air shocks for DH

MisterMental said:

question,
surely if your running an air shock in the rear and have Xpsi in it at the top of your mountain by the time you get to the bottom the air pressure in the shock will have increased due to the heat from the shock working over the bumps.
im probabally wrong with this or they wouldnt be selling them but why doesnt the pressure increase? do they have a bladder like disc brakes do in the resi?

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Yes, the pressure will increase. Whether or not it increases enough to be an issue will depend on the rider, the bike, and the terrain.

Ugh, is this discussion really gonna happen again?

Lollapalooza said:

Ugh, is this discussion really gonna happen again?

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wow, i see you took your douche pills today

did you use the search?

Fill it with nitrogen if you really think its a big issue!

The heating is not significant to cause a problem My CCDB damper is significantly hotter then my manitou evolver ISX-6 Damper at the end of a 15 minute run and its moderately warm at best. The air can does not feel hot in the slightest.

That said, my shock leaks about 10 PSI for a day of N* (about 8-9 runs) so I actually could use it heating up...

At any rate, its kind of analogous to asking if your tires heating up over the course of a day is a problem (stupid)

William42 said:

At any rate, its kind of analogous to asking if your tires heating up over the course of a day is a problem (stupid)

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Disagree, that statement holds no relevence. An air shock has to do a lot of work, and at high pressures as well, there is moving componants = friction = heat.
The reason fox factory riders use a coil still? You do a WC style track in length at WC speeds and you get pump up.

I would think that shocks with larger chambers (Roco WC) or on 3:1 ratio+ bikes would be ok.
What I wonder is why nobody has made a air bag style DH shock? Solve all the problems IMO.

MrPlow said:

Disagree, that statement holds no relevence. An air shock has to do a lot of work, and at high pressures as well, there is moving componants = friction = heat.
The reason fox factory riders use a coil still? You do a WC style track in length at WC speeds and you get pump up.

I would think that shocks with larger chambers (Roco WC) or on 3:1 ratio+ bikes would be ok.
What I wonder is why nobody has made a air bag style DH shock? Solve all the problems IMO.

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your right. everybody here is riding WC level. How silly of me. In fact I don't know why they even have world cup races, because everybody is at that level of riding.

Oh, and if you actually watch the races, several riders are starting to use air shocks in WC races.

At any rate, the reason they are not running air shocks is because of the spring curve, not because of the damper or air heat. I have an air shock. Heat is not an issue. Its because its not linear enough. Some shocks are getting better at that. Fox still sucks balls (although Udi, and i'm sure others, have fixed this to a degree), RS has no offerings, and since 99% of the people racing WC level are sponsored by RS or Fox, theres not alot of chance you'll see an evolver or roco.

But hey, it was a good argument while it lasted huh?

I have been playing with air shocks for my DH bike for a while now. The heat is not a huge issue. The mid stroke support is lacking and when you bottom, air gets into the rebound. If you get it tuned with those things in mind there are huge possibilities. I am running a new tune by Suspension Center in Switzerland to address these issues and the results are amazing. This is the fourth different tune I am trying and it is set up for pinning. I am running much more low speed damping and much less high speed damping than ever before and I am liking it way more than I thought I ever could. I have some of the longest, steepest and most technical tracks in the world and the shock is begging for more. I sometimes can't believe it is an air shock. A stock DHX air doesn't work well at all for me and gets very hot half way down most tracks but this new tune is making me think that it is possible to get the performance out of the platform. In conclusion, I think it is possible to run an air shock but you need to have one of the best suspension tuners out there completely rebuild it for it's intended purpose.

Or just find a bike that has a leverage ratio and shock curve that suits an air shock, and fine tune yourself to suit. I've run two dhx air's on a sunday over the last 1.5 years and they've been pretty sweet.... no heat excess, no blowing through travel, and no issues with air in damper (sounds like a one-off thing to me). I'm running about 130psi and 4 clicks of propedal atm, so there's a reasonable amount of LSC... these bikes don't need much obviously though.

The bigger problem is lack of mid stroke in some airs. I used my bike with an air shock for over a season and had no problems with overheating. Even when riding on long chalenging trails like Maribor. But I'm pretty light (65kg)

MrPlow said:

Disagree, that statement holds no relevence. An air shock has to do a lot of work, and at high pressures as well, there is moving componants = friction = heat.
The reason fox factory riders use a coil still? You do a WC style track in length at WC speeds and you get pump up.

I would think that shocks with larger chambers (Roco WC) or on 3:1 ratio+ bikes would be ok.
What I wonder is why nobody has made a air bag style DH shock? Solve all the problems IMO.

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I think you mean a Big Chamber and low leverage since on higher leverage you would have the shock working more. In fact, the whole unit would be smaller by definition.

not only does it lack Mid Stroke, most people hate the small bump compliance of air shocks. In most cases, manufacturers stock air shocks either to attain a certain progressive curve or to lighten up the frame to fit the description

buckoW said:

I have been playing with air shocks for my DH bike for a while now. The heat is not a huge issue. The mid stroke support is lacking and when you bottom, air gets into the rebound. If you get it tuned with those things in mind there are huge possibilities. I am running a new tune by Suspension Center in Switzerland to address these issues and the results are amazing. This is the fourth different tune I am trying and it is set up for pinning. I am running much more low speed damping and much less high speed damping than ever before and I am liking it way more than I thought I ever could. I have some of the longest, steepest and most technical tracks in the world and the shock is begging for more. I sometimes can't believe it is an air shock. A stock DHX air doesn't work well at all for me and gets very hot half way down most tracks but this new tune is making me think that it is possible to get the performance out of the platform. In conclusion, I think it is possible to run an air shock but you need to have one of the best suspension tuners out there completely rebuild it for it's intended purpose.

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what frame do you have it on? and what was the original coil shock on it?

buckoW can you tell us a bit more about the tuner? I did the mojo tune on mine and told them I needed more mid stroke and it's much better now. Fall on the flat ledge from 3.5m drop and it didn't bottom! but still better tunes are always welcome.

Also can any1 confirm the rumor that 09 DHX airs have better mid stroke?

Curious_George said:

I think you mean a Big Chamber and low leverage since on higher leverage you would have the shock working more. In fact, the whole unit would be smaller by definition.

not only does it lack Mid Stroke, most people hate the small bump compliance of air shocks. In most cases, manufacturers stock air shocks either to attain a certain progressive curve or to lighten up the frame to fit the description

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Jesus dude, you are the worst of the internet riders I have ever met. "Not only does it lack mid stroke," - mine doesn't. Roco WC Airs dont. Udi's doesnt. A properly set up DHX Air doesn't, and the other offerings don't at all either. Have you been reading this thread?

"most people hate the small bump compliance of air shocks" - what? What the hell are you talking about? Are you saying they have too much HSC? because I can tune my HSC and my evolver has better HSC controls then any shock I have used period. (Currently riding a CCDB). The small bump is 100% there. I would guess if you asked anybody who actually took the time to set theirs up, or to get one that worked well without additional tuning they'd say the same. My guess is Udi wouldn't be running a DHX5 Air if it felt like poo on small stuff, and I know I wouldn't ever run my evolver if that were the case.

I'm sure you have lots of ride time on all of them though, you must be right.

Anyway, rant off, heres an honest question: does the DHX 5 fit most frames better or something? I'm just wondering why its considered the "go to" air shock even though it has crappy stock midstroke (and yes you can tune it, but its clear from the "my shock sucks I'm getting a coil" that people don't). Why is everybody interested in whether or not it doesn't suck (with stock setup, without playing with oil adjustments and just using the external adjustments) as much for 09? Fox has had several years to fix this, but they haven't, and you'd think if it were as simply as upping the oil level slightly they could have nailed it. I know they're playing it conservative, but with two other fantastic options on the market, why is everybody dead set on fox?

but with two other fantastic options on the market, why is everybody dead set on fox?

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OEM
Also roccos have had their share of problems. Evolers pay the price of being a manitou product.

About the mid stroke - it's all personal feelings. Imho without the tuning the 9.5'' Air on my dh-230 had very bad mid stroke and even different settings couldn't help it.

air shocks can loose air or dampening, coil shocks aren't likely to break a spring(though it does happen).

air chamber size depends on the bike frame.
rising rate bikes are good with bigger chambers
linear or falling rate bikes are better with the smaller chambers.

air shocks take more maintenance and more patience to set up, check air pressure a lot, and keep the seals clean and lubed.

Teoreticaly yes but practicaly I didn't loose any air and the only dampening loss was because of the factory error that would do the same for coil. Set up of my DHX air was easy and I could set the sag more acurately than I'd on coil. My shock is still perfectly at 33% sag after a full season of riding.

I keep my shock well dampened. I have a sprinkler system set up for it to make sure it stays quite damp even on the hottest and dryest of days.

Your right, roco's have had there share of problems, but no more then say, a vivid (unthreads itself anybody).

LMC said:

what frame do you have it on? and what was the original coil shock on it?

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Stock is a 240mm i2i DHX on a Scott Gambler in the 210mm travel hole.

norbar said:

buckoW can you tell us a bit more about the tuner? I did the mojo tune on mine and told them I needed more mid stroke and it's much better now. Fall on the flat ledge from 3.5m drop and it didn't bottom! but still better tunes are always welcome.

Also can any1 confirm the rumor that 09 DHX airs have better mid stroke?

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http://suspensioncenter.ch/products.php
There isn't much info on there but they run the Suspension Center WC DH team. Emeline Ragot did pretty well last year. They used to do the euro Fox service at the WC races up until two years ago.

I ride for them and have been running their tuned Fox stuff for 4 years but recently he started putting me on the custom stuff. My new shock has been on my bike for 10 or so days of lift access DH so I am just starting to get to know it well. It has zero mid stroke "problems" and corners better than anything I have ridden before. My bike doesn't squirm as much when slamming into berms or g-outs. I noticed that it pops off lips much better as well. I am sponsored by them so take what I write how you will. I used to think I rode air shocks for the weight and accepted less performance but now I know they can work as well as a coil for me.

Pic of me dh-ing my air shock.

William42 said:

Anyway, rant off, heres an honest question: does the DHX 5 fit most frames better or something? I'm just wondering why its considered the "go to" air shock

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I think you're just giving into regurgitating what everyone else says, the shock genuinely works quite well IMO. Unless you've tested and tuned all shocks back to back in your frame, it's not really a fair call to say one is better than the other. I spent a fair while messing with the first one I got and it ran well apart from being a little sticky. Second one I got was smooth as silk, and apart from changing the pressure and external settings, it's bone stock, and I'm dead stoked with it.

Anyway the reasons I'd run the DHX Air are:
- It's 90g lighter than the Roco
- Given the above weight increase I'd rather run a coil/Ti
- DHX has more damping range and a better damper IMO
- The Evolver runs an MCU (elastomer) negative spring which I'm not a big fan of in the long-term (correct me if I'm wrong though), and 12mm hardware which no one likes - also I'm pretty sure the shock shape and hardware makes it impossible to run in my bike (sunday).
- It's probably a little delusional to think that all air shocks don't have some midstroke falloff, it's just something inherent in an air spring curve and in my experience they are all fairly similar. I've tried a few different air shocks and the problem hasn't been significant in any of them (in a progressive to linear frame), put them in something like a 22x/morewood and they feel pretty horrid though. I'm sure most other bikes fall in between those.

To everyone else though, if you don't like them, don't run them. Honestly, a lot of the newest frames (eg. new v10) can be fairly light with a coil shock / ti combo so if you can get the right springrate for your frame then by all means stick with coil. I like the air for the tunability as well as the weight (and price vs ti.) and to be honest I find them very reliable, and have probably spent a lot more time changing oil and seals on my forks.

I have a Roco Air R on my mongoose khyber and I am happy with it but I am still having trouble getting it set up properly for my weight. Could someone give me some pointers on getting it set up? im 150lbs.

Udi said:

I think you're just giving into regurgitating what everyone else says, the shock genuinely works quite well IMO.

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I've never ridden an oil or air can tuned DHX 5 air, but I have ridden several on several different bikes, and they all have that same characteristic. I'm not denying that if you adjust air can volume with oil levels you can get it nailed, as I'm sure you can, but most people don't do that. I have ridden a couple bieks with a DHX 5 Air (untuned oil levels, just stock) and then an evolver (same bike) and I liked the evolver more.

I would love to ride one tuned but I can't find anybody who will do it, most people think their shock will explode and void warranty if they do.

Udi said:

Or just find a bike that has a leverage ratio and shock curve that suits an air shock, and fine tune yourself to suit. I've run two dhx air's on a sunday over the last 1.5 years and they've been pretty sweet.... no heat excess, no blowing through travel, and no issues with air in damper (sounds like a one-off thing to me). I'm running about 130psi and 4 clicks of propedal atm, so there's a reasonable amount of LSC... these bikes don't need much obviously though.

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Yeh Udi, but you weigh nothing too. That has to be a factor.

William42 said:

your right. everybody here is riding WC level. How silly of me. In fact I don't know why they even have world cup races, because everybody is at that level of riding.

Oh, and if you actually watch the races, several riders are starting to use air shocks in WC races.

At any rate, the reason they are not running air shocks is because of the spring curve, not because of the damper or air heat. I have an air shock. Heat is not an issue. Its because its not linear enough. Some shocks are getting better at that. Fox still sucks balls (although Udi, and i'm sure others, have fixed this to a degree), RS has no offerings, and since 99% of the people racing WC level are sponsored by RS or Fox, theres not alot of chance you'll see an evolver or roco.

But hey, it was a good argument while it lasted huh?

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Sorry man, forgot I wasn't allowed to make comparison to WC riders. oops!

I didn't fall in love with the Roco Air that I ran on my Sunday but didn't particularly hate it either. I only got rid of it in the end because (a) I'm a partswhore who likes changing bits and (b) the lack of 'feel' I got from the shock didn't mesh with what I like in a DH bike.

Stuff about air shocks over-heating is hilariously misinformed.

Your old shock also felt much better after a service toods

A bottom out bumper from a normal DHX on the internal shaft makes them feel very good, imo.

The X-Fusion H3 works really really well for downhill.

Jonny5 said:

Your old shock also felt much better after a service toods

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Yeah I thought it needed a service but just sold it off to some sucker...

toodles said:

Stuff about air shocks over-heating is hilariously misinformed.

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From a 3min Aussie track perspective. I think a 8min plus rocky run would make a difference.
I did a lot of jumping on an old Fox(I think they were called alps)air shock, and the spring rate did get stiffer, and the damping went out the window, and I went over the bars high up in the air,this was 7 years ago, and yes things have changed, but not air or oil.
I'm a fly weight like UDI, and am happily rocking a Rocco right now. It does feel soulless and dead, but I'm amazed at how quick I get through certain rock gardens,possibly I'm skipping over the top of them, where my old coil DHX was sinking into them?

When I do a 1500+ meter run then the shock definitely gets hot, almost too hot to touch. It starts chirping on brutal square hits or hard landings. When it starts chirping, usually my brakes are on the limit of overheating and my arms are getting almost so tired that the bar could get ripped out of my hands if not careful. The damping or spring rate never becomes so noticeably bad that I risk crashing it just starts making funny noises like a dying chirping bird. But to get it to do that then you need to ride some stuff very hard for a pretty long time. Usually runs aren't that long or you get tired. It heats up but has not caused any problems for me.

Another thing to consider is the air can insulates the damped body and makes it run hotter the a coil. Heat is the reason my V10 is my only bike with a DHX Coil. I own 2 smaller bikes with Fox air shocks.

The overleveraging of the shock in the V10 magnifies the problem, imo.

Could you consider a air spring to have a massive amount of preload? Because preload can have major effects on dynamic tyre loading. Because you have a strong spring force near the end of the travel. With a coil spring you dont have that.
I am still trying to figure out what the effects are but there are negative effects would be my guess.

No, because there's a negative air spring that works with the positive. If it were just positive pressure what you say would be true, it'd also feel horrid (ie. unusable). Ultimately it's just like a coil spring except instead of being perfectly linear it has a slight curve.

Udi said:

No, because there's a negative air spring that works with the positive. If it were just positive pressure what you say would be true, it'd also feel horrid (ie. unusable). Ultimately it's just like a coil spring except instead of being perfectly linear it has a slight curve.

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Isn't the Sunday designed to use a progressive shock? So an air shock might be complementary to the suspension geometry of a Sunday letting you adjust HSC separately?