# What causes the rear to pop on lipped jumps?



## thesacrifice (Mar 12, 2004)

I believe it's sometimes reffered to as bucking, but twice this weekend while at Whistler I experienced the rear wheel really want to pop and throw me nose heavy off of lipped jumps...jumps I've done numerous times before with no difficulty. I'm really trying to get the hang of preloading down as opposed to resorting to speed so this may be coming into play. Preload too early? too late? 

Thank god for 8" forks


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## Apache249 (Jul 30, 2009)

Sounds like you need more rebound damping on the rear.


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## igotbanned (Oct 20, 2007)

Specifically more end-stroke rebound damping. The rear end goes from (close to) full compression to none as it exits the lip, meaning that while beginning and mid-stroke rebound feels good, the end-stroke rebound will make a large difference in this sort of situation. Slow it down some.

I've had the exact same problem and had no idea what was wrong until someone explained that to me.

What shock do you have, anyways?


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## Scythe (Nov 23, 2011)

SLow your rebound down some and maybe add a bit of compression to stop your suspension from compressing so much. You also said you hit the jumps before with no problem, maybe your riding style changed or your just not riding the way you were before.


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## craigstr (Sep 19, 2003)

I believe its called spiking. If your shock has a boost valve try lowering the pressure. Essentially what is happening is your shock is taking a really high speed hit, the boost valve thinks its bottoming out so it creates a lot of rebound speed based on the pressure.


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## bengxe (Oct 11, 2009)

You didn't have your weight back far enough, your shock is probably fine.


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## kenbentit (Jan 2, 2003)

^Exactly what I was thinking. Jumping with long travel bikes is kinda tricky since the geometry can change drastically as you compress into the face of the takeoff. Too much forward weight will compress the fork more than you might believe which steepens the HA a lot and unweights the rear of the bike. I've even gone OTB on steep jumps before, not a good feeling when you're in the air looking at the landing that you're coming into headfirst


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## stevehollx (Apr 6, 2010)

I've noticed that since switching to a DW link bike from FSR that I'm having more of an issue with nose diving too. My RP23 is currently setup for 1 click from fastest for rebound (145 lbs geared).

I've been trying to keep my weight back more than I am used to, but that's interesting regarding slowing the rear dampening up some.


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## 62kona (Mar 25, 2008)

That was happening to me a lot at Northstar the first time I went there. A friend told me my toes would sometimes point down/forward and that's when I would nosedive. If I made sure to keep my toes up/back it really leveled out the bike alot. Didn't new to touch my suspension settings.


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## Deerhill (Dec 21, 2009)

Your rebound is slower on the fork (or spring rate)

Try to balance this on the fork and shock for equal boost


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## drastic. (Nov 22, 2010)

stevehollx said:


> I've noticed that since switching to a DW link bike from FSR that I'm having more of an* issue with nose diving* too. My RP23 is currently setup for *1 click from fastest for rebound* (145 lbs geared).
> 
> I've been trying to keep my weight back more than I am used to, but that's interesting regarding slowing the rear dampening up some.


you run your shock at 1 click from fastest rebound, and you are trying to wonder why your bike bucks?


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## Deerhill (Dec 21, 2009)

RP poo pee = buck or spike, take yur pick


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## stevehollx (Apr 6, 2010)

drastic. said:


> you run your shock at 1 click from fastest rebound, and you are trying to wonder why your bike bucks?


Well, that's based on Pivot's guideline:



> In general, rebound should be turned all the way out and dialed back in 1-3 clicks depending on rider weight. A sub 145lb rider is full out (fastest setting)


It's never felt too fast at 1-click, to be honest. Quite the contrary to my previous FSR bike. But I've never tried to compare rebound rates on front vs. back. I should have a friend take a look when I'm bouncing on top a bike and see.


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## thrasher_s (Oct 5, 2009)

I know that feeling well. I aired out a tabletop right under the chair at whistler (either A-line or B-line) and I thought for a LOOOONG time that I was going to endo. Felt like I rode a good 100ft on just my front wheel while leaning back as hard as I could.

It only happens every once in a while for me, so I assume its a technique or body position thing.


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## Swell Guy (Jan 20, 2005)

bengxe said:


> You didn't have your weight back far enough, your shock is probably fine.


I'm going with this one. Center your weight on the bike. Cycle the suspension before hitting the jump, you'll find the center spot and hit the lip at the same spot.


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## 1niceride (Jan 30, 2004)

You didn't say what shock you had.. Any chance the ifp chamber might be low on pressure? That will cause cavitation in the rebound with corresponding loss of rebound control. Not sure how big the lip is but if there is a change in behaviour in your shock...


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## mattyrides07 (Mar 9, 2012)

I think it's all already been said-
1. Your body position when hitting the jump
2. Rebound from rear might be too fast

"Dream like you'll live forever, but live like you'll die today."
-James Dean


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## danmanholl (Jan 13, 2012)

sounds sketch to me


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## Tree (Jan 27, 2004)

Try slowing down your rebound a little.
It will help with hitting jumps but you might notice some spiking
in rougher parts of the trail because the suspension isn't rebounding fast enough.(packing up)
You have to find that happy medium.


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## 1niceride (Jan 30, 2004)

The shock has changed character. Has been good until now if I read the OP correctly. When the ifp chamber gets low on pressure the rebound becomes unreliable. When the shock is compressed quickly space appears in the rebound chamber. This space will collapse quickly upon rebound, kicking the back up hard. 

Still don't know what shock the OP has...


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## Iceman2058 (Mar 1, 2007)

thesacrifice said:


> ... I'm really trying to get the hang of preloading down as opposed to resorting to speed so this may be coming into play. Preload too early? too late?...


This sounds like a clue. If you are experimenting with your jump technique, probably no need to look at the gear. You can always add a couple of clicks of rebound in the rear for extra security (in numerous situations not just jumping), but IMHO, I think it's more likely that as you are now trying to pump the lip more, you are just getting your timing thrown off a little. If you really load up the suspension into the lip, and then get left behind a bit going up it, it'll buck like a rodeo bull.

Somebody else said to do a couple of suspension compressions on the way up to the jump to find the balance point, this works well and also helps loosen up before the jump. Then, you can still load the jump like you've been experimenting with, just remember to pull up on the front end a bit as you go off it. If you leave the front completely alone, and pump the lip a lot, I typically find the bike wants to pitch you forward. Pull the bars towards your chest/stomach as you go off the lip for a bit of extra security. You need to sort of get ahead of the bike a bit (not the opposite!). Then as your timing improves, start to leave the front more and more alone to find the exact spot where the jump just puts you on a nice natural bell shaped curve thing. That'll give you the extra pop you are looking for, without the bucking.


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## aedubber (Apr 17, 2011)

Funny you mention this , as i have been moving onto some bigger tables i tend to get a little sloppy as well .. Sometimes when im a little tired or just not focused i tend to lean a little front heavy and my rear end almost bucks me over ..

If you keep your body positioned centered or back a little , knees bent , and someone mentioned something about your feet , i think you will hit it nice .. I feel like when i dont think about the jump or table , i hit it perfectly .


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## adjunkie (Feb 20, 2007)

You want to compress into the jump and then pop out of it. If your rear end is getting bucked, you need to be exploding up with your arms more.


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## thesacrifice (Mar 12, 2004)

Thanks for all the replies. The shock is a fox van rc. I'd hate to tinker with rebound because it feels great where it's at. I've also hit the same jump after bucking without bucking so I'm leaning towards technique over equipment. 

Still not getting the height I want so I'll try some of the things mentioned here such as cycling the suspension a couple times on the way towards the jump.


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## stunzeed (Mar 17, 2007)

simple...if you like the rebound how its set currently to your rear, you need to speed up the rebound on your fork


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## Ithnu (Feb 16, 2007)

Scythe said:


> SLow your rebound down some and maybe add a bit of compression to stop your suspension from compressing so much.


I had my rebound really slow to prevent this but setting it any slower made it ramp up in the bumps. So I backed it out a bit and turned up the low speed comp to keep it higher in its travel on the way up the lip. Surprised me how much it helped actually.


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