preload/tire pressure advice - Stromtrooper Forum : Suzuki V-Strom Motorcycle Forums
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post #1 of 17 Old 04-23-2013, 09:40 PM Thread Starter
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preload/tire pressure advice

Hi guys,

I just got new Shinko 705s installed on my Wee strom. I am at least 200 pounds with gear, and I have 2 rather heavy hardcases on the sides.

Since I'm newb, I was wondering if you guys could give me advice?

After a lot of googling I have right now:

35 Psi front, 38 Psi rear

front preload at 3, rear preload at 5 (max). I recently got my fork oil replaced and am not sure what type of fork oil was put in.

Are these settings about right? How would I change them if I would ride 2-up with my much lighter wife?

Thanks a bunch.

R
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post #2 of 17 Old 04-23-2013, 09:56 PM
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Tire pressure is a rider's choice. Something between the sticker on the bike and the number on the tire is the range to test. Preload is best set so that the suspension settles about 40mm from full extension at each end with you and the luggage. The Science and Black Magic of Suspension Setup

Pat- 2007 DL650A was ridden to all 48 contiguous states. I didn't quite make it to 17,000 miles on the 2012 DL650A.
Nicknames I use to lessen typing, Vee = 2002-2012 DL1000s. Vee2=2014-2016 DL1000s. Wee = 2004-2011 DL650s. Glee = 2012-2016 DL650s
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post #3 of 17 Old 04-23-2013, 09:58 PM
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Just be careful cutting off the zip tie... I sliced my fingers open last week

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post #4 of 17 Old 04-24-2013, 09:40 PM Thread Starter
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Well, I tried to do the zip tie method, but not sure I did it correctly. I put the bike on the side-stand, zip tie as close as possible to the fork seal. Then I carefully sat on it with feet off the ground for a moment. Back on side-stand. The movement of the zip tie was about 16mm. If I try to lift up the front wheel a few more mm appear for say a total of 20mm. I guess the sentence I don't get is:

"- Measure how much the front suspension is compressed. The difference between available travel (exposed length, L2) and the total travel (L1) is your sag."

The difference between 160 and 20 is 140, not even close to 40-53mm.. I must be doing something wrong.
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post #5 of 17 Old 04-24-2013, 10:00 PM
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Lift the front to get it to full extension first before running the zip tie down to the fork seal. If the bike is sitting there on the wheels and side stand, the front is being compressed some by the weight of the bike.

Pat- 2007 DL650A was ridden to all 48 contiguous states. I didn't quite make it to 17,000 miles on the 2012 DL650A.
Nicknames I use to lessen typing, Vee = 2002-2012 DL1000s. Vee2=2014-2016 DL1000s. Wee = 2004-2011 DL650s. Glee = 2012-2016 DL650s
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post #6 of 17 Old 04-24-2013, 10:12 PM
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tire pressure

I have run a number of 705 and have had good luck with 34 front and 38 back, I weigh around 200 with gear and have large side cases. To get the proper sag on my bike I have rear 1 click from max and 1 1/2 lines showing on front.

The real truth of the matter is that V-Stroms are like orange popsicles ... kind of generic and unexciting, but on a nice warm day - everybody loves them
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post #7 of 17 Old 04-25-2013, 11:09 AM
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Quote:
Originally Posted by culturedape View Post
Hi guys,

front preload at 3, rear preload at 5 (max). I recently got my fork oil replaced and am not sure what type of fork oil was put in.

Are these settings about right? How would I change them if I would ride 2-up with my much lighter wife?

Thanks a bunch.

R
You want your preload sag to be 30-35% of your total travel. The setting number or number of clicks is less important than the right measurement.

The zip-tie method is fine if you're very careful. Often times when mounting the bike, the bike will go down beyond normal preload and come back up. You can see this behavior by simply bouncing on your bike. Anyway, having a helper lift the bike up to the top of the suspension travel (one end at a time, of course) then letting it settle back down slowly might give you a better measurement.

You might also need to factor in "stiction"; we won't get into that here, but if you grab the Total Control book by Lee Parks, he has a very good and detailed chapter on sag and initial suspension setup.

I'm assuming your total travel is 6.3" at each wheel (let's do metric - it's easier ) or 160mm.

Let's go with a nice even number of 33% for preload, or 53mm (rounded).

So you want to tune your preload so you have about 50-55mm of sag when mounted and geared up. Don't include luggage (filled), but do include the luggage cases (empty) if that's how you normally ride around. You can tune the rear preload as you see fit for load/pillions, but that's your starting point.

Don't forget to include your gear and helmet when setting your initial sag. That stuff can sometimes weigh a bit more than we think.

If you can't achieve your preload within, say, 80% of your total available preload adjustment, you need to get the bike resprung. A simple set of springs and some heavier oil can take you a long way.

If you want *better* suspension and need to revalve, seek a suspension expert like Metric Devil Moto -, Race Tech Suspension, Motorcycle Suspension by Traxxion Dynamics, etc. Many options, and that's beyond the scope of this discussion.

Don't slack on suspension; it's the single most helpful and productive upgrade you can do for yourself or the bike after proper riding skills.


Last edited by Carbonero; 04-25-2013 at 02:31 PM.
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post #8 of 17 Old 04-25-2013, 11:10 AM
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*edit for accidental double post*
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post #9 of 17 Old 04-25-2013, 01:43 PM Thread Starter
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So the key measurement is from the zip tie position when seated on it, up to the triple clamp? That's 131mm for me. According to the owner manual the 2004 dl650's front fork has 150mm total travel? So that would be 19mm sag. 25%-33% of 150mm is 38-50mm. That means I have to decrease the preload quite a bit? That doesn't seem to rhyme with what I've heard about the suspension not being stiff enough.

As you can see, I am a newb in all this stuff but I really appreciate all your help.
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post #10 of 17 Old 04-25-2013, 01:59 PM
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Quote:
Originally Posted by culturedape View Post
So the key measurement is from the zip tie position when seated on it, up to the triple clamp? That's 131mm for me. According to the owner manual the 2004 dl650's front fork has 150mm total travel? So that would be 19mm sag. 25%-33% of 150mm is 38-50mm. That means I have to decrease the preload quite a bit? That doesn't seem to rhyme with what I've heard about the suspension not being stiff enough.

As you can see, I am a newb in all this stuff but I really appreciate all your help.
No, the measurement you're describing is not the suspension travel; it's just a length at an arbitrary point. By itself, it's meaningless.

No matter where and how you measure, you need two measurements... you need one with the suspension unloaded, and you need one with the rider geared up and on the bike. The difference between these two is your sag.


A single measurement simply won't do. Forget what an exact bike or a thousand other exact bikes have as measurements from the triple tree or where ever. The only measurements that matter are YOUR bike's unloaded and loaded heights.

Side discussion: The measurement from the bottom of the triple tree to, say, the tip of the seal may be different on various bikes if the owners have adjusted the height of the forks in the tree. It may be different with different dust seals in place, or if the dust seals aren't fully seated, are worn or swollen, or missing altogether. It may be different if the triple tree was replaced and the casting is different. It may be different if a lowering kit was installed, and so on and so on. Another bike's measurement should never be considered a gospel number and should never be blindly applied to your bike. Ever.

This becomes insanely easy if your bike has a center stand. Does it? I'm writing this with the assumption it does. Follow these steps.

Front:
1- put a wire tie on the forks.
2- run the wire tie all the way down so it's touching the seal.
3- gear up and mount the bike, slowly so as not to bounce the bike.
4- have a friend support the bike without putting any weight on the front, and you lift your legs to fully weight the bike.
5- carefully dismount the bike so as not to bounce the bike.
6- carefully put the bike on the center stand, slowly so as not to bounce the bike.
7- have a friend lift the front or weight the back so the front wheel comes off the ground.
8- measure the space between the bottom of the wire tie and the top of the seal. This is your sag.
9- adjust, rinse, repeat.

As an alternate, if you don't have a center stand, borrow or buy a pin-type front stand that will lift the front end of the bike under the triple tree and not at the wheel.

This picture shows this measurement on upside down forks, but you get the idea...



Rear:
1- pick a point directly above the axle nut but on the frame/tail section of the bike.
2- bike on center stand, measure the distance from the top of the nut to the bottom edge of whatever you've selected, record the measurement
3- take the bike off the center stand.
4- gear up and mount the bike
5- use only enough pressure/strength with your legs to keep the bike upright but not to affect height.
6- have your friend measure the same points again; this is your rear sag.
7- adjust, rinse, repeat.

alternative:
4- put the bike on a rear race stand supporting the swing arm.
5- gear up and carefully mount the bike
6- have your friend measure the same points again; this is your rear sag.
7- adjust, rinse, repeat.

Again, your goal is to measure the difference between completely unloaded suspension and loaded as normal riding.

Using the method above for the rear, you want to ensure that the difference between the two numbers is roughly 30-35% of the total overall height (measurement A in the diagram). I believe the same numbers apply: 6.3inches/160mm for overall vertical wheel movement (at the axle) so a difference of 50-55mm is an appropriate sag.

This picture shows an example:


And again, if you cannot attain proper sag within 80-90% of your available adjustments, you need to consider respringing. Any more than 50% sag and you're looking at a bike that will wallow and become very sloppy, and bottom out often. Not only is it uncomfortable and can seriously and negatively affect handling, but a bike that bottoms out a lot will damage suspension components.

Last edited by Carbonero; 04-25-2013 at 02:56 PM.
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