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  1. #1
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    Set sag but psi much higher than recommended

    I just replace my fork with with Rockshox 100mm recon Silver 29". I set my sag at bike shop and at home.it is set for about 175 psi with 25% sag.

    Rockshox chart says 100psi is the estimate.

    Why such a huge difference?

    I weigh about 182.

  2. #2
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    what steps did you take to get your sag? general ballpark estimate is usually half your weight +10 lbs or so. That's a pretty big difference from 175 psi.

  3. #3
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    Quote Originally Posted by michihir0 View Post
    what steps did you take to get your sag? general ballpark estimate is usually half your weight +10 lbs or so. That's a pretty big difference from 175 psi.
    This is how I set it at home. Right now it is about 170 psi (was 175ish when set at bike store)
    I put the zip tie on, deflated all the air, pumped to 100 psi. Sat on bike and get off. I double checked also by riding 10 feet and then gently getting off without using brakes. the top of the zip tie was about 45-50%. I pumped it up to 135 psi. Did the same process. The top of zip tie was about 35-40%. I pumped it up to 170 psi. The top of the zip tie at about 25-30%


    EDIT: These numbers are more along the lines of what the 80 mm shock setting according to Rock shox chart. http://www.sram.com/sites/default/fi...4148_rev_a.pdf

    I guess I really should be using the bottom of the zip tie but that is probably only 5% difference.

    EDIT: Should I adjust from the standing or sitting position? I probably sit 65% of the time and I am out of the saddle 45%.

  4. #4
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    try standing up while on your bike and use your weight and compress the fork several times. then push the zip tie down while seated. then get off the bike. the zip tie shouldn't be super tight either.

  5. #5
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    Quote Originally Posted by michihir0 View Post
    try standing up while on your bike and use your weight and compress the fork several times. then push the zip tie down while seated. then get off the bike. the zip tie shouldn't be super tight either.
    What is the point of standing up and compressing fork several times before sitting down? Just curious.

    I did ride off my curb a few times and bounces up and down while standing up.

    This is where the zip time stopped. I don't know if it would bottom out on the trail but it didn't around my cul de sac.


  6. #6
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    Something is pretty kooky about these pressures. Last time I rode a Recon silver 100 it was about 110 psi and that was maybe too hard and I weigh a bit less than you. You must have a gauge that's way off.

    Like Michihir0 said, about half your weight plus ten is a good ballpark figure. 175 is for sumo wrestlers.

  7. #7
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    Quote Originally Posted by joepa150 View Post
    What is the point of standing up and compressing fork several times before sitting down? Just curious.
    Just to make sure the fork is traveling up and down freely and really an extra measure to make sure it settles properly. what are you using a shock pump? are you certain about your pressures?

  8. #8
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    Pressures are pretty accurate. The bike shop that installed the fork set it to 100 psi. I got on and road it around shop. They said I need to increase pressure. Then we finally got up to 175 psi on their shock pump. So I have used theirs and my Rockshox pump (came with shock).

    Could it be bike geometry?
    How about the valve stem?

    How about Rebound? Could that effect Sag?

  9. #9
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    Sounds to me like there is confusion between front and rear shock pressure.

  10. #10
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    Quote Originally Posted by Surfdog93 View Post
    Sounds to me like there is confusion between front and rear shock pressure.
    Please explain. I only have a front shock. The chart I linked is for front shocks only.

  11. #11
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    wierd, rs usually needs lower pressures. maybe with a more basic damper it is different. but 175 wont hurt anything, if it works cool.

  12. #12
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    Put the numbers aside & ride the bike (I'd start w/ the recommended pressure's) Personally I will find the largest trail obstacle, on my usual riding, and see how much travel is used. Adjust the pressures to control bottomout w/o hindering small bump compliance.

  13. #13
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    Quote Originally Posted by b-kul View Post
    wierd, rs usually needs lower pressures. maybe with a more basic damper it is different. but 175 wont hurt anything, if it works cool.
    It is Solo Air so maybe that has something to do with it. I am not worried about the 175 psi since the max is 225. I am just worried that either the shock is defective, or the bike shop messed it up (don't know how but anything is possible).

    If defective, I would want to get the shock swapped out for a non defective one rather than ride on it for awhile and then trying to swap it for free.

    Quote Originally Posted by keen View Post
    Put the numbers aside & ride the bike (I'd start w/ the recommended pressure's) Personally I will find the largest trail obstacle, on my usual riding, and see how much travel is used. Adjust the pressures to control bottomout w/o hindering small bump compliance.
    I am afraid to start with a psi of 100 (recommended) for fair of bottoming out my shock and causing damage. Would bottoming out a few times do any damage?
    How would I know if it bottoms out (feel, sound, both)?
    My photo shows that the zip tie is about 90% to the top from bouncing around while riding and riding off my curb a few times. This is around 170 psi. Maybe I will test something in the 130-150 range before testing the 100 recommended psi.

  14. #14
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    Yeah, here's the thing about sag and weight and air pressure. Those are ball park numbers. If you're like a friend of mine who used to be a body builder and is short, but weighs more than me, because of the frame size he needs, he's very close to the shock, and basically has to max out the air pressure to get the sag right. But to get the ride right he has to back off it a little. If he was on a larger frame, it would require even less air, but he's a big guy. So here's what I'm saying.

    Your position on the bike may be affecting what it takes to make the sag right. Throw your shock pump in your camel back and go for a ride with the sag set right. See if the fork works like it should. See how it feels over small bumps. See how it works on big stuff. Is it soaking up the small bumps? If not let some air out. Is it bottoming out on big bumps? Add some air or damping. Once you have the ride how you want it, forget what "they say" about air pressures and sag, all that is basically just a starting point. When it rides the way YOU like it, make a note of the air pressure, and let that be it unless YOU decide you want to fiddle with it some more.

  15. #15
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    Quote Originally Posted by joepa150 View Post
    Please explain. I only have a front shock. The chart I linked is for front shocks only.
    I was referring to your LBS suggestion of 175psi....that sounds more appropriate for a rear shock (if you had one), at your weight. 100psi (as per your chart) sounds much more suitable for a front shock.

  16. #16
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    Quote Originally Posted by b-kul View Post
    wierd, rs usually needs lower pressures. maybe with a more basic damper it is different. but 175 wont hurt anything, if it works cool.
    Quote Originally Posted by keen View Post
    Put the numbers aside & ride the bike (I'd start w/ the recommended pressure's) Personally I will find the largest trail obstacle, on my usual riding, and see how much travel is used. Adjust the pressures to control bottomout w/o hindering small bump compliance.
    Quote Originally Posted by Surfdog93 View Post
    I was referring to your LBS suggestion of 175psi....that sounds more appropriate for a rear shock (if you had one), at your weight. 100psi (as per your chart) sounds much more suitable for a front shock.
    That is what I have been reading BUT using the zip tie method of 25-30% sag puts my psi around 170-175.

    I know I shouldn't look at psi and just go by the ride and my preference as long as I am not bottoming out. BUT I am just worried my fork is defective.

  17. #17
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    Quote Originally Posted by joepa150 View Post

    I know I shouldn't look at psi and just go by the ride and my preference as long as I am not bottoming out. BUT I am just worried my fork is defective.
    If the fork has a defect you will need to be able to tell, the place of purchase, it has an actual performance problem. It would be like buying a car and saying a car doesn't drive right but had never been driven . If the fork didn't hold air, leaked oil or had a cosmetic issue then it could returned as is.

  18. #18
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    Quote Originally Posted by joepa150 View Post
    It is Solo Air so maybe that has something to do with it. I am not worried about the 175 psi since the max is 225. I am just worried that either the shock is defective, or the bike shop messed it up (don't know how but anything is possible).
    no,my rtc3 rev is solo air, i weigh 150 and have to run it at ~60psi to get proper sag and full travel.

  19. #19
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    That is an unusual difference on the chart between 80 and 100.
    It almost seems like your fork has 80mm internals.
    I'd give the Rockshox techs a call.

  20. #20
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    Funny thing is I have the pressure set at 90psi on my Rebra RL shocks to get the sag right and I weigh around 200lbs.

    But then again I ride like a girl..

  21. #21
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    Quote Originally Posted by b-kul View Post
    wierd, rs usually needs lower pressures. maybe with a more basic damper it is different. but 175 wont hurt anything, if it works cool.
    Quote Originally Posted by keen View Post
    Put the numbers aside & ride the bike (I'd start w/ the recommended pressure's) Personally I will find the largest trail obstacle, on my usual riding, and see how much travel is used. Adjust the pressures to control bottomout w/o hindering small bump compliance.
    Quote Originally Posted by eb1888 View Post
    That is an unusual difference on the chart between 80 and 100.
    It almost seems like your fork has 80mm internals.
    I'd give the Rockshox techs a call.
    I was thinking they may be 80mm. I don't know if you can tell by measuring the stanchions (terminology?) but I measured about 4"/100mm.

    EDIT: I called yesterday and left a voice mail. I also emailed them.

  22. #22
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    I was just messing with it outside my house. I backed it down to 110 psi. Riding around and going of my curb a few times standing up and sitting down didn't bottom them out BUT if I hopped up and down on the fork moderately aggressive, I could get the zip tie about 1mm from the top. I probably could get it all the way but I fear damaging fork from zip tie.

    I then bumped it up to 130 psi. Doing same routine I got it to about 97mm but I might be able to bottom out if I bounced aggressively.
    I then bumped it up to 140psi. Doing same routine I got it to about 95mm but I might be able to bottom out if I bounced aggressively.
    170 psi is show in photo above. I guess it maybe about 90mm contracted.

    I am not an aggressive rider (yet). The trails I ride are intermediate - advanced singletrack trails with lots of rocks/roots and I don't do any large dropoffs.
    So I have two questions:
    1) Would intentionally bouncing up and down (moderately aggressive force) on the fork while riding down my street produce more or less fork travel than riding on a intermediate to advance trail?
    2) As stated above, when I bounce, I don't bounce with all my might for fear of damaging fork. If I did, do you all think that I can contract the fork the extra say 5mm to bottom it out?

  23. #23
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    1. maybe, maybe not. but that question is irellevant. you want sag, so sit on your bike and fill the fork so the zip tie moves up about 25mm.

    2. bottoming out the fork will not damage it.

  24. #24
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    Another recon owner, I had mine converted to 120mm, an undocumented feature. None the less 175 seems way high. I haven't adjusted mine in a long time. Lol. Just checked my notes and it looks like I go t,one dialed in for me at between 80 and 90. I weigh about 170 and easily carry an extra 10 in water and peripherals.

    175 seems way to high.

    As others have alluded to it could be fit. Although I run a long stem so more of my weight is over the forks.
    Sent via my heady vibes from the heart of Pisgahstan

  25. #25
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    When are you measuring sag? I have a bad feeling after reading this, you're trying to compress the fork then reading how close it comes to the crown of the fork. Completely wrong.

    Devinci Sag Setup - YouTube
    13 Lenz Lunchbox punkass

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