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Rear shock lock out
NB: Originally posted elsewhere on the Global Riders Network and appears via syndication.
I have a Trance X2 2011 only 2 months old and I am new to MTB riding
when rear shock RP2 is locked out how much travel should there be, seems to be the same
where ever the lever is dose the lock out position only make it stiffer
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The lever is not a lock out. IT is adjusting the way the suspension works. When the lever is to the left the suspension is working (or open). when you have the lever to the right it is in "Pro Pedal". Pro pedal should give you a more efficient pedaling platform while the open position is good for rough terrain. That is the basic way of explaining it.
Pro Pedal is a Fox brand name for their version of a pedal platform. Other brands have other names. Call it what ever you like. What it really is this; control for the low speed compression of your shock.
So, what's the difference between low and high speed compression?
Low; your pedalling influence into the bikes suspension. This is the same whether it be the fork or shock. When the rider is climbing, accelerating, pedalling up to a jump....all of these things. When the suspension moves about as a result of rider movement, that is low speed compression. Also, the effect of the brakes. This is most notably brake dive up front and squat or brake jack out back. Rear suspension fundamental design can address this yet nothing will save you from brake dive up front...well, except for separate low and high speed compression control....
High; this is bump force. The suspension taking a hit from a bump, a rut or landing after a jump or drop. This is the suspension doing it's main job. To smooth out the trail.
So, Pro Pedal. What it is doing is controlling low speed compression by slowing down the initial stroke of the shock. It's in relation to the sag point so when your sag is correct and Pro Pedal is engaged the first part ( approx 20 percent )of the available stroke is prevented from moving too quickly, yet when passed this point the shock compresses freely. Modern versions have the Boost Valve. This bit of cleverness will overcome the platform if need be, that is if a sudden impact or unseen drop arrives on the trail.
The Fox RP23 and RP2 shock allows riders to have the Pro Pedal on or off. The RP23 has three settings of Pro Pedal to choose from. Couple this with modern suspension design and a rider can either a) fiddle with their suspension settings endlessly or b) find a setting that suits them best, most of the time, and then leave that dial the hell alone!
The same feature is available in some fork models. It just doesn't carry the Pro Pedal name and simply called low speed compression adjust dial. Some models have separate low and high speed adjustment dials. On most shocks high speed compression rate is factory set and cannot be adjusted by the rider ( save for a custom tune )
Remember kids, none of all this affects rebound so don't forget to set that where you like too.
Does that about cover it? In simple terms, modern bikes are designed to be easy to set up and ride by everyone. Buying new? The shop guy should help with initial set up. Follow the guidelines for sag set by the manufacturer and measure sag using mm on the shock/fork stroke NOT psi. By all means, record the psi reading for easy future reference.
Then, find a happy place for the rebound and Pro Pedal and ride your bike. The idea of modern suspension design ( of the bike ) and these shocks ( and the Boost valve ) pretty much means that you can set and forget and ride around with your Pro Pedal on all day and your bike will be awesome...
Lube your chain. C'mon.
That put 2 and 2 together for me
Don't suppose you would like to give a succinct explanation of rebound speeds
Could that be the longest post on nobmob?
normally I wouldn't read a post that long ,I don't have the patience ,But that one I did, very informative !
Nice work peter. One little thing
It's not just the rider moving around but the effects of the changing effective chain length as the suspension cycles.
As very few bikes have the main pivot around the bottom bracket as the wheel moves up in it's travel the effective chain length will either grow or in the case of most simple designs decrease.
So what? you might say but with equal and opposite effects taking place we can see that in a design where the effective chain length decreases then as we pull on the chain, ie crank the pedals it naturally wants to pull the wheel up into it's travel. This is called bio pacing and is effectively managed by a pedal platform like foxes propedal.
Very informative post and interesting, and I don't own a dualy.
If have the time to post about rebound speed, that'd be great. I suppose it's pretty self explanatory by it's name but I've tried my fork at both extremes and it doesn't seem to make a difference. I've got a RS Tora SL air if it makes any difference.
I know it is a motorcycle related page, but it describes rebound damping very well.
http://www.sportrider.com/tech/146_9604_tech/ind...
@Pete B - how old are your forks and when were they last serviced? Have you set the sag correctly?
My Tora SL's do respond to rebound damping adjustments.
My forks are about 3 months old, not had them serviced yet but I do check the pressure after every trail ride as part of my cleaning and lubing ritual. So far they've never lost any pressure.
I'm pretty sure I set the sag correctly using instructions on the 'net and what the guy in the shop told me. I've got it set for 120mm travel.
If I've got it set to fast, the forks should come back to their rest position straight away and when it's set to slow then they should return more slowly, is this correct? And why would you want the forks to rebound slowly?
Sorry for hijacking the OP's thread!
"And why would you want the forks to rebound slowly?"
So you don't pogo stick across the trail in a rutty corner or get bucked on a big drop.
Mostly you will want reasonably fast rebound, you certainly want it fully rebounded before you hit the next bump otherwise it will pack down.
Rule of thumb stand next to your bike and push down with all your weight and let go. You want the rebound to come up fairly quick with just enough force to pop the front wheel off the ground ever so slightly but with out a harsh top out.
That's your starting point and then you dial it in a few clicks either way till it feels good to you on the trail.
Really muddy conditions I tend to slow both compression and rebound down quite a bit. Not sure why tbh, it just feels good for me
Thanks Flynny, It's good to hear how others with experience approach things like this. I see the logic of your method. Will give it a try and see how it goes. I tend to set my front rebound on the fast side for the reasons you mention.
Wouldn't mind hearing how you go about finding a starting point for rear rebound as well.
On the rear open it all the way up and ride off a gutter sitting down. Slow it one click and repeat. You want to get it so it comes up reasonably fast but not so fast that it unweights you enough to make it bounce a second time. Then play from there.
Thanks chaps, I'm pleased my info is well received. Flynny, I left chain length ( and growth ) out of that article as it can create confusion, especially if I embark on info regarding the instant centre and how it moves about and affects shock rate and, in some suspension designs from certain brands, can actually eliminate the need for a platform type shock....
Rebound. That little red dial that creates so much confusion. Flynny has certainly explained it perfectly. Here's my take.
First, lets learn about the guts of an RP23 shock. The fat air can is just that. A can holding the air under pressure. That pressure is what holds you up and is the spring. When the shock compresses it's this air which is compressed even further.
The shaft contains ( starting at the bottom ) nitrogen ( for about a cm or so ) then a little piston and then oil all the way to the top of the shock. The oil flows through both the rebound and the compression controls. That is the blue switch ( dictated by the position of the blue three position dial ) controls the flow of the oil when the shock is compressing ( including the boost valve which will open up under sudden, sharp compression ) and the red dial controls the flow when the shock is rebounding. This control has a name that we've all heard...damping. NOT dampening! Damping. But...
To make life easy forget this word. Also, forget the words more and less and increase and decrease. Think in terms of fast and slow.
With all suspension, all brands, forks and shocks this next part is the same. When looking straight at the adjuster from front on, the dial marked rebound will turn clockwise to slow down the rate at which the unit rebounds ( after compression ) and turning the dial anti clockwise will speed up the rate at which it rebounds.
The preferred rate of rebound is a personal thing. If the sag is correct, ( set sag with rebound set fully fast and pro pedal off ) the rebound should be as fast as possible without feeling a kick. Like Flynny said, one doesn't want to be pogoing about the trail or get bucked. Mind you, anyone can get bucked off their bike no matter what! What the rebound is doing is returning from compression to prepare for the next compression. Modern shocks are very clever and can handle a multitude of hits without fuss.
I like this expression; if you can feel your suspension doing its job, it's not doing its job properly.
I'll leave you all with that...
Always best to start off with rear rebound slightly slower than the front.
A few newbies have gotten this wrong and wonder why they keep getting thrown over the handle bars on drops.
Also get sag set first, then rebound before finally tuning compression.
I personally find leave compression at fastest first until have rebound dialled on the trail and drops. The rebound setting will hit a sweet spot of minimum chatter and good all round plushness. On larger travel bikes it's like a powder day boarding. Best to test on open down hill fire trail. Keep retesting on same place between adjustments.
Once sag and rebound is set get the high speed compression dialed by checking out larger drops, it's no substitute for having the right spring rate or preload/air pressure but i find it useful to tune as I run 40mm sag on '10 36 TALAS. If you start to get chatter again then you have too much high speed compression.
Once high speed is set on fork, adjust low speed. Too little and you get a falling through the fork feeling under braking or when moving around bike over rough terrain during weighting and unweighting of the bike. Too much low speed compression and the front end of the bike won't settle into a corner and the front wheel washes out.
On rear have only had bottom out and propedal. Propedal which is low speed I run as much as I can without getting to much chatter on the flat or going up. On way down turn it off.
I don't race but find this best for me on 6" play bikes.
On my fun bike, I use the suspension set slightly softer for compression than normal, and the rebound is slower than normal. I find I tend to underestimate my ability to soak up the bumps and drops, and instead I rely on the equipment to do the work for me.
On my XC bike, I use the suspension set harder for compression, and the rebound is faster than normal. I find it makes most of the riding easier over the long hours, and I simply have to hack out these settings being uncomfortable sometimes, like when you hit a rocky or bumpy patch.
I am normally too lazy to start re-adjusting everything just because I approach a section of trail I know will require a change of settings.
Great post Peter.
Thanks guys.
A learning for me from what you've said is to set the sag with the rebound set to full fast. In the past, I've just done that with the rebound set at my normal ride setting.
As it came from the shop, the Rize was set with the rebound at one click off full slow with the RP2. I eased that off a bit (ie faster) and found I needed a 40psi increase in pressure to keep the sag at 25%.... so it seems adjusting the rebound has an impact on compression as well on some shocks? The ride was very firm compared to the Jekyll, now there's still a difference but it's not as stark.
I'm trying to get a handle on what the feel "should" be, as when I ride other guys bikes they seem *very* firm in the suspension in the initial travel, and they all comment on how plush mine is. All I've done is set the sag to 25% and the rear rebound pretty much as has been described (ride off kerb etc). Some will be travel difference (130 vs 100) and some rider weight (my 80kgs vs their 90-95) but it's got me wondering if I've been setting mine too soft.
No real point of comparing others, bikes. They will have different weight, preferences and ratios affecting there settings.
Stick to the rules of 25% sag and rebound as others have suggested. As you get more experienced, you may tweek it, to suit your style and riding conditions.
That's what I figured, but a little bit of comparing your own with others' is hard to say no to
It is hard to say no to. If you offered to swap bikes with me to compare suspension, I would have to say yes. Especially seeing as I have 0mm of travel atm, but soon to have 100mm in the front.
Suspension is a very personal thing. Use manufacturer's guidelines ( the bike or the suspension unit, or both ) and then experiment from there. Don't be swayed by what others state how much air pressure they use or where they set their adjustments. Stick to your guns on how you like your bike to feel.
Remember;
1. Set your sag with compression and rebound set fully fast. And any Pro Pedal or platform feature off. Rear sag is easy...sit on your bike gently then get off. The fork is tricky. I apply the front brake and put all my weight over the bars and hold this rather gymnastic manoeuvre for a moment. Then measure where the o ring moved too. Always measure in mm, not psi. This is what's important. However, record the pressure reading for easy reference.
2. For goodness heavens sake, don't change suspension settings after a prolonged downhill or fast section. Let your bike cool down a bit. On very hot days your suspension will feel stiffer. Don't remove air to compensate. Go to the beach instead.
3. Be aware of the relationship between tyre pressure and suspension pressure. I'm happy to discuss this phenomenon for those who are interested.
4. Get your suspension units serviced regularly. Every 50 hours of use. Your bike will feel awesome with correct maintenance.
5. Modern suspension bikes from most brands are all pretty awesome, their suspension designs all work well and have very good reliability. Each brand has its unique take on things which is what makes life interesting. As time rolls by bikes get lighter and easier to ride. We truly are experiencing some interesting times.
Tyre & shock pressure...
Also a little more about your fork setup method - sounds like a very different approach to what the fork manuals recommend. What are you looking to achieve or prevent?
I set my forks and shock with me on the bike in an aggressive riding position, whilst being seated of course.
The other thing I've noticed, is newer forks feel so much stiffer until they bed in properly. This effects sag setting and plushness feeling as they bed in.