...It worked well enough on the max pre-load and never bottomed. Ok, steering is not as good as unloaded but you wouldn't expect it to be..... I quite like the stock damper which gives a very comfortable ride so that's my solution. In any case, I have a very British aversion to spending unnecessary cash that could be better used for travelling.

I suppose it depends how you define the term "Needs", most suspension experts (if not all) would describe it as softly sprung for solo use.

I think if you rode my bike two up you would find the difference quite staggering, I am sure you would go a fair bit quicker, find the ride far more controlled, and probably more comfortable / less tiring over distance.

I would not describe mine as "working well enough" it works beautifully, and the steering is much sharper than it was two up on the OE shock and ground clearance is definately better (I no longer drag my foot on every corner). My point is the difference between solo and two-up performance has been massively narrowed to the point I do not really need to do anything differently when two up (where before I needed to be more gentle on the gas, lean over less etc)

Like many mods, it is not a case of if it "needs" it, as in it point blank refuses to work without it (like the bike "Needs" fuel) but the difference is quite considerable - but working out if it is "worth it" is impossible, as without doing the work you would never know, what you will find is nobody who has modifed the suspension has ever been anything other than 100% happy with the ROI.

Of course if your happy enough the money you have saved will probably net you about 3,500 miles worth of fuel / tyres / servicing ::008::

 

[Mzee]

mzee

just knowing he is 230 I can tell it would do better with a stiffer spring

ac

;D ;D ;D