Fiddling with my fork
 

As some of you are probably aware, before my chameleon I hadn't set foot in the world of proper suspension. Now that I have however, I am trying to get as much out of it as possible.

So far whilst out on the trails I've fiddled with the rebound knob, just seeing what effect it has and trying to find a point I like.

My fork has so many adjustability things though, that I haven't touched so far and I was wondering if you guys could give me a bit of a hand.

I have a revalation 426 dual air u-turn something or other, and have read the manual on it, most of which makes sense, just unsure on one or two points.

First is air pressure. For starters do I have to get a suspension pump, I'm a bit tight on money and my floor pump will go up to a high enough pressure.

Assuming, that I find some way to increase tha air pressure, what should I change. I weigh about 120 pounds (manual recommends 120-135psi for the positive air pressure), but am taking the bike off some quite big things, so should I use a larger psi so it doesn't bottom out as quickly? So around about 155psi.

What about the negative air pressure. It says if you want more small bump sensitivity you should have it set higher than the positive air pressue. How much higher though? I presume the main downside of this is more bob, any other downsides I should know about?

The rebound setting on my fork I understand, and can merily fiddle with that until I find something that feels right.

Compression dampening I'm pretty sure I get as well, I only ever really have it fully open or fully locked though. One little question though. Will I damage my forks if I have then partially/fully locked at go off a drop? Haven't done it yet because I don't want to break them and wasn't sure.

Last but not least, what an earth is floodgate adjustment? What should I be doing with it and what effect does it have. I've set it up according to recommended weight in the manual, but don't have a clue why it's there.

I think thats about it, I know it's alot of questions, sorry. I probably sound like a complete nubbin as well, and that because, when it comes to suspension at least, I am.

Thanks in advance for any help you give. If anyone knows of a link that answers all these questions in simpletons terms, then feel free to post it and tell me to bugger off there. Be warned though, it may just result in more questions.

Dont' use the floor pump. You need tiny incriments. You could accidentally blow your cartridge up and then you'll really be tight on money. :)

Why would big increments blow the cartridge (whatever that is). Could I get away with just using the bottom inch of the pump stroke? If I really have to use a shock pump can you recommend me a good (cheap) one?

What about what I should be doing once I've got a way to safely change air pressure.

I just spent 30 minutes replying to your first post telling you how to set up the suspension...but I accidentally tapped "back" and lost it all.

Doh!

If at first you dont succeed...:lol:

Well thanks for trying. Any chance you could try again :D

seriously do not use a floor pump.

Any suggestions on a good cheap shock pump then?

Don't buy a "Wrench Force". Mine leaks at the joint.

Yes, buy a suspension pump. You could prob. get by with a floor pump, but one wrong "twitch" and you could accidentally blow up your preload chamber. Floor pumps push alot of air really quick.

Start off by setting your rebound and compression damping really fast. (low) Put a zip-tie around one of your fork legs (stanchion [upper]) just snug enough so it won't move on it's own, but can slide up and down the fork leg easily.

Now, depending on your style (it may take time to figure yourself out) you may want anywhere from 15%-30% sag on your fork. Sag is the amount your fork compresses when you sit on it with all your gear. Start with the mfgr. recommended air pressure for your "geared up" weight. Push the zip tie all the way down your stanchion tube unitl it touches the wiper seals, and gently sit on your bike. (flat surface) spin around a flat pkng lot or tennis court or something smoothly and gently...roll gently to a stop. If you use your brakes, you will sink into your suspension a bit, so be careful. Get off your bike and measure the distance from the bottom of the zip tie to your wiper seal. This is your sag. As stated above, it should be around 15%-30% of your total fork travel. 15% will feel more "firm" and be more efficient for XC'ish stuff. 30% will be more plush and feel more supple over the bumps.


Negative spring pressure is a magical thing. More negative spring will make the first portion of your fork travel very supple and smooth and when you reach the end of your negative spring, it becomes more progressive and resistant to the big hits. Less negative spring will give you a little less sag and make the ride feel a little more firm.


I usually set the rebound damping first. Rebound is what slows down the forks "extension". (obviously) I back it off to where it's pretty fast (low) and ride off a curb. If the bike wants to "pogo" like a car with bad shocks...then add rebound. I usually have it set to where the fork cycles up-and-down one time (ish) for starters. Too much rebound will cause the fork to "pack up" over washboard or repeated bumps. It doesn't allow the fork to extend fully enough for the next bump. If the fork feels good off a curb, but packs up over repeated bumps, decrease the rebound damping a little.


Compression damping is a beautiful thing. Compression allows you to run the optimal sag but still resist bottoming out. (use your zip tie) When you have your sag set where you think you want it, hit some larger bumps that resemble some of the bigger hits you will encounter on the trail. If your fork bottoms out (zip tie goes all the way to the crown) then increase the compression damping. I usually set it to where it comes fairly close, but doesn't bottom out over a bigger hit. Your suspension should just barely bottom out on the biggest hit on your trail. (doesn't have to...it's all up to what feels good to you in the end) Ride a few loops on your trail and check the zip tie once in a while to see how it's going. If you're not coming close to bottoming out...back off the compression a little and enjoy an even smoother ride. If you have it set to where it's just barely not bottoming out, but it feels like it compresses really sluggish...back of the compression and add a little more preload. (note: this will decrease your sag as stated above) A little less compression and slightly more preload will probably feel better in that situation.

As far as partially/fully locking them out. It probably won't hurt it, but I wouldn't make a habit of locking out the fork and hucking a 6footer. You can partially turn the lockout knob for more compression for a big drop though. That's what compression adj is designed for as I stated above. If your trail is really smooth, but has say "1 big drop"...reach down and turn the knob a few degrees for that drop then turn it back for the rest of the trail and enjoy the cush.


Floodgate is a really KEWL Rockshox feature. You can set it basically one of two ways.
1. Turn the floodgate really low and lock it out completely. This will cause the fork to feel fairly efficient for sit'n'spin pedaling without bobbing, but when you hit a bump it will compress and suck it up. This is "platform".
2. Turn the floodgate up high and leave the fork unlocked for general riding. When you get to a long gradual "middle ring" climb that you want to stand up and honk on the pedals...lock it out and you have a super efficient fairly rigid fork for climbing that will only compress an inch or there'bouts in case you screw up and hit something big with it locked out.

It just depends on if you're a sit'n'spin climber, or a stand and honk climber.

(obviously you can set it anywhere in between for your weight and style)


Isn't that what Chandler Bing called his 3rd nipple?

Thanks, that was awsome help... now all I've got to do is get a pump so I can put it into pratice.

One last little question. I've been reading to much about bike parts. It's a terrible habit, all it does is make me think all my stuff is crap and needs a change. One thing I have read about though is axles, and lots of places seem to be saying QR is basically worse than dog poop. Is it really THAT bad compared to through axles or whatever they're called? I've never used a decent fork that isn't quick relase, so have never had anything to compare.

Just curious, I probably won't change anything until I completely mush up my current wheel set anyways (or start doing stuff that I know will mush up my wheelset and sell them before they get too bad).

You'll be fine, man. I rode a long time on QR's. They're not for freeriding, but trail riding is fine with 'em.

20mm TA is the bomb though. I like 'em. Just not necessary for "trail riding".

At what point does it become freeriding?

Are QR more likely to brake is is it just about the added control. New wheels and forks would cost best part of £500 if I get off ebay. I'm begining to wonder if I should have asked them to swap out a few more parts before I bought it.

When it doesn't cost money anymore.

That happens with age......even to the best of us.

Dang, I hope it gets to that point soon.

Seriously though, I don't want to be riding stuff which is just waiting to break. I'm already starting to wonder as to whether I'm really putting my current cranks and bars through more than what they're designed for.

What are you really doing.....how big are you going?

All the trails around me contain at least one, two foot drop, one of them also has quite alot of 4ish ft drops (they're actually just a few rooty stepdowns, but I prefer to jump them).

What is worrying me more though, is the trail that I'm starting to ride more has a freeride park half way round, and you can take a detour onto quite a jumpy downhill course at the end.

Anything which I see when riding which is 5 ft or under though I'll quite happily try riding off.

If you are worried about the pump thing, just take it to the LBS and use theirs. Its funny when you get the owner of the shop, and he has no idea how to use a shock pump :rolleyes:

Fortunally pumps aren't as much as I thought they were. It seemed like they were all £40 and up, but I've just been looking in silly places.

I'd also rather be able to use it whenever I wanted rather than having to go back to the bike shop every time I wanted to tweak it.

Yeah, thats why I got my own. I run mine at about 100PSI for urban stuff and 90-85 for trail riding.

Looks like you've sussed-out all your RS thingymewotsits, chelboed.

In addition, regarding the lock-out being fully on, I believe the RS designers had added a "blow-off" valve, so that ning-nongs like me who occasionally forget that the fork is still fully locked and begin descending - don't blow them up and splatter fork oil all over the place. :o

.

(shhhh...Floodgate= blow off...shhh);)

suspension is complicated at that level....
0_O

^ Yeah, it is and it isn't. At first I struggled with the intricacies too until I slowly learned more about shocks and understood the fundamental basics - then it all makes sense when you know why it's there and what it's for.

The beaut about all those features that chelboed mentioned is that Rockshox haven't gone off in all sorts of tangents, developing endless gimmicks. Those features have been in RS forks for about a decade now - tried and true and perfected. There's a lot of good people in SRAM with their heads screwed on properly... and it shows in their stuff...

.

With the air setup, I'm still not quite sure how I should go about it.

I've got it so that there is prob about 20% sag, but I still seem to sail though my travel. Should I just take my pump and repeatadly chuck my bike of the biggest thing I find, increasing the pressure each time until it doesn't bottom out? Kinda seems logical to me, just wondering if their is any reason why it's good to have a certain amount of sag, or if it's just a useful rough measure. Also if I put the negative air pressure higher enough, will this keep the first poition of the travel soft enough for smaller bumps?

I know you mentioned the compression, but is it better to just leave this on all the time, or have a higher air pressure.

I would start with the pressures recommended for your weight (some RS forks have them printed permanently on the sliders, or refer to the manual). If you bottom-out every once in a while (on big hits) some say this is about right. I prefer to add another 10psi until it no longer bottoms-out - that way I know I'm not far from the optimum and I get to use all the travel that I paid for. If you've never bottomed your fork, take the pressure down 5 or 10psi at a time until you do. Then bring it back up by 10psi for head room. Once you know what pressure that is, write it down somewhere handy (tape on your fork pump or under your helmet). Your pressure rating could change in the future, as your skill levels and aggression increase (higher jumps, deeper drops) or as you get older like me and put on extra weight (potato chips, beer).

The negative pressure makes the beginning of the stroke nice and plush, and you can use that to fine-tune how much sag you want. Best to stay within the recommended pressure range for your weight. The higher the pressure, the more the sag, the plusher it is at the start... which can be a good or a bad thing depending on what sort of riding you do. Coil spring forks don't have negative pressure chambers, but have spring pre-load adjusters instead (different story, similar effect). You need a bit of sag so that your fork (and wheel) can first extend "into" dips in the terrain rather than the whole front-end just falling into them.

Rebound dampening "slows" down the return action of the fork, so you don't bounce straight back into the air like in a trampoline (think pogo stick, or human catapult). You don't want too much though, best to go for the least allowable. Like chelboed said earlier, the forks will pack-up in the rapid stuff (washboards) if you've got too much rebound damping. It's like the fork's having a brain-freeze cuz it can't react fast enough to what's happening beneath it.

Generally you want the positive air pressure (or spring firmness on coil forks) to handle ALL of the compression duties. Use the compression damper if you want to "slow down" the upward movement or lock it up completely for climbing or hammering in the flats. It's not a good idea to use the compression damper to compensate for an under-sprung fork. I mean it will work, but in some designs it will overheat the fork oil too much and could cause your compression AND rebound to fade (if the circuit design shares the same oil reservoir). In very extreme instances, using the compression damper as an added "spring," or simply when it is over-worked, can froth up your fork oil. High performance systems are sealed with pressurized nitrogen to prevent this.

.

^^ Oh yeah, I forgot.

You really do need a proper shock-pump. It's not that the tire pumps can't get to the pressures required, but when you take the nozzle off, tire pumps release an awful lot of air and unpredictable at that.

Shock-pumps have more accurate air-pressure gauges and the nozzles are designed to screw onto the valve and lose very little pressure when taken off. What's more important is that this pressure loss is consistent so it gets factored in whatever pressure reading you settle on.

.