Lets talk about free bleed.

marcusgunby

Lifetime Sponsor
Joined
Jan 9, 2000
Messages
6,450
Likes
2
#1
In my quest to get the KTM suspension to my liking ive talked to many experts, and one thing thats common is they talk about the modern WP stuff not having enough free bleed in the forks.How important is free bleed-do we need any at all?Is more free bleed(within reason) better than less?Will a fork with too little free bleed be harder to set up?
 

JTT

Subscriber
Joined
Aug 25, 2000
Messages
1,407
Likes
0
#2
First I want to make it clear, I know nothing about WP components (and very little about suspension in general, but learning :) ). So, that being said, I would like to test my gained understanding so far....

1. Do we need free bleed at all? I would say you no need free bleed. Without any, the piston would be forced to flow everything (we are talking a substantial volume and rate of flow here). That would mean ports would likely be quite large and seat pressures very low (in order to overcome initial movement).

2. Is more better than less? I would say that there must be a magic balance somewhere. Too much adn you would loose the accurate metering of the valve stack, too little and you would be getting into trying to flow too much oil through piston.

3. Too little free bleed be harder to set up? I would think so, as it, again it would put the "load" of adjustment onto the piston and stack and render clickers relatively ineffective, or at least less effective.

If I'm way off, I'll blame it on a lack of sleep last night...still a little dopey ;)

JTT



------------------
Logic Over Hype Coalition
 
Joined
Oct 26, 1999
Messages
41
Likes
0
#3
I too have started to here more about "free bleed". Seems to be a "sub-low speed" thing. Meaning that it improves ride or feel in really low shaft speeds that normally wouldn't open the low speed stack and seems to be done more on bikes set up for like SX, with overly stiff springs.

I don't see how you can control were the fork would ride in the travel with it though.
 

marcusgunby

Lifetime Sponsor
Joined
Jan 9, 2000
Messages
6,450
Likes
2
#4
Jer i know this is now old for me but could we have your input on free bleed and its importance-thanks.

------------------
 

Jeremy Wilkey

Owner, MX-Tech
Joined
Jan 28, 2000
Messages
1,453
Likes
0
#5
Bleed is good.. Anyone who questions this ride a bike with the clicker maxed out.. Even with real soft valve settings it will not get much traction.. Or feel very good unless your nailing it or riding SX..

Bleed is diffrent from free bleed.. Free bleed is a fixed orfice that always bleeds regardless of clicker postion..

(I'm asumeing we are talking passive valving on the fork and active in the shock..)

I don't like free bleed at all!!

Bleed can be changed it is variable based on clicker postion..

What dooes free bleed do.. IT does increase the suspension inhernent respioncesiveness however it dramaticaly reduces your ablity to adjust the suspension..

(Lets talk about the forks..)

Lets say we have a basevalve and it has a free bleed.. The clicker can no be full stiff and we can't control the fork as well in a lower speed range.. The clicker now is impacting a faster speed range as it's flow threshold will be achived later in the speed range.. This might leed you to beilev this is good but is it? I don't think so... The basevale does a really poor job of modulating midspeed compression and it never will. So you end up adjusting a speed range that is very narrow and dificul to notice..

Now the KTM (God bless it) has a 14mm rod. This rod produces a veryt strong passive valve characteritic.. It flows lots of oil at very low speeds which makes everthing very resposive.. If there is a bike that might use one this is it.. But I still don't like the idea... The clicker still does the job just fine..

IT all comes down to once again my old song about tunning the diffrent aspects of the suspension for the ideal. If you don't run a midvalve, and have to run very stiff passive valving, well then you'll need a bleed to have traction. So I feel you've solved a problem but created another.. And as a tuner I can attest that you don't want to reduce a customers ablity to make adjustments..


Ok.. So back to some examples the new Yam desiel pigs come with paasive bleed shims.. (So did the 00 CR125) This is a shim stack that works against the clicker bleed.. It is a cool idea for SX but outdoors makes the fork just brutal..

The 80's with there linear valves have a free bleed circut that works to exstend the range of the valve. (this also renders the clicker usless in stock form) The low speed is the free bleed the mid speed or bottoming restiance is the combination of the clicker bleed and the lower range of the valve as it just starts to defelect.. The curve then goes flat once the valve opens.. Werid and stupid stuff..

Well hope that helps..

Regards,
Jer