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Discussion Starter #1
Ok...my sag is good at 40mm

I really like the feel of the front end. The dive on braking is well controlled, and allows for good turn in, especially on tight technical roads.

However, I'm using up all of my fork travel. At track speeds I would surely bottom out.

I increased one click of compression on both forks. Now I really don't like how the front end feels. Too stiff, barely any fork travel. I'm only using up a little over half of my available fork travel.

So what's the ideal improvement for this?

-Increase spring rate (stiffer springs)
-Increase spring preload
-Increase oil level
-Increase rebound compression on one fork

Thoughts???
 

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More oil (reduce air gap).

However, how are you getting that 40mm of sag? That's rider sag, I assume...whats your free sag? What's your spring weight and your weight?

If you are bottoming the forks often on the street, you need either stiffer springs or a dirt bike. :)

I increased one click of compression on both forks. Now I really don't like how the front end feels. Too stiff, barely any fork travel. I'm only using up a little over half of my available fork travel.



*edit* Increasing the compression one click did all that?
 

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The following is a personal opinion, not professional advice.

If your fork spring rates are correct for your weight, chances are they are bottoming on hard braking - not much you can do if you want them plush for their intended use, e.g. cornering. If the springs are too weak at your weight then even at correct sag (spring pre-load) they will over compress under hard braking leaving little additional travel. Adding additional compression damping wont help as that only damps higher frequency fork travel - high speed late braking is a low frequency occurrence. Suggestions might be - a) verify your forks are correctly sprung for your weight or add turn or two of pre-load as a band-aid. b) check your braking habits, if you are quickly grabbing a handful then the fork will dive eating into available fork travel. Instead apply the brake gently at first until the fork is allowed to initially compress a bit then progressively apply full braking. adding compression damping to offset this will help but at the expense of corner entry stability and feel. Also dabbing the rear brake between the final down shift and heavy front braking will help settle the chassis at bit before you lay into them.
 

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*edit* Increasing the compression one click did all that?
I was thinking the same thing.

40mm seems a bit much to me. I'm more in the 30mm range in the front.

If you are riding quick pace or track I'd double check that. If you have to crank in your preload adjusters to get you sag right you need new springs. If not increase oil level as Chuck said.

pjonte has a good point about your braking. I watched a guy that was complain about bottoming on the track. In the brake zone I could watch he was jabbing the brake and blowing through all his travel. I'm not saying that is you but its something to think about.

Can you give us more info? Where are your preload and comp settings? You must have a zip tie or other method of monitoring your travel. When did your forks seem to bottom(edit. sorry, use up all there travel. How much was left?) Normal riding, hard corners, hard braking?
 

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1. Try 30-35 mm sag.
2. More fork oil (smaller air gap). Helps resist bottoming.
3. Stiffer springs. This is probably what you really need.

As Chuckracer said, what is your weight and what spring rate do you have now? I'd suggest 9-10 kg/mm for a 160-180 lb rider. I weigh 150 and I use 10 kg fork springs at the track. They don't bottom ;).
 

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Discussion Starter #6
Thanks for your responses guy.

Just to update I found that compression on one fork was actually 8 clicks out from fully closed, and the other at 13. I suspect the wide differences may have one fork nearly closed. I've set both at 12 clicks and will test again.

Good point about not grabbing the brakes. But I don't do that as i'm pretty comfortable with trail braking.





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Discussion Starter #7
Timmy, I have one of those silicone thing on my fork instead of a zip tie.

I ride mostly through the hills on Santa Cruz mountains. Spirited pace.

And at these speeds, moderately heavy braking, but not to the point where the rear tire gets squirmy, my fork indicator is at the very bottom of the travel, nothing left. I have yet to 'feel' bottoming out, but I suspect if I pick up the pace I will
 

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Guys I have a question about adjusting the air spring measurement. If say you're at 160mm, what makes for an effective / noticeable oil level adjustment from the initial 160mm air spring: 5 (155), 10 (150), 15 (145) mm etc?
 

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Guys I have a question about adjusting the air spring measurement. If say you're at 160mm, what makes for an effective / noticeable oil level adjustment from the initial 160mm air spring: 5 (155), 10 (150), 15 (145) mm etc?
I'm not sure about that one. I can let you know in about a month. I have about 2mm under my indicator(that 40 dollar Ohlins thing). My pace was off this last weekend and I'm afraid when I'm back where I should be or better it may bottom. If I'm happy with my pace and keep the 2mm I'll leave it. I'm going to bring up the stuff to add oil and play with it if need be. Should be entertain anyway.

My fork oil is set at 112mm now(not sure where it was before), stock springs, 175ish in full gear. I was told by some much better then me to try 100mm(this may be where it was last year). I'll work my way up until I have the travel I want.
 

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Guys I have a question about adjusting the air spring measurement. If say you're at 160mm, what makes for an effective / noticeable oil level adjustment from the initial 160mm air spring: 5 (155), 10 (150), 15 (145) mm etc?
Usually, 10cc per leg is good or fine tuning. And by the way, if you're at 160mm now no wonder your bottoming.

Edit: that really is 10 cc not mm I said. Once on the bike it's easier to add known amounts rather than measuring each time you add a little.
 

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I'm not sure about that one. I can let you know in about a month. I have about 2mm under my indicator(that 40 dollar Ohlins thing). My pace was off this last weekend and I'm afraid when I'm back where I should be or better it may bottom. If I'm happy with my pace and keep the 2mm I'll leave it. I'm going to bring up the stuff to add oil and play with it if need be. Should be entertain anyway.

My fork oil is set at 112mm now(not sure where it was before), stock springs, 175ish in full gear. I was told by some much better then me to try 100mm(this may be where it was last year). I'll work my way up until I have the travel I want.
Thanks for the insight and please let us know how it turns out. :)

Usually, 10cc per leg is good or fine tuning. And by the way, if you're at 160mm now no wonder your bottoming.

Edit: that really is 10 cc not mm I said. Once on the bike it's easier to add known amounts rather than measuring each time you add a little.
Thanks for responding DM,
My forks are bottoming out but I have not pulled the forks apart since purchasing the bike and so currently have no idea what the air srping is or for that matter how much oil is in each fork. I do have new (10nm) springs (track day) for my 999S Ohlins. The number (160) was just a figure I was given. Do you know what the factory air spring gap is by any chance? Also I like the idea of changing oil by volume, as after reading the manual I thougt it must be a pain in the arse to try and measure with the tool. I'm all good for volume additions & withdrawals. Thanks in advance. :)
 

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I not sure what the factory setting is for your R model but most seem happy in the 110 to 120 mm range. That's with springs out. I think the 06 S model with Ohlins speced 115 mm.

Oops, I got you confused with the OP. I have no idea what you ride. :)
 

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Discussion Starter #13
Since you guys know more about oil level setup than I do, maybe you can give me some inputs.

06 999R
I'm about 175 lbs with no gear
Fork spring is 9.5Nm / 10.0 Nm
Spring preload 6 turns in from minimum (40mm sag)
Upgraded to Superbike valves by DK
Oil level: 140 mm (measured without preload tube and without main spring)

(This whole setup was done for my by Dan Kyle)

So how is oil level measured? Is 140mm the air gap or the actual oil level? In other word, say, between 100mm and 140mm, which one has more oil?
 

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Since you guys know more about oil level setup than I do, maybe you can give me some inputs.

06 999R
I'm about 175 lbs with no gear
Fork spring is 9.5Nm / 10.0 Nm
Spring preload 6 turns in from minimum (40mm sag)
Upgraded to Superbike valves by DK
Oil level: 140 mm (measured without preload tube and without main spring)

(This whole setup was done for my by Dan Kyle)

So how is oil level measured? Is 140mm the air gap or the actual oil level? In other word, say, between 100mm and 140mm, which one has more oil?
With the fork completely compressed it's the distance from the top of the outer tube down to the oil level.
 

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So a fork with 100mm oil level will have more oil, less air?
If you have half a glass of beer and you want a full glass of beer what do you do? :)
 

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Discussion Starter #17
So how do I convert mm level to cc if I was to use a syringe to squeeze in a few drops of oil into each fork (by opening the cap of course)?
 

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I not sure what the factory setting is for your R model but most seem happy in the 110 to 120 mm range. That's with springs out. I think the 06 S model with Ohlins speced 115 mm.

Oops, I got you confused with the OP. I have no idea what you ride. :)

lol no problem and thanks...I have a 999S :)
 

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Discussion Starter #19
The specification sheet for Ohlins FG5100 calls for 139mm oil level as stock

 

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So how do I convert mm level to cc if I was to use a syringe to squeeze in a few drops of oil into each fork (by opening the cap of course)?
Ok, this is what I plan on doing next race weekend.

I was told by a very reliable source that in my fork(04 749R Ohlins) 1cc = 1mm.

I told him what was going on and he suggest putting 10cc in each leg bring my oil level up to 102mm from 112. I have a 10cc syringe I'm going to put 5cc in each and try it.
 
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