Fork Suck Down
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- Опубліковано 5 лют 2020
- I am looking at the issue of fork suck down on mountain bike air suspension forks and fitting a debonair air spring upgrade to a set of RockShox Lyrik's
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#forksuckdown #debonair #mountainbiking #mountainbike #mtb #bikelife #cycling - Спорт
What actually causes the suck down of the fork is that people that do the lower leg service release the air from the air chamber and then assemble the fork back together with the air shaft not fully extended. It causes negative pressure in the lower legs when inflating the fork. Next time, try the zip tie trick while sitting on the front wheel and yanking up ob the bars. You will hear a hissing sound and it is actually air being pulled in the lower legs, i.e. pressure being equalized. Or, do it more civilized and flip the bike, unscrew the lower legs and tap out the shafts so the lowers dislodge, move the lowers up and down slightly and retighten the screws. The pressure will equalize, dust seals won‘t get damaged and you won‘t loose any oil. While doing lower leg service, I leave the air in the air chamber, unless I inspect the air shaft. In that case I alway pump about 50psi in the air chamber BEFORE putting the lower legs back on to make sure the air shaft is fully extended. Never get any suck down that way on none of my forks ;)
Got exactly the same issue with a brand new revelation RC I don't understand the thing is brand new why does it have negative air inside?
@@pb8582 Same here
@@pb8582I think it is because of the fork being assembled at a lower ambient atmospheric pressure. I hope this makes sense lol.
You have a fox fork don't you?
Thanks a bunch lux!! Your post was radically useful!!!
This is everything I know about the topic after years of dealing with this issue. Nicely done man!
I am having this exact issue on my Pike. Just order the debonair upgrade spring. This video was a massively big help. Very well done. Thank you!
These maintenance videos are killer, keep em coming!
I appreciate it and thanks Antti for watching.
I used the second technique with great discomfort and very hesitantly, it worked! Thank you very much 👌🏼
I did what you did on my rockshox revolation and it feels like a completely different fork now. Thank you!!
Thanks for the tip! Was ready to send into Fox service but you saved me a month of down time. To prevent damage to the bottom of the Fox fork I cut a 4 x4 down to 4" with a 5/8" hole centered 1" from the top for the axle. Then I could do the yanking up and down you detail to clear the blockage without fear of damage. Now I have full travel back!
Went straight to tip number two. Emptied both air chambers on my old u-turn, pushed it up and down a few times. Noticed it didn't go down and pumped it up again. Looks good but seems it was necessary to get the air out first. Thanks for the great video👍
Only just heard of this man and the first of his vids I have watched ( 16/3/22 ). Seems to me the most informative and easy to follow I have come across, hopefully will watch more after subscription and will be going straight to Jed MTB in the future ( better than Doddy ). thank you Jed.👍
Thank you!!! The fork push/pull method worked (after maxing air pressure) on my Fox 34 that dropped from 130 to 100mm. Avoided the time and hassle of pulling lower legs, etc. Nice explanation and stepwise process- Thx again and keep up the great work!
do u have to let the air out first?
What a time to find this.. right when I've just had this happen to my forks. Thanks
Super helpful! I totally forgot to burp the damper side on my for that had this issue. I had only burped the air spring side. That solved it for me.
Just installed the charger 2.1 and the 2020 Debonair spring on my 2019 Yari RC. Worried I had done something wrong but after watching your video at the very end you answered my question about the fork sinking in a bit!!
Same here. I thought the C1 upgrade was to resolve the way it sinks with no weight- by having it sit high in the travel. Mine still sinks by 5mm.
Great video dude thanks, solved my problem on my 2021 debonair upgrade as after fitting the upgrade it was sunk in it travel. Pushing down and pulling up worked a treat 🤛🤛
do u have to take the air out before?
Onr of the best instrucion of suckdown in negative chambars in forks! Thnks!
Thank you! My ZEB fork got this problem! Worked after maxing the PSI and pushing it. Then i emptied it all out and pumed it up my normal PSI again. Now its up and running! Nice video
Thank you for diagnosing my fork issue (it was air trapped beneath the seals) a great video
Thank you! That was extremely helpful and solved my problem!
Thanks. Method with pulling/pushing handlebars worked for me.
Thanks so much the Methode of pushibg down and pulling up fixed my fork suck down.
Very comprehensive tutorial.thank you!
Thank you very much for going from the simpliest / easier steps to more complex maintenance. The two steps solved my 1cm suck down issue on my Fox 36, now I have my full travel bike and the fork feels better (placebo effect ? ;) )
Worked on my 32sc. Thank you!
Great vide! Just used this to sort out my Revelation fork. Someone decided it needed LOTS of tacky red grease inside.
Thanks for the video. stepping on the axle and yanking the up the compressed forks cleared the grease right out and works great. So easy. Great tip.
I presume the air needs to be released from the fork before performing this manoeuvre?
1st and 2nd step solved my fork issue. Ty
I'm going to try some of this stuff out tomorrow. Ever since I installed a MRP Ramp Controller on my 2017 Fox 36 it's been sucking down when I add air to it. MRP told me to use the ziptie trick but it doesn't work. I already know there isn't any grease blocking the port because I serviced it when I installed the Ramp Control cartridge.
Great easy to follow video man !
This worked for me. Thank you sir!
Prior to taking the lowers off you can try removing the air pressure, and also removing the air can itself and repeating the pull up technique (this seems to work best on the debonair springs, which tend to suffer from this a lot more). It also makes the sound of the pressure equalising easier to hear.
Good ideas thank you
This man is a what a true hero looks like
Thanks Jed! the first method worked for me :)
Great vid, helped solve my problem. Cannot believe ive been riding around with 10% less travel than I should have .. would the rear shock have the same issue with sucking back into its travel?? Thanks again
Very well done!
I'll try these methods tomorrow
thanks 👍
Nice vid! I've just subscribed.
I unfortunately had this happen on a brand new 150mm Pike last week. It's currently in the LBS but if I'd seen this before then, I think I'd have given it a go myself.
Hi Jed! Very good video!
I have a question: My Pike RC3 160 mm and 27.5, 2015 began to do noisy extension knoks after disassemble it to clean, grease, put new seals on debonair and main bottle seals. It seems the opposite problem as yours... but with the same origin: unbalanced + and - air chambers.
I disassembled it and purged the charger, which had some bubbles, but the problem didn't disappear. After disassembling the fork several times, I tried to enter the debonair but not with the shaft extended (like the manual says), leaving about 5-6 cm of the shaft out of the stanction. It was the only solution I found, liying the fork. Doing this, I preloaded the negative camera with a big amount of air which was useful to solve my problem retaining the stanctions at the end of the travel during the extension, but: Now I have a doubt: I think the two cameras haven't a good communication and I think too may be the bypass is obstructed. I've tried to under and overload the positive camera bumping the fork to try to clean the communication hole, but without results...
I will have to disassemble again my fork... If the communication hole is clean, what can I look for more?
Thanks you and best regards!
This was great, thank you!
My Reba suspension also got a little bit of travel at the beginning of the stroke, as shown in minute 24:55 of the video. In one of my maintenance, I put 5ml more oil on the side of the hydraulic cartridge. When testing, I saw that this initial travel disappeared
zip tie down the air side of the fork did it for me along with the wheel off pull method :)
Spot on great videos
Thank you so much
That was very helpful
Question if for any chance that the damper inner rod got scratch is the fork still useful and safe??
I am really struggling with my suck down fork it's a RockShox Pike Select+ 150mm of travel. Quick question my fork has a damage straight scratch on it stanchion does it makes the problem suck down?
In the begining, after you mentioned the nylon tie trick, you suggest finding the maximum air pressure listed on the fork. Then you jump right into the fork tear down. What do I do with the fork after I put in the max air pressure? Also, why wouldnt the nylon tie work in the first place? Maybe a different type of nylon tie? a bigger one? Maybe if I let all the air out of the air shaft side to reduce the pressure required to get that tie in between the o ring and the air shaft? Thanks
The tie method is independent of the air pressure, what it does is let any trapped air out from the lowers as they shouldn't have any, only the upper stanchion on the air spring side has any air, after you set the max pressure just do the same thing as show in video, I recommended this as the extra pressure can sometimes help force the grease out and stop the fork sucking down, if it fixes it then return the air pressure back to the correct setting for your weight.
Hi is it normal to have the travel of the fork sitting at 20% sag on rockshock lyrik
This is amazing! Thanks a lot for being so thorough and logical. I wonder where exactly in the travel the balance valve is located? In the fox info vid at the beginning of your video makes me think its at the top out?
Thanks, the placement varies between different brands but most have it at about a quarter of the travel.
That no resistance thing on the first 3-5 mm of travel also happens on suntour forks
zip tie fixed my problem thanx alot!!! the suck down occurred when i took all the air out when trying to put air....does that make sense to you?
ps: manitou circus pro
Hi! Great vid on the topic! I have an issue with my fork. Its a Reba xx dual air 29 fork. I got the air spring rebuild kit and changed it because it would suck down the fork and only use about 30% of its 100 mm of travel, but after installing the air springs, its gotten even worse! Now it bottoms out all the time. Please, I would really appreciate some help on this issue. Any commehts?
Thank you.
I have a 2023 Fox 38 factory… the fix I made was to let out all the air > insert a small zip tie between the seal and stanchion on both sides as mentioned in this video > pull up the handlebar while sitting on the front wheel > push it down a bit for a couple seconds > pull the handlebar back up… do this about 5 times. And on the 6th time of pulling the handlebar up, hold it for as long as you can, even trying to pull it higher than in previous tries. It should eventually release or remove some air (I couldn’t tell which one happened)… once this happens, start pumping air every 50psi and cycle through a few times. Hope this helps anyone.
i had a very very small crack around the air valve on top of the alloy fork cap, this resulted in sucking the fork in (after a fork rebuild, it looked fine but after a few hours it started to drop) took me a while to figure this out! air valve was fine, everything seemed fine. use some leak detection spray or soap and spray this on the fork cap and you will see if this is the case. Cheers!
I only lightly paid attention to this 'issue' and swapped out the air spring on my rockshox with a newer version (increased travel also). Yet is it an actual issue? The effect only occurs unweighted and since nobody rides unweighted, once sag is set is it not the same in actual effect?
Thank you so much.
On my Bluto fork I noticed it was stuck down, on the air spring side lowers I removed the nut and noticed a scharader valve I compressed the valve and the fork extended. Does this resolve the problem?
My Lyrik RC2 came with a machining default near the transfer port (inside the stanchion) that scratched the seal of the Debonair airshaft. After a few rides, once the seal was no longer tight, the air passed into the negative chamber making the fork sucked down (25%). It took 2 fork services and 3 new seals to find out the cause...Only new fork stanchions under warranty solved this problem!
Sounds like a nightmare, good to hear you got it sorted.
Does it need to be low in pressure when uou pull it because i see you squish it really easy
OMG that did worked! Thanks
Such a good tutorial
Great VIdeo!!! Thanks
wen i like bounce on my suspension it does a sound that like the metal smacks something if i went to pull it up to do wheelie it does it..??
can you explaining recurring fork suck down? I know how to fix it but after every ride i have air trapped and i get fork suck down. i have changed the airshaft and it did not help.
Thank you so much for the video
Hi, i need to put all the air out of the fork before puting the cable tie? i am having this issue with my rockshox 35 gold RL, first time with an All Mountain Bike
You leave the air in when doing it.
Great !
Hi I hope someone will see this and can help i have a rockshox lyrik 170mm travel like the one in the video and i have the opposite problem (a lot of "sticktion") is there a reason for this and is there a fix
The explanation of the issue is @25:00 is all I needed to hear
thanks awesome video
the pull-up technique worked great, but my rebound dial got stuck, i can’t move it either way. what should i do?
Unscrew the screw that hold the rebound dial on then pull it down a tiny bit and retighten the screw, be very careful not to over thighten it, the dial should move freely again.
My fork only goes around 5mm down before it sorta bottoms out, any idea
I have just received a brand new set of 2019 pikes that are stuck around 5-8% sag. I have removed the air cap, pulled up on the stanchions and I did hear some air come through the port but has made no difference. Would you have any ideas?
Hi Luke, 5-8% is normal for Rockshox, they have just released a C1 airspring which claims to make them sit higher but I've not tested one yet so can't verify if it works or not. www.sram.com/en/rockshox/models/fs-upk-db-c1
@@jedmtb thanks for the reply buddy. I may order the new airshaft when it's first service gets done.
I'm having an issue with new Fox Fork 36 on new bike. The fork is almost completely sunk down the tube. When I press down on it, it "bottoms out" but doesn't rebound back. Any tips?
Is your air pressure set ok?
@@jedmtb Honestly, I just purchased the bike and assembled the front and back tire. I believe the fork was pre-assembled with the proper air pressure. It feels like it has almost no air pressure as the fork looks completely sunk. The stem of the fork is only about 4 or 5 inches visible. The remainder of the stem is inserted into the fork. I can pull it out - but over time it just sinks in by itself, even without use.
How come u don’t have 1 million subscribers??? :)
Have you ever come across a suck down that you cant pull apart? I did all the necessary procedures on my fox float 29 and the lowers are so sucked down that they wont pull apart. Seems like I over charged the fork so bad. Tied it to a tree and used full body force and still couldn't pull it apart. release all air pressure, knocked the bottoms out, oil drained, etc etc. trying to avoid paying 200$ to send it in when I can do it myself. Any thoughts?
Sounds like air is trapped in the lowers, try removing the lower foot nuts and pushing the damper and airspring, this video shows what I mean at 6:00 ua-cam.com/video/xB5rc602MhQ/v-deo.html
@@jedmtb Thanks for the reply! I actually just sent the fork in this morning to fox to get a full service. I did what you said and still nothing. Hope I get it back in one piece. thanks again!
Hey what fork oil are you using I noticed it’s not rockshox, wanted to service mine but don’t wanna pay full price for rockshox oil
I use MOTOREX Supergliss 100k in my lowers.
Does this solve the suck down problem on spring loaded forks like the sun tour xct?
I can but it depends on what the issue is, as suck down issues can be caused but a number of things.
i have the same problem but in my case the charger leaks oil
My rock shock yari is about suck down like 8mm it’s pretty new is that normal
Yes if you want it to sit higher you'll need to replace the the air spring with a C1 version
www.sram.com/en/rockshox/models/fs-upk-db-c1
My rockshox front suspension is stuck all the way down with no air in them and I've tried so many to to pump air in them but the air won't go through the valve
You could try removing the Schrader valve core and checking for any blockages from grease or oil.
You do the push pull whit the regular air set up?
Yes this only works on air.
I got a push ACS3 kit. Solved.
When are the crush washers supposed to be used ?
Between the fork lowers and the foot nut bolts.
Zip tie would let air in if that sorted the suck down. It doesn't affect the fork anyway.
Excellent video, now I'm actually quite surprised by "if it's at 10mm isn't a issue"... I got a san Quentin 3 and went from 130 to 140mm both cases I got my fork not using the all traveling cos it's sit at 10% it's a RC revelation now 10 percent doesn't seem a lot when you have 170mm but when I had my set up at 130mm it was a lot it's like having 120mm suspension and a saggy one coming from a fox 36 my revelation feel like absolute cheap made... I mean the san Quentin 3 is a dirt jumper all mountain when you start sending 2 metres drops and 3 metre gap jump you don't want your suspension to feel like this particularly on a hardtail... Very disappointed by rockshox we tried everything and nothing works it's going back again to the mechanic to check it but I don't feel like this feeling is normal. And I run my suspension at 4 tokens 100 psi and I'm 77kilos that when I feel it alive a bit... And still losing 10% of my fork... Weird
You'll need to get a DebonAir C1 airspring which makes the fork sit higher. www.sram.com/en/rockshox/models/fs-upk-db-c1
@@jedmtb cyclinic.com.au/collections/fork-spares-rockshox/products/rockshox-air-spring-sealhead-kit-debonair-c1-my18 I think you can only get this and that will work as they are exactly the same shaft
Can this “suck down” apply to rear suspension
Yes but it's normally a failed seal or air mixing into the oil (Cavitation)
Arent their also rock shox forks that have that isually? Mine have that.
Mine is sucked down like 5%
The butter is worthless. All it does is pack up on top the seal heads and doesnt lube anything.
I recommend taking butter and 30wt oil and mix until the butter un thickens. Pour over seals. Put .03 ml in the middle of the air chamber. Then remove the top cap and add .05ml so just enough to coat the seal head. This will give you the best sbc you can have. Use this mixture on dropper post as well as on stanchions. Its the best of both worlds.
Appreciate the tip, I'll give it try next time I'm changing the oil.
My rockshock reba fork is losing air presure, and the left dust seal is coming out. Also the fork does not come back and just stays down while riding. Any solitions ?
That sounds like the seals on the air spring have failed, it’s a fairly common issue on the reba’s Rockshock sell seal kits to fix it or you could send it to a suspension shop for a full service.
@@jedmtb I can't realy find the air spring seal kit. Where can i order one ? I live in Europe.
@@kristapains1833 What year and model do you have?
@@jedmtb i have RL 27.5'' 100mm solo air spring rockshock reba
@@jedmtb I don't know about the year but it is not the old 2014 model it's like 2019 or something like that
There’s no need to worry about air bubbles with the oil?
Not in the lowers, only in the damper but they're normally sealed units with their own oil.
Can I install a debon air kit in a Lyrik dpa - 17? 🤔
No, unfortunately. 😕
@@jedmtb oh crap! 😔
If anyone has a debonair lyrik and it's sucking down about 10mm, that is a feature not a flaw.
Yep and if you want it to sit higher then Rockshox now offer a new 2021 DebonAir airspring and Vorsprung Suspension make the Luftkappe which does the same thing.
Lol dying
@Tomi_Henrik @Jed MTB is that really true? I got a used Lyrik and was a bit confused about that "SAG" ... A friend of mine did a little service and i was worried that he did a mistake or trapped some air in the lowers. But if its a "feature" than ... WOW :D haha
@@simbic53 Well all 2020 debonairs do that...so its a kinda unwanted "feature"
Really? My rockshox yari also sinks 10mm down. Is it normal for debonair?
I need to do this trick on coil fork?
No as the height is controlled by the coil spring.
bro, super nice video. I have a rockshox 35 gold and i think my fork have problem. can i send you a 5 seconds video to show you how my fork is working? becouse im thinking to send it to warranty but maybe is just need mantention. i dont understand nothing of forks
Yes no problem.
@@jedmtb here is the video Jad! ua-cam.com/video/tw_BqNY1P9c/v-deo.html&ab_channel=mauricioaguirre
@@mauricioaguirre89 hi man. Same issue on my Commencal RockShox 35 gold. How did you fix it? Lower leg service helped a little. But still not good
@@jancincar6747 i send the fork to commencal and them change all the tubes. names "botellas" in spanish. after it the fork works ok
@@mauricioaguirre89 oh, not happy to hear that. I dont want to send it anywhere. This fork is nightmare. Sram should take all this forks back for free, they selling crap
It went together easily in less than an hour. ua-cam.com/users/postUgkxHL1v1R3NE5x4KiYfyt8dnQmyNYz7qi5L Make sure the front fork is forward or the pedals will hit the front tire. Tires are both a little soft so it needs air before I ride it. The rear wheel didn't come with a clamp regular bolts hold it on. The front had the clamp. No scratches out of box. Rims are a little off with a slight wobble. They could have spent more time with the spoke tool fixing the run out. So far out of the box I'm happy with it. I did replace the pedals with a nice aftermarket set. After riding it a bit my A$$ is a bit sore so I ordered another seat. Overall I'm nearly 60 and didn't ride a bike in 30 years. I like my new 29" Schwinn. It will be used for casual rides with my friend.
Nothing a full service won't cure.
Depends on the issue, RockShox removed the sag indicators from its newer forks making it harder to spot.
Corrosive oil? Are you sure? Isn't this basically the same as the motor oil I have on my hands all day anyway?
I must have soft hands :) it makes my skin peel.
What you trying to say about my forks. No scratches on them..
I scuffed them up for you.
Thinking that the grease in the equalisation port is a reason for suck-down is a very common misconception. This won't be cause of the fork sucking down. When you consider that the left stanchion has 50psi upwards in it, there's no way that a blob of grease is going to stop the air from channeling though the little port.
More often than not its either a worn seal on the air piston, or that its been inflated incorrectly. People believe the 'grease in the port' myth because they pull the air assembly apart, clean it, and put it back together to discover it works again, when all they've actually done is released the trapped when disassembling. The grease has nothing to do with it.
Its also worth noting that if you find trapped air under wiper seal when you slide a zip tie under it, then you've got an air leak. Air will only be present in lower left hand leg if the seals on the seal head are leaking and allowing air to leak from the stanchion into the lower leg. In which case you need to replace the air seals on the seal head.
The pressure release buttons found on the back of some forks are for use when reaching the top of extremely high mountains to let you release the build up of atmospheric pressure (unlikely to ever be needed in the UK).
To avoid this, use coil fork lol.
I like your thinking :)
Go to 7:00 for the fix