Morning,

Still playing around with my new bike’s suspension and last night had a new sensation…I didn’t feel as though I was riding over the terrain but did feel as though I was pinballing over it…if I increased my speed it got better but the technical stuff that wasn’t being ridden at speed (as I’m a wuss!) had me rocking all over the place – didn’t feel I was holding my line at all.

Also in some cases where the rocks/roots had me stuttering, I felt as though the suspension was wallowing and then moving me forward.

The fork pressure is spot on and I think the rear shock needs a wee bit less pressure, but I was wondering if it had anything to do with rebound? Obviously tweak it and go ride the line again, but thought I’d ask on here as my knowledge of suspension is pretty limited…I thnk I’ve set the rebound up on both fork and shock to be on the slower side…could this be aiding to the wallowing sensation?

If not, what could be?

New bike feels great – 120mm travel as opposed to the 100mm of before and after last night’s ride, it was apparent that it needs to be riddens lightly differently, just still getting used to it as I’ve only ridden it 4 times so far! New handlebar is seriously wide and I’m finding it very easy to be knocked off line with the slightest thing…I know I need to get used to it but thought I’d ask about suspension…

it sounds to me like your suspension is too stiff either in spring rate or compression damping note compression not rebound, as the ride is harsh on low speeds but gets better as the speed increses,,

if you have too much rebound the suspension will tend to jack down,, over a series of bumps/roots,,

i test my bike by laying a ladder on the ground and riding over the rungs along the ladder (but if you get it wrong(rung) you can have a nasty off)
if you have too much rebound front or rear your suspension will gradualy get lower as you ride along the ladder,

too much compression damping or spring rate too hard it will be very harsh with very little movement

remenber riding mountain bikes along ladders is dangerous

Cheers Ade, but I’m not clearer on what I should be tweaking…I have a RP23 on the rear and 100RL on the front – fork has 80psi in it and I think 2 clicks slower than halfway on the rebound – I’ll do it 2 clicks faster so it is the middle and see if that helps…

The inability to stay on my line I think is down to my lack of riding coupled with some very wide bars and a new bike…that will get fixed with practice (but I thought I’d ask the question in case it was down to incorrectly set up suspension.

The wallowing as I hit bumps at slow speed could probably be fixed by riding faster but I also wonder if it is down to slow rebound – compression seems to be ok in the sense that it is compressing but I can’t adjut the compression rate…which makes me wonder if the fork has enough air in it or my rebound is maybe a bit too slow.

I’m not wanting to be sitting on a pogo stick either though…

Any thoughts? Ladder tirck sounds like a good one, I’ll try that.

It depends on so many things, it’s not easy to diagnose someone else’s suss set up over the net, but here’s my tuppence; slow rebound works better when you’re hitting things fast, come this time of year, for example, I always add a couple of clicks as you tend to be hitting stuff faster. then come winter everything slows down again. Personally I like my suspension to work better when I’m going DH fast, as that’s when you need most control, I almost ignore slow speed stuff, as I don’t really care about smoothing out roots and what have you.

You know what to do though really, just a bit of commitment by the sounds of it…

Have you really set the air pressures correctly? 🙂
Triple check that first. Set about 25% of the travel as static sag (But RTFM first! Some bikes are reccommended by the manufacturer to run more or less than this)

Once that’s done, concentrate on the rebound damping first. (Rebound is the most important. That’s why most shocks and forks only have rebound adjustment!) if the bike feels skittish or bouncy it’s probably rebounding too quickly (trying to buck you off in the process), so slow it down by adding more damping (More damping=more contol!) If it feels wallowy or sluggish, take some off. Just do small adjustments, ride for a bit, notice the difference, adjust a bit more, and so on.

As a rough guide, a heavier rider will need LESS(Faster) rebound damping as their weight will slow the return speed of the suspension, and a lighter rider will need MORE(Slower) rebound, for the exact opposite reason

One more thing – There is very little point copying someone else’s set-up, or letting someone else do it for you. There are simply too many variables to consider. The only real way to get suspension set correctly is to UNDERSTAND what each adjustment does, then you’ll know what to do to get the correct setting!

Hope this helps
🙂

slow rebound works better when you’re hitting things fast

Err, no it doesn’t.
Rebound damping (Or compression for that matter) depends more on rider weight than anything else. Terrain does have a bit to do with it, but speed? Not so much….
That said, it follows that the faster/harder/more bumpy you go, the faster your suspension needs to react to recover between each bump, so if anything, more speed = less/faster rebound.
[Mr Spock]
It’s logical, Jim!
[/Mr Spock]
😀

Yoou need to set the sus up.

Start off by setting sag. Depends on the bike but usually around 20/% each end.

Find a line with bumps on it that you can ride repeatedly. (or a ladder) A line with a tight corner and a wide corner as well as bumps is good.

Turn all damping to minimum and ride the line. Note how the bike feels

Increase rebound at the front a bit at a time – maybe 20 % of the adjustment at a time Ride the line each time and note how it feels.

When you have an approximate setting for the front then do the same with the rear.

When you have approximate settings front and rear redo it looking for finer adjustments.

Myself I like fast rebound. IMO many bikes are set up too slow / hard. Again IMO you want the least damping that controls the bike.

Too much damping leads to packdown over stutter bumps, too little leads to bouncing around. Too little rebound on the front will have the bike running wide on corners.

This is mainly from motorcycle experience as I haven’t run a full sus MTB but I think it is applicable to MTBs as well.

Its a case of trial and error. One adjustment at a time and note the effects of that adjustment

Cheers for the info…makes sense…I suspect the biggest thing is the need for more commitment…I really do need to get my bottle sorted…will remove a click of rebound off both ends and see what is what. I used the Marin guide to set the suspension up – says 12.5mm sag if I was firm or 15mm sag if I want soft…last time I checked it was sitting at around somewhere just over 13mm.

Will check the other bits and pieces and give this all a try…I’ve never really bothered setting full bounce up before other than putting air in the shocks…but with the extra 20mm travel, I am noticing the bike moving more and I think it does require more time spent on setting it up (hence my questions – I’m a luddite with suspension).

Cheers.

Again IMO you want the least damping that controls the bike.

Correct.
🙂

But too little is just as bad!
🙂

PP, I’ve found that if you have the rebound fast (less) and hit repeated obstacles fast, the bike just starts to Porpoise down the trail. I’m not talking about cranking the rebound all the way to max, I’m talking a couple of clicks either way. But, as you say, suss set up is a personal thing, and my set up works for me.

The other thing I forgot is an o rinf or cable tie around the fork stanchion and shaft of the shock to see how much travel you are getting. You should be aiming to use all the travel once per ride or so.

PP i was told that the lighter rider needs less rebound damping.

I have used suspension bracketing to get to my ideal settings.

PP i was told that the lighter rider needs less rebound damping.

You were told wrong, or you got it confused with compression

Put as simply as I can describe it:

Light rider –
Less (Faster) compression because their lack of weight makes it harder to compress the suspension
More (Slower) rebound because their lack of weight enables it to spring back faster, so you need to contol it.

Heavy rider –
More (Slower) compression to contol the fall of the extra weight
Less (Faster) rebound as their weight contols the return stroke

This also neatly explains why you hear of people adding more compression damping to ‘prop up’ a fork that’s too soft. In effect it just moves slower so less travel is used for a given obatacle/bump, but it’s not any ‘stiffer’ as such…

That’s not opinion, it’s cast iron fact.
🙂

But then there’s spring rates to consider at the same time as well, and it all starts to get more tricky….
Do yourself a favour, and take time to learn about suspension. It’s not hard to grasp the basic concepts then you can make informed decisions about what to adjust
🙂

Aha, just taking it from my secialized set up guides.

http://cdn.specialized.com/OA_MEDIA/pdf/08%20Fork%20Setup%20Chart.pdf

I think you are wrong PP. Heavier rider needs more rebound damping as they are compressing the spring more thus there is more force to return it.

think you are wrong PP. Heavier rider needs more rebound damping as they are compressing the spring more thus there is more force to return it.

You’ve got it all muddled there TJ. 🙂
They might compress the spring more, but they have more weight to stop it bouncing back again. Gravity helps on the downstroke (So you need more compression to slow it), but you’re working against it on the way back up again. (So you need less rebound)
Is it easier to lift or drop a heavy weight at a given speed? There’s your answer…..
I know I’m right. And it’s not my opinion anyway, just what I’ve learned.
🙂
But like I said, factor in spring rates and it starts to get a bit more complicated, more complicated than I have time to explain here, anyhow…

P.S.

There’s a whole load of BS talked in the MTBing world about suspension, the mags especially…
🙂

PeterPoddy – Member

P.S.

There’s a whole load of BS talked in the MTBing world about suspension, the mags especially…

Utterly correct in that. 🙂 Same in the motorcycle world

I’d like to see some backup with what you say tho cos it is directly opposite to anything I have ever read or learnt, opposite to the setup info given in the link after your post.

The damping is to control the return of the spring. a heaveir rider will put more energy into the spring so there is more energy to be released so more damping is needed.

PP you’re sort of right but sort of not.

Light rider –
Less (Faster) compression because their lack of weight makes it harder to compress the suspension
More (Slower) rebound because their lack of weight enables it to spring back faster, so you need to contol it.

Heavy rider –
More (Slower) compression to contol the fall of the extra weight
Less (Faster) rebound as their weight contols the return stroke

You’d be right if both riders were using the same spring rate but they probably don’t – they’re likely to be using spring weights/air pressures relative to their weights. As such, the heavier rider will have a harder spring which in turn requires more rebound damping to get the same relative speed related effect (though since it’s not linear, this won’t necessarily linearly more than the lighter rider).

God, agreeing with TJ. I feel sick. In fact, I might just agree with you anyway, PP.

the other thing that might be happening..

when you are trying hard you tend to get into the attack position a more forward position? or more rewards on decents,, standing?

when you are just crusing you may be sitting on the saddle

now do you set spring rates and sag standing sitting ,, weight over the front etc,,

i normaly ride along standing on the pedals and bounce the bike and try to set up so i am seeing about the same movement and level of damping front and rear,,

lets face it you can only have the bike setup perfectly for one bump at acertain speed,, for everything else it’s a comparmise it’s up to you what you set up for,,
the normal stuff you ride over,,,,, or the worst stuff you are going to ride over

….. You should be aiming to use all the travel once per ride or so.

I’ve always wondered about this statement… as I may do a ride that doesn’t require full travel, am I supposed to set up the suspension so soft just to achieve it…

lets face it you can only have the bike setup perfectly for one bump at acertain speed,, for everything else it’s a comparmise it’s up to you what you set up for,,
the normal stuff you ride over,,,,, or the worst stuff you are going to ride over

And the above statement sums it up really.

The using the travel once per ride thing was kinda how we used to setup MX suspension, we were looking to bottom out on the biggest bump on the track, its a valid guidline, but better for something you do laps and laps of the same course.

On A MTB I think setting sag is the king, get that set right and you can ride around most other problems as long as your not miles off on rebound and compression (its only a pussh bike after all). Not sure about how much you need the rebound to be stopping your weight from bouncing about I thought it more for keeping the wheels from flailing about once its all unloaded, I stop myself from being bounced about by body english and being in the right position on the bike for any given obstacle.

As adeward says its about getting front and rear working together one end allwrong will mess the other up.

Dickbarton as you have changed bikes recently have you paid any attention to where your weight is relative to the cranks on the swap from your old bike to the new one? Could you be too far forward or backward on it upsetting the suspension?
Sadly the best setup bike in the world will only aid your riding, it isnt a cure, and more riding is the only way forward from there, and dont try to go too fast all in one go, up the ante gently at your own pace.

I keep telling him that his 100mm stem is way too long but will he listen…

in my experience,,in general low speed damping controls the movement of the unsprung weight that is the rider, frame etc,, and the high speed damping controls the sprung masses the wheels swinging arm and fork lowers

now as we cant all have 4 way adjustable dampers,and forks and those damper and forks we have mainly have low speed adustable damping we can control the movement of the frame and rider and how well the wheels follow the terrain is mainly down to the high speed damping the shock manufactorer has built in to it

some of the problem on t’internet is the language used to describe problems and the use of buzz words wallow, patter etc i could always tell more what was happening by watching a bike over a section rather than riding,, so get someone to video it,, or get yourself a datalogger,, i used to run one of these with Dave Hemming in 99 best development tool the logger not Dave

He won’t listen Hugo cos that’s magazine chat too.

The using the travel once per ride thing was kinda how we used to setup MX suspension, we were looking to bottom out on the biggest bump on the track, its a valid guidline, but better for something you do laps and laps of the same course

Cheers, tinsy; I’ve haven’t setup my suspension based on that statement for the type of riding I do and what you say that makes absolute sense and confirms what I thought. I can see situations in mtbing (e.g. DH) where you might use it, but for me I don’t think it applies.

For me sag and rebound are what I focus on. If I have the rebound too fast it feels like I’m being pinged off the bike, but maybe I can correct that by better body postioning….

Same here re: Bottoming out the suspension times per ride.
Again start with say 25%
For me I find a sweet spot and I stick to it, never really bottom out, though achieve 90% of the travel on the usual loops. Technically could reduce the PSI in the fork and shock, but at the moment on my new bike just enjoy it for now. LS compression I use for the brake dive/body position. Just on the front, soft compression on the rear>

someone linked a tim flooks ‘how to’ video off here a month or so ago – look it out. the thing i took away from it was:
set the sag, then set front rebound a bit fast, the back a bit slow. so go to the extreme on both, then back them off a bit. then ride it. that sets the bike up safely – head angle gets slacker as the back will tend to pack and the front won’t. progress from there. worked for me.
do it the wrong way around and the thing will try and throw you off as the head angle steepens and the saddle kicks you in the ass…