Suspension tuning tech question

[Flows]

Gentlemen, it is a pleasure to be comprehended, terrific content kml and zee

You are 'maxed out on fork preload'
How much do you weigh?
220 lbs+ ?

Close 6, 210 geared. I wonder if the radiator and oil cooler protectors, double bubble, and tank bag are starting to add up..

Zee, I did feel like the front was pushing a bit but is a bit better since I pulled some rebound out. Still feels front heavy though. Interestingly with all that rebound the rear doesn't feel stressed at all. Our NZ roads approximate mx tracks so we don't really understand what smooth actually is

As discussed in the Tyre Reading thread I'll drop rear end some more (I am still leaving the seat on some dips) then _maybe_ add another click of rebound to it and ride some corrugations.

kml, one symptom that did get close to the less rear sag = standing up in turns OP issue is this:

That did cross my mind but I thought it might be more rake / trail ratio hitting some crossover threshold with far to much front sag + not enough rear sag. I need to better understand the impact of the various longitudinal and lateral contact patch offsets..

Anyway time to go riding... for science.

 

[sixpack577]

If you are still 'leaving the seat' on certain bumps, yes rebound, but; can you stand beside the bike, on the kickstand, grab the tail or grab bar, and lift up some slack/extend the rear shock there?
Or is it ridgid?

 

[Flows]

Hey 6, check out all of the data in the OP table. I was leaving the seat on dips rather than bumps so not enough sag as you point out with the tail lift. I just took out another 6 notches (0.6 of a turn) ~+3mm rear sag and it is a different bike.

This is where I was:

Rear Preload / Sag

~4.5 Turns In / 9mm Static / 29mm Dynamic

Turns measured from min rather than max. / 420mm / 400mm (bottom of hump key to bottom center of axle internal diameter - 429mm unloaded) ~0.5mm sag per preload ring notch, 10 notches per turn. Stiction: 1mm

Bike is sooo much more settled now. Might go back up 2 notches as it is starting to get a bit lazy on corner entry.

Rear Preload / Sag

~5.0 Turns In / 13mm Static / 33mm Dynamic

Turns measured from min rather than max. / 417mm / 397mm (bottom of hump key to bottom center of axle internal diameter - 429mm unloaded) ~0.5mm sag per preload ring notch 10 notches per turn. Stiction: 1mm

One thing that was really interesting is that it got a tiny bit of that 'want to stand up in corners' feel back now that I have gone too far with rear sag. Looks like too much rear sag and too little sag have similar effects. Starting to think my hunch about some kind of rake trail ratio cross over thingy might actually be in play. Anyone have any clues on that contact patch offset stuff?

 

[zeepopo2]

Hey 6, check out all of the data in the OP table. I was leaving the seat on dips rather than bumps so not enough sag as you point out with the tail lift. I just took out another 6 notches (0.6 of a turn) ~+3mm rear sag and it is a different bike.

This is where I was:

Rear Preload / Sag

~4.5 Turns In / 9mm Static / 29mm Dynamic

Turns measured from min rather than max. / 420mm / 400mm (bottom of hump key to bottom center of axle internal diameter - 429mm unloaded) ~0.5mm sag per preload ring notch, 10 notches per turn. Stiction: 1mm

Bike is sooo much more settled now. Might go back up 2 notches as it is starting to get a bit lazy on corner entry.

Rear Preload / Sag

~5.0 Turns In / 13mm Static / 33mm Dynamic

Turns measured from min rather than max. / 417mm / 397mm (bottom of hump key to bottom center of axle internal diameter - 429mm unloaded) ~0.5mm sag per preload ring notch 10 notches per turn. Stiction: 1mm

One thing that was really interesting is that it got a tiny bit of that 'want to stand up in corners' feel back now that I have gone too far with rear sag. Looks like too much rear sag and too little sag have similar effects. Starting to think my hunch about some kind of rake trail ratio cross over thingy might actually be in play. Anyone have any clues on that contact patch offset stuff?

Well,there is a lot truth in too low is very smiliar too too high when it comes to settings. For example compression, I'll ride a friends bike that complains is too stiff, actually wasn't stiff enough. Best way to find out is to keep going. Skip any harmonics you may encounter. Sometimes 1 works, 2 doesn't but 3 and 4 do. So experiment a little.

If your roads are poop just like some of the country roads I'm on you need a ton more faster rebound. But your spring is too soft. So the spring is limiting how fast a rebound you can run. My rebound has revalved quite a few times. At the moment I think I'm at around 250% faster than stock. But that's with revalve and spring upgrade and a new hydraulic curve. Try and experiment. Open the rebound to 12 clicks out. Make the rear the same. When riding you should feel your helmet diving forward first then back. If you go back then forward need stiffer compression until you get to just around 60 percent weight transfer to the front. If thise reboind settings jump you around too much control the fork travel with stiffer compression. Gotta keep the front end loaded at all times. Number one reason people crash. Not enough load on front tire. On a theoretical perfect suspension a 1 inch bunch will only more the suspension up 1 inch and immediately return to its starting point. But in reality it overshoot and then undershoots. Controlling that up and down wave to a minimum oscillation is the goal. But for that you need speed and control in your suspension components, lots of it.

Rake and trail, nah you are miles away from too far lol. I'm up 1 inch on the rear and aftermarket triple up front that let me raise the forks thru the clamps around 10 mm. So with the sag I use im at around 19 degrees rake last time I measured. Not saying to take it this far, it's dangerous without the right hardware upgrades and correct valving and settings so that you don't loose the front end on corners but shows ya how far you can change geometry and still have it function properly like the MotoGp track star the Hayabusa is lol.

 

[Flows]

Great info zee, love the remove the rebound, isolate the compression test. I just added back another 2 notches 0.2 of a turn to the rear so 32mm sag now and she is the best I have felt. Can feel the trail wanting to turn at low speeds, a bit less lazy at high speeds and the stand up has gone. It is crazy what 1mm of sag can do..

 

[zeepopo2]

Great info zee, love the remove the rebound, isolate the compression test. I just added back another 2 notches 0.2 of a turn to the rear so 32mm sag now and she is the best I have felt. Can feel the trail wanting to turn at low speeds, a bit less lazy at high speeds and the stand up has gone. It is crazy what 1mm of sag can do..

Oh yeah once you get to a certain point 1 mm is worlds apart. Wait until you start outriding your springs. Every spring rate up is a whole new world you have to learn from scratch. Previous settings go out the door each time. I did 1.1 1.2 1.3 and now 1.4. That was the sweetspot for me. Rebound still a tad slow but going to keep it as it is until I get my new custom cartridges built by Penske later this year.

Oh BTW the stock needle adjuster for compression are crap. They ain't linear at all. Upgrade to a finer needle that will give you precise and consistent linear results. Anything below 4 click becomes magnitudes of change between clicks. A must have when fine tuning the front. K tech compression adjusters is the way to go.

 

[Cruising180]

If you're getting that deep into the weeds on this I'd say email Dave Moss and get a remote suspension tune done. I just set my sag to between 30-35mm then my rebound to when you give the suspension a sharp shove it bounds back quickly the settles just a bit ala Motojutsu on youtube. That's worked well for me although I am too heavy for the stock front springs but I work around it.

 

[Flows]

Part art part science isn't it Cruise. I actually emailed Dave a couple of days before I picked the bike up. Primarily to get some ball park figures that would keep the wife happy (stable, smooth and sure footed) for the long 2 up cruise around the South Island and home, he came back straight away and didn't charge me anything. I know some recoil from his undeniable 'swagger' and some racers may chuckle or even scoff but his depth of experience is legitimate and I think a good start. I am signed up for a day course of his at the end of Feb. I am happy to try things out even if they don't make sense initially and also to filter out or adjust / flesh out any over simplifications or dogmas.

These were his numbers for that use case BTW, ended up pretty close but some numbers were not achievable with the factory spring rates.

Weight	225 lbs rider 150 lbs pax geared up including 15lbs back packs each, no paniers
Fork Oil	1000 miles
Tires	1000 miles factory
Riding Style	Touring, don't scare the misses, comfort and planted.

Setting	Factory	DM Suggested
Front Preload / Sag	10mm out	95 - 85mm leg or 5 turns out
Front Rebound	8 clicks out	6 clicks out
Front Compression	8 clicks out	8 clicks out
Rear Preload / Sag	195mm shock length	Rider sag with both on at 25-30mm without extending the shock
Rear Rebound	8 clicks out	5 - 6 clicks out
Rear Compression	6 clicks out	6 clicks out
Front Tire Pressure Cold	42 psi	38 psi You can test 40
Rear Tire Pressure Cold	42 psi	40 psi You can test 42

Another diagram from Total Control that I find are good reminders of the nuance involved are these.