Fork sag for racing? Gen 1.

[Som]

I'm on my cell (I'm at Willow Springs) so searching sucks. Can someone give me the static/rider sag for the forks on a gen 1? My rear sag is 9mm/25mm. My front is 6mm/20mm.

Thanks!

- Som

[Kurt'sSV]

Rear should free sag 10mm (meaning sag that much with it's own weight, no ridder). Total sag should be 25-30mm.

Forks should free sag 20mm. Total sag 30-35mm.

Per Zoran, free sag is more important than total sag. So take out a lot of pre-load on your forks!

I can never remember what "static" sag means. I guess it means what I'm calling (and Zoran calls) "free" sag.

[Som]

Well, I tried loosening up the front on the bike... I loosened the front preload by 3 full turns. Shouldn't have been a huge difference (not 14 mm)... but I didn't remeasure the sag... just went out to see if I could feel a difference.

Essentially, while the suspension has been okay for me, I thought it could feel better. Which is why I was looking for proper sag numbers.

So, anyways, went out with the loosened front, and every turn now started to feel like the front end was coming out from under me. So I came in, tightened the front back up again (3 turns), went out, and the front end *still* kept feeling like it was going.

But then... here's the thing... the front tire wear isn't anywhere near the edge. Does that make sense? Feeling like you're losing the front when there's still an inch of tire left?

I'm so fucking confused now. To add to it, bettwen races on Sunday I went to check the free sag while it was sitting on the front fork stand -- zero. Wtf? Maybe when I went to loosen the front 3 turns to begin with I accidentally tightened 3 turns. Then when I went to "undo" my change, I added *another* 3 turns. So this time, I unwound 6 or 7 turns to bring it back to the sag it was at before. Which seemed to work... except...

The front still felt like shit. On almost every fucking turn.

Anyways... I ended up crashing in 3 in the Solo-GT race on Saturday. Lowside. Sunday races were worse than Saturday with the feel of the bike and the crash on my mind. If Sunday was my only problem I'd have said it was mental, but the bike was feeling weird all Saturday, too.

I usually run 39/40 in practice and 34-36s in races. I was running 37s in practice on Friday, but on Saturday I think I was in the 45s or something -- I couldn't keep my throttle on in 2... 3 felt like the bike was going to go... and 8 -- well, forget 8/9, I probably lost 5 seconds right there from the wind and the constant feeling that the front was going to slide out from under me.

Last month I was running in the 34/35s. I hadn't touched anything on the bike until Saturday's preload adjustments.

I'm gonna recheck the sag again this week and see what the hell is going on.

Fucking ruined my double points weekend.

- Som -- rambling post because i'm pissed.

[Kurt'sSV]

You don't have enough weight on the front tire. What shock are you running?

[J.Moto]

Rear should free sag 10mm (meaning sag that much with it's own weight, no ridder). Total sag should be 25-30mm.

Forks should free sag 20mm. Total sag 30-35mm.

Per Zoran, free sag is more important than total sag. So take out a lot of pre-load on your forks!



If after static sag is set and you get on the bike not having enough total sag, the springs are too heavy. If total sag is too much, the springs are too light. By using preload to adjust for improper springing means the suspension travel will not be operating in the correct range of motion.

I learned that motocrossers only worry about static sag. With the jumping they do, proper springing is imperative and once that is set, you never have to look at total sag. That said, you can still adjust preload to fine-tune the suspension action (fine tune the preload before seriously adjusting compression settings) because springs are made to work for a range of rider weight.

Som, check out the RRW Trackday Directory issue and Michael has a good start-up article on suspension adjustments.

[Monsterdood]

Take the bike off the stands, get someone to help, and set the sag to the values Kurt mentioned. Make sure you take 2 measurements when checking sag. Push down and let the bike slowly come up to a position and measure, and then lift it up a bit and let it slowly fall to a position. Average these two positions to get the sag. Then do the same thing with you on the bike.

As for your description of what was going on, I would suspect tire wear, tire pressure, track temperature, or rider position before I blamed it all on the sag settings. Like Kurt said, get your weight over that front wheel if you feel like it is lacking in traction. Crotch to the tank, torso leaned forward and your head on top of or close to your inside hand.

It is normal for front tire wear to not go to the edges like the rear tire normally does. This just has to do with the profile of the front versus the rear. Different brands will have different profiles and may exhibit this effect to varying degrees. When my bike stops holding the line I want in turn 1, I know my front tire is ready to be replaced. Then with a new front, it magically holds every line I want and feels quite planted. Good luck.

[Som]

I'm running the Penske rear shock. I put the right spring on it for last month's race which made the bike feel a lot better (I was running 36s the month before and 34/35s last month).

Fronts are stock with emulators. Don't know the spring rate yet, though. Gonna do full service on it these next two weeks.

The sag measurements accounted for stiction with both the free and the rider sag.

After Saturday's crash, I bought new tires for Sunday. It didn't help. They're the same tires I was running before -- Power Races. I usually get them down to about a quarter-to-half inch from the edge in the front. At the end of Sunday they weren't within an inch of the edge. Which is why......

... I definitely suspect body positioning -- though that hadn't been *that* big of a problem before. I wonder if the winds really affected me that much. My fairings are rather wide (gsxr fairings)... I dunno... maybe they were like a sail. I'm kinda tallish, too -- 6'3"... maybe that didn't help.

Another thing that has me leaning to body positioning is that I was exhausted. I had to ride back to San Diego on my street bike on Friday night and come back Saturday morning. 6 hours of riding within a 12 hour span of time. I was thinking maybe I was too tired to keep my weight on my legs and keep my body positioned appropriately.

I dunno... while my body positioning wasn't ideal, it just seemed like too drastic of a feeling on the front to actually have that be the only thing different. It was kind of a chicken/egg problem... I would concentrate on my body positioning to try to get the bike to feel right, but I couldn't get comfortable putting my body in the proper position because every time I leaned to the inside of the bike, it felt like the front was going out on me. Gah. I dunno.

Another question... I just bought a couple bathroom scales to weigh the bike... what ratio front/back should I expect?

I appreciate all the help guys... I've got 1 month... I just pissed away a perfectly good double points weekend. I don't want next month to suck, too.

- Som

[Kurt'sSV]

Who'd you get your Penske through? More importantly, what it's length set at? 14"/356mm?

[J.Moto]

I will point out two major mistakes you made:

1. You did not document your settings.

2. You did not make changes from adjustment end-point.

For 2., if you are at 2.5 turns out and want to dial it in .5 more turns, you should turn it all the way back in and turn it out 2.0 turns. This would eliminate you accidently turning it the wrong way, for the most part.

But you're a smart, enginerding type, so you probably already figured that out.

[Som]

The Penske came with the bike, but I swapped the spring out with a Hyper Coil 700lb spring I got from Traxxion. It was a shorter spring (by, I believe, an inch or two) than the one that was on it before (which was, I believe, a 4-hundred-something (460lb, maybe?)). This was the recommended spring by Traxxion for that shock for my bike. It looks kind of odd since the top spring perch has to come way down to meet with the spring, but I don't think that matters -- a spring is a spring, right? If the free sag/rider sag match up (9mm/25mm), wouldn't that mean the shock will have it's full range of travel?

I never measured the length of the shock... do I measure it while it's on or when it's off?

It felt great last month (much less wind)... except for one thing, now that I think about it. In the last race last month, the wind was picking up... and the front end started feeling... um.. unplanted... through 8 (front end tucked twice going into 9... scared the crap out of me). I was running 35s in that race... ran 34s in the race before when the wind hadn't picked up yet.

Maybe I just suck at dealing with wind.

Jason, good suggestion... I'll probably start doing that from now on.

- Som

[Som]

On a side note... there's a GSXR 750 180 rear rim for sale right now. Would that be something that would work on my bike? Do I even want to go to a 180 rear with how much power I'm putting out (~73hp)? Andy mentioned that it had slowed turning and that it was more suited to higher hp motors... does that mean it's a *bad* idea for what I've got?

- Som

[twf]

if spring on your shock was ~460 you may have wrong shock on.like second gen shock,or gsxr,which is to short.
measure eye to eye centers with no load on shock.

[trey_loco]

Everything you mentioned in your big post above are valid points Som. But a piece of advice that was given me when I was going through the same scenario proved invaluable over the long run.

Relax. Don't over analyze everything. Work on being smooth and identify your reference points.

Again, your considerations mentioned above are valid...but sometimes, no matter what you do to the bike or how you incrementally adjust this, or adjust that, when you just relax and ride the bike, your times will drop drastically.

See you out there Som.....

[Kurt'sSV]

Don't get the GSX-R rim.

[BlueEyedLion]

Everything you mentioned in your big post above are valid points Som. But a piece of advice that was given me when I was going through the same scenario proved invaluable over the long run.

Relax. Don't over analyze everything. Work on being smooth and identify your reference points.


I second that.

[Som]

So, I pulled the forks off. Two things.

One, the oil was really really dirty.

Two, the levels were uneven. The right fork oil level was considerably lower than the top of the spacer while the left was about a 5mm from the edge of the top of the fork from spilling out.

I had gone on the RaceTech site and ordered .90 springs based on their site calculator. The recommended rate was .879. Though, I came to realize after I'd order them that the calculator is based on stock bike weight. I *believe* my bike is about 30-40lbs lighter than stock (if I remember, I measured the wet weight at about 365)... don't shoot me if that's way off. There seemed to be another calculator on there that allowed you to enter bike weight, and it said somewhere between .800 and .850. I tried to call RaceTech today but the woman in sales wasn't 100% on my application and every other line I got to was a dead end (including where she forwarded me to).

Anyways, the springs in the fork turned out to be .90 (I assume that's what a "9" etched into the top of the spring means).

Unless I get a strong recommendation otherwise (I'm 200lbs, btw), I'm just going to reuse the .900 springs and see what I can do with them. I never really got the sag to the right spot but then again apparently I was retarded when trying to adjust it. So, before I try again, does anyone think that rate may be significantly too stiff for me?

Is there a way to measure the rear shock without removing it? Is there a way/place to measure it while it's on the rear stand?

- Som

[twf]

springs are fine.
you had way to much oil in there.make sure you read how to set oil level.

[Som]

One more question... how can I figure out what the emulators are set for right now? What should they be set at? I remember reading 2 turns from how you get it when you buy them, but these were already installed when I bought the bike. I just want to make sure they're at the right setting for me before I put it back in the fork.

- Som

[twf]

back out screw with spring until you have 0 preload on spring.than screw in 2 turns or whatever you want it to be.