[Closed] suspension question Geeks/designers/STW opinion please!

Low speed compression. Get some.

Low speed compression. Get some.

Being on steep tech/forks settling further into travel/HA steepening too much is mainly due (IMO) to difference in steady state weight distribution, damping, a dynamic state control has little effect on.

What im saying is, when you set your sag on flat ground, the amount of sag is controlled by the spring, of which controls steady state load. Damping, when you're setting sag has zero effect, damping can only control dynamic effects.

Though low speed compression will prevent fast pitching but will not prevent the steady state weight distribution effects.

OP _ the effects you're describing are the exact reason why i dislike long travel hardtails, the effects are exaggerated further.

World cup DH racers account for this in their bike setup. For tracks like Champery, they reduce the rear spring rate while increasing the fork stiffness. It helps the suspension sag stay in the correct range for the track but in a flat carpark the settings would be off.

I guess if you were predominantly riding steep terrain you could do the same. If the terrain is more varied then it's tough to make such a change without it ruining your handling everywhere else. I myself always run my fork quite stiff, on my hardtail, to prevent major nose dive. I don't care if I lose a bit of small bump compliance.

Cant see how that will preserve the head angle any more than a short travel fork. The wheel still moves closer to the head tube causing the head angle to become steeper.

Can anyone tell me what I've got wrong?

long travel forks will squish down when your weight goes over the front on slow techie stuff.

Therefore, would it not make sense to keep a lock out or limiting the travel on a longer travel fork in order to preserve that precious head angle keeping things nice and slack?

for low speed technical stuff, head angle is more important.

the most important gain in handling from a slacker H/A is added stability at speed.

I've gone from a Boardman frame to a C456 with a slackset with the same forks and kit and the only difference I can detect is that it feels more stable when going fast. It climbs just as well and steers just as well going slowly.

why are you pitching your weight forward in this situation? keep your weight centred, as the terrain gets steeper this involves moving your arse (COG) behind the saddle

I'm not. even putting weight further back when on super steep stuff will still mean more weight on the front - you can only get your weight so far back as arse (COG) is stopped by rear wheel.

The crux of my argument is that a steepening head angle is undesirable on slow, steep descents. Low speed compression doesn't sort this as it's a weight distribution thing.

wouldn't a beefier version of the spesh brain work in these circumstances?

Rockshox thing.. what's it called.. Motion Control? Pop lock? On my Revs.

It looks like a lockout, but you can tune how much force it takes to temporarily unlock it, and how much damping there is when it's unlocked.

For the situation you describe, slow nadgery steep stuff, I've got mine set to unlock reasonably easily and to move quite a bit when unlocked, so it just becomes like a really stiff fork. It'll take the sting out of hits, but it doesn't dive so I don't get chucked over the bars. Plus it's also stiff enough not to bob around at all on the road.

Great system I reckon.

molgrips - I think that's the cookie. As I said, my mind was just wandering a bit last night and wondered what the consensus was on importance of maintaining a slack HA on steep techy stuff.

From another point of view..

Imagine your frame is in a stable condition when riding, ie, the frame is the reference point.

When you hit a bump, your forks will travel along their axis, which will not alter the head angle at all.

Your argument assumes that when the forks compress the whole bike pivots downwards around the rear wheel. It is in fact the front wheel coming up towards the frame, not the frame going down towards the front wheel.

You've just come up with the one of the limiting factors or telscopic forks (HA reducing when braking negotiating steep sections)
Designers have been trying to solve this issue since (motor) bikes were first designed with suspension forks.
The problem is the weight/strength,stiffness/feel of other systems, the telelever/paralever and other 'funny front' end designs are usually complicated and lack feel, hence one is running them in moto gp although there was talk of a frame being used in Moto 2 but has yet to appear.

So you're left to compensate with the setup of the fork, agin this is a comprimise between 'holding itself up' in steep sections and not rattling you to pieces on the rougher flater sections.
A gate/threshold system such as the 'Brain' you metioned isn't really ideal as when you hit a larger bump it will become active and the fork will dive anyway, at least with non threshold forks they will work consistently.

Your argument assumes that when the forks compress the whole bike pivots downwards around the rear wheel.

He's talking about slow steep stuff, where that does happen with sometimes disastrous consequences 🙂

One big reason we still use teles is that we're used to it, and bikes are designed around it.

Apart from my old Gary Fisher Cake. A fantastic bike for riding hard and fast until it got steep, then it was difficult to avoid being thrown overboard. It was a 130mm travel bike with a 70.5 I think.. steep and XC ish anyway.

That bike would've really benefited from a linkage or anti-dive fork I reckon. Even the Revs would've been great on it.

A gate/threshold system such as the 'Brain' you metioned isn't really ideal as when you hit a larger bump it will become active and the fork will dive anyway,

Well unless it's a two-mode thing as above - when it becomes active it still has loads of compression, more than normal. Of course you have to manually activate it when you think you're going to need it.

What about a dual-chamber system like Trek's DCRV with a manual switch to open the second chamber?

1deg steeper makes next to no difference. If you are struggling to ride steep stuff it's YOU that's the limiting factor, not your choice of telescopic fork.

1deg steeper makes next to no difference. If you are struggling to ride steep stuff it's YOU that's the limiting factor, not your choice of telescopic fork.

I agree.

Pretty much everything on a mountainbike is some sort of compromise. Head angle is just one of them. If your bike has a slacker angle, then even if it dives on slower, steeper sections, its still slacker than its steeper head-angled cousin on the same section, but come to the next climb and the steeper bike may be in a better position.
Compromise....thats all it is, and get your @rse off the back of the bike...

GW, although a better damped fork and slacker HA will certainly help 😉

GW - When things point down, regardless of where your COG is, the front wheel will tend to receive a greater share of the rider weight, compressing the fork further than a flat ground situation, steepening the HA.

You of all people should know that arse over back tyre helps, but its only survival riding, not the best position to work the bike from. If you can get more central without being flung over the bars, you're going to ride in more control. Stiffer (not more damped) forks and maybe softer rear shock combined with a slacker HA will achieve this.

I'm really not a fan of arse over the bike riding, looks and feels ****.

1deg steeper makes next to no difference. If you are struggling to ride steep stuff it's YOU that's the limiting factor, not your choice of telescopic fork.

Total failure to grasp the point, apparently in favour of having a dig. If I am me, which I am, then a bike with a slacker HA will make it easier to go down very steep stuff.

That's not blaming my equippment, it's not claiming to be great or otherwise, it's how it is. I'm sure better riders would be able to ride stuff I can't on bikes with steep angles, but that's besides the point.

If I still had the bike I'd invite you to try it out. It was a great bike for some things, due to unusual geometry for the amount of travel, and not a great bike for other things.

Wise words as a suspension tuner 😉

Slacker HA on it's own won't actually help. I'll happily ride a vert roll in or overhanging drop to near vert chute etc. on mtbs with anything from 71 to 63deg HAs.

Slacker HA on it's own won't actually help

I think it would. Slacker angles overall would help more.

I'll happily ride a vert roll in or overhanging drop to near vert chute etc. on mtbs with anything from 71 to 63deg HAs

Not quite the situation being discussed. We're talking about steep stuff where you have to be on the brakes, to negotiate obstacles, rocks etc.

If you are struggling to ride steep stuff it's YOU that's the limiting factor, not your choice of telescopic fork.

skillz innit 😆

I often ride much the same trails on a 1994 rigid Kona Explosif as I do on my 160mm travel hardtail (and full suss)... ignoring all the big drops and concentrating on the gnarly techy bits the big difference is the confidence and hence speed I can ride them at with the long travel forks. I can get the Kona down much the same stuff but it's a very different type of riding (i.e. mincing).

FWIW... the best fork set up I have found for the long travel hardtail is exactly the same as the set up I had on the full suss... no changes.

I'd sy the ability to absorb bumps is way more important than HA for the riding in the OP.

HA matters more at higher speeds.

This thread is like 5 people saying "I'm not amazing, and because of that I find x a problem, is there a way to fix it mechanically or make it less of a propblem",

and GW saying "Well you're a khvnt and you don't deserve to ride bikes then".

Could it be possible that someone has spent too long on pinkbike?

As on so many subjects you're simply not experienced enough to make a sensible comment.

Lolz. I honestly have no idea why you are so nasty on here. It's really weird. You have absoutely no idea about me!

AS for BMX - I don't think that, in terms of physics, there's much similarity between a steep slow rocky trail on an MTB and a vert ramp on a BMX.

Why do you think the makers of DH or freeride (or whatever it's called nowadays) bikes use slack HAs and long forks, if it doesn't help?

I've got mine set to unlock reasonably easily and to move quite a bit when unlocked, so it just becomes like a really stiff fork

I'd think the main benefit of slack HA in steep, slow riding is just that it reduces the likelihood of somersaulting by pushing the front wheel forwards - I suspect it also makes the fork slightly easier to compress (a bad thing for preserving front end height) as you're bringing it more in line with the forces applied when you hit a bump

(or a meringue ?)

I don't get this mol' - you let your fork unlock easily and then you let it move a lot, but this makes it really stiff ??

I meant move a lot compared to locked out... but still a lot more damping than normal. Badly worded, I know.

Gents! Gents!

I completely own up to not having the rad skillz need for tough, techy stuff. My OP was more of a technical interest. I'm sure some people could get down stuff that would make me cry on their pinarello dogma. Well done. My point was more to do with whether the same rider could do it quicker on a slack HA bike with very little travel.

consensus is that slack is useful for slow, on the brakes steep descents. No?

Yes, and GW is telling us we're shite riders. Just to add a bit of colour to the thread I think.

I had a Whyte 19 Steel - on paper this has a slack head angle with 120mm forks which should have made it a good handling bike for the gnarly low speed techy stuff which I like to ride... unfortunately it has a bottom bracket which is the height of the ozone layer which meant that in the afformentioned terrain it was a bit of a handful (IMHO etc etc). I still quite liked it though 😳

Head angle is not the only important variable etc etc.

I'm not sure its so much of an issue as it might seem when you first start thinking about it.

Firstly you need to give some credit for the rider shifting their weight back on steeps (Which most do instinctively) this does to a certain extent help re-balance the suspension loading.

I think generally I'd prefer more active front suspension to a 'held up' (but stiffer action) front end on steeps, you often find rough lines come out on steep sections due to more brake dragging and roots/rocks becoming exposed, having suspension thats better at tracking that sort of ground with the compromise of potentially diving a bit under heavy braking/weight shifts forwards is acceptable IMO. it's also worth considering rebound speed perhaps, a fork which can recover faster following hits might achieve a similar sort of effect to a stiffer fork by simply not packing down as redily.

Also I'm not so sure that having a Slacker HA is so much about holding the front up as having the front wheel further out in front; that is to say the bike is better balanced generally when the wheel is tracking ahead and not so prone to tucking under, so a slacker HA in itself isn't the be all/end all, more where it places the front axle relative to the mass of the bike and rider, further forwards is more stable but the fork still need to be active and working for this to be of any benefit.

addressing rear suspension setup as a factor is a pretty wise idea too, sofening it while considering reducing rebound and compression rate might help create faster acting suspension that sits further into its travel, this makes sense to me fir a DH bike but does come with obvious compromises...

What about a dual-chamber system like Trek's DCRV with a manual switch to open the second chamber?

I did think about something similar a while back; modifying a 'standard' air shock by adding a remote 2nd volume to the spring, which the rider could choose to open/close a valve to, increasing the effective spring volume, sofening the spring, making it sag more and track better but retaining the same damping settings (assuming that is acceptable) the trouble comes when you need to stiffen the suspension again later (closing off the valve) for which I think you'd need to include some form of non-return valve to allow the main shock volume to re-balance pressure, or you have to stop, get off and unweight the bike for the shock volume to be reset, But it could easily be done though...

All of this is marginal gains though and if we're talking more about AM/XC FS bikes (Which I sort of assume we are) then is the risk not that the bike is compromised for pedaling up/along just for some relatively small gains on the DH sections?

The biggest benefits will of course not come from pissing about with suspension but from the most basic component, tires the right choice of tire at the right sort of pressure will do far more for grip, traction and ride than endless hours playing with suspension settings...

The biggest benefits will of course not come from pissing about with suspension but from the most basic component, tires the right choice of tire at the right sort of pressure will do far more for grip, traction and ride than endless hours playing with suspension settings...

YEEEEEEEEEEESSSSSSSSSS, basically. Tyres are the limiting factor in our tyred vehicle systems, they set the boundaries the system can achieve, suspension and everything else aids in operating hopefully somewhere near those boundaries.

Firstly you need to give some credit for the rider shifting their weight back on steeps

Well of course they do. But say you have a steep HA, then you need a longer reach otherwise your front wheel will be really close to you and the COG. So with a steep HA you need a longer top tube. This makes it harder to get your weight as far back - at least it has done on the bikes I've ridden.

The biggest benefits will of course not come from pissing about with suspension but from the most basic component, tires

Er well in general maybe, but tyres aren't going to stop you going OTB on a steep techie section of steps are they? Anywya they do mostly different things. Tyres are important, syspension is important, for different reasons. No-one's talking about shaving seconds off their lap time here.

Well of course they do. But say you have a steep HA, then you need a longer reach otherwise your front wheel will be really close to you and the COG. So with a steep HA you need a longer top tube. This makes it harder to get your weight as far back - at least it has done on the bikes I've ridden.

Nah... can't follow your stream of consciousness, arrange your thoughts and make a coherent point please...

Er well in general maybe, but tyres aren't going to stop you going OTB on a steep techie section of steps are they? Anywya they do mostly different things. Tyres are important, syspension is important, for different reasons.

Er if the the aim of the game is control in a marginal situation the thing that counts more than anything is the ~2" patch at either end providing grip and traction for braking and direction changes as well as being the primary means of 'suspension'... Without that your fancy pogo sticks mean bugger all, don't underestimate what job the tires actually have to do on and MTB... They prevent you 'going OTB' by providing better control of the bike and allowing you to avoid a stack...

No-one's talking about shaving seconds off their lap time here.

If the objective is not to go faster by having more control then what is?

Remember the U.S.E. fork?

Behaved really well on the slower steeper stuff.
Unfortunately had really old fashioned internals, so not active enough in other situations.

As regards the original post, a fork on which you could reduce the amount of travel without reducing the axle to crown height, would be an interesting product for some.

As regards the original post, a fork on which you could reduce the amount of travel without reducing the axle to crown height, would be an interesting product for some.

Er if the the aim of the game is control in a marginal situation the thing that counts more than anything is the ~2" patch at either end providing grip and traction

Most tyres give you enough traction in that situation. This is a thread about suspension, not sure why we are bringing tyres into it.

If the objective is not to go faster by having more control then what is?

Really? You treat MTBing like motor racing or something?

Sometimes the challenge is to go fast, sometimes the challenge is not to fall off. Suspension tuning can really help in the latter situation, hence this very thread. Or more accurately, poor suspension tuning or bike geometry can be a hindrance...

Have you read this....

http://singletrackmag.com/blogs/2009/01/benjis-long-termer-genesis-alpitude/

its relevant, honest...

I think a fork with more mid-stroke support and a better rebound tune might help the OP's problem. I certainly know since I fitted the blackbox dual flow rebound to my ex-sektors now revelations it rarely ends up packing down on technical rocky descents.