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Odd ball shock problem!

bullcrew

3 Dude Approved
OK So I got the F1 ready to rock and have ridden it several times now, the bike is GREAT.
I noticed that on stairs it packs up and rides hard. I adjusted the compression but?
Here is the problem:
If I jump up and land on the seat the bike squats, raises then squats again in a down-up-down motion (like bouncing but one time). I adjust the rebound all the way to get rid of the bounce and it seems to pack up.
I have a 550 ti spring on it and I can preload but I have to have the rebound clicked all the way to keep it from doing its 1 bounce. I have dialed all my other rides in and this is the first time I have dealt with this. My sag is roughly 30% - 35%
Bike: Canfield f1 large
Shock: avalanche DHS with hi/lo comp and rebound
Spring: RCS 550ti

Is it possible it has too little nitrogen for it to work effectively?
Is it a compression issue, maybe not enough?
Maybe it has too little rebound valving?

I'll give a ride report of the 888wc and the f1 later in the week with pics. I hit a few jumps today as well as some drops, one in the range of 7' to almost flat and this bike rocks so far.
 

DHS

Friendly Neighborhood Pool Boy
Apr 23, 2002
5,094
0
Sand, CA
i've notice that it now sucks on stairs. but havent noticed the pogo stick feeling.
so use tmx for stairs, and racelink for offroad
 

dhkid

Turbo Monkey
Mar 10, 2005
3,358
0
Malaysia
try the stairs at different speeds, or different stairs. what i belive is wrong is that the frequency of the stairs hitting your wheel is much lower then your bound speed? (well, not really, but thats the best way i can explane it) so your wheel drops into the 'holes' inbetween each step and slows you down. but if you try it at a higher speed, your wheel will start to skip all the holes, and you will accelerate...

OR, it could be that your rebound is too slow, but i dont think thats the problem. you can also experiment with running different amounts of sag, i found on some suspension designs if you run too much sag, and say get to a linear part of its travel, the suspension will sit too low in its travel, giving a harsh ride. as its reaches the progressive part of the travel much faster.
 

thaflyinfatman

Turbo Monkey
Jul 20, 2002
1,577
0
Victoria
If your rebound is so slow that you don't get ANY oscillation when you bounce on it, that's too slow for sure (technically and in riding terms, that's overdamped). Speed your rebound up, I almost guarantee that's your problem.
 

SKYWAYBUZZ

Monkey
Mar 16, 2002
227
0
Pittsburgh, PA.
did it come from Craig shimmed for the 550 spring? If you added a stronger spring or use a lighter one with much preload, most likely it needs more rebound shims. Too litle NO2 psi will feel like its softer.
 

davep

Turbo Monkey
Jan 7, 2005
3,276
0
seattle
If your rebound is so slow that you don't get ANY oscillation when you bounce on it, that's too slow for sure (technically and in riding terms, that's overdamped). Speed your rebound up, I almost guarantee that's your problem.
agreed 100% both from a riding perspective in the real world and from the math. No oscilations = overdamped.
 

Jm_

sled dog's bollocks
Jan 14, 2002
18,855
9,559
AK
I adjust the rebound all the way to get rid of the bounce and it seems to pack up.


Of course, riding your bike at 2mph off a curb, or jumping up and down on it has NOTHING to do with the rebound at 30mph or during high frequency impacts.

The notion that a bike should not "bounce" when you drop it or bounce up and down is a worthless indicator of rebound IMO.
 

bullcrew

3 Dude Approved
Just because you haven't taken any notice of the three people who have said it already:

YOUR REBOUND IS TOO SLOW.
Wow incase you didn't read my post "the bike bounces down/up and down again with too little rebound!"

I have been riding avys for over 3 years and love em and had 5 different frames with them, I have never had a pogo problem! I know what suspension acts like under normal circumstances and this is not normal to me.
If it was too much rebound don't you think the bikes return rate would be too slow to pogo! It would come up and not have enough energy to pass the static point and go up and down again because IT WOULD BE TOO MUCH REBOUND!

Turning the rebound up is what gets rid of it pogoing.
 

bullcrew

3 Dude Approved
agreed 100% both from a riding perspective in the real world and from the math. No oscilations = overdamped.
I did and it bounces even worse, I look like a carnival ride. UP/DOWN/UP/DOWN I dont even need to go to the hills I have all the whoopdeedoos right here. :D
Not trying to be difficult, I have adjusted alot on it from starting at 0 and going all the way up, the NO2 is the only thing I haven't tried so far.
Its just frustrating.
 

DHS

Friendly Neighborhood Pool Boy
Apr 23, 2002
5,094
0
Sand, CA
i'd say call craig at avy, but he'll usually just state you're doing something wrong. so its your fault. but sometimes its worth a shot.
 

Kntr

Turbo Monkey
Jan 25, 2003
7,526
21
Montana
I bet your low on nitrogen.

One other thing to try is this.

Turn up your highspeed compression. I have to run mine at 2.5-3. There is only 3.5 turns of adjustment. The bike will go too far into the travel and the bike likes to buck at anthing less than 2 turns.

Turn your lowspeed to 3-5 clicks. I think there is 22 clicks.

Turn rebound to 4 or 5 from slowest.

All bikes will be different but this has worked for me and a few other riders. The bike will ramp up real quick on big drops, plush on the small stuff, and feel faster on rebound.
 

offtheedge

Monkey
Aug 26, 2005
955
0
LB
i had the same issues with a 550 ti spring. try softening the spring preload and upping the compression, if it helps then the shock is over sprung.
 

bballe336

Turbo Monkey
Mar 3, 2005
1,757
0
MA
I'd like to commend you on not listening to a couple of the most knowledgeable people on this board (suspension wise at least).

I'm also very curious on how you think you can properly tune your suspension for downhill riding by jumping down stairs?
 

NateH

Monkey
Feb 25, 2004
438
0
Are you on the brakes down said stairs? Canfields are designed to have suspension squat, i.e. when you brake instead of jacking and locking the suspension out they move into the travel resulting in a better head angle for super steep stuff where heavy braking is likely. It is entirely possible this is what you are feeling. If you have had 5 differenct frames and the shock has been good and now with this frame all of a sudden no good then that seems to be your problem.
 

bullcrew

3 Dude Approved
Are you on the brakes down said stairs? Canfields are designed to have suspension squat, i.e. when you brake instead of jacking and locking the suspension out they move into the travel resulting in a better head angle for super steep stuff where heavy braking is likely. It is entirely possible this is what you are feeling. If you have had 5 differenct frames and the shock has been good and now with this frame all of a sudden no good then that seems to be your problem.
Thank you, a different angle. :thumb:
Thats kind of a concern I had being the mounts are also only 1/16th different on the 2 frames (both F1's 1-med and 1 large)
As well as new to parrallel link or miniature a arms. :D
 

davetrump

Turbo Monkey
Jul 29, 2003
1,270
0
Yeah I know I am new to this, never mind the 12k (In shocks) I had on my 7U truck that I built with Shane Casad (score and off road division) or Bill Hindorf (nascar division) or Doug the engineer and designer at Bilstein and where I spent a ton of time dilaing my suspension in and re designing the break away points of the shim stacks and blowby. Or designing a 4 link in the rear and how its effected under compression or what droop and speed we are looking for for each course as a general. Not only on my coilovers front and rear my Eibach springs as well as my 4 tube bypass shocks for the rear + the custom valved hydraulic bumps I had on all 4 corners. I have a little knowledge of shocks and how they work or what they are supposed to do over the course as well as adjustments.
From not bouncing back on my medium F1 to bouncing back on my Large F1 and they are the same frames and 1 just being a little bigger than the other it has to be something either NO2 related (pressure) or it has to be the progression of the mounts possibly being a little different on the frame as far as the shock angle and where the top/bottom mounts are in which case a 1/4" can make a difference.
But thanks though I do appreciate your words of wisdom, I am by far not a shock designer but I do know a crapload when it comes to them.
if so smart why post asking for help on RM... why not ask all the people you just name dropped for help
 

bullcrew

3 Dude Approved
i had the same issues with a 550 ti spring. try softening the spring preload and upping the compression, if it helps then the shock is over sprung.
I will, I have it already over at GP racing suspension to charge the NO2 and see if that works then I'll adjust from there. It could like someone above mentioned as well just be me and not having really rode a parrallel link bike as opposed to one that has more direct resistance due to links.
 

bullcrew

3 Dude Approved
if so smart why post asking for help on RM... why not ask all the people you just name dropped for help
Its a bike not a vehicle! People may have had issues similair to this on here! People on here are more familair on a overall to bikes vs. vehicles so this would warrant a good place to ask. Besides the fact that I have gotten answers here from good people on problems that have stumped me.

Because unlike adjusting the coilovers on a truck that preload is the only adjustment you have unless you shim it different internally, bikes have the external adjustments and NO2 as well. So if someone has had this problem or a parrellel link act differently then others I'd like to know. If there is a good place to start with the settings it would be helpfull.
I base how the other frames were compared to this one and granted that may be the problem initself. Shocks are shocks are shocks they have a main job to do, the variables are what concern me. Is it me letting pressure out by accident, does this frame act this way with a 550ti spring, etc...
I have answered the facts that I did not have the rebound up too much and still I get drilled with this. I know which knob adjust it and what direction effects it so I am again saying NO it is not too much rebound. All the way off and it bounces alot, all but 1 click from full and it bounces very little. All the way and it packs up!

I will be the first to post here if I am wrong as well as what it turns out to be. More than likely user error. But i will still post it so someone else has a problem like this they have a place to start.
 

bullcrew

3 Dude Approved
I bet your low on nitrogen.

One other thing to try is this.

Turn up your highspeed compression. I have to run mine at 2.5-3. There is only 3.5 turns of adjustment. The bike will go too far into the travel and the bike likes to buck at anthing less than 2 turns.

Turn your lowspeed to 3-5 clicks. I think there is 22 clicks.

Turn rebound to 4 or 5 from slowest.

All bikes will be different but this has worked for me and a few other riders. The bike will ramp up real quick on big drops, plush on the small stuff, and feel faster on rebound.
Thanks B
I'll give it a try.
 

Kornphlake

Turbo Monkey
Oct 8, 2002
2,632
1
Portland, OR
Are nitrogen charged shocks really filled with NO2? I always thought it was pure nitrogen, not the stuff that ricers spray into the intake.
 

thaflyinfatman

Turbo Monkey
Jul 20, 2002
1,577
0
Victoria
Wow incase you didn't read my post "the bike bounces down/up and down again with too little rebound!"

I have been riding avys for over 3 years and love em and had 5 different frames with them, I have never had a pogo problem! I know what suspension acts like under normal circumstances and this is not normal to me.
If it was too much rebound don't you think the bikes return rate would be too slow to pogo! It would come up and not have enough energy to pass the static point and go up and down again because IT WOULD BE TOO MUCH REBOUND!

Turning the rebound up is what gets rid of it pogoing.

Thanks for listening. On any suspended, long travel vehicle (and bicycles most definitely fall into this category), there will and should be some amount of oscillation if you bounce on it. If you set it up so that it doesn't go up past the sag point then your rebound IS too slow, that's not even up for debate (in my mind at least). That is the technical definition of "overdamped" and in terms of riding (where you generally require a technically underdamped setup simply because of the shaft speeds required, low rigid sprung mass, blah blah) that's most definitely too slow to be suitable. I can't guarantee that this is the ONLY problem, but you really shouldn't be setting rebound so slow. A bit of "pogo" is not bad, as long as the rebound is not so fast that it ejects you from the seat or pedals when you bounce on it.

I'm sorry if I'm talking down to you, but again I will just about guarantee that your rebound is simply too slow. You might make analogies to cars etc, but bike rebound also has to be run quite a bit faster than any other kind of vehicle because the rigid sprung mass (ie the front triangle and attached parts) is very low compared to the unsprung mass (whereas on a car or motorbike you might be looking at mass ratios of 10:1 or more, on a pushbike you might be looking at 2:1 or thereabouts) and the rider's weight is high compared to both of these. This means that you can't run much compression damping compared to a car or motorbike (because too much shock will get transferred to the rider, since there's not much rigid sprung mass to plow through the compression damping), and if you can't run much compression then you're always going to need to run faster rebound.

BTW - it is possible that your rebound valving is waaaaay off and somehow you've got way too much HSR and not enough LSR, but I doubt it if you've successfully used this shock on similar frames.
 

bullcrew

3 Dude Approved
Thanks for listening. On any suspended, long travel vehicle (and bicycles most definitely fall into this category), there will and should be some amount of oscillation if you bounce on it. If you set it up so that it doesn't go up past the sag point then your rebound IS too slow, that's not even up for debate (in my mind at least). That is the technical definition of "overdamped" and in terms of riding (where you generally require a technically underdamped setup simply because of the shaft speeds required, low rigid sprung mass, blah blah) that's most definitely too slow to be suitable. I can't guarantee that this is the ONLY problem, but you really shouldn't be setting rebound so slow. A bit of "pogo" is not bad, as long as the rebound is not so fast that it ejects you from the seat or pedals when you bounce on it.

I'm sorry if I'm talking down to you, but again I will just about guarantee that your rebound is simply too slow. You might make analogies to cars etc, but bike rebound also has to be run quite a bit faster than any other kind of vehicle because the rigid sprung mass (ie the front triangle and attached parts) is very low compared to the unsprung mass (whereas on a car or motorbike you might be looking at mass ratios of 10:1 or more, on a pushbike you might be looking at 2:1 or thereabouts) and the rider's weight is high compared to both of these. This means that you can't run much compression damping compared to a car or motorbike (because too much shock will get transferred to the rider, since there's not much rigid sprung mass to plow through the compression damping), and if you can't run much compression then you're always going to need to run faster rebound.

BTW - it is possible that your rebound valving is waaaaay off and somehow you've got way too much HSR and not enough LSR, but I doubt it if you've successfully used this shock on similar frames.
Makes sense, didn't take into account the leverage of 2 wheels and the middle flex vs. 4 wheels and corners compressing. If I take the rebound down and increase the compression then It bucks a little. I was low on nitrogen and adjusted the settings last night and it seems to be better but the rebound has to be up or I pogo too much. I think it needs a little more valving in the rebound side to slow the flow and control the 550 spring.
I'll talk to craig today and see.
 

flymybike

Monkey
Jan 7, 2004
260
0
Jackson Hole
OK So I got the F1 ready to rock and have ridden it several times now, the bike is GREAT.
I noticed that on stairs it packs up and rides hard. I adjusted the compression but?
Here is the problem:
If I jump up and land on the seat the bike squats, raises then squats again in a down-up-down motion (like bouncing but one time). I adjust the rebound all the way to get rid of the bounce and it seems to pack up.
I have a 550 ti spring on it and I can preload but I have to have the rebound clicked all the way to keep it from doing its 1 bounce. I have dialed all my other rides in and this is the first time I have dealt with this. My sag is roughly 30% - 35%
Bike: Canfield f1 large
Shock: avalanche DHS with hi/lo comp and rebound
Spring: RCS 550ti

Is it possible it has too little nitrogen for it to work effectively?
Is it a compression issue, maybe not enough?
Maybe it has too little rebound valving?

I'll give a ride report of the 888wc and the f1 later in the week with pics. I hit a few jumps today as well as some drops, one in the range of 7' to almost flat and this bike rocks so far.
The F1 is fairly linear in the compression rate so running the right spring to get you slightly higher in the travel than you might expect is a good thing. Our pivot moves from high to low thoughout travel. Sag position will greatly effect everything, pedaling, bump performance, braking. When you sag too much the pivot, at sag, is too low and you start to get more compression during pedaling. With less sag you'll effectivly move the pivot higher which gives more lift during pedaling. I suspect from what you've said, that this is the problem.

I always start from the begining, like this.

Preload: Remove all preload without the spring being loose. Remove all compression damping, both high speed and low speed. Back the rebound way off. Now you should have nothing interfering with your true sag point. I run my F1 at about 25-30% sag. If your saging more than this, try a #600.

Rebound: With your sag correct, set rebound too fast, then slow the rebound to the right spot. To do this I compress the bike, don't get on - just stand to the side, compress it and release it completely and without interering with the return to topout. Watch the rear wheel where it contacts the ground, your looking for a bounce or hop where the wheel looses contact with the ground. You want to slow the rebound in small adjustments until the wheel stays in contact with the ground. Now to test if it's right, you speed up the rebound by 1 or 2 clicks the wheel should hop again. Yes? OK This is about as close to proper as you can get for perfect bump compliance without fine tuning on trail.

Low speed compression: With proper sag and rebound, jump on your bike and pedal around, looking for the bounce. Slow the low speed compression until it feels close to eliminating the bounce. I've found if you add to much it can effect the bump performance and cause a pressure spike.

High speed compression: High speed damping is the hardest to adjust properly. You really need to do this on trail at full speed. Do a fast run, watch for using excessive travel (or packing up) and slow the high speed compression until you get minimal hard bottomouts. Adjust in small amounts until the bike is getting full travel once or twice a run (depending). If it feels harsh, use less high speed compression damping. I like to run my high speed damping as close as possible to fully open. This gives the smoothest ride.

hope this helps. Cheers
 

bullcrew

3 Dude Approved
The F1 is fairly linear in the compression rate so running the right spring to get you slightly higher in the travel than you might expect is a good thing. Our pivot moves from high to low thoughout travel. Sag position will greatly effect everything, pedaling, bump performance, braking. When you sag too much the pivot, at sag, is too low and you start to get more compression during pedaling. With less sag you'll effectivly move the pivot higher which gives more lift during pedaling. I suspect from what you've said, that this is the problem.

I always start from the begining, like this.

Preload: Remove all preload without the spring being loose. Remove all compression damping, both high speed and low speed. Back the rebound way off. Now you should have nothing interfering with your true sag point. I run my F1 at about 25-30% sag. If your saging more than this, try a #600.

Rebound: With your sag correct, set rebound too fast, then slow the rebound to the right spot. To do this I compress the bike, don't get on - just stand to the side, compress it and release it completely and without interering with the return to topout. Watch the rear wheel where it contacts the ground, your looking for a bounce or hop where the wheel looses contact with the ground. You want to slow the rebound in small adjustments until the wheel stays in contact with the ground. Now to test if it's right, you speed up the rebound by 1 or 2 clicks the wheel should hop again. Yes? OK This is about as close to proper as you can get for perfect bump compliance without fine tuning on trail.

Low speed compression: With proper sag and rebound, jump on your bike and pedal around, looking for the bounce. Slow the low speed compression until it feels close to eliminating the bounce. I've found if you add to much it can effect the bump performance and cause a pressure spike.

High speed compression: High speed damping is the hardest to adjust properly. You really need to do this on trail at full speed. Do a fast run, watch for using excessive travel (or packing up) and slow the high speed compression until you get minimal hard bottomouts. Adjust in small amounts until the bike is getting full travel once or twice a run (depending). If it feels harsh, use less high speed compression damping. I like to run my high speed damping as close as possible to fully open. This gives the smoothest ride.

hope this helps. Cheers
Thank you Lance!
 

bullcrew

3 Dude Approved
My appologies to all! I humble myself to the mercy of the monkey.
OK so its not all my bad, I was trying to set it up for drops and quick stop landings not multiple hits. This bike just acts a little different then the rest in the past due to travel angle. So yes the nonkies were right and I was wrong! It was over dampened!

So heres the lesson whithin:
1- Do not argue with the masses.
2- Do not try and set a suspension up for all out FR/DH/single track based on a long set of stairs or a 7' drop. IT WONT WORK!

So, THANKS!