Forks - High Speed Characteristics

All Mountain · Dec 20, 2006

What makes a fork good at high speeds through rough terrain ?~?

I will sacrifice low speed qualities to gain high speed response over rough terrain.

When your pushing downhill (and it doesn't have to be steep) and at high speeds where your fork is into the middle portion of travel and there are plenty of rocks and ruts .... I have found many forks are just dead in this zone.

What is happening with forks in this scenario and what do I have to do to get better performance. Or is it something I have to live with? I'm not interested in fork bashing just opinions on how forks and certain fork designs perform in this scenario.

Chris9702l · Dec 20, 2006

Four letters

PUSH:thumbsup:

FM · Dec 20, 2006

I'll take a crzack at it!

The two big things I've noticed with forks are; people use to much rebound damping and the fork packs down, and; people mis-use compression damping and pre-load to firm the fork up.

In many instances, if the fork offers adjustable compression damping, you can run a softer spring and use the compression to prevent the fork from diving. The important thing is to use pre-load to make sure your sag is correct (compression damping usually doesn't affect this so much) then tune the compression damping to prevent brake dive/ bottoming.

Rebound- in general I run it faster than I think makes sense, which benefits high speed performance.

If the fork feels like it's folding under teh fron of the bike, that often means rebound is too slow. Likewise, if the bike feels like it's "snaking", or you are having a hard time getting the front to stick in corners, it may be too fast.

Amazing what a difference fresh oil makes sometimes.

Oh yeah, last thought- weather and altitude make a huge difference. I always re-tune my suspension on MTB road trips; likewise I do it a few times a year as the seasons change.

blackagness · Dec 20, 2006

All Mountain said:
What makes a fork good at high speeds through rough terrain ?~?

I will sacrifice low speed qualities to gain high speed response over rough terrain.

When your pushing downhill (and it doesn't have to be steep) and at high speeds where your fork is into the middle portion of travel and there are plenty of rocks and ruts .... I have found many forks are just dead in this zone.

What is happening with forks in this scenario and what do I have to do to get better performance. Or is it something I have to live with? I'm not interested in fork bashing just opinions on how forks and certain fork designs perform in this scenario.

You absolutley read my mind! I've been ponderig this very question for a while now. I think the faster and rougher the terrain get's, the better the fork should feel.

All Mountain · Dec 20, 2006

ok.... lately I've been running rebound almost full fast (if not) and certainly has helped things. I get some snaking at lower speeds especially the fork with real fast rebound but all pay that price in many instances. My RP23 is full fast and really not fast enough at times. Why is this so ?~?

I have troubles setting my sag... I mentioned before it is so variable due to my HA. I slight weight shift can make it 35% or 20%. Any advice ?~?

Preload in AM series is air which seems to affect damping, or is this my imagination ?~?

Are you saying too much sag is bad for high speed damping ?~?

I use no low speed compression (well knob is at lowest setting) and cater for dive when I ride trails I know. Unknown areas or where I know I need to keep my noes up I will crank it. At these times it's not high speed so I'm ok with that. I assume low speed damping settings can/could interfere with high speed damping so i back it off regardless (as I don't really fully understand relationship yet).

Is this a primary limitation and directly related to a particular forks damping system ?~?

Anyways, keep the thoughts coming FM and other people. Please post anything to let a few things fly !~!

Cheers

FM said:
I'll take a crzack at it!

The two big things I've noticed with forks are; people use to much rebound damping and the fork packs down, and; people mis-use compression damping and pre-load to firm the fork up.

In many instances, if the fork offers adjustable compression damping, you can run a softer spring and use the compression to prevent the fork from diving. The important thing is to use pre-load to make sure your sag is correct (compression damping usually doesn't affect this so much) then tune the compression damping to prevent brake dive/ bottoming.

Rebound- in general I run it faster than I think makes sense, which benefits high speed performance.

If the fork feels like it's folding under teh fron of the bike, that often means rebound is too slow. Likewise, if the bike feels like it's "snaking", or you are having a hard time getting the front to stick in corners, it may be too fast.

Amazing what a difference fresh oil makes sometimes.

Oh yeah, last thought- weather and altitude make a huge difference. I always re-tune my suspension on MTB road trips; likewise I do it a few times a year as the seasons change.

blackagness · Dec 20, 2006

Am!

As for your first question IMHO just set your sag sitting square on the bike. Don't worry about slight leans forward or back. What can ya do? Ya just gotta set it, and not worry about it.

I once read that you should set less than recommended... like for going down hill your sag would even out to recommended. I have no idea as to the validity of this theory? But on occasion I'll consider that when I feel I'm unable to get "enough sag.

All Mountain · Dec 20, 2006

blackagness said:
As for your first question IMHO just set your sag sitting square on the bike. Don't worry about slight leans forward or back. What can ya do? Ya just gotta set it, and not worry about it.

I once read that you should set less than recommended... like for going down hill your sag would even out to recommended. I have no idea as to the validity of this theory? But on occasion I'll consider that when I feel I'm unable to get "enough sag.

I'm not too fussed on sag... except for the AM fork. The preload is air and it goes in the damping side. Does it affect damping ?~?

blackagness · Dec 20, 2006

All Mountain said:
I'm not too fussed on sag... except for the AM fork. The preload is air and it goes in the damping side. Does it affect damping ?~?

IMO it does greatly!

But I'm in the same boat as you on this one "ie" just what it feels like to me?

But also in my air lose adventures, I'm able to get a very good feel for how it "IMO" affects damping.

All Mountain · Dec 20, 2006

blackagness said:
IMO it does greatly!

But I'm in the same boat as you on this one "ie" just what it feels like to me?

But also in my air lose adventures, I'm able to get a very good feel for how it "IMO" affects damping.

Did you find any bubbles ?~?

Can you describe how it affects it at high speeds ?~?

blackagness · Dec 20, 2006

Hmmm... Let Me Think??

All Mountain said:
Did you find any bubbles ?~?

Can you describe how it affects it at high speeds ?~?

Too much air and it feels harsh and you loose traction. Too little air and it feels harsh, and SLOW , it bottoms like crazy, and you loose any abilty to pre-load the fork safely. I 'd say too little air is worse as it slows the rebound down so much, and it looses that "sweet supple feel" when hitting bumps.

FM · Dec 20, 2006

On both "All mountain" forks I have owned, I have been happiest with the "one click firmer than the plushest DH setting". This allows me to run less air preload, so I still get the small bump compliance.... and the compression damping keeps the fork from diving/bottoming. When I have tried the plushest setting, I end up wanting to add pre-load. But, less pre-load and more compression damping feels way better to me.

Interestingly, my roco TST seems pretty much the same way- the softest setting is just too soft (so far- still tweaking & getting to know it)

Talking to the Marzocchi techs up at whistler this summer, they were big on adding 3-5 pumps of air pre-load to their forks, even for lighter riders. Not enough air pressure to register on a gauge or even effect the feel in the first inch of travel- but enough to help the fork sit higher in it's travel. It makes sense and I was much happier with my 66 after trying it.

All Mountain · Dec 20, 2006

FM said:
On both "All mountain" forks I have owned, I have been happiest with the "one click firmer than the plushest DH setting". This allows me to run less air preload, so I still get the small bump compliance.... and the compression damping keeps the fork from diving/bottoming. When I have tried the plushest setting, I end up wanting to add pre-load. But, less pre-load and more compression damping feels way better to me.

Interestingly, my roco TST seems pretty much the same way- the softest setting is just too soft (so far- still tweaking & getting to know it)

Talking to the Marzocchi techs up at whistler this summer, they were big on adding 3-5 pumps of air pre-load to their forks, even for lighter riders. Not enough air pressure to register on a gauge or even effect the feel in the first inch of travel- but enough to help the fork sit higher in it's travel. It makes sense and I was much happier with my 66 after trying it.

Thanks. I will try a bit less air and using 1 click instead of none. Would you like to hazard a guess as to how much preload psi for 220 lbs ?~?

demo_slug · Dec 20, 2006

All Mountain said:
Thanks. I will try a bit less air and using 1 click instead of none. Would you like to hazard a guess as to how much preload psi for 220 lbs ?~?

for you....
I would recomend a girvin linkage fork, with a noleen coil.

All Mountain · Dec 20, 2006

demo_slug said:
for you....
I would recomend a girvin linkage fork, with a noleen coil.

your getting a bit cheeky... have you got some aussie blood in ya ?~?

blackagness · Dec 20, 2006

FM said:
On both "All mountain" forks I have owned, I have been happiest with the "one click firmer than the plushest DH setting". This allows me to run less air preload, so I still get the small bump compliance.... and the compression damping keeps the fork from diving/bottoming. When I have tried the plushest setting, I end up wanting to add preload. But, less preload and more compression damping feels way better to me.

Interestingly, my roco TST seems pretty much the same way- the softest setting is just too soft (so far- still tweaking & getting to know it)

Talking to the Marzocchi techs up at whistler this summer, they were big on adding 3-5 pumps of air preload to their forks, even for lighter riders. Not enough air pressure to register on a gauge or even effect the feel in the first inch of travel- but enough to help the fork sit higher in it's travel. It makes sense and I was much happier with my 66 after trying it.

Are we talking about the same fork? I could see one or two pumps in a Z1 but an AM1??? Maybe your just saying "run as little air as possible" I don't know but in my exp it bottoms, and lives at the bottom half of it's travel unless I run 15-20 psi "180lb rider". Also if I get any speed on rough terrain with anything but the DS setting it feels "platform-y" and harsh.

FM · Dec 20, 2006

All Mountain said:
Thanks. I will try a bit less air and using 1 click instead of none. Would you like to hazard a guess as to how much preload psi for 220 lbs ?~?

blackagness said:
Are we talking about the same fork? I could see one or two pumps in a Z1 but an AM1??? Maybe your just saying "run as little air as possible" I don't know but in my exp it bottoms, and lives at the bottom half of it's travel unless I run 15-20 psi "180lb rider". Also if I get any speed on rough terrain with anything but the DS setting it feels "platform-y" and harsh.

Ah yeah, sorry guys that was a bit misleading.

The main thing I was trying to get at, is to try running less air pre-load and then use some compression damping (i.e. one click of TST) to help keep the fork near the top half of it's stroke.

With no compression damping/TST, you need to add excessive air pre-load to keep the form from diving/bottoming, then you are losing high-speed/small bump compliance. That's been my experience anyways.

As for pressure- I think I settled on 25-30psi in my all mountain 1, I weigh 175lbs and usually carry a decent sized pack. Feels perfect with 1 click TST.

All mountain, for you? I am not sure. I wouldl check the manual and try 5-10psi less then they recomend. Have you looked into the availability of a firmer coil spring? seems like you'd be better off to get a firmer coil so you could keep your air pre-load pressure lower.

OT: All Mountain, did I read in another post that you have a 500# DHX spring that didn't work out? I need one for my roco- PM me if it's up for grabs....

blackagness · Dec 20, 2006

Very Clear Thanks...

FM said:
Ah yeah, sorry guys that was a bit misleading.

The main thing I was trying to get at, is to try running less air preload and then use some compression damping (i.e. one click of TST) to help keep the fork near the top half of it's stroke.

With no compression damping/TST, you need to add excessive air preload to keep the form from diving/bottoming, then you are losing high-speed/small bump compliance. That's been my experience anyways.

As for pressure- I think I settled on 25-30psi in my all mountain 1, I weigh 175lbs and usually carry a decent sized pack. Feels perfect with 1 click TST.

All mountain, for you? I am not sure. I would check the manual and try 5-10psi less then they recommend. Have you looked into the availability of a firmer coil spring? seems like you'd be better off to get a firmer coil so you could keep your air preload pressure lower.

OT: All Mountain, did I read in another post that you have a 500# DHX spring that didn't work out? I need one for my roco- PM me if it's up for grabs....

I'd say you cleared that up nicely... Thanks! And thanks for the insight. Your suggestions will be helpful for me to keep in mind while doing my tuning. :thumbsup:

Seriously. It's info like what you described above that helps "me" in getting this type stuff dialed in. If anything else springs to mind, and you have a notion please... don't hesitate!

blackagness · Dec 20, 2006

Very Clear Thanks...

FM said:
Ah yeah, sorry guys that was a bit misleading.

The main thing I was trying to get at, is to try running less air preload and then use some compression damping (i.e. one click of TST) to help keep the fork near the top half of it's stroke.

With no compression damping/TST, you need to add excessive air preload to keep the form from diving/bottoming, then you are losing high-speed/small bump compliance. That's been my experience anyways.

As for pressure- I think I settled on 25-30psi in my all mountain 1, I weigh 175lbs and usually carry a decent sized pack. Feels perfect with 1 click TST.

All mountain, for you? I am not sure. I would check the manual and try 5-10psi less then they recommend. Have you looked into the availability of a firmer coil spring? seems like you'd be better off to get a firmer coil so you could keep your air preload pressure lower.

OT: All Mountain, did I read in another post that you have a 500# DHX spring that didn't work out? I need one for my roco- PM me if it's up for grabs....

I'd say you cleared that up nicely... Thanks! And thanks for the insight. Your suggestions will be helpful for me to keep in mind while doing my tuning. :thumbsup:

Seriously. It's info like what you described above that helps "me" in getting this type stuff dialed in. If anything else springs to mind, and you have a notion too please... don't hesitate!

All Mountain · Dec 20, 2006

FM said:
All mountain, for you? I am not sure. I wouldl check the manual and try 5-10psi less then they recomend. Have you looked into the availability of a firmer coil spring? seems like you'd be better off to get a firmer coil so you could keep your air pre-load pressure lower.

Yikes.. the manual says > 60 psi I didn't realise you could get a stiffer spring. All they talk about is air preload. The real solution sounds like a stiffer spring so I can drop the air and get a more consistent ride through the travel range. I will look into this. I will drop 5 psi from what I'm doing now and give 1 click a go, it may be the better option for me at the moment.

demo_slug · Dec 21, 2006

All Mountain said:
Yikes.. the manual says > 60 psi I didn't realise you could get a stiffer spring. All they talk about is air preload. The real solution sounds like a stiffer spring so I can drop the air and get a more consistent ride through the travel range. I will look into this. I will drop 5 psi from what I'm doing now and give 1 click a go, it may be the better option for me at the moment.

the seal stiction of an air fork, combined with the weight of a coil. sounds great.

Forks - High Speed Characteristics

All Mountain

Chris9702l

FM

blackagness

All Mountain

blackagness

All Mountain

blackagness

All Mountain

blackagness

FM

All Mountain

demo_slug

All Mountain

blackagness

FM

blackagness

blackagness

All Mountain

demo_slug

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