Sag measurement confusion

[basmntdweller]

I finally got my wife to help me measure the sag on my C-14 today. Front checked right at 30mm like I expected as many here have used the same 14mm setting with success. However, the rear was not like I expected. I don't recall what I had it set at but it was from the spreadsheet someone posted on here. I was only showing 20mm sag at the rear. I kept cranking out the adjuster until got 30mm sag same as front. The strange part is the adjuster is all the way out to get that 30mm. Sitting on the kickstand the rear suspension is topped out, zero sag when fully unloaded. It is almost as if there is a heavier spring or a big shim in with the spring. My geared up 250lbs should put more on it than that according to everything I have read. A 150lb rider wouldn't get it anywhere near proper sag.
Any ideas?

Matt
 

[rcannon409]

Matt, try the measurement for the rear while its on the centerstand.  The c14 is HEAVY and will sag some even on the sidestand.   you'll see a significant difference in the back when no weight is on it.

[texrider]

You can use a dab of white grease on the fork slider to check things by yourself, after the wife gets bored...

I gave up on trying for a dimensional setting, and just fiddle with them until the bike is compliant enough to avoid back pain, and still gives sporty feedback on the roads I ride most often. 

[basmntdweller]

Matt, try the measurement for the rear while its on the centerstand.  The c14 is HEAVY and will sag some even on the sidestand.   you'll see a significant difference in the back when no weight is on it.

After I posted, I thought I would double check it that way. No difference in static sag. I intend to get out and ride tuesday a bit. I'll get a feel for it with the adjuster fully unloaded.

Matt

[Jay]

I had my SAG adjusted last month by Dave Moss. He worked so quickly--and I knew so little about what to watch for--that I don't remember the exact numbers. The front wheel was in a chock stand when he did the SAG. The forks were pretty close, but the rear shock was way off.

One thing I do remember quite clearly was that he adjusted the dampening screw at the base of the rear shock; 1-1/2 turns out, I think. Then he clicked the adjuster all the way out. Told me to screw it in 2 to 4 clicks for a rider (150 lbs).

I was/am astonished at the difference. Some basic adjustments by a seasoned pro and suddenly my bike is MY bike. Amazing how sloppy it was and how much I had to compensate for that sloppiness because of my suspension ignorance. Honestly, the handling is so much more agile that the bike feels 100 pounds lighter. I'm having to relearn the bike's characteristics.

I have since added another click in the rear shock to better handle these crappy roads in Sonoma County.

[Beamer]

I myself am a bigger guy (270lbs) but was shocked too when I realized that I had to soften the rear of the bike to get to where I wanted (35mm).

My front pre-load I have almost all the way firm, minus one turn on each adjuster from bottom, and I am about 10 clicks in on the rear shock. On my bike however, the first 3 or 4 clicks on the adjuster in the rear has no tension on it at all, so I am assuming it is not even making contact with the diaphragm in the reservoir until about click 5.

My suspension was all screwed up from the dealer, and really didn't realize it until the front tire was almost bald on the sides at 5000 miles. Still has tread in the middle.


 

[RideBellChain]

My understanding is that  you're NOT supposed to do any settings while the center stand OR side stand is being used. It's at least a 2 person job, and 3 will be even more accurate since you don' t have to balance the bike yourself.

You need to bounce the bike a bit with nobody sitting on it, then measure...that's the STATIC number.  Now get on the bike, with all your gear and helmet on, bounce around to make sure the suspension is not binding, etc. and measure again.  Subtract the two numbers and then adjust until you're at 30mm front and rear.

Don't go by spreadsheets, unless you are the exact same build as the author, with the exact same body positioning on the bike.  In other words, throw the spreadsheet away.      Just like shoes, gloves, girls...everyone has their own preferences...trust your measurement and numbers, not someone else's numbers.

[basmntdweller]

My suspension was all screwed up from the dealer, and really didn't realize it until the front tire was almost bald on the sides at 5000 miles. Still has tread in the middle.
 

Mine was that way at 3500 miles. An old HS buddy that is a long time MC racer said that comes from hard braking, not bad tires or suspension. He was bitching at me to use the rear brake a lot more.

My understanding is that  you're NOT supposed to do any settings while the center stand OR side stand is being used. It's at least a 2 person job, and 3 will be even more accurate since you don' t have to balance the bike yourself.

I mentioned it being on the side stand attempting to illustrate that the suspension was topped out under it's own weight. All measurements were done while the bike was being balanced with me on it

You need to bounce the bike a bit with nobody sitting on it, then measure...that's the STATIC number.  Now get on the bike, with all your gear and helmet on, bounce around to make sure the suspension is not binding, etc. and measure again.  Subtract the two numbers and then adjust until you're at 30mm front and rear.

Actually per my understanding from the set up books I have read, your static measurement starts at the fully extended position and then you subtract the measurement while you are fully geared up and with the suspension settled holding your weight. In the case of my bike, with the adjuster fully out, it still is topped out under the weight of the bike alone and I get approximately 30mm of sag when I am on it. I can't get anymore sag since the adjuster is all the way out. I am in the 250lb range geared up.

Matt

[rcannon409]

You really wont use the side, or centerstand for any measurement, but having zero weight on the back wheel wheel, or front, will be the only way to get an accurate measurement  of overall length, or distance,  for the static sag (without rider, bike standing up on its wheels) or the sag with a rider.  Being the amounts of sag are so small, a difference of 5-10 mm off will be a big deal. 

So, if we start at the back, the first measurement needs to be with the bike on the centerstand and the wheel off the ground.  Measure from the center of the axle to a point on the bodywork directly above the axle.  On my bike I put a dot of sharpie on the bodywork at 22 inches from the axle centerline. 558mm.

So, when I'm sitting on the bike, feet up, I need this measurement to decrease to 523mm. This is after bouncing up and down a few times to let the bike settle in where it needs to be.   I've never been able to do this without someone else holding up the bike.

The front gets set the same way.  Its harder to find the base measurement in fornt for two reasons.  First, the front end has quite a bit of weight  on it while on the centerstand.  Second, the top out spring in the forks is long.  This makes the length measurement tough to get since the forks extends a slightly different amount every time it extends....not much different, but enough to drive you nuts unless you use the average of several measurements.

I dont know how people feel about bit-torrent, but searching Dave Moss is not a bad idea.....I ended up buying his video AFTER viewing it there since its really, really good. 

[basmntdweller]

That is pretty much how I did mine. I was able to put the bike on the centerstand and sit all the way back on the seat/cargo rack and get the front to lift off the ground. Had my wife measure it then for the static and then dropped it back to the ground and measured it with me in normal riding position. Lee Parks book said to pull the front down and then release it slowly and take a measurement then lift up on the front end and let it settle slowly. take another measurement and then average these two and subtract that from the static measurement.

Matt

[Jay]

Here's one of Dave's online videos:  Motorcycle Suspension - Setting Sag

http://youtu.be/mK3flKxf41U

Dave Moss sets the sag on a 2009 Yamaha YZF-R6.
Setting sag properly puts the suspension into it's optimal working range, based on a riders weight.

[Beamer]

Here's one of Dave's online videos:  Motorcycle Suspension - Setting Sag

http://youtu.be/mK3flKxf41U

Dave Moss sets the sag on a 2009 Yamaha YZF-R6.
Setting sag properly puts the suspension into it's optimal working range, based on a riders weight.

Yep, this is probably the most direct explanation on setting sag and rebound that I have seen. It tells you exactly what you need, not a extra 100 things you don't

[Beamer]

Mine was that way at 3500 miles. An old HS buddy that is a long time MC racer said that comes from hard braking, not bad tires or suspension. He was bitching at me to use the rear brake a lot more.

I will admit, I use allot of front brake due to the weak rear brake on this bike (my only real complaint)

[basmntdweller]

I will admit, I use allot of front brake due to the weak rear brake on this bike (my only real complaint)

I felt the rear brake was rather weak as well but I have found that it just takes a whole lot of pressure to use it. I am wondering if a different set of pads would help as the feel of the brake balance is terrible IMO.

Matt

[VirginiaJim]

I've used different pads (kwak and CL)...no difference in the feel to me.

[stewart]

Per the Dave Moss post by Jay, I've started watching and learning a lot more.

These videos really helped further my knowledge, I plan to watch more as I prepare for my next trackday this coming Monday.

Unsprung tire wear analysis - http://www.onthethrottle.com/howto/dave-moss-unsprung-tire-wear/
Two Clicks Out - http://www.onthethrottle.com/howto/two-clicks-out-9-wera-racer-gets-a-tune/      (this one actually made a lot of sense building on the previous)