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  1. #1
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    Coil shock or air?

    I am replacing the shock on my older iron horse sinister sport. I am heavy 340lbs. and I know the 800 lb shock does good but not sure if an air shock with 300psi is even close to the power of the spring. Any help??

  2. #2
    roots, rocks, rhythm
    Reputation: Dawgprimo's Avatar
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    Go with coil.
    You would be at the extreme limit of any air shock.
    I am not sure any air would work for you either......

  3. #3
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    Back when I was riding coil spring shocks, no one made one that could get me to less than 40% sag. Of course, it will depend on the leverage ratio of your rear suspension as to whether or not you can get either to work. The higher the leverage ratio, the more spring pressure you'll need to counteract it.

    If you're planning on staying at 340lbs, then it won't be necessary to buy new springs. But, if significant weight loss is your goal, then be prepared to shell out for a new spring as the weight drops. With an air shock, that won't be necessary.

    IME, 340lbs will be near or maybe even exceed what most bikes will require for an air shock to keep you in the 30% to 35% sag range. But like I said, I had even more trouble finding coil springs that would support me when I was in the 275lb to 295lb range (that was my weight as I stepped out of the shower, not dressed and ready to ride). I see the 2004 Iron Horse Sinister uses a Fox Vanilla and that is the shock I had trouble finding a heavy enough coil spring for.

    When I rode a Giant Reign with a Manitou Swinger Air, I only needed about 200psi and it has a max rating of 300psi. I could still have had a lot of room to spare if I weighed 340lbs to run an air shock.

    Bottom line is that it depends on the bike's suspension design, and which air shock you use, as to whether or not an air shock would work. by an older Sinister, I am assuming you're talking about something like a 2004 model? Those used either a Fox Vanilla (coil) or an RST coil shock. If that is the bike you have, I would guess that it is something like a 6.5" x 1.5" size (165mm x 38mm), but you should measure to make sure. Then start shopping and see what you come up with. I wouldn't put much more than $150 into a shock for that bike.

    Jmho. Good luck.

  4. #4
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    Coil shock or air?

    I run a rockshox ario at 250 psi and still don't get full travel. I'm 300 even nekkid. Since the shock can go up to 275 psi, seems like there is some room to grow there,

    I've put around 1000 miles on the shock and am just now starting to see some fluid leakage. Seems fairly durable but this being my first fs bike don't really know.

    Going to get a kit an rebuild over the Christmas holiday.
    Not only is my short term memory horrible, but so is my short term memory.

  5. #5
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    Thanks guys. The shock is RST 650mm x 38mm. The other bad thing I have found is not alot in a good coil shock out there for the size. I did find the dnm burner-rcp comes new in that size still. I don't know how good it is? There is alot more options in air for sure.

  6. #6
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    Yeah man, like a few other folks have already stated, it all depends on the bike's suspension design. I've been just a tad under 340 a couple of times now and definitely more than that geared up for a ride and when I used a Fox DHX Air 5.0 on my Niner WFO I had to run 300psi (max) to get the right sag and for it to work for me. But, I just put my CCDBA from my other bike on my WFO and the max psi for it is 250psi and right now I have it down around 200psi and it's perfect.

  7. #7
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    Well I really am planning on shedding some lbs. so maybe the air is not such a bad idea. I was over 400 so going the right direction anyway. lol

  8. #8
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    Fwiw, I just swapped out the fox ctd on my ventana el cap/Zeus for a fox vanilla and love the difference. I'm 260 and was blowing through the mid stroke of the travel at max psi even though I was not bottoming. The coil (800 lb spring) seems to be much better in midstroke for me...

  9. #9
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    Quote Originally Posted by ohiogsp View Post
    Thanks guys. The shock is RST 650mm x 38mm. The other bad thing I have found is not alot in a good coil shock out there for the size. I did find the dnm burner-rcp comes new in that size still. I don't know how good it is? There is alot more options in air for sure.
    Not a lot of good 6.5 x 1.5 options out there for coil shocks. Just not enough stroke there for a coil spring to work well IMHO. I'd just get an air shock and keep adjusting to your weight as the lbs continue to come off.

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