Setting Suspension Sag On Your Motorcycle By Yourself

clutchslip · 06-25-2006, 2:03 PM

Setting sag by yourself.

This came up here:
Suspension questions...........went for a ride today and realized mine sucks
So I thought I'd post-up the technique for everyone to set sag all alone.

For further information on sag, please see the many threads and articles about setting sag.
A good description by ABTECH is in this thread:
lowering front end does what ?

Setting sag without help:
These procedures assume you have your kick-stand in place, otherwise you need a chock.

Things you need -
(If you use the manufacturer's full suspension travel numbers, you do not need to lift the bike front or rear. Their numbers may or may not be accurate for setting sag at home.)

1. A steering pin lift for the front.
(Or other means to unload the forks with the wheel attached.)
2. Measuring tools. Accuracy is good.
The forks only need a tool to 150 mm.
The shock requires a tape measure or yard stick.
3. Zip ties for the forks.
4. Marks-a-lot or other pen/pencil.
5. Cardboard or other stiff material that can be marked.
6. Tape.

Two things you NEED to be able to do.
1. Lift the bike so the rear wheel is off the ground for a split second. (unless using the manufacturer's numbers)
If you cannot do this by yourself, you will need to hoist the bike rear from the sub-frame (tail area).

Very important:
2. You need to balance on your bike for 1 second or less.
If you cannot do this, you cannot set your sag.
(If you can't do this, you should practice a lot more.)

What you are doing:
You just need the three length numbers: unloaded, bike weight, bike+you weight.
Please see elsewhere for what these measurements mean. This is covered, over and over, on this forum and elsewhere.

Sag numbers are RELATIVE. That means as long as you take your measurements the same way from the same locations, they are correct. You can do all the bouncing or whatever you like during testing. That's up to you. Just remember to give about 1 sec for the suspension to settle down.

Forks:
The forks are easy, once you have the unsprung number.
1. Measure the unsprung length to a zip-tie on the left fork to stay consistent with the other measurements.

When you put a zip-tie on the left fork, it marks the farthest the forks have compressed.
When you lean the bike onto the kick-stand, it unloads the forks. The zip-tie stays in place.
2. Bike weight - just hold the bike upright for a split second.
3. You and bike weight - balance on board for a split second.

Shock:
There are a couple of ways to mark the measurements. Please do what you like. One way is not better than another. Remember, the numbers are RELATIVE, so take the measurements the same way.

Set-ups:
(It is easier to use the right side of the bike if you have a kick-stand.)
Method 1 -
A. Tape a marks-a-lot (or other pen) to/or near the rear axle.
B. Tape cardboard or other stiff material to bike directly above the axle.
(Obviously the cardboard must be long enough to be marked by the pen)
Method 2 -
A. Tape cardboard to the axle/swing-arm.
B. Tape pen to to bike directly above the axle.

In both methods, mark the cardboard exactly where you attached it, in case it comes loose or you need to move it. If you do a lot of adjusting, you will need to move the cardboard or change pen color so you don't get confused. (Changing colors helps, anyway, btw.)

The hardest part - the unsprung length:
1. Measuring the unsprung distance.
Without a hoist, you have to lift the rear wheel off the ground. You do NOT need to hold the wheel off the ground. This takes a thousandth of a second. The mark will be left on the cardboard. (I can lift my 2004 Fireblade. I weigh 175, I'm over 50, and I don't pump much iron.)
Please, use leverage and don't hurt your back.

Like the forks; when you lean the bike onto the kick-stand, it unloads the shock. The pen will leave a mark the farthest it has traveled.
1. Bike weight - hold the bike upright for a split second. Again, the pen will mark the farthest travel.
2. You and bike weight - balance on board for a split second. The cardboard has a new mark.

You now have all the numbers necessary.

Notes:
You can perform the front and rear measurements at the same time. (Not the "unsprung" length, though. Don't be silly.)
Keep those full length, unloaded numbers. They should never change much and they are the hardest to get.
Chock users - if you cannot get on/off the bike cleanly, use a crate or other step.

All interpretation of numbers and "proper sag" settings I leave to others.

If there is any confusion about my instructions, or there are errors, please post-up.
Good luck and good sagging by yourself.

-the clutchslip
P.S. Wow - this is big when posted!

seamus · 06-25-2006, 11:02 PM

Quote:

Originally Posted by clutchslip

...Not the "unsprung" length, though. Don't be silly...

I can.

clutchslip · 06-27-2006, 4:56 AM

Look I found a pic of seamus doing his one man pit crew:
I think he's saying: "You WILL set your sag, properly!!!!

BDA116 · 06-27-2006, 10:35 AM

Ever notice how the Hulk's pants always stay on nicely there in the groin area? That area is never large enough to bust open the shorts, rather it always stays as small as it is.
Hmmmmm.......................................

seamus · 06-27-2006, 1:38 PM

Quote:

Originally Posted by BDA116

Ever notice how the Hulk's pants always stay on nicely there in the groin area? That area is never large enough to bust open the shorts, rather it always stays as small as it is.
Hmmmmm.......................................

That's because it's the one thing I don't need when I'm angry and it would just get in the way. When I'm prepped for action, the blood flow causes the rest of my body to shrink.

My real cause for concern is why you would notice that. Got something you'd like to tell us, BDA? It's okay, we can still be friends.

BDA116 · 06-27-2006, 2:01 PM

Quote:

Originally Posted by seamus

That's because it's the one thing I don't need when I'm angry and it would just get in the way. When I'm prepped for action, the blood flow causes the rest of my body to shrink.

My real cause for concern is why you would notice that. Got something you'd like to tell us, BDA? It's okay, we can still be friends.

Your green skin makes me horny, baby.