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  1. #1
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    New to tubeless... psi help

    So I finally decided to go tubeless and did so with a new fall / winter tire set up... My big question is what pressure(s) I should be running.. I was running 35 f and r with tubes.

    I am an athletic 230lbs out of the shower.. Ride aggressively...

    SC Tallboy..

    Stan's Flow Ex / King wheels with Schwalbe Nobby Nic 2.35s front and rear..

    From Stan's site formulas I should be start at 32 F and 35 R...

    Suggestions?? Anyone have any real world feedback?

    Any help would be greatly appreciated.

  2. #2
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    You should be able to go way lower than that with no problems. I'm 240 and also run Flows. Front right now is 26, rear 28. It's really difficult to burp Stans Rims.

  3. #3
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    Honestly it is all based on the terrain you ride and how aggressive you ride it as to how low you can go on air pressure. We have almost no rocks around here so potential wheel denting is not much of a concern for me running low air pressure. Your trails may not be so forgiving.

    IMO Stan's recommendations are way to high for our trails around here. I weigh 250 lbs and run 20 psi front and 23 psi rear with no burping or any problems.

    Carbon Flash 29'er, 2.25 Racing Ralph's, 21mm rim ID Sun Ringle' Equalizer 25 wheels.

    I would start with 25 front and 28 psi rear and see how it feels. If good go down 1-2 psi and try again. If the tires fold over too easily or are too squirmy for you add 1-2 psi and try again.

    Good Luck!

  4. #4
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    Whatever you are set at ... Lower.

  5. #5
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    Tyre pressure is dependent on weight, yes, but also other factors as mentioned - riding style, riding terrain, how aggressive you ride, how fast your trails are.
    If you're riding slow, rocky, rooty, slippery, technical trails where speeds doesn't go high, you'll benefit from lower pressures to help grip those rocks and roots and help the tyre conform to the terrain.
    If you ride very fast, flowy smooth trails with lots of tighter corners a bit higher PSI will help keep the tyre from rolling/squirming and give better cornering technique.

    My advice to you is to start at these pressures, ride your bike, see if you like them there or not, try dropping the pressures a bit see if they work better or not, it's all really a personal experiment and it's best not to run what someone else runs just because they do, you and them and their terrain could be vastly different.

    BTW Tubeless is not all about running low pressures, it's also about having a tyre that better conforms to the trail, rolls better and has better flat protection.
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  6. #6
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    Quote Originally Posted by SS LS1 View Post
    Honestly it is all based on the terrain you ride and how aggressive you ride it as to how low you can go on air pressure. We have almost no rocks around here so potential wheel denting is not much of a concern for me running low air pressure. Your trails may not be so forgiving.

    IMO Stan's recommendations are way to high for our trails around here. I weigh 250 lbs and run 20 psi front and 23 psi rear with no burping or any problems.

    Carbon Flash 29'er, 2.25 Racing Ralph's, 21mm rim ID Sun Ringle' Equalizer 25 wheels.

    I would start with 25 front and 28 psi rear and see how it feels. If good go down 1-2 psi and try again. If the tires fold over too easily or are too squirmy for you add 1-2 psi and try again.

    Good Luck!
    Great advice ... and so close to what I would have suggested, 24F and 28R.

    That's what I ride and I'm 215# on a rigid ss. Fairly technical terrain ... rocks, roots, etc.

    Wheels are kings with flows, Racing Ralphs 2.4F and 2.25R.

    SPP
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  7. #7
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    215 lb on a Tallboy with wide Chinese carbon rims and those exact tires. I run between 20 and 25 psi with no problems whatsoever. The key to tubeless and low pressure is wide rims, which you have.

  8. #8
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    Thanks!

    Thanks for the feedback... This is a very helpful sample.

    I have never been one to like low pressure in tubed tires as I had always run (tubed) a low rolling resistance tire in the summer and switch to a more gnarly set up for the winter both with higher pressures... The more I research the more I am coming to the understanding as to how wider tubless tires have less rolling resistance at lower pressure (to a point of diminishing returns).. So despite my reluctance it seems as if lower PSI's are the way to go...

    I'll play around with the pressures starting at 25F and 28R and go down from there if I feel a need to.. My local terrain is kinda all the above.. Rocky, Rooty, Off Camber, Flowy, and can get slippery when only slightly damp as we have a lot of Clay based areas..

    Thanks again!

  9. #9
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    Here's something to keep in mind:

    What your pump says on the guage is irrelevant. Going higher or lower than that, and being able to do it over and over again is more important.

    Your "25psi" could be 35psi. Doesn't matter. If you need to drop it down to "22psi" on your pump, do it. And do it every time you ride.

  10. #10
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    Quote Originally Posted by Le Duke View Post
    Here's something to keep in mind:

    What your pump says on the guage is irrelevant. Going higher or lower than that, and being able to do it over and over again is more important.

    Your "25psi" could be 35psi. Doesn't matter. If you need to drop it down to "22psi" on your pump, do it. And do it every time you ride.
    So are you saying don't be concerned with the number but how the bike rides, then back into what the number is on a given pump? Then be sure to use that same pump to keep the pressure set?... If so how low is too low?... I am assuming that given the ability of a Stans rim to seal I won't burp a tire unless I drop a huge increment ay once... So if dropping a little bit at a time I will know from the feel of the bike when I get to that point of diminishing returns?

    I know that riding the bike is the only way to figure this out for sure and trust me I would love to be out on it now but I am stuck in my office and limited to keyboard research..

    I am planning to go out either tonight or tomorrow am early weather dependent and park at a lot that lets me do laps of about 3 miles through some pretty aggressive trails.. I'll take a floor pump and lower it each lap and compare until it feels squirmy..

    Thanks again.

  11. #11
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    I am going to be the odd man out and suggest you start w/ your current pressures possibly ending up higher. Losing the tubes means less rubber and support for the tire. I recently converted 2.3" tubed style tires to tubeless on 28mm Flow rims. I read plenty of posts where riders were running lower pressures so I went from my usual 35 rear 30 front to 28 / 25. Within 50ft I thought my tires going flat felt like they lost half their air. Checked the pressures and they were spot on. I decided to add air (no gauge) until they felt better w/o feeling so much squirm. When I got home I checked the actual pressure on a gauge and ended up having 30 in the front and 38 psi in the rear! So much for lower psi in my case but I have not flatted since.

  12. #12
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    Yes, you have that absolutely right, each pump reads differently, the only important thing is that you be consistent in using the same pump or pressure gauge.Yes, you will feel when they're too soft and squirm/roll on the rim.
    Only you can know that, but anything softer than this and you'd most definitely end up with dented rims. After seeing these pics I reminded myself to up the pressure just a tad if doing any riding where I'd be slamming into stuff like this and not risk pinch flatting or worse.
    Quote Originally Posted by Diesel8810 View Post
    So are you saying don't be concerned with the number but how the bike rides, then back into what the number is on a given pump? Then be sure to use that same pump to keep the pressure set?... If so how low is too low?... I am assuming that given the ability of a Stans rim to seal I won't burp a tire unless I drop a huge increment ay once... So if dropping a little bit at a time I will know from the feel of the bike when I get to that point of diminishing returns?

    I know that riding the bike is the only way to figure this out for sure and trust me I would love to be out on it now but I am stuck in my office and limited to keyboard research..

    I am planning to go out either tonight or tomorrow am early weather dependent and park at a lot that lets me do laps of about 3 miles through some pretty aggressive trails.. I'll take a floor pump and lower it each lap and compare until it feels squirmy..

    Thanks again.
    Attached Thumbnails Attached Thumbnails New to tubeless... psi help-gil_3089.jpg  

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  13. #13
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    ^^^^ This ^^^^

    That pic is worth a 1000 words. The limit on softness will, along with other factors, depend on what you're likely to hit and with how much force.
    Use it, use it, use it while you still have it.

  14. #14
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    Quote Originally Posted by keen View Post
    I am going to be the odd man out and suggest you start w/ your current pressures possibly ending up higher. Losing the tubes means less rubber and support for the tire. I recently converted 2.3" tubed style tires to tubeless on 28mm Flow rims. I read plenty of posts where riders were running lower pressures so I went from my usual 35 rear 30 front to 28 / 25. Within 50ft I thought my tires going flat felt like they lost half their air. Checked the pressures and they were spot on. I decided to add air (no gauge) until they felt better w/o feeling so much squirm. When I got home I checked the actual pressure on a gauge and ended up having 30 in the front and 38 psi in the rear! So much for lower psi in my case but I have not flatted since.
    What tires were you using? Sometimes the sidewall just isn't strong enough to support lower pressures, but I've found this is the fault of the tire, primarily.

  15. #15
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    Quote Originally Posted by Diesel8810 View Post
    So are you saying don't be concerned with the number but how the bike rides, then back into what the number is on a given pump? Then be sure to use that same pump to keep the pressure set?... If so how low is too low?... I am assuming that given the ability of a Stans rim to seal I won't burp a tire unless I drop a huge increment ay once... So if dropping a little bit at a time I will know from the feel of the bike when I get to that point of diminishing returns?

    I know that riding the bike is the only way to figure this out for sure and trust me I would love to be out on it now but I am stuck in my office and limited to keyboard research..

    I am planning to go out either tonight or tomorrow am early weather dependent and park at a lot that lets me do laps of about 3 miles through some pretty aggressive trails.. I'll take a floor pump and lower it each lap and compare until it feels squirmy..

    Thanks again.
    Yep.

    Don't worry about what others put into their tires. They ride different bikes, on different rims, on different trails, etc. Make it work for YOU.

    Only you can figure that out. A small, hand-held digital gauge can help if you're visiting a friend and don't have access to your own pump. Again, it doesn't matter what the number is, as long as you can repeat it. 60 is 60, 30 is 30.

    SKS Airchecker Digital Pressure Gauge at BikeTiresDirect

  16. #16
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    Quote Originally Posted by keen View Post
    I am going to be the odd man out and suggest you start w/ your current pressures possibly ending up higher. Losing the tubes means less rubber and support for the tire. I recently converted 2.3" tubed style tires to tubeless on 28mm Flow rims. I read plenty of posts where riders were running lower pressures so I went from my usual 35 rear 30 front to 28 / 25. Within 50ft I thought my tires going flat felt like they lost half their air. Checked the pressures and they were spot on. I decided to add air (no gauge) until they felt better w/o feeling so much squirm. When I got home I checked the actual pressure on a gauge and ended up having 30 in the front and 38 psi in the rear! So much for lower psi in my case but I have not flatted since.
    Hmmm... This is what I was fearing... Previously (Same bike same wheels) I ran 35 front and rear RoRo and RaRa 2.25s and Occasionally lowered the pressure up front to 32ish when it got slick (again we have a lot of clay based areas and it gets super slippery quick).. These pressures were much lower that I used to run on my 26" bikes when I was younger.. I hated the feeling of a mushy tires and felt the bike just wouldn't roll... But again I was 17-22 years old (36 now) and rode18- 20lb rigid or front susp original Kleins on tubed 26" tires..

    So KEEPING IN MIND the different rolling characteristics of a tubeless set up, tire size, bike, age, etc... I am going to keep an open mind and like I said run a few laps around the same short loop starting the pressure at Stans recommendations (Given your advice and which are lower than my Tubed pressures anyway) and lower the pressures until I feel the bike not behaving like I would like it to given my riding style

  17. #17
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    Quote Originally Posted by LyNx View Post
    Yes, you have that absolutely right, each pump reads differently, the only important thing is that you be consistent in using the same pump or pressure gauge.Yes, you will feel when they're too soft and squirm/roll on the rim.
    Only you can know that, but anything softer than this and you'd most definitely end up with dented rims. After seeing these pics I reminded myself to up the pressure just a tad if doing any riding where I'd be slamming into stuff like this and not risk pinch flatting or worse.
    Wow... That is nuts... But def gives perspective as to how a tubeless set up forms around stuff at lower pressures..

  18. #18
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    Quote Originally Posted by Diesel8810 View Post
    Stan's Flow Ex / King wheels with Schwalbe Nobby Nic 2.35s front and rear..

    From Stan's site formulas I should be start at 32 F and 35 R...
    I suggest that you do not pay much attention to the Stan's formula. It very specifically states:

    "To determine a starting tire pressure when running NoTubes tires with our ZTR rim use this simple formula."

    Those tires are essentially fairly narrow racing tires which will require higher pressure than 2.35 Nobby Nics. I'm 220lbs. and Nobby Nics at 24 and 26psi. front and back.
    The trouble with having an open mind is that people will insist on trying to put things in it.

  19. #19
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    And also casing construction - the rear is one of the original 2.25" Ardents (quite thin sidewalls) think around 26PSI, the front is a newer 2.4" EXO Ardent with TLR bead, run around 23PSI.

    Quote Originally Posted by Diesel8810 View Post
    Wow... That is nuts... But def gives perspective as to how a tubeless set up forms around stuff at lower pressures..
    Last edited by LyNx; 10-08-2012 at 02:06 PM.
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  20. #20
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    I have a Tallboy. I have Nobby Nics. I'm not 230 though. I run 26-30 psi and like I have all my life, I can usually tell what I like by squeezing the tire. I'd rather have too much air than not enough. I hate the squishy feel.

  21. #21
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    Quote Originally Posted by hillharman View Post
    What tires were you using? Sometimes the sidewall just isn't strong enough to support lower pressures, but I've found this is the fault of the tire, primarily.
    Pacenti Neo-moto & a Panaracer Rampage - both quite commonly run tubeless. I always felt they would be decent candidates because the tread /sidewalls felt a bit stiffer than other tires I have used. As I mentioned lose the tube you lose support / reinforcement of the tire. I will run what I have @ the current pressures but in the future will try a dedicated tubeless tire. If think if I ran less than 35 psi tubeless rear I'd think I'd knock the tire off the rim or flat spot it.

  22. #22
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    if I'm feeling the rim, I know I need more air.

    SPP
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  23. #23
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    No set pressure. All highly dependent on the tire, rim, terrain, and style.

    The heavier the tire, and wider the rim, the lower the pressure.

    Squirm and rim shots are what will limit your pressures.

    Keep going lower until you get too much squirm or rim shots (kind of like setting shock pressure by bottom out, not sag).

    I find I'm limited more by squirm than rim shots. Corner too hard with too much squirm and you'll roll a bead.

  24. #24
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    When going slow not an issue, never had a bead roll off from this, but do just blow through corners, makes you feel like the damn bike just won't turn, no matter what you do, just pushes the front.
    Quote Originally Posted by Miker J View Post
    No set pressure. All highly dependent on the tire, rim, terrain, and style...................I find I'm limited more by squirm than rim shots. Corner too hard with too much squirm and you'll roll a bead.
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  25. #25
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    Quote Originally Posted by Miker J View Post
    No set pressure. All highly dependent on the tire, rim, terrain, and style.

    The heavier the tire, and wider the rim, the lower the pressure.

    Squirm and rim shots are what will limit your pressures.

    Keep going lower until you get too much squirm or rim shots (kind of like setting shock pressure by bottom out, not sag).

    I find I'm limited more by squirm than rim shots. Corner too hard with too much squirm and you'll roll a bead.
    yup.. I hate the feel at low pressures, I'm 180 now but was jus above 200 not too long ago and I didn't have bead issues, but the tires squirmed and felt like they were losing control at speed, I was running right around 30 front, 30-35 rear.. have dropped it 2-5 lbs do to my weight loss.

    don't like my rear under 30lbs, not only for squirm but also noticed the wider rims (P-35's) were pillowing the sidewalls too much and I was basically riding on them, got LOTS of sidewall slices...


    Honestly, I have a new-ish way I set friends up with tubeless and tire pressure...

    I sit them on the bike with a hand on the wall to support, want them just a tad back on the bike when doing the rear and a tad forward from normal riding position to do the front. Obviously make sure there is just enough air to keep the rim off the ground before starting (like 10-15lbs), add pressure till I see the sidewall lift off the ground and make sure the tread is supporting the bike/biker, add 2-5 more lb's and that's done.
    Going to try and bring Trail Tire TV back. go take a look... http://trailtiretv.blogspot.com/

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