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  1. #1
    I've got a Stiffee
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    Coil vs. air on Pack/RFX, my mini review

    I'm sure this probably has been covered before but for those prospective buyers of a Pack/RFX here is my review. I just bought a 5 Spot and ordered it with the DHX coil with the intention of putting it on my Pack. I have ridden the Pack with the DHX air for about 5 months now and was happy with its performance but it certainly had its downfalls.

    For one the air blows through the travel too easily, especially on drops. I had to put more air than I wanted to in the boost valve to keep the thing from bottoming out on 4ft drops which made the ride a bit harsh. It also seemed to use a lot of travel for medium sized hits, which gave it the feeling of being super plush but at the same time not as "efficient" as it could be. Overall it felt pretty damn good for air shock, although at high speed on braking bumps and rock gardens I felt the rear end just jumped around too much and could have been a little more plush.

    Now I put the DHX coil on w/ a 500lb spring (I weigh 160lbs w/o gear). Danno suggested the 500lb spring and he was spot on, thanks Danno! I put about 1 turn of preload on it and about 130psi in the boost valve to start off with. First thing I noticed was how the shock didn't use up as much travel on smaller bumps compared to the air. It felt stiffer, yet still plush and more efficient because I wasn't using 3/4 of the travel going over 3-4" bumps. It climbed surprisingly well, just as well if not better than the air. Then I got to my first downhill run (5 Oaks in Aliso). I noticed right away how the coil just felt better over the braking bumps, much more plush and the rear tire just stayed glued to the trail better. It felt even better the faster I went (although I think there is still room for improvement......Darren are you reading this????.....we're all waiting for those PUSH mod kits!!!). I ran the rebound about 7 clicks in from full fast the 1st run. Climbed up Cholla and the shock almost felt too stiff and uncompliant when climbing over bumpy sections....like the rear suspension just got hung up on step ups. I had the propedal crank all the way in and I let it out a few clicks and it felt better.

    Went down Rock it and that's where I knew the coil was the right choice for the Pack. It felt like my AS-X going down the rock garden, I flew down it a lot faster and in more control than I could with the air shock. I sped up the rebound by about 2 clicks for that run and it felt even better. For the final run down Lynx I let about 10 psi out of the boost valve and 1 more click of rebound out. I was very impressed with the coil shock in all aspects, it simply is the better choice in my opinion for the Pack. I'm really glad I went with the coil shock and I can't wait for the PUSH mods to come out, I think it will be a little slice of heaven at higher speeds once it has been Push'd

    Rob

  2. #2
    Leash Law Enforcer
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    Thanks for the perspective and review. I've been thinking about this topic recently. Very timely review.
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  3. #3
    Bodhisattva
    Reputation: The Squeaky Wheel's Avatar
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    Good write up.
    If you have a chance try the 550 lb spring.
    I'm exactly your weight. Started with a 500 lb spring but graduated to the 550 lb which provides better control under hard cornering without any detectable loss of small bump sensitivity.
    “Life is like riding a bicycle. To keep your balance, you must keep moving.”

    ― Albert Einstein

  4. #4
    I've got a Stiffee
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    Quote Originally Posted by The Squeaky Wheel
    Good write up.
    If you have a chance try the 550 lb spring.
    I'm exactly your weight. Started with a 500 lb spring but graduated to the 550 lb which provides better control under hard cornering without any detectable loss of small bump sensitivity.

    That's interesting, I'll definately try it if I come across a 550 lb spring.

  5. #5
    No, that's not phonetic
    Reputation: tscheezy's Avatar
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    I agree with all of your observations, but not entirely with the conclusions. I like the mushy mid-stroke of the DHX Air on the Pack. Yes, it needs high pressures to keep from bottoming, but boy is is a couch on wheels!

    Great summary.
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  6. #6
    Just another FOC'er
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    Quote Originally Posted by The Squeaky Wheel
    Good write up.
    If you have a chance try the 550 lb spring.
    I'm exactly your weight. Started with a 500 lb spring but graduated to the 550 lb which provides better control under hard cornering without any detectable loss of small bump sensitivity.
    Squeak, I mentioned to Rob your post where you talked about your settings, including the fact you ran the BO all the way out. I think Darren had some input in this? Anyway, I opened mine all the way after reading that, and I do like the feel. I was a little surprised about the pressure you were running, but I upped mine as well, and it still feels compliant. Because the linkage is slightly progressive, it makes sense that it should reduce the need for progressive compression damping, but I really need some charts and graphs to know what's going on here.

    What was the problem exactly with hard cornering? Wallow or bottoming during g-out? I usually find that as long as you don't bottom out the softer the setup, the better the control is.

    At my 160 lb weight the 500 lb spring seems to work pretty well, and although I don't feel it bottoming out, I guess it might be interesting to try a 550. I don't want to steepen the HA though, which would happen somewhat due to reduced sag. If I swapped out my Z150 for say a 66 or Boxxer Ride, I wouldn't sweat it. Some of the stuff we ride is extremely steep, which means part of the time I'm almost riding a front wheelie, and sometime it's not 'almost' - I am

    I also do this stuff sometime too, where maybe I'd like it stiffer (snappier) and HA is not a big concern... Always the tradeoffs!


  7. #7
    mtbr member
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    DHX coil for the Pack.. What about aggressive riding on the Spot? Including some good sized drops.

    Air or Coil?

    Cheers

    Rich

  8. #8
    Brass Nipples!
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    I came to the same conclutions as FXRob. I have a section of test trail that I've ridden a bunch of times with various bikes. It has a variety of very sharp edged irregular bumps.

    The Pack with a DHX air felt great on this stretch until I rode my Moment with a DHX coil over the same trail. I couldn't get the air shock to duplicate the effortless plushness of the coil shock. I ended up getting a DHX coil for the Pack and I rode it and the Moment back to back again and the ride seemed identical once I set up the shock.

    I think the air shock feels plusher on solitary hits, but looses the plushness on stutter bumps. Something about the nonlinearity of the shock rate or maybe even air pressure echoing around in the shock makes the ride less pleasant. The air shock isn't bad, but the coil just is better overall for me.

    I am going to be building up a lighter wheelset with CK hubs and DT 5.1's to use with the air shock when I want to make the bike lighter for days with lots of climbing.
    {Principal Skinner} Hmm. Whoever did this is in very deep trouble.
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  9. #9
    Elitest thrill junkie
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    Quote Originally Posted by FXRob
    I

    Went down Rock it and that's where I knew the coil was the right choice for the Pack.

    Yep, I've been through the same, and I agree. I've tried the RP3, DHX-A and DHX-C on the pack, and the DHX-C is much better, much more consistant, more controlled. The DHX-A becomes a joke when it starts blowing through the travel, and you simply can't run it with similer settings, and it gets harsh because you have to jack up the boost pressure so much, and because it doesn't have enough travel left for the next bump that comes along.

    I run 40% sag with the DHX-C, but with the DHX-A 40% is a joke and feels horrible. I tried all sorts of settings and pressures to try and make it perform as well as the coil, but could never really get there.

    Damping makes a difference, and the DHX-A lacks the midstroke control of the DHX-C. They're different internally, despite looking similer externally.

    It seems like the DHX-A was made for tooling around at slow and medium speeds. It's plush as heck at those speeds over certain bumps.
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  10. #10
    Just another FOC'er
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    Quote Originally Posted by Jayem
    Yep, I've been through the same, and I agree. I've tried the RP3, DHX-A and DHX-C on the pack, and the DHX-C is much better, much more consistant, more controlled. The DHX-A becomes a joke when it starts blowing through the travel, and you simply can't run it with similer settings, and it gets harsh because you have to jack up the boost pressure so much, and because it doesn't have enough travel left for the next bump that comes along.

    I run 40% sag with the DHX-C, but with the DHX-A 40% is a joke and feels horrible. I tried all sorts of settings and pressures to try and make it perform as well as the coil, but could never really get there.

    Damping makes a difference, and the DHX-A lacks the midstroke control of the DHX-C. They're different internally, despite looking similer externally.

    It seems like the DHX-A was made for tooling around at slow and medium speeds. It's plush as heck at those speeds over certain bumps.

    Jayem, what's your weight, spring, BO setting, and IFP pressure for the DHX-C? I think your setup is kind of opposite of Squeak's, except maybe pressure.

    Does anyone know how the pressure affects compression damping? And how does BO change it? I hate to ask, but has anybody come across any CURVES that show this stuff?

  11. #11
    I've got a Stiffee
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    Quote Originally Posted by Bob the Wheelbuilder
    I think the air shock feels plusher on solitary hits, but looses the plushness on stutter bumps. Something about the nonlinearity of the shock rate or maybe even air pressure echoing around in the shock makes the ride less pleasant. The air shock isn't bad, but the coil just is better overall for me.
    Couldn't agree with that statement more, the air does feel great until you get into choppy terrain where the shock takes repeated hits. The coil definately reacts better to this, and I feel it could be even better with more oil flow (ie. PUSH mods).

    I ran my bottom out knob about 3/4 of turn in......so you guys are all saying you pretty much run it all the way out??? What kind of air pressures are you all running?

  12. #12
    Elitest thrill junkie
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    Quote Originally Posted by .Danno.
    Jayem, what's your weight, spring, BO setting, and IFP pressure for the DHX-C? I think your setup is kind of opposite of Squeak's, except maybe pressure.

    Does anyone know how the pressure affects compression damping? And how does BO change it? I hate to ask, but has anybody come across any CURVES that show this stuff?
    About 190lbs (probably 210 with full water and gear in my large camel pack), 650lb spring, boost around 100-120max, propedal...lol...I don't care about propedal so it's off, rebound pretty fast, maybe 6-7 clicks from full fast. Bottomout is about half a turn to one turn from all the way out.

    I sag about 30-40% on it depending on which spring and setup I'm using. The 66 Light fork caused my weight to shift back further, so while I was pretty happy with the 600lb spring before at around 40% sag, it seemed like it was a little overwhelmed with the 66 fork and the weight shift, so I went back to the 650 spring, and I think my sag is a little less, but my ride quality is about the same as before when I was running the lighter spring without a fork as tall as the 66. I was out the weekend before last doing some drops in sedona and I didn't have any bottom out issues (although you should have heard the azonic saber bottom out there ), the 6pack seems progressive enough that it doesn't need much bottom out help...at least with the DHX-C. With the DHX-A it's another matter completely.

    These are the settings I'm using now, which doesn't mean that I used the exact same settings with the DHX-A all the time. I started with these settings, and found them to be woefully inadaquate, but I could never get the DHX-A to perform nearly as consistantly, even after trying all sorts of different settings.

    I set my suspension up to perform as well as possible. I don't want any tradeoff for pedaling performance, so I'll almost never run any propedal or really high BP. I've had the 5th element shocks and others and they flat out sucked for suspension peformance when compared to a shock with no compramise. I bought the pack because it was a resonably good pedaling bike, not perfect, but not like some single pivots that have to run a lot of boost pressure/SPV pressure just to pedal decently.
    Last edited by Jayem; 03-28-2006 at 09:20 AM.
    "It's only when you stand over it, you know, when you physically stand over the bike, that then you say 'hey, I don't have much stand over height', you know"-T. Ellsworth

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  13. #13
    Just another FOC'er
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    Quote Originally Posted by Jayem
    About 190lbs (probably 210 with full water and gear in my large camel pack), 650lb spring, boost around 100-120max, propedal...lol...I don't care about propedal so it's off, rebound pretty fast, maybe 6-7 clicks from full fast. Bottomout is about half a turn to one turn from all the way out.

    I sag about 30-40% on it depending on which spring and setup I'm using. The 66 Light fork caused my weight to shift back further, so while I was pretty happy with the 600lb spring before at around 40% sag, it seemed like it was a little overwhelmed with the 66 fork and the weight shift, so I went back to the 650 spring, and I think my sag is a little less, but my ride quality is about the same as before when I was running the lighter spring without a fork as tall as the 66. I was out the weekend before last doing some drops in sedona and I didn't have any bottom out issues (although you should have heard the azonic saber bottom out there ), the 6pack seems progressive enough that it doesn't need much bottom out help...at least with the DHX-C. With the DHX-A it's another matter completely.

    These are the settings I'm using now, which doesn't mean that I used the exact same settings with the DHX-A all the time. I started with these settings, and found them to be woefully inadaquate, but I could never get the DHX-A to perform nearly as consistantly, even after trying all sorts of different settings.

    I set my suspension up to perform as well as possible. I don't want any tradeoff for pedaling performance, so I'll almost never run any propedal or really high BP. I've had the 5th element shocks and others and they flat out sucked for suspension peformance when compared to a shock with no compramise. I bought the pack because it was a resonably good pedaling bike, not perfect, but not like some single pivots that have to run a lot of boost pressure/SPV pressure just to pedal decently.
    Cool, thanks. I thought maybe you were running more BO, but that's not the case. Based on weight ratio, the 600 for you would be similar to the 500 for me Rob, or Squeaky. If I tried a 550 spring, I'd probably drop the BP quite a bit, but I think that's contrary to Squeak's setup, and he had input from Push (I think).

    I'm with you on rebound and PP. Rebound's got to be pretty fast to track, and PP ought to be as little as possible. I do use some PP, but just enough to damp out bob resonance, however not enough to really screw up the fun part when I'm point down.

    I might put an air shock on my Spot at some point, but only for weight reasons. On my bigger bikes I don't really care about saving a lb, and have always liked the feel of coil over air. The only hassle with coil setups is getting the right spring.

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