They suggest bottoming out every ride?

Mmm. Under “Helpful Hints” :

“Most riders prefer a setting which allows them to bottom out once per ride”

Clicky

Mind you they also suggest using zip ties which I wouldn’t recommend.

No – It means you are using all your fork. If you never bottom it out you need a lighter spring.

Sorry, that’s not necessarily so. Different forks have different internals. Rockshox air forks, for instance, have a rubber bottom out bumber. It’s fairly easy to compress the fork until you’re on that, but when you do there’s 5-7mm of travel still left. They will go all the way to the crown if you hit them hard enogh, but you’ll NEVER do this in a test. I truly bottomed my Rebas out twice in all the 3-4 years I used them, the first time at Glentress, crossing a ditch in Deliverance. I tried to wheelie through it at speed and just slammed into the opposite side, pretty much flat. It was one HELL of an impact, and I got every single one of the 115mm available! but in normal riding, properly set up, 105mm-ish was about the maximum. The travel is available, but it’s for emergency use only to my way of thinking.

Conversely, my Fox Vanillas would readily bottom out. You could feel the clang when they did so, metal on metal it felt like! a 1-2ft drop would do it, or a biggish hit

If you’re only riding XC, there’s no reason to bottom the forks out. As long as they are set correctly for your weight then that’s great. If you were to set them to bottom out ‘once a ride’ they’d most probably be too soft.
MrsPP is a good example of this. It’s not often she used the last 1/4 of the travel on her forks becausue she’s a gentle rider. But the forks are set up perfectly for her……

PP – I would say if you hit the bump stop you have bottomed it out.

As for your missus – if she doesn’t use the last 1/4 of her fork travel I would say as softer spring is needed as they aren’t set up for her weight

PP – I would say if you hit the bump stop you have bottomed it out.

As for your missus – if she doesn’t use the last 1/4 of her fork travel I would say as softer spring is needed as they aren’t set up for her weigh

And you’d be wrong.

Rebas were stated as 115mm travel. Last 5-7mm is rubber bump stop. Fact. No argumnet. 🙂
(I might have a picture of it…)

Mrs PPs forks are air Rebas. Air pressure is lower then RS state (They always seem to be OTT anyway) and the sag is bang on, maybe a tad soft actually. You can see they are working, but she’s a pootler. They’ll go to 115mm, but she just doesn’t use it most of the time.

I know what I’m talking about here you know…… 🙂

Most riders prefer a setting which allows them to bottom out once per ride

So?

I know what I’m talking about here you know…..

I will concur. PP has helped me solve the mystery of my reba forks (on a ride)

Here you go, pics 11 & 12 in this:

https://docs.google.com/viewer?a=v&pid=explorer&chrome=true&srcid=0B1AoGIWBz4H1M2E5ZTc0MTItNjM4NS00YjBiLWEwZDgtMjEyYTQ5NWZlMjc5&hl=en_US

The slightly tapered black thing below the circled travel spacer is the bump stop. That stops the forks at around 105-108mm out of 115mm., but they will go all the way to the crown. There’s actually a mod you can do to that bumper and the internals to get 120mm out of a 115mm Reba, and make it give the last 10mm up more easily….. 🙂

What was that Ernie? I forget now….. Twas a long time ago! 🙂

So?

So, that might help you understand : “Why does this myth persist” ie, maybe it’s ’cause manufacturers such as Rockshox suggest it.

I would say if you hit the bump stop you have bottomed it out.

Then you’ve changed your position or you didn’t understand in the first place. As PP says, the bumper is there for the last few mm of travel – something most obvious on most rear coil-spring shocks.

What was that Ernie? I forget now….. Twas a long time ago!

You pointed out that I wasn’t getting the full travel out of my Rebas, which I suspected, but armed with your advise I was able to insist to my LBS that they were not right, eventually after much hassle they were sorted out ……thanks 8)

So, that might help you understand

It helps me understand that ‘most riders’ should try better damping and/or a higher spring rate.

Only if they want a fork that is too hard for them.

Why do you persist in trying to get us to accept that a fork that is too hard so that you don’t get all travel is right and telling the manufacturers they are wrong?

Explain that orange bumper on the shock above. Describe what it does and what would happen if it wasn’t there.

TJ – I thought they were arguing with you for asserting that tree-magnet was correct in saying that we should get full travel out of our suspension forks on every ride. Do you get full travel on every ride?

Thats the bump stop to prevent bottoming out with a clang. Its all very simple.

TJ You should bottom or nearly bottom out the fork on the biggest hits you usually take.

Unless you do this then you are simply not using all the travel and your spring rate is too high. You should never use compression damping to reduce the amount the fork travels

Edit = sum – no the quote above is what I said – almost but not the same thing.

Yes – I have my forks set up properly so that the biggest hits I take I will get full or almost full travel which II have measured by compressing the forkl with no springs or air in it. I actually alter teh air pressures depending on the type of riding I am going to be doing to ensure this (IE I put a few psi in for trail centres). No point in having 120 mm of travel and only using 100.

its a bit like saying.. i’m taking my new ferrari back cos the fastest i can drive it is 70 mph and it says 220 on the speedo. the 150 quoted travel will be the maximum available under the most extreme of conditions.
i suspect that if you let a little oil out of each leg or replace with lighter weight you’ll get much closer to your dream..

Why do you persist in trying to get us to accept that a fork that is too hard so that you don’t get all travel is right

**slaps forehead**

JUST BECASUE YOU’RE NOT GETTING FULL TRAVEL DOES NOT MEAN A FORK IS “TOO HARD”!!!!!!!

(Although in the OPs case there may be more to it as already suggested, I don’t know much about tuning Marzocchis)

I could set my forks up with 50psi in and go for a ride and not bottom them out if I rode smooth trails and/or carefully enough. What does that prove? Nowt.

You’re thinking about this in to simple a fashion. It’s not black and white, there are no hard and fast rules. What DOES matter is that you UNDERSTAND how to set MTB suspension up to get the best out of it for you and your ride.
I regularly ride with people who obviously don’t understand. You can ride beside them and see an expensive pair of forks set far too soft, 50% sag, and with the damping wound up so far its hardly moving.
I know someone who has a Superlight. Following them I noticed that the rear suspension wasn’t moving much, if at all. So I had a play and discovered the rebound was wound up to full, so the rear was just packing down and staying there.

Some people just don’t understand. And that’s perfectly fine, I’ll help every one of them if I can, but there’s so much mis-information in the MTB world about suspension it’s incredible, and this blinkered “must get full travel every ride” is simply more of it. it’s NOT TRUE all the time. Following that could lead someone into having LESS travel available because they’ll be running so much bloody sag purely because someone halfwit has said the fork must compress all the way every bloody ride. So the fork is sitting too low, the steering goes all to cock and it bottoms out too easily, which will give more handling problems (Tucking in, lack of grip due to no suppleness etc)

It’s BS. STOP IT!!!

There. That said it.

teh air pressures

Oh, and whilst I’m at it, can you please learn the correct order for the letters in the word “THE” You do it ALL THE TIME.

It’s:

T
H
E

or,

Tee
Aitch
Eeee

See that key up there near the top right? It’s called BACKSPACE. USE IT!!!!!

Why should anyone listen to someone who can’t spell “THE”?

😉

(I’m gonna hound you on this from now on. It’s been bothering me for yonks)

TJ – Goodo, I thought Tree was incorrect in suggesting that we should get full travel once ride. I’ve set my forks for the biggest hits I’m likely to do, but not all rides are the same, and the maximum travel I get will depend upon the ride.

I understand what you’re saying about adjusting forks to suit the ride but it can be hard to predict what the biggest hit is going to be in the ride that you’re about to embark upon e.g. if you’re riding somewhere new for instance. I’m impressed that you get to use more than 80% of your fork’s travel on every ride.

PP teh teh teh teh

Waht i actually wrote was

You should bottom or nearly bottom out the fork on the biggest hits you usually take.

Some people just don’t understand….. but there’s so much mis-information in the MTB world about suspension it’s incredible,

Is absolutely true. So many folk have badly set up sus its untrue. You clearly do know how to set up sus and we are only arguing over fine nuance.

I can spell , honest I can, but if I type for long enough my butter fingers invariably miss a key or two, or my fingers go faster than my brain, or some other such thing which is commmonly know n as a typo.

Blow ’em up till you can get about 3/4 travel leaping around the garden and they’ll be fine on the trail.

…we are only arguing over fine nuance.

You’re still arguing because you can’t/won’t admit that you are wrong.

Three fish = but I am not wrong – you are.

You should bottom or nearly bottom out the fork on the biggest hits you usually take

Is correct.

You even make one of the common mistakes people make. You suggest more compression damping if bottoming too much. All that does is mask the symptom at the expense of compliance. It is no cure.

If you want to have a fork that is uncompliant and does not get full travel then thats your choice. But don’t try to pretend it is right.

Why have a fork that does not get full travel? why have a120 mmfork that only travels 100 mm cos your spring rate and compression is too high?

Oh yeah that’s another good point – sag. On some forks if you want a good amount of sag you have to put enough air in to mean that you never get full travel.

I’d say three things dictate how much air you should have in your fork.

1) sag
2) how much it dives and wallows
3) how much travel you get/how often you ‘bottom out’

These things usually co-incide imo but not always. Not least because 3 can be affected by damping also. Certainly not the case on my 66s as above. If I set them up to get full travel on typical rides they’d be too soft at other times. Trust me, I’ve spent forever pissing about with them and have resolved to live with the lost 15-20mm travel. It’s worth it.

It’s the notion that there is a “correct” answer that bothers me. Correct for what and for whom? When my son, who weighs 5kg less than my wife, gets on her bike he bottoms the suspension within seconds. I don’t recall my wife ever bottoming her suspension. I’ve just asked her and she confirms.

Exactltly Edukator. Your son might get slightly less sag with the same setup, but despite that he would need MORE air in the forks.

Is correct.

As a complete statement, it isn’t correct. If you just said “nearly bottom out” then we would perhaps agree; but that’s not what you’re saying. It’s the assertion that riders *should* be bottoming out that I am challenging.

A well-damped fork will perform throughout its range of travel, from its starting point (in sag) to any point before it can not move any more. At the point where it bottoms out – ie it can’t move any further – it becomes useless and the bike becomes difficult to control.

Cafeful Molgrips, us agreeing might set a dangerous precedent.

TJ is familiar with Marz Dirt Jumpers, I’ve got a couple of pairs too of which one on a tandem. On the jump bike I run the oil level high enough that the pressure goes up pretty much exponentially at the end of the stroke. It’s impossible to bottom thm out which means on landing I never get that horrible end-of-travel shock. However, on the tandem where they are used as a strong trail fork I run the oil level lower, more air assist and put up with the odd bottoming to enjoy a more supple, better tracking fork.

Why would you want a fork to bottom out, surely if you can get it to within a couple of mm its even better? Your getting 99% of the travel without the risk of damaging internals and without that horrible thudding which inevitably will hurt your hands.

You may aswell go run rigids, your obviously not smart enough to use suspension.

Edukator – I was deliberately avoiding talking about air volumes to avoid even more confusion and misunderstanding. 🙂 Its one place people get vbery muddled – several of the examples given the solution would be to adjust air volumes

I adjust air volumes in forks to get the correct ramp up progression as you have done there.

On the tandem now is a z1 lite – with coil one side, air the other and its open bath.

Its running with 15 mm of extra preload on teh coil side, low oil level to give high air volume and high air pressure low compression damping Works perfectly giving a plush and supple travel with full travel achieved.

I can’t run the oil low enough to get close to full travel on mine. Much lower than about 100cc and I get air bubbles in it and only a smidge more travel.

Btw they are air only with an air spring in one side and an open bath damper in the other.

Re air volumes, my old Pace RC38s had a +ve air chamber in both legs, but one was quite a bit longer than the other. So you could tune amount of rate rising by adjusting the pressure ratio. Nice design.

TandemJeremy – Member
TJ You should bottom or nearly bottom out the fork on the biggest hits you usually take.
Unless you do this then you are simply not using all the travel and your spring rate is too high. You should never use compression damping to reduce the amount the fork travels

What’s it for then?

How about calling TF?

What’s it for then?

To stop you getting full travel too quickly. If you are landing froma huge gap jump then you want lots of compression damping because otherwise the imapct is so hard that you would slam through the travel really quickly. You could instead prevent this by having your forks harder but they’d have to be rock hard and would be rubbish everywhere else.

PeterPoddy, PeterPoddy, TandemJeremy said “teh” again.
Tell him, PeterPoddy.

Cheesburger – to slow the travel and stop bouncing – low speed compression to slow dive under braking and slow response thru compressions, high speed damping to stop the fork from moving too quickly / too far on square edged hits. If you have too low a spring rate so bottom hard / too much and increase compression damping to stop it then you lose bump compliance. Much better to get the spring rate right so uyou run less compression so you get good small bump compliance

Most folk would run the minimum compression damping – most forks have very little anyway although some folk use poplock as a crude crompression damper.

What’s 100cc in terms of oil level below the top caps with the caps off and the fork fully compressed Molgrips? All Marz forks froth up and doesn’t seem to adversly affect damping, it just makes squishy noises.

The longer travel your fork the more compression damping you want typically. Otherwise you’ll use up all the travel on a big rock then have none left if there are subsequent big hits. Shorter travel forks have to have a higher rate so this is less likely to hapen.

Edukator – I did know when I was messing with it before but I’ve forgotten. I had a manual (possibly THE official manual) that told you oil volumes and heights at the same time. I kept emptying lots of oil out and it was really bubbly, but still dint help.

I’ve had the air spring out and to get all the travel the insides have to compress to nothing at all, which is not gonna happen, especially as there’s a floating piston in there taking up volume. I’m considering running it without the floating piston, it might make it better.