Results 1 to 48 of 48
  1. #1
    mtbr member
    Reputation:
    Join Date
    Jan 2010
    Posts
    139

    Air pressure for tube in tubeless and standard tires on tubeless wheels?

    Hello,

    I just bought a bike with a pair of Mavic Crossmax UST wheels and tubeless tires. I am new at cycling. The front, I believe, already has a tube in it (the Presta valve can be wiggled around and does not have a locking nut on the outside). Having read a few articles about tubeless -> tube, I have some questions.

    1) I presume it is okay to run tubes in these wheels indefinitely?

    2) Is it possible to run standard steel/kevlar/clincher bead tires in these wheels? (with tubes, of, course).

    3) The tubeless tires indicate a maximum 50 PSI air pressure. When I have a tube inside, should I observe the same maximum PSI?

    4) Once I go with standard tires, presuming it is okay, can I run the higher pressure supported by the new tires?

    I plan to do only light XC and path/trail riding for now, so I want a simple and higher-pressure set up.

    Bonus questions:

    Do "Kevlar inside" or Kevlar-belted tires do a good job as being puncture resistant? Or, do thicker rubber work better? What is the best puncture-resistant set up?

    Thanks very much.

  2. #2
    mtbr member
    Reputation:
    Join Date
    Feb 2008
    Posts
    1,058
    1) Yes

    2) Yes (it's possible to do it without tubes too)

    3) You could (each tire brand has a max psi stamped on it)

    4) Yes, but I think the max of the rim is 60....check

    I strongly recommend running a lower pressure. While riding on the road may be a bit faster, there have been numerous tests that show a lower pressure is faster on trails.

    I have the a set of crossmax ST and run regular tires on them without tubes (plus some sealant) and I run them at around 30-32 psi (I am ~210lbs). Save the high pressures for the road bike.


    EDIT** Check out these threads

    Tire pressure for all around XC riding?
    stans rolling resistance 101
    lower pressure= less rolling resistance!
    Quote Originally Posted by snovvman

    Bonus questions:

    Do "Kevlar inside" or Kevlar-belted tires do a good job as being puncture resistant? Or, do thicker rubber work better? What is the best puncture-resistant set up?

    Thanks very much.
    IIRC kevlar belted only refers to the bead that clinches the rim, and kevlar is lighter than a steel bead and can be folded. Thicker rubber works for puncture resistance, running tubeless with sealant works very well too.
    Last edited by civil; 01-25-2010 at 10:07 AM.

  3. #3
    cougarbait
    Reputation: Lambdamaster's Avatar
    Join Date
    Nov 2008
    Posts
    1,783
    you should take advantage of your setup and go tubeless indefinitely
    09AS-Rsl/09Six

  4. #4
    Can't feel my legs
    Reputation: JPark's Avatar
    Join Date
    Aug 2009
    Posts
    852
    I strongly recommend running a lower pressure. While riding on the road may be a bit faster, there have been numerous tests that show a lower pressure is faster on trails.
    I've only seen one study, and it was an absolute twisting of data to support a false statement. Don't get me wrong, I support the idea that lower air pressures does have advantages, but speed is not(directly) one of them.
    Care to share some of these "numerous tests"?

  5. #5
    Underskilled
    Reputation: CaveGiant's Avatar
    Join Date
    Aug 2007
    Posts
    4,118
    You have tubeless rims, it would be a huge waste to run a tube.

    Lower pressure has higher rolling resistance, much less of an effect when running tubeless.
    However the tractionincrease means you can corner faster, brake later ride at a higher speed.

    So rolling resistance is faster at 60PSI, but I will get around my local trail centre faster at 30 PSI.


    Get your tyres set up tubeless and run at 30-40 psi, trust me, worth it.

  6. #6
    mtbr member
    Reputation:
    Join Date
    Feb 2008
    Posts
    1,058
    Quote Originally Posted by JPark
    I've only seen one study, and it was an absolute twisting of data to support a false statement. Don't get me wrong, I support the idea that lower air pressures does have advantages, but speed is not(directly) one of them.
    Care to share some of these "numerous tests"?
    Maybe "a couple" would have been a better choice than "numerous". Over the last 3 years I've seen two on this site from a german magazine, 2 from some separate manufacturer's and some independent ones (3) on the net. I can't pick them out as they are buried somewhere but with some searching you should be able to dig them up.

    They are just tests, subject to error, mis-interpretation and assumptions, however they all point to lower pressure being faster on the trail, for various reasons. Some of which I agree with and thus run my tires low.

  7. #7
    mtbr member
    Reputation:
    Join Date
    Jan 2010
    Posts
    139
    Thanks for your replies.

    Quote Originally Posted by civil

    1) Yes

    2) Yes (it's possible to do it without tubes too)

    3) You could (each tire brand has a max psi stamped on it)

    4) Yes, but I think the max of the rim is 60....check

    I strongly recommend running a lower pressure. While riding on the road may be a bit faster, there have been numerous tests that show a lower pressure is faster on trails.

    I have the a set of crossmax ST and run regular tires on them without tubes (plus some sealant) and I run them at around 30-32 psi (I am ~210lbs). Save the high pressures for the road bike.

    EDIT** Check out these threads

    Tire pressure for all around XC riding?
    stans rolling resistance 101
    lower pressure= less rolling resistance!

    IIRC kevlar belted only refers to the bead that clinches the rim, and kevlar is lighter than a steel bead and can be folded. Thicker rubber works for puncture resistance, running tubeless with sealant works very well too.
    Follow up questions:

    From #2, if I were to use a standard tire without tubes on the UST wheels, I presume I have to use glue?

    #4, I searched for maximum pressure specifications for the Crossmax SL UST, but have not been able to find one. If I were to use an inner tube, does the max pressure rating for the wheel still matter? I thought it was only the pressure rating on the tire?

    Quote Originally Posted by Lambdamaster
    you should take advantage of your setup and go tubeless indefinitely
    I do want to. At the same time, there is something attractive about the easy support/change for a tube-based setup.


    Another question: How does the NoTube sealant work? Like Slime?

    Thanks again.

  8. #8
    mtbr member
    Reputation:
    Join Date
    Jan 2010
    Posts
    139
    Quote Originally Posted by civil
    IIRC kevlar belted only refers to the bead that clinches the rim, and kevlar is lighter than a steel bead and can be folded. Thicker rubber works for puncture resistance, running tubeless with sealant works very well too.
    These are two Kevlar belt tires I'm talking about. I spoke with the manufacture and it is not in the bead. These are Kevlar belts embedded across the tread of the tire to help prevent puncture.

    http://www.maxxis.com/Bicycle/Hybrid/Overdrive.aspx

    http://www.csttires.com/Bicycle/City...r/Selecta.aspx

    I looked for reviews but didn't find much. I just wonder how effective it is.

  9. #9
    Probably drunk right now
    Reputation: Ken in KC's Avatar
    Join Date
    Jan 2004
    Posts
    6,645

    I've only seen one....

    Quote Originally Posted by civil
    Maybe "a couple" would have been a better choice than "numerous". Over the last 3 years I've seen two on this site from a german magazine, 2 from some separate manufacturer's and some independent ones (3) on the net. I can't pick them out as they are buried somewhere but with some searching you should be able to dig them up.

    They are just tests, subject to error, mis-interpretation and assumptions, however they all point to lower pressure being faster on the trail, for various reasons. Some of which I agree with and thus run my tires low.

    Please cite your sources. The only "study" I've seen was the magazine article in the German magazine. If you dig a little deeper, you would have learned that the study was funded by Michelin and Maxxis shortly after both companies launched the UST standard.

    I'd love to see one credible study and source, much less a couple.

  10. #10
    fresh fish in stock...... SuperModerator
    Reputation: CHUM's Avatar
    Join Date
    Aug 2004
    Posts
    8,615
    Quote Originally Posted by CaveGiant
    You have tubeless rims, it would be a huge waste to run a tube.

    Lower pressure has higher rolling resistance, much less of an effect when running tubeless.
    However the tractionincrease means you can corner faster, brake later ride at a higher speed.

    So rolling resistance is faster at 60PSI, but I will get around my local trail centre faster at 30 PSI.


    Get your tyres set up tubeless and run at 30-40 psi, trust me, worth it.

    +1

    except 40 psi is a bit on the high side IMHO......i weigh 180# and run my tubeless for rigid at 28 lbs(r) and 26lbs(f).....

    also...go here...great site:
    http://www.sheldonbrown.com/tires.html
    Click Here for Forum Rules

  11. #11
    mtbr member
    Reputation:
    Join Date
    Feb 2008
    Posts
    1,058
    Quote Originally Posted by Ken in KC
    Please cite your sources.
    Your answer is in what you quoted.

    Quote Originally Posted by Ken in KC
    you would have learned that the study was funded by Michelin and Maxxis
    That was obvious from the article, but while it may be biased (as with almost all scientific research) it was better that the data you presented for me (nothing).

    Quote Originally Posted by Ken in KC
    I'd love to see one credible study and source, much less a couple.
    I'd love to see more too, but it isn't exactly a high priority area of study, so you have to take what you can get and interpret those results.

  12. #12
    Probably drunk right now
    Reputation: Ken in KC's Avatar
    Join Date
    Jan 2004
    Posts
    6,645

    Ah.....

    Quote Originally Posted by civil
    Your answer is in what you quoted.



    That was obvious from the article, but while it may be biased (as with almost all scientific research) it was better that the data you presented for me (nothing).



    I'd love to see more too, but it isn't exactly a high priority area of study, so you have to take what you can get and interpret those results.

    So "numerous" went to "a couple" and now it's one German mountain bike magazine writing an article about a "study" conducted conducted by the two companies that introduced the UST system? Got it.

    Since you brought up scientific research, then I'm sure you know that the burden of proof is with the person presenting the theory and their approach is to set out to disprove their theory, right?

    You made some pretty sweeping generalizations about tubeless benefits based on "numerous" and then "a couple" "studies" from the german magazine, manufacturers and some independent ones. I'm just asking to see the studies that I haven't seen.

  13. #13
    fresh fish in stock...... SuperModerator
    Reputation: CHUM's Avatar
    Join Date
    Aug 2004
    Posts
    8,615
    Quote Originally Posted by civil
    ...While riding on the road may be a bit faster, there have been numerous tests that show a lower pressure is faster on trails.

    ....
    CaveGiant already responded to this accurately.....don't know what the hubBub is about....

    yes...lower pressure will be faster on trails.....simple answer is more/better traction....
    Click Here for Forum Rules

  14. #14
    mtbr member
    Reputation:
    Join Date
    Feb 2008
    Posts
    1,058
    Quote Originally Posted by Ken in KC
    So "numerous" went to "a couple"
    Fair enough, I re-stated that before you joined this thread though.

    Quote Originally Posted by Ken in KC
    and now it's one German mountain bike magazine writing an article about a "study" conducted conducted by the two companies that introduced the UST system? Got it.
    Nope, I never said it was one, you did.

    Quote Originally Posted by Ken in KC
    Since you brought up scientific research, then I'm sure you know that the burden of proof is with the person presenting the theory and their approach is to set out to disprove their theory, right?
    Sure, but I'm not presenting the theory. I merely stating what I have seen. It's up to you if you want to believe it, or pursue it any further.


    Quote Originally Posted by Ken in KC
    You made some pretty sweeping generalizations about tubeless benefits
    No sweeping generalization, just the observation that lower pressure is better/faster.


    Quote Originally Posted by Ken in KC
    I'm just asking to see the studies that I haven't seen.
    And I've told you, your answer is in your first quoted post. Unfortunately I don't keep 3 year records of my browsing history.

    This isn't a scientific community, people can present stuff and the reader has to interpret it as he/she see's fit. If you don't agree that's fine. If you want to call it full of @@$$ that's fine too.

  15. #15
    IdontShootPeopleAnyMore
    Reputation: DriveByBikeShooting's Avatar
    Join Date
    Mar 2009
    Posts
    730
    snovvman you are dam lucky (or loaded) if you are just getting into mtn biking and you are rocking crossmax wheels thats like buying a lotus to learn how to drive... what kind of bike are they on if you dont mind me askin?
    What mountain bike forum do pirates use? .....



    MTB-arrrrrrrrrrrrrrr

  16. #16
    IdontShootPeopleAnyMore
    Reputation: DriveByBikeShooting's Avatar
    Join Date
    Mar 2009
    Posts
    730
    oh and to all you debating about what is faster low psi or hi psi, if its rocky and rough and you run high psi you will proabaly shake your self to death and have a dam violent ride glancing off every root and rock and not have good grip on the trail and proabably fall off a clif and impale your rib cage with your handlebars. so yes in MTN biking low psi winns races so therefore is scientifically faster... trust me Im a scientist
    What mountain bike forum do pirates use? .....



    MTB-arrrrrrrrrrrrrrr

  17. #17
    Can't feel my legs
    Reputation: JPark's Avatar
    Join Date
    Aug 2009
    Posts
    852
    I'd love to see one credible study and source, much less a couple.
    My point exactly, so.....anyone?

  18. #18
    mtbr member
    Reputation:
    Join Date
    Feb 2008
    Posts
    1,058
    Quote Originally Posted by JPark
    My point exactly, so.....anyone?
    Well sorry, I can't provide any links.

    Feel free to run higher pressures if you like.

    But did I mention that I have seen numerous studies that have shown.........

  19. #19
    fresh fish in stock...... SuperModerator
    Reputation: CHUM's Avatar
    Join Date
    Aug 2004
    Posts
    8,615
    Quote Originally Posted by JPark
    My point exactly, so.....anyone?
    Sheldon Brown:
    Overinflation:
    * An overinflated tire will have slightly less rolling resistance.
    * An overinflated tire is more prone to damage from sharp rocks and similar road hazards.
    * An overinflated tire will give a harsh ride on anything but the smoothest pavement.
    * An overinflated tire can bounce on surface roughnesses. This can cause dangerous interruptions in traction, particularly if it happens during cornering.

    traction is king.....higher pressure solely to decrease rolling resistance will get you clobbered...
    Click Here for Forum Rules

  20. #20
    Can't feel my legs
    Reputation: JPark's Avatar
    Join Date
    Aug 2009
    Posts
    852
    CaveGiant already responded to this accurately.....don't know what the hubBub is about....

    yes...lower pressure will be faster on trails.....simple answer is more/better traction....
    Missed his post the first time.
    Again, I agree that lower pressure has advantages, but speed is not a consistant advantage to be gained by simply lowering your air pressure.
    Unless you consistantly ride to your technical riding limits over the entire ride, the advantage gained will never overcome the higher rolling resistance, which is a constant over the entire ride.
    Though obviously there are exceptions, most riders will be faster by running as high a pressure as terrain and ability will allow.

  21. #21
    fresh fish in stock...... SuperModerator
    Reputation: CHUM's Avatar
    Join Date
    Aug 2004
    Posts
    8,615
    Quote Originally Posted by JPark
    Missed his post the first time.
    Again, I agree that lower pressure has advantages, but speed is not a consistant advantage to be gained by simply lowering your air pressure.
    Unless you consistantly ride to your technical riding limits over the entire ride, the advantage gained will never overcome the higher rolling resistance, which is a constant over the entire ride.
    Though obviously there are exceptions, most riders will be faster by running as high a pressure as terrain and ability will allow.
    true...true.....too low is muy mal.....

    too high is also no bueno

    just right is:
    * A correctly inflated tire will have negligible rolling resistance.
    * A correctly inflated tire will not get pinch flats in normal use.
    * A correctly inflated tire will absorb minor surface irregularities, improving rider comfort.
    * A correctly inflated tire will absorb surface irregularities without bouncing and losing traction.

    (again...from Sheldon Browns site...damn good site)

    PS....tire pressure is also dependent on the tire/tread itself.....this is where Shiggy would have some solid answers/experience......
    Click Here for Forum Rules

  22. #22
    mtbr member
    Reputation:
    Join Date
    Jan 2010
    Posts
    139
    Quote Originally Posted by DriveByBikeShooting
    snovvman you are dam lucky (or loaded) if you are just getting into mtn biking and you are rocking crossmax wheels thats like buying a lotus to learn how to drive... what kind of bike are they on if you dont mind me askin?
    Thanks. Giant NRS Air is what I bought. I realized that I wanted a mountain bike that I can ride on paths, trails, and take jumps off stairs, steps, curbs, etc. I wanted something light and does not bob when pedling. We'll see--I haven't ridden it yet...

    The bike is cool, XT parts and XTR rear derailer, hydraulic disc brakes, carbon handle bar and seat post, carbon frame and rocker, all in a neat 24 lb package.

  23. #23
    mtbr member
    Reputation:
    Join Date
    Jan 2010
    Posts
    139
    Sorry to have started a fire about inflation pressure vs. rolling resistance.

    Still my questions: If I were to use a tube, the maxium pressure is determined by the tire--correct? Does the wheel itself have a pressure rating, when the tube is used?

    Please see post #8,

    http://www.maxxis.com/Bicycle/Hybrid/Overdrive.aspx

    http://www.csttires.com/Bicycle/City...r/Selecta.aspx

    These tires seem to have Kevlar belts in the tread that resists puncture. I would like to get feedback on how well they work.

    Thanks.

  24. #24
    Can't feel my legs
    Reputation: JPark's Avatar
    Join Date
    Aug 2009
    Posts
    852
    Quote Originally Posted by snovvman
    Sorry to have started a fire about inflation pressure vs. rolling resistance.

    Still my questions: If I were to use a tube, the maxium pressure is determined by the tire--correct? Does the wheel itself have a pressure rating, when the tube is used?

    Please see post #8,

    http://www.maxxis.com/Bicycle/Hybrid/Overdrive.aspx

    http://www.csttires.com/Bicycle/City...r/Selecta.aspx

    These tires seem to have Kevlar belts in the tread that resists puncture. I would like to get feedback on how well they work.

    Thanks.
    You didn't start a war, just a healthy debate on the merits of proper inflation.
    Yes, max inflation is determined by tire manufacturer. I doubt you will ever exceed the limits of any rim by inflating to the max recomended pressure of any tire.

  25. #25
    Probably drunk right now
    Reputation: Ken in KC's Avatar
    Join Date
    Jan 2004
    Posts
    6,645

    You're missing the point....

    Quote Originally Posted by civil
    Well sorry, I can't provide any links.

    Feel free to run higher pressures if you like.

    But did I mention that I have seen numerous studies that have shown.........

    I've seen numerous studies indicating that I can outride Ned Overend, Steve Pete and Allison Dunlop.

    Do you assume that my statement is correct because I said that I've seen studies?

  26. #26
    Old man on a bike
    Reputation: Bikinfoolferlife's Avatar
    Join Date
    Feb 2004
    Posts
    12,382
    Well, there is a small relation between tire pressure and rim width to an extent for a given tire. Perhaps even to a very small extent with rim bead design now that there's a couple different ones out there. Not a lot to worry about. Worrying about max recommended (or even minimum recommended) pressures isn't a big deal as most are conservatively rated anyways. It always amazes me how, even for road riding, that people still try to relate rolling resistance strictly with tire pressure.
    "...the people get the government they deserve..."
    suum quique

  27. #27
    Vaginatarian
    Reputation:
    Join Date
    Oct 2005
    Posts
    5,686
    Quote Originally Posted by CHUM
    CaveGiant already responded to this accurately.....don't know what the hubBub is about....

    yes...lower pressure will be faster on trails.....simple answer is more/better traction....
    actually it not better traction that gets more speed its less resistance, the lower pressure allows the tire to conform to the small irregularities in the trail ,rather than bounce up and back the tire absorbs and continues rolling

  28. #28
    Vaginatarian
    Reputation:
    Join Date
    Oct 2005
    Posts
    5,686
    Quote Originally Posted by CHUM
    +1

    except 40 psi is a bit on the high side IMHO......i weigh 180# and run my tubeless for rigid at 28 lbs(r) and 26lbs(f).....

    also...go here...great site:
    http://www.sheldonbrown.com/tires.html
    +2
    I dont even run tubes with more than 30psi, I weigh 225 and run 27psi or lower
    of course , if you havent developed trail finese and bash into/over everything you may need more

  29. #29
    Can't feel my legs
    Reputation: JPark's Avatar
    Join Date
    Aug 2009
    Posts
    852

    This makes no sense

    Quote Originally Posted by dan0
    actually it not better traction that gets more speed its less resistance, the lower pressure allows the tire to conform to the small irregularities in the trail ,rather than bounce up and back the tire absorbs and continues rolling
    What is the conforming tire absorbing? Energy. Chum was correct.

  30. #30
    Vaginatarian
    Reputation:
    Join Date
    Oct 2005
    Posts
    5,686
    Quote Originally Posted by JPark
    What is the conforming tire absorbing? Energy. Chum was correct.
    no, its absorbing the defects in the trail, if your high pressure tire hits a small rock it bounces up and back, a low pressure tire absorbs the bump and keeps rolling

  31. #31
    Can't feel my legs
    Reputation: JPark's Avatar
    Join Date
    Aug 2009
    Posts
    852

    Correct...sort of

    Quote Originally Posted by dan0
    no, its absorbing the defects in the trail, if your high pressure tire hits a small rock it bounces up and back, a low pressure tire absorbs the bump and keeps rolling
    In "absorbing the defects," the tire is actually absorbing the energy that would have otherwise have sent the tire(and bike) up, and back down. Don't get me wrong, this is a good thing, it allows for greater comfort and controll. The problem is, when running lower pressures, energy is constantly being absorbed, even on smooth surfaces. This is why a blanket statement of "lower air pressure is faster" is absolutely incorrect. As with most things, it's about compromise. A balance between rolling resistance, and comfort/controll is the goal in this case.

  32. #32
    Vaginatarian
    Reputation:
    Join Date
    Oct 2005
    Posts
    5,686
    Quote Originally Posted by JPark
    In "absorbing the defects," the tire is actually absorbing the energy that would have otherwise have sent the tire(and bike) up, and back down. Don't get me wrong, this is a good thing, it allows for greater comfort and controll. The problem is, when running lower pressures, energy is constantly being absorbed, even on smooth surfaces. This is why a blanket statement of "lower air pressure is faster" is absolutely incorrect. As with most things, it's about compromise. A balance between rolling resistance, and comfort/controll is the goal in this case.
    I agree
    but I didnt make a blanket statement, nor did anyone else. I believe the original statement was lower pressures are faster on rough surfaces and higher pressures are faster on smooth

  33. #33
    Vaginatarian
    Reputation:
    Join Date
    Oct 2005
    Posts
    5,686
    Quote Originally Posted by JPark
    You didn't start a war, just a healthy debate on the merits of proper inflation.
    Yes, max inflation is determined by tire manufacturer. I doubt you will ever exceed the limits of any rim by inflating to the max recomended pressure of any tire.
    from the no tubes site
    The ZTR Podium MMX series is a low pressure rim and it must be run at pressures of 15- 33 psi maximum. Higher pressures may cause damage to the rim and will not be covered

    The ZTR Race 29er is a low pressure rim and it must be run at pressures of 15- 33 psi maximum

    for the arch rim
    Maximum Tire Pressure
    1.0 tire 55psi
    1.5 tire 50psi
    2.0 tire 43psi
    2.3 tire 40psi

    flow
    Maximum Tire Pressure
    2.0 tire 40psi
    2.3 tire 38psi

    from the sidewalls
    specialized eskar s works 29" minimum psi 35-65
    kenda nevegal 29 30-50psi
    panaracer rampage 35-55psi

    now, I run all these at 27psi without problems. I think the psi ratings on the sidewalls are kind of like the psi rating on car tires. alot depends on weight and type of riding

  34. #34
    Can't feel my legs
    Reputation: JPark's Avatar
    Join Date
    Aug 2009
    Posts
    852

    Sorry

    Quote Originally Posted by dan0
    I agree
    but I didnt make a blanket statement, nor did anyone else. I believe the original statement was lower pressures are faster on rough surfaces and higher pressures are faster on smooth
    The "blanket statement" comment was not directed at you, or anyone for that matter. I just think it is important to understand energy conversions(kinetic to heat) and resulting energy loss(to convection), when you are dealing with an extremely low horsepower machine(a person on a bike).

  35. #35
    Vaginatarian
    Reputation:
    Join Date
    Oct 2005
    Posts
    5,686
    Quote Originally Posted by JPark
    The "blanket statement" comment was not directed at you, or anyone for that matter. I just think it is important to understand energy conversions(kinetic to heat) and resulting energy loss(to convection), when you are dealing with an extremely low horsepower machine(a person on a bike).
    not a problem
    but since you opened that can of worms... care to elaborate on why a tire without a tube is faster that a tire with a tube
    I read a study somewhere that said the friction of the tube rubbing against the tire makes it slower. That I dont understand

  36. #36
    fresh fish in stock...... SuperModerator
    Reputation: CHUM's Avatar
    Join Date
    Aug 2004
    Posts
    8,615
    hahahaha....you guys are purty funny....keeping yourself upright...and air in your tires will make you faster....

    when i was referring to traction i was implying a more 'real world' application.....

    too high and risk low-siding on a hard right hander down a fireroad, cutting a sidewall...or getting more fatigued on longer rides/races

    too low and risk rolling a bead, pinch flatting....or dinging a rim hitting square edge (rock)..


    PS - terrain makes a huge difference.....in Moab i tried to run Amassa Back with tubeless xc tires at 'buff-ST-Norcal' pressures.....destroyed both tires within 2 miles. Picked up tubes, SB8(r) and Nevegal(f) and ran them in the upper 40's psi....not 1 flat the rest of the trip....
    Click Here for Forum Rules

  37. #37
    fresh fish in stock...... SuperModerator
    Reputation: CHUM's Avatar
    Join Date
    Aug 2004
    Posts
    8,615
    Quote Originally Posted by dan0
    not a problem
    ....care to elaborate on why a tire without a tube is faster that a tire with a tube
    ....
    dry tubeless tends to be lighter.....and as everyone knows reducing weight in rotating mass (specifically tires) makes for a noticeable improvement in performance....

    my .02

    edit....ummm....the obvious....less flats make you faster too.....
    Last edited by CHUM; 01-27-2010 at 04:16 PM.
    Click Here for Forum Rules

  38. #38
    Can't feel my legs
    Reputation: JPark's Avatar
    Join Date
    Aug 2009
    Posts
    852

    Simple...sort of

    Quote Originally Posted by dan0
    not a problem
    but since you opened that can of worms... care to elaborate on why a tire without a tube is faster that a tire with a tube
    I read a study somewhere that said the friction of the tube rubbing against the tire makes it slower. That I dont understand
    First you have to realize that energy is a real thing, that can be neither created, or destroyed, it can only change forms. In this paticular case, kinetic energy(motion) of the tube and tire rubbing together is converting into heat. This heat is then absorbed into the surrounding air, and therefore becomes lost(energy) to you. This also happens in the same way(to a lesser extent) in tubeless tire, from the moving air and rubber.

  39. #39
    mtbr member
    Reputation:
    Join Date
    Jan 2010
    Posts
    139
    It appears that the front UST wheel has a tube in it. I have since read that sometimes they stop holding air. What are the common causes of USTs not holding air, aside from physical damage?

    To verify my understanding related to my original question: Theoretically, I CAN use the typcial clincher tube tire, with a tube, inflated to the maximum pressure rating of the TIRE, CORRECT? Is there a danger of the tire/sidewall blowing out because of differences of rim design between UST and typical bike wheels?

    Thanks again.

  40. #40
    Old man on a bike
    Reputation: Bikinfoolferlife's Avatar
    Join Date
    Feb 2004
    Posts
    12,382
    Quote Originally Posted by snovvman

    To verify my understanding related to my original question: Theoretically, I CAN use the typcial clincher tube tire, with a tube, inflated to the maximum pressure rating of the TIRE, CORRECT? Is there a danger of the tire/sidewall blowing out because of differences of rim design between UST and typical bike wheels?
    Could be material for a thread on the wheels & tires forum?
    "...the people get the government they deserve..."
    suum quique

  41. #41
    mtbr member
    Reputation:
    Join Date
    Jan 2010
    Posts
    139
    Quote Originally Posted by Bikinfoolferlife
    Could be material for a thread on the wheels & tires forum?
    Sure. I posted here because I figure since I'm a newb and know very little about this stuff, less is less of a chance that I will get dogpiled.

  42. #42
    Can't feel my legs
    Reputation: JPark's Avatar
    Join Date
    Aug 2009
    Posts
    852
    If your wheel is not holding air without a tube, there is some type of physical damage. Whether it's a small crack or bend in the wheel itself, or a defect in the rim strip, the air has to be going somewhere.
    The max recomended pressure of a standard tube tire will not change due to being mounted on a tubeless wheel, though some tubeless rims do have lower recomended pressures as danO pointed out.

  43. #43
    mtbr member
    Reputation:
    Join Date
    Jan 2010
    Posts
    139
    Quote Originally Posted by JPark
    If your wheel is not holding air without a tube, there is some type of physical damage. Whether it's a small crack or bend in the wheel itself, or a defect in the rim strip, the air has to be going somewhere.
    The max recomended pressure of a standard tube tire will not change due to being mounted on a tubeless wheel, though some tubeless rims do have lower recomended pressures as danO pointed out.
    Thanks. I'm not suggesting that the tube-tire would yield a higher pressure ceiling when mounted on a tubeless wheel. But if the tubless wheel's pressure rating is for when it is used without a tube (say, 60 PSI @ 2" tire), I presume I can go to, for example, 65 PSI if I have an inner tube and the tube-tire allows for it 65 PSI printed on the sidewall?

    Also, is there an INCREASED chance of side-wall blow out if I ran a tube-tire and tube because either 1) the rim of the UST design is different such that tube tires don't hold as well, or 2) the UST rim/wheel is somehow less capable of supporting higher pressure, even with a tube inside and a tire that is inherently rated for higher pressure?

    I just want to understand the theories. Thank you guys for bearing with me.

  44. #44
    Can't feel my legs
    Reputation: JPark's Avatar
    Join Date
    Aug 2009
    Posts
    852
    Using a tube or not will not change the max pressure of tire or wheel.
    To put it as plainly as possible: the lowest max recomended pressure of the two, whether it is the rim, or tire is the pressure you should not exceed. Whether or not you use a tube is irrevelant.

  45. #45
    mtbr member
    Reputation:
    Join Date
    Jan 2010
    Posts
    139
    Quote Originally Posted by JPark
    Using a tube or not will not change the max pressure of tire or wheel.
    To put it as plainly as possible: the lowest max recomended pressure of the two, whether it is the rim, or tire is the pressure you should not exceed. Whether or not you use a tube is irrevelant.
    Why?

    I can understand, under tubeless conditions, the sealing components of the wheel can only hold so much pressure. But when a tube is inside, the air is contained inside the tube and the rim/wheel no longer needs to seal the air. So if the wheel's rating is 60 PSI, but the tube-tire's inherent rating is 65 PSI, why can't one use 65 PSI with a tube?

    In my mind, the wheel is a stronger than the rubber. What could be damaged?

    Thanks.

  46. #46
    Can't feel my legs
    Reputation: JPark's Avatar
    Join Date
    Aug 2009
    Posts
    852
    Max pressures have nothing to do with the sealing, rather they are dictated by the structural limits of the components. If over-inflated, a tire can burst, and a wheel can crack. Neither of these things are affected by having a tube or not.

  47. #47
    Vaginatarian
    Reputation:
    Join Date
    Oct 2005
    Posts
    5,686
    Quote Originally Posted by snovvman
    It appears that the front UST wheel has a tube in it. I have since read that sometimes they stop holding air. What are the common causes of USTs not holding air, aside from physical damage?

    To verify my understanding related to my original question: Theoretically, I CAN use the typcial clincher tube tire, with a tube, inflated to the maximum pressure rating of the TIRE, CORRECT? Is there a danger of the tire/sidewall blowing out because of differences of rim design between UST and typical bike wheels?

    Thanks again.
    well, if the UST doesn't have sealant you could have a puncture, or small leakage around the bead or valve . all of my setups UST, tubeless have lost a lb or 2 between rides ( or maybe during) I always check the pressure before a ride. my Tubed setups have always held air better

    using regular tire without tubes or tubeless tires (not UST) will have a weaker sidewall and with lower pressures will tend to tear or wear out faster than UST or higher pressures
    with 26" tires there are plenty of selections with extra sidewall protection (usually extra kevlar layers) on 29" tires not so much.

    you can use any tire /tube combination inflated to the maximum pressure of the tire or rim whichever is lower. see my earlier post the Stans rims are rated fairly low for maximum pressure. I'm not sure about other brands
    http://forums.mtbr.com/showthread.ph...43222#poststop

  48. #48
    mtbr member
    Reputation:
    Join Date
    Sep 2009
    Posts
    504
    Quote Originally Posted by snovvman
    Why?

    I can understand, under tubeless conditions, the sealing components of the wheel can only hold so much pressure. But when a tube is inside, the air is contained inside the tube and the rim/wheel no longer needs to seal the air. So if the wheel's rating is 60 PSI, but the tube-tire's inherent rating is 65 PSI, why can't one use 65 PSI with a tube?

    In my mind, the wheel is a stronger than the rubber. What could be damaged?

    Thanks.
    Regardless of whether it's holding a tube and tyre combination or a tubeless tyre the rim has a maximum pressure that must be adhered to.

    Why?

    Because it'll blow a piece of aluminium out of the side of the rim if someone decides to ignore the manufacturers maximum.

    I've seen the result of that with a mate's sprint kart rim (6mm thick).....previously undamaged.....a loud crack and it shot a piece of the rim bead out like a bullet.

    He was putting in about 65psi at the time for a wet track.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •