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  1. #1
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    Need help on Firebird suspension

    Hi guys, i just got the 2012 FB, am loving the bike so much. Its really climbable on my local trails and yesterday i went to try out its DH capabilities. I use to own a giant glory and a titus ftm, but sold them both as i hoped the FB can be my do it all bike. But after the ride yesterday i find that there are issues with the rear shock.

    My setup is 170mm fox float rc2 upfront and the dhx air for the rear. I followed the suspension setting as posted in the pivot site for the fb, i weight abt 170lbs geared so the base line setting is nearly there.

    Issues is when i started to clear kicker jumps abt 4 feet high and launching me abt 3-4 bike lenghts away, with slight gradual receivers. the rear dhx feels abit harsh on the landing. i dont like how the bottom out feels. the feeling is not the same as the front forks. Felt that the rear compresses too fast and harsh near the end of the travel. after clearing the jumps both the front and rear nearly bottoms out, sparing the sag o-rings abt 3-5mm from max travel.

  2. #2
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    Dimensionally, you and I are probably pretty close. I'm riding a large frame w/ DHX 5 Air and a Totem coil @ 180mm up front.
    I have not ever managed to get that shock to function amazing for park riding. It definitely does not have a 'bottomless' feel as pretty much any hit will blast through the travel. I do not feel the bottom out but I generally don't have the O-ring on the stanchion after about 3 minutes into the ride.
    My plan was to get a RC4 coil but that never came to fruition in the light that I have an 09 frame with the skinny carbon rocker and I'd have to replace that as well. I have too many repairs to spend that much on an upgrade.

    28lbs in my rear 2.35 Nevegal tire.
    I run about 20mm +/- 1 on my sag.
    180lb in the boost (I can't often tell because my pump bleeds so much when it is removed)
    2 1/4 turns of bottom out (1/4 turn past the 2nd line on BO indicator lines)

    Good luck
    Common sense is not so common - Voltaire
    Never underestimate your own ignorance - Me

  3. #3
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    Quote Originally Posted by btibben View Post
    Dimensionally, you and I are probably pretty close. I'm riding a large frame w/ DHX 5 Air and a Totem coil @ 180mm up front.
    I have not ever managed to get that shock to function amazing for park riding. It definitely does not have a 'bottomless' feel as pretty much any hit will blast through the travel. I do not feel the bottom out but I generally don't have the O-ring on the stanchion after about 3 minutes into the ride.
    My plan was to get a RC4 coil but that never came to fruition in the light that I have an 09 frame with the skinny carbon rocker and I'd have to replace that as well. I have too many repairs to spend that much on an upgrade.

    28lbs in my rear 2.35 Nevegal tire.
    I run about 20mm +/- 1 on my sag.
    180lb in the boost (I can't often tell because my pump bleeds so much when it is removed)
    2 1/4 turns of bottom out (1/4 turn past the 2nd line on BO indicator lines)

    Good luck
    yeah man.. whats up with the boost losing so much air and a pain to pump up to the required pressure. I pumped up the boost to 170 psi and 165 for the shock itself. ill get abt 5mm up from the sag indicator that comes with the dhx air.

    the dhx is amazing on those smaller jumps but the bigger hits you have to nail the landing spot on to get just an ok feel...

    if... and its abig IF, i intend to run coils on the bird, i have to get the alum rockers right? any chance i can still use the carbon ones?

  4. #4
    dog
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    ... when you say gradual receivers, i am assuming you mean it does not have a steep slope or it's somewhat flat? if so then, yeah, i would think that is probably normal. my DHX air will push the o-ring off in those situations even on smaller jumps. i never feel a harsh bottom though (with a 4 foot drop to flat or somewhat flat)... on the other hand, i don't go much bigger than that though ...

    i have found that if my fork is set a little "softer" (less air and/or high speed compression) then it does seem to to reduce somewhat the tendency of the DHX air to go through the travel so much... i am not sure if that even makes sense or is a factor of my poor technique though...

    gticlay runs a coil i think (or has) on his, maybe he can chime in ...
    i need to develop my crashing skills...

  5. #5
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    I know you can't run a coil with the old carbon rocker, but I thought I read they modified the new ones so a coil will fit. Ken,Dan, or gticlay can answer better.
    Common sense is not so common - Voltaire
    Never underestimate your own ignorance - Me

  6. #6
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    I'd double check the setup before swapping out shocks. I've been running the DHX for years with no issues, it's very tuneable so you can pretty much make it feel any way you like. The biggest issue I've seen is riders not getting the sag set properly. You MUST bounce hard on the saddle to get the suspension deep into it's travel (past the static sag point) then move the O-ring up to the wiper seal while remaining on the bike. If you just sit on the bike and measure it there you'll end up running too much sag and will def. blow thru the travel easily. The 2nd setup item is the Boost pressure and Volume. I've found these to be VERY sensitive and a change of only 10 psi will really make the bike ride different. The baseline settings on the setup chart are really meant as a starting point and you can fine tune from there. I like to do multiple runs on the same section of trail when dialing the shock/fork and only make 1 adjustment at a time. It takes time but getting the suspension balanced is the key to a good feel. The coil will def. make the rear suspension more supple but you won't have the fine adjustment that the air provides....
    Desert Sunset Calls/Upward, Pain, Perseverance/Welcome Solitude

  7. #7
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    OK, thread-jack, sort of...

    kenbentit, now i am aware we had a similar mtbr discussion before... but i am slow to learn...

    let's say my ride weight is about 160-165... right now i think my air chamber is about 170and my boost about 160, and my bottom out is about 2/3 in from full out... i like my ride a little soft in the middle because i suck at cornering and a soft middle seems to help with traction... i know my sag is good because if i mash my pedals up a steep asphalt grade i get almost no movement in my suspension... (and yes i am too uncoordinated and/or not smart enough to confidently set the sag in the prescribed meathod - if i do it 3 times in a row, maybe two will agree and one won't, for instance).

    anyway, i can hit a nice 2-3 bike length jump with a 2-3 foot drop and a perfectly sloped transition and barely use any travel, for instance. At the other end of the spectrum, there is this annoying little ditch jump at the bottom of a hill on one of the trails i ride that is a little over a bike length and a 2' drop to flat, and i have to absorb the stupid-flat (probably upsloped) landing using my whole body and pretty much all the travel in the fork (set at 180mm) and i'll push the o-ring off the rear 1/2 the time - i don't feel it bottom per se, but the landing still feels harsh ... (i really don't know why i even hit that jump... i guess because it's there )...

    so, my question is (and i am not asking to be difficult - i really want to make sure i understand): can i really monkey with the adjustments on the DHX air enough to get the "normal" performance i want and at the same time un-harshifying annoying landings like the one i described above? if so, i will begin the monkeying process (again )...
    i need to develop my crashing skills...

  8. #8
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    You should be able to get that feel just by working on the Boost settings. Try adding some pressure to the boost chamber (170 psi) and see what kind of change that makes. Checking the sag doesn't take any special coordination. I'll use something convenient to balance against (bike stand, tree, rock, car, etc) and hold onto that with one hand while using the other to reset the O-ring. You do need to make sure the ring gets pushed all the way up though. It's easy to only get part of it pushed up and it has a tendency to roll/slide back down a bit of that happens.
    Desert Sunset Calls/Upward, Pain, Perseverance/Welcome Solitude

  9. #9
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    Quote Originally Posted by kenbentit View Post
    You should be able to get that feel just by working on the Boost settings. Try adding some pressure to the boost chamber (170 psi) and see what kind of change that makes.
    OK... you're usually right... i'll monkey with it again... but my past experience is that this will affect my prefered mid-travel squishiness...

    Quote Originally Posted by kenbentit View Post
    Checking the sag doesn't take any special coordination.
    ... i know... pretty pathetic, huh?
    i need to develop my crashing skills...

  10. #10
    dog
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    OK... test run complete... 170lbs in the boost chamber may a llittle better for a single harsh hit, but kinda pogo-ie over roots for me... I'll stick with 160...
    i need to develop my crashing skills...

  11. #11
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    Also try fine tuning the Boost Volume. That's the good thing about that shock, very tuneable. Or bad if you have no patience
    Desert Sunset Calls/Upward, Pain, Perseverance/Welcome Solitude

  12. #12
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    acutally, i pretty happy with my set up the way it is ... i make adjustments and try new settings from time to time. a month or two ago i did monkey with the boost pressure and bottom-out adjustment thingy, after which i spent a day and a half at the Snowshoe MTB park and maybe pushed the o-ring off only once the whole time (i did not try the infamous road gap, though)... i really like the DHX air 's performance and adjustability with the FB... i guess i was just yammering on that there are some situations where you do seem to blow through the travel...
    i need to develop my crashing skills...

  13. #13
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    Hmm after much read I think I'll be patient with the dhx.. I'll tinker with the bottom out adjust and try running with only white 1 line showing. I'll try and see what these will do on the end stroke compression bcos right now that is the the only thing that seems to bother me. Ouh forgot to tell you guys that i miss to adjust my rebound after adding some air volume to both the front and rear suspension..

    Plan b, I'm running the 2012 small, just in case my patience run out can I run coils on theses carbon rockers?

  14. #14
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    Joe; The carbon rocker will clear the coil spring on some models but not all of them. Some of the Ti springs have larger diameter coils and they can rub. The biggest reason we recommend running the aluminum rocker with coil springs is to give an added level of security in case of a hard bottom out situation while getting the shock setup. Air is a naturally progressive spring so even if you have it set too soft it will resist hard bottoming somewhat. Coils tend to be very linear and you're relying on having the correct spring rate and Comp. damping to avoid a harsh bottom out. This combined with the fact that most riders who run a coil are using the bike as more of a DH rig are why we recommend using the aluminum rocker with those shocks.
    Desert Sunset Calls/Upward, Pain, Perseverance/Welcome Solitude

  15. #15
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    I just threw the RC4 back on my bike after running air for quite some time and dayum it feels good. I had forgot just how bottomless it feels on a harsh hit and how sensitive it feels over little rocks and roots.

    That said, the DHX-Air is pretty adjustable and I really like them on the Firebird. One thing people also forget to do is turn the pro-pedal to the off position when setting sag although the heavy bounce and o-ring reseat should generally make that not matter.

    Joe - when you do adjust the bottom out knob, you will also have to re-set the psi. I'd personally start at 180 and see how that feels, then 170, then 160. I think even 5psi makes a difference on the boost valve settings.

    Last - I think the firebird works well with quite a bit of rebound on them so play around with that - do some bracketing runs where you turn the rebound way up and way down.
    "It looks flexy"

  16. #16
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    Thanks for the tips guys. I'm giving the boost valve some air and will adjust the bottom out. Hopefully the next ride will be better. Ouh I gotta change to a shorter stem. The 70mm I'm running is making me doing bar pulls as I like to lean really far back when taking the jumps. I know it's the wrong techniques but it has become a habit after some really nasty crash sending g me over the bars.. It's a long story.. Thanks again guys

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