Page 1 of 2 12 LastLast
Results 1 to 50 of 60
  1. #1
    Toby Wong?
    Reputation: Tappoix's Avatar
    Join Date
    Mar 2004
    Posts
    1,307

    rear tire pressure - the clyde enigma

    I just don't seem able to run anything less than 40 psi in the rear or I will pinch flat while slamming through rock gardens.

    I'm 225 w/o gear, Mavic 819 UST rims, typically a 2.25 to 2.3 tire on the back

    tires i've tried (trying to stay below the heavy 900g rear tire weight):

    Schwalbe Nobby Nic 2.25
    Nokian NBX 2.3
    Geax Sturdy 2.25 and Barro Marathon 2.3 (actually, no problems with these)
    WTB Motoraptor 2.3

    If the pressure goes below 40 psi, the tire begins to see stress lines along the sidewall when i land a jump or run through rocky terrain.

    What are you lads running for rear tire pressure?

    It's all relative right? I mean, 40 psi shouldn't be some magic number you can't cross, especially given the larger mass of a clyde over it, compared to some 165 lb. dood who can run 32 psi and actually talk about the benefits of lower tire pressure.
    lets not make it a religion, it is recreation

  2. #2
    local trails rider
    Reputation: perttime's Avatar
    Join Date
    Aug 2005
    Posts
    12,228
    There's no magic numbers: whatever works is good.
    I do not worry about the exact pressure. I only recently got myself a pump with a gauge (pretty inaccurate too). Looks like my eyeball method has put my "2.3" tires (Racing Ralph, Gravity) close to 3 bar / 40 psi.

    edit: the front tyre gets a little less pressure, as there is less weight on it. Enough to make it compress about the same as the rear when I just sit on the bike.
    Last edited by perttime; 07-17-2007 at 12:43 PM.

  3. #3
    Nightriding rules SuperModerator
    Reputation: crisillo's Avatar
    Join Date
    Jul 2004
    Posts
    20,799
    yep.. I am about your weight, Tappoix... I also run the tires around 40 psi... and they feel good... given our weight 40 psi might feel like the 32 psi for a lighter dude..

  4. #4
    On MTBR hiatus :(
    Reputation: Speedub.Nate's Avatar
    Join Date
    Dec 2003
    Posts
    9,145
    Sounds about right. I'm around 210 and am pretty particular with my pressures (2 PSI can make a difference!), and I usually ran 40 PSI on my 2.1 26" rear, and 38 PSI on my 2.1 29" rear.

    "Lower tire pressure" is relative to the weight it is supporting.
    speedub.nate
    ∑ MTBR Hiatus UFN ∑

  5. #5
    Chilling out
    Reputation: bear's Avatar
    Join Date
    Feb 2004
    Posts
    5,727
    On the square-edge limestone ledgy and sharp rock gardence of Texas ... at 235# w/o gear and riding a 35# bike ...

    - tires smaller than 2.2 on the back needed like 45-50 psi to be safe
    - tires 2.25-2.4 seem to be good around 35 psi
    - tires 2.5+ seem to be good above 25 psi

    BUT, still, infrequent pinch-flats at those pressures from abnormally high-impact situations.

    I do *not* focus on riding lightweight tires, so for some samples of tire selection ...

    2.2 Geax Sedona
    2.2 Kenda Cortez
    2.25 or Geax Sturdy
    2.24 WTB MotoRaptor
    2.4 WTB MotoRaptor
    2.35 Kenda Blue Groove
    2.35 Kenda Nevegal
    2.35 Kenda Small Block 8
    2.4 Kenda Cortez
    2.5 Kenda Nevegal (current favorite)
    2.6 Kenda Kinetics (folding)

    I completely walked away from tires < 2.2 for me back in '01 and have never gone back.

    I do think I need to branch out some more into other tire lines though. Hard to argue with tires that Just Work And Don't Make Me Complain though.

  6. #6
    mtbr member
    Reputation:
    Join Date
    Jul 2003
    Posts
    6,762

    Yup, it's all relative...

    to your weight, riding style, terrain, and the tires involved. I'm 230, ride pretty much XC/Trail and do just fine on Nevegal 2.1's at 35psi. Not much for rocks round here. But if I know I'm going somewhere with rock gardens etc. I'll jump to a 2.3 Nev at 35 to 40psi. I've also found that going tubeless isn't the "holy grail" allot of folks think that it is either. With Stans I can drop my pressure by an average of 5psi, depending on the tire, with no problems. But much lower than that I start burping tires and dinging rims. So what's the big deal?!?! I have just as much control and traction with a little more pressure and a tube as I do with a Stans set up. And I think the tubed tires with a bit more pressure roll faster for me.

    So yeah, it's all relative to weight, tires, terrian, and riding style. No magic formula or mirical product, just what works for you and your set up.

    Good Dirt
    "I do whatever my Rice Cripsies tell me to!"

  7. #7
    NormalNorm
    Reputation: norm's Avatar
    Join Date
    Feb 2005
    Posts
    935
    Another Clyde here running around 40psi. Dont give up on tubeless yet. Try some Ust tires. I thought the same thing when I first tried the Stans setup. After the Stans I bought a couple of Ust tires and loved it. Ust is great for us Clydes.

  8. #8
    Klydesdale
    Reputation:
    Join Date
    Feb 2005
    Posts
    304
    Quote Originally Posted by norm
    Another Clyde here running around 40psi. Dont give up on tubeless yet. Try some Ust tires. I thought the same thing when I first tried the Stans setup. After the Stans I bought a couple of Ust tires and loved it. Ust is great for us Clydes.

    I've had just as much trouble with pinch-flatting UST tires as I have with tubed tires.

  9. #9
    mtbr member
    Reputation: Sasquatchcycles's Avatar
    Join Date
    Jul 2007
    Posts
    246
    Convert with Stan's NoTubes to Tubless...end the pinchflat nightmare.

  10. #10
    mtbr member
    Reputation:
    Join Date
    Mar 2005
    Posts
    35
    beware, non-tubless content below

    I was the pinch flat king until I switched to those "thorn proof" tubes which are a lot heavier, but when pumped to 40psi allow me to hammer over everything. That's with 2.1 panracer fire xc's. Have yet to have a flat in a season and a half...

  11. #11
    R.I.P. DogFriend
    Reputation: jeffj's Avatar
    Join Date
    Jan 2004
    Posts
    6,547
    I'm in the 'upper 200's' and need to run over 50psi to avoid pinch flats with a 2.10" tire so your numbers sound about right to me. Now I'm running a 2.5" tire and can run much less pressure (closer to 40psi) with the larger volume. However, there is a weight and rolling resistance penalty to pay for the increased traction it provides. It's worth it me, but YMMV.

  12. #12
    mtbr member
    Reputation: bikemanla's Avatar
    Join Date
    Feb 2006
    Posts
    78

    More to think about.........

    I'm 210 and ride rough XC. In Southern California I got tired of thorn flats and changed over to Stan's notubes. Ran 2.0 specialized Roll-x both front and rear at 22lbs in front and 34 lbs in rear. No problems, no flats, better performance.

    With my move to Vancouver, BC have changed to 2.35 Nevegals dct to take the nasty large rocks and roots. I am now experimenting with pressures. Rode nasty trails near Banif last week at 22/32 and am trying 20/30 just now. Jury is still out on best pressures.

    Added thoughts on Stan's:
    1) first time I set up a tire it was hell.....last week no problem at all. There is a learning curve, just as there was with tubes.
    2) Rode tires with tubes between the switch over....felt hard,and slow like a solid rubber tire. Back to the Stans and The tires just eat the roots and rocks with a soft smooth ride.
    3) Stans works as well on blackberry thorns as it did on desert nasties.

  13. #13
    long standing member
    Reputation: PCinSC's Avatar
    Join Date
    Oct 2005
    Posts
    3,093
    Quote Originally Posted by Tappoix
    What are you lads running for rear tire pressure?
    I'm pretty much an oddball here, with higher pressure in a heavy, high volume tire. I'm running 40-44psi in a Hutch Octopus UST 2.5" rear on Mavic 823's. This is on my "one bike" which sees techy trail use as well as dedicated DH. For reference, I'm 260lbs plus gear. I have no complaints about its performance.

    It's all relative right? I mean, 40 psi shouldn't be some magic number you can't cross, especially given the larger mass of a clyde over it, compared to some 165 lb. dood who can run 32 psi and actually talk about the benefits of lower tire pressure.
    I would think that a heavier rider would see some those same benefits at a higher pressure. That is until the capabilities of the tire are exceeded. I'd be curious to know how heavy a rider tire companies consider when they are designing/manufacturing tires.

  14. #14
    R.I.P. DogFriend
    Reputation: jeffj's Avatar
    Join Date
    Jan 2004
    Posts
    6,547
    Quote Originally Posted by PCinSC
    I'm pretty much an oddball here, with higher pressure in a heavy, high volume tire. I'm running 40-44psi in a Hutch Octopus UST 2.5" rear on Mavic 823's. This is on my "one bike" which sees techy trail use as well as dedicated DH. For reference, I'm 260lbs plus gear. I have no complaints about its performance.


    I would think that a heavier rider would see some those same benefits at a higher pressure. That is until the capabilities of the tire are exceeded. I'd be curious to know how heavy a rider tire companies consider when they are designing/manufacturing tires.
    Another thing to look at is the max pressures rim manufacturers recommend for the various size tires. As Clydes, we're more likely to exceed recommendations on the rims than we are the tires.

  15. #15
    long standing member
    Reputation: PCinSC's Avatar
    Join Date
    Oct 2005
    Posts
    3,093
    Quote Originally Posted by jeffj
    Another thing to look at is the max pressures rim manufacturers recommend for the various size tires. As Clydes, we're more likely to exceed recommendations on the rims than we are the tires.
    Indeed. Mavic recommends a 44psi max with a 2.5" tire on the 823. I pump 'em up to 50-55psi when installing just to seat the bead (and rode with them at 50psi once just to see how they felt), but as a rule keep them between 40 and 44psi.

  16. #16
    mtbr member
    Reputation: nachomc's Avatar
    Join Date
    Apr 2006
    Posts
    6,682
    Have you considered either going tubeless, or possibly running a rear tire that is a tubeless tire and running it tubed? I was using the Specialized S-works 2Bliss tire (tubed) in the rear and was getting as low as 35 in some pretty technical and rocky sections. I weigh 225 without my gear.
    :wq

  17. #17
    mtbr member
    Reputation:
    Join Date
    Jul 2007
    Posts
    23
    I'm 215 and anything less than a 50# rear-end feels mushy in the turns (45# up front). However I use cheap tube tires tho, Continental Explorers w/ cheap Alexrims.

  18. #18
    Nightriding rules SuperModerator
    Reputation: crisillo's Avatar
    Join Date
    Jul 2004
    Posts
    20,799
    Quote Originally Posted by Big Pwn
    I'm 215 and anything less than a 50# rear-end feels mushy in the turns (45# up front). However I use cheap tube tires tho, Continental Explorers w/ cheap Alexrims.
    that's because of the size... the conti explorers are really small volume tires.. if you moved to something bigger, you would be able to run a bit lower pressure

  19. #19
    mtbr member
    Reputation: Joules's Avatar
    Join Date
    Oct 2005
    Posts
    2,841
    try thinking about it this way: 165# rider with 32psi in his rear tire and say 60% of his weigh on that tire, contact patch is 3.1square inch. A 225# guy, same weight distribution, same tire would need 43psi to get the same contact patch.

    you don't run the same spring in your fork as a lesser [weight] rider, do you?

  20. #20
    mtbr member
    Reputation:
    Join Date
    Dec 2006
    Posts
    314

    big tires

    why dont you just use 2.5 tires? it sounds really dumb running 2.1 tires when you weigh 200 lbs. it might be a bit heavier, so what? im 145 lbs with gear, and i run 2.5 tires, still manage to pedal.
    being thicker and larger in volume they eliminate all puncture related issues.

    you dont have to be an aggressive rider to use sturdy components. weighing over 200 lbs is more stressful to the bike than a light rider hucking the crap out of it (i witnessed that myself with complete astonishment).

  21. #21
    mtbr member
    Reputation:
    Join Date
    Jul 2007
    Posts
    23
    Quote Originally Posted by crisillo
    that's because of the size... the conti explorers are really small volume tires.. if you moved to something bigger, you would be able to run a bit lower pressure
    Great suggestion, thanks! I've only seen the bigger tires on AM bikes doing the same XC stuff as I do, so I had it in my mind that a thinner tire was a bonus for XC handling. I'm sure it would help in all my areas of riding, including the "over-compensation issue" we all cling to lol.

    Seriously tho, how does the handling characteristics differ for 2.1 & 2.5?

  22. #22
    Nightriding rules SuperModerator
    Reputation: crisillo's Avatar
    Join Date
    Jul 2004
    Posts
    20,799
    Quote Originally Posted by Big Pwn
    Great suggestion, thanks! I've only seen the bigger tires on AM bikes doing the same XC stuff as I do, so I had it in my mind that a thinner tire was a bonus for XC handling. I'm sure it would help in all my areas of riding, including the "over-compensation issue" we all cling to lol.

    Seriously tho, how does the handling characteristics differ for 2.1 & 2.5?
    well..depending on the tire of course..usually there is a bit more rolling resistance and weight... but traction is improved as well as comfort, since the higher volume tire at a bit lower pressure can conform to the surface while still giving good support..

  23. #23
    Toby Wong?
    Reputation: Tappoix's Avatar
    Join Date
    Mar 2004
    Posts
    1,307
    WHAM!

    Another pinch flat today. CRAP!

    psi was 42 when i left the car. I was totally flowing through the trail and rode *firmly* over a square edged rock. (Hey, what do you want me to do i was feeling it! )

    pssssssssssssssssssssssssssssssst.

    what a pain in the butt.

    i might go back to Geax tires, they have probably been the most dependable UST tires i've tried (i think )
    lets not make it a religion, it is recreation

  24. #24
    El Pollo Diablo
    Reputation: SnowMongoose's Avatar
    Join Date
    Feb 2007
    Posts
    1,474
    fwiw, I can't stand to run anything under 40PSI in the rear...
    and usually run closer to 50.
    freaking hate feeling the rubber get squirmy under me during cornering/riding over stuff.

  25. #25
    mtbr member
    Reputation: drewactual's Avatar
    Join Date
    Nov 2005
    Posts
    142

    ... and if we just ...

    strange concept this thread holds........(my best yada impression)

    I top out at #270, ride Heckler on Cloud Nine rear shock, and Super Minute 20mm qrta fork (fwiw)......

    Wheels are Halo Tornado- Tires Hutchinson Spider UST 2.3....Stan'd to hellnback....Stans FR strips over velox tape.....

    I tore a sidewall once, but that is the only problem I have ever had running this set-up. No set-up could live through that, so I chalk it up as a anomaly.... I have never cased the wheels, and I do drop up to 3' to flat semi regularly.... and jump often.... here is the thing that I just don't get- I run 28-29psi in those tires....too my knowledge I have never rolled a tire while cornering- certainly not to the point of burping, and have not had a single trail flat with that above exception in well over two years of using it.....to say I am sold on Stans is an understatement.

    I just can't grasp the problems you guys have stated and relate to them.... at the risk of peeving a few: when you are as heavy as we are it is easy to blame much of our issues on weight.....but on this issue I bet it is something else- rims/tire compatibility for one- I personally believe Clydes should run wider rims (27mm+) to square the tread more and discourage roll off and bites.... the volume is a no brainer- Clydes shouldn't run anything below 2.2 imo... thicker sidewalls meaning Clydes will benefit from UST tires whether they run them tubeless or not unless they are riding on solid smooth surfaces and in a straight line.... My God man, go tubeless-- and if you do or don't use UST rims, use the Stans...... It makes riding a lot more enjoyable as you don't have to worry about it anymore.....

    hmmmm- better traction at lower psi, eliminate snakebites, clog up pesky thorn punctures without even knowing they are there, durability and dependability- vs the exact opposite of what I just said.....cost? how many tubes do you go through in a year? How many rim welds have you broke because of high psi? How often do you have to stop and tear a tire off the rim and repair the tube? frustration alone it is worth it....

    This has been an advertisement.....Mr Stan please make check payable to DrewActual...

  26. #26
    Shortcutting Hikabiker
    Reputation: Acme54321's Avatar
    Join Date
    Oct 2003
    Posts
    3,135
    I usually run 35-40psi in 2.3 Weirwolfs, 230lbs. Haven't pinch flatted in years. 4 foot drops, rocks, climbing stairs, no problems.

  27. #27
    mtbr member
    Reputation:
    Join Date
    Aug 2007
    Posts
    169
    I used to get pinch flats when I first started riding and I wasnt smooth. In the last few years I havent had pinch flats since I have changed to tires with a beefy sidewall.

    I use a Michelin Comp16 2.2 on the rear of my bike and I cant pinch flat it. Its mounted on a Sun Singletrack rim. I use a standard 2.1 tube to keep the weight down and run it at 30psi. Im a six foot four clydesdale so im no lightweight.

  28. #28
    mtbr member
    Reputation: bongo_x's Avatar
    Join Date
    Aug 2006
    Posts
    103
    I'm 230-240 and I think I've only pinch flatted once in my life, riding since '89. I tend to run higher pressure though. I'm not sure how much since I don't really check it, I just hate it too low. it makes it too much work and feels mushy.

    bb

  29. #29
    Hairy man
    Reputation: Dwight Moody's Avatar
    Join Date
    Jan 2004
    Posts
    4,936

    Downhill tubes

    I run downhill tubes and don't have an issue with pinchflats. When I went from rigid to hardtail, I was pinchflatting all the time because I'd kicked up my speed a couple notches and my smoothness not one bit. When I finally got downhill tubes my problems were solved. I don't check my pressure regularly, but I'm guessing (based on the old pinch test) that it's about 45psi.
    We all get it in the end.

  30. #30
    Probably drunk right now
    Reputation: Ken in KC's Avatar
    Join Date
    Jan 2004
    Posts
    6,645

    Flogging Trigger....

    Ever feel like a broken record?

    Is there really a good reason for someone over 200 pounds to save a couple grams by running a small volume tire? No, there's not. But there's plenty of reasons for Clydes to run higher volume tires. Namely, lower pressures and better traction without pinch flatting.

    Tubeless? Whatever. You'll still pinch unless you run higher volume tires. Unless you run tubeless for flat protection from thorns, there's not a huge advantage in tubeless for big guys. Higher volume is where it's at.

    The general understanding here is that you still have to have some degree of skill. Casing your rear wheel in to a rock will still trash your wheel and cause a flat.

    Now before you get all uppity and suggest that I don't know what I'm talking about, please consider the trails I ride. Kansas City is nothing but millions of years of rivers exposing limstone ledges and glacial till. In other words, rocks. Lots and lots of rocks.

    Higher volume tires for Clydes. Man law?

  31. #31
    Captain Underpants
    Reputation: Random Drivel's Avatar
    Join Date
    Oct 2006
    Posts
    4,281
    Quote Originally Posted by Ken in KC
    Ever feel like a broken record?

    Is there really a good reason for someone over 200 pounds to save a couple grams by running a small volume tire? No, there's not. But there's plenty of reasons for Clydes to run higher volume tires. Namely, lower pressures and better traction without pinch flatting.
    Well, the only reason I can think of running a lower volume tire on the rear of my giant man-carcass bike is because lower volume tires sometimes have less flexy sidewalls. The Nevegal comes to mind here, the 2.1 was less flexy than the 2.35 on the rear of my Flux.

    But I agree with your comment; I run 2.35 Rampages (29ers) f/b at 30 psi and have not pinch flatted in over 3 months. They are tremendously awesome when mated to RhynoLites or any wide rim.

    Oh, and forget the boyracer lightweight tubes--use a real man tube and pinch flats are a thing of the past . .

  32. #32
    Toby Wong?
    Reputation: Tappoix's Avatar
    Join Date
    Mar 2004
    Posts
    1,307
    Quote Originally Posted by Ken in KC
    Ever feel like a broken record?

    Is there really a good reason for someone over 200 pounds to save a couple grams by running a small volume tire? No, there's not. But there's plenty of reasons for Clydes to run higher volume tires. Namely, lower pressures and better traction without pinch flatting.

    Tubeless? Whatever. You'll still pinch unless you run higher volume tires. Unless you run tubeless for flat protection from thorns, there's not a huge advantage in tubeless for big guys. Higher volume is where it's at.

    The general understanding here is that you still have to have some degree of skill. Casing your rear wheel in to a rock will still trash your wheel and cause a flat.

    Now before you get all uppity and suggest that I don't know what I'm talking about, please consider the trails I ride. Kansas City is nothing but millions of years of rivers exposing limstone ledges and glacial till. In other words, rocks. Lots and lots of rocks.

    Higher volume tires for Clydes. Man law?
    Ken

    Totally agreed. I learned that lesson and never run less than 2.25. And the part about casing....OK, maybe I'm a bit guilty. But only a bit!

    But your part about larger tires/lower pressures.....i'm having to go 40+psi to avoid the tire rolling when I land jumps and bang through rock gardens.....I don't call that lower pressure. But that is the point of the thread....that it's all relative, eh?

    Now, high volume, beefier sidewalls, and a reasonable weight.....well, the "reasonable" part is the relative part of that equation!

    Tell me the tires you like to run, good sir.
    lets not make it a religion, it is recreation

  33. #33
    mtbr member
    Reputation: dwnhlldav's Avatar
    Join Date
    Feb 2006
    Posts
    1,027
    I'm 250 in my underoos.

    2 things, I just can't under stand why a clyde would run anything less then a 2.25 and even that is little.

    Up until recently I ran 2.5 Nevegal folding beads for about a year and a half and didn't have a single flat. Pressure was anywhere from 25 to 35 depending on when the last time I pumped them up was. Never had them roll on the rim and they never felt squirly. And PA has rocks.

    I just switchback to a pair of 2.35 Nokian Gazzallodi (sp?) Core folding bead. I only switch back to these because the Nevegals were rubbing the chain stays and fork of my current ride. Previously I experimented with these tires and had them down to about 23psi before they started to roll. I generally run them at 35psi. Two weeks ago I had them down to 30 and pinch flatted but it was a hard square hit That I didn't see coming so I had no finesse.
    Disclaimer: I no longer fix bikes for a living.
    National Ski Patroller to feed my winter habit.

  34. #34
    Probably drunk right now
    Reputation: Ken in KC's Avatar
    Join Date
    Jan 2004
    Posts
    6,645

    WTB Motoraptor 2.4....

    Quote Originally Posted by Tappoix
    Ken

    Totally agreed. I learned that lesson and never run less than 2.25. And the part about casing....OK, maybe I'm a bit guilty. But only a bit!

    But your part about larger tires/lower pressures.....i'm having to go 40+psi to avoid the tire rolling when I land jumps and bang through rock gardens.....I don't call that lower pressure. But that is the point of the thread....that it's all relative, eh?

    Now, high volume, beefier sidewalls, and a reasonable weight.....well, the "reasonable" part is the relative part of that equation!

    Tell me the tires you like to run, good sir.
    WTB Motoraptor 2.4. I've been running them for several years. They don't do one thing *great* but they do everything really, really well. They're the best all trail, all condition tires that I've ridden. For clarity: They're the best *for me*. Someone else might hate them.

  35. #35
    Brackish
    Reputation: carbuncle's Avatar
    Join Date
    Dec 2005
    Posts
    1,828
    While I've been freeriding I have ranged between 215# and 255#, currently at about 230#. I have never once given a thought to tire pressure as regards my weight, and run 30 psi for the Shore or anything with wet, rooty and rocky terrain and maximum 35 psi for Whistler or similar dry, fast terrain. I have used 2.35 Maxxis High Rollers and Minions and 2.5 Tioga DH Pro and Kenda Nevegal tires. For street riding I have run Tioga City Slickers on my commuter at 80 psi, and Kenda K-rads and Maxxis Holy Rollers at 40-60psi depending on the day and the ride. I have taco'd one wheel, an Azonic Outlaw, and that was about six weeks ago in a freak occurance at Whistler, and have experienced 0 pinch flats and only regular wear and tear on wheelsets (except on the Azonic front wheel, which I am convinced is a complete POS: I'm rebuilding the set with Mavic EX 729s, DT spokes and the AZO hubs next month). Wheelsets have mostly been OEM, with a mix of Shimano, Formula and no-name hubs and WTB or low-end Mavic rims, and abuse has been dished out liberally on the Shore, Whistler, Blackrock in Oregon, local trails, etc. I'm thinking that with high volume tires, decent tubes (no butyl or similar lightweight shite) and a modicum of riding finess that even a fairly good-sized individual such as myself can get away with just making sure that your wheels are tensioned and maintained by a professional (something I have done to ALL of my wheels) and running a standard range of pressure suited to the conditions.
    But that's just my experience.

  36. #36
    mtbr member
    Reputation: Qfactor03's Avatar
    Join Date
    Dec 2005
    Posts
    773
    On a recent trip to Ellijay, GA (home of some very high speed, rocky descents) I was able to run 38 psi in a Maxxis Ignitor (29er) without problems on my ti hard tail. I have also run 35 psi in a Panaracer Rampage on the back of a rigid single speed successfully, but it is a very large tire for a 2.35. At my weight of 265, I don't see a practical reason to run any lower than the mid-thirties in the rear and typically run 40 psi on my local trails.

  37. #37
    Toby Wong?
    Reputation: Tappoix's Avatar
    Join Date
    Mar 2004
    Posts
    1,307
    ok guys, you're not going to believe it......another flat

    i did a 2.4 hour ride last week and was just hammering the whole time, the tire pressure was probably 45psi and it held the whole time.

    today, with 10 minutes left on a 2 hour ride, WHOOOOOOSH, on a smooth piece of trail, the nut fell off the valve stem and there was a hole in the tube and the rear totally deflated. In fact, the valve stem retreated completely into the rim (819s) adn a Nokian NBX 2.3

    WTF is going on here, this is getting ridonkulous!

    MeanTodd at Webcyclery built my rear wheel, I'm going to have him look at it. do I really have to get some 900g tire? fack!
    lets not make it a religion, it is recreation

  38. #38
    HAHA PWN
    Reputation: Vhom's Avatar
    Join Date
    May 2007
    Posts
    177
    I know it's kind of odd, I was running close to 40 PSI on my 2.1 Kenda BlueGrove and getting lots of pinch flats. I then tried running around 32-35 psi and had none since I've lower the psi in the tires. I know it sounds crazy, but give it a try.

  39. #39
    Underskilled
    Reputation: CaveGiant's Avatar
    Join Date
    Aug 2007
    Posts
    4,118
    One way of looking at it is you want to keep the rear weight down to keep your speed.
    Well these flats are slowing you down and do those lost seconds really mean that much out of a race.

    If you flat get a bigger tire and keep getting bigger until you can finish a ride.

    One thing though, is I ride Maxxis ignitor 2.1 LUST on a mavic XC717 with Joe's tubeless (stan knock off, didn't even relise till I got home) and the rear pressure is only at 20 at the moment.

    Now not sure how hard I ride compared to you guys but took a 30mph off road descent where no-one else was doing above 15 on a HT and broke my rear hub by the time I got to the bottom. fun as anything and definatly worth the £10 hub repair.
    Havn't damaged the rim or lost pressure in the tire. I am also learning drop offs but nothing bigger than 1-2' at the moment, 240lbs

  40. #40
    Underskilled
    Reputation: CaveGiant's Avatar
    Join Date
    Aug 2007
    Posts
    4,118
    I should add a few weeks back I hit a rock so hard on the trail it broke my rear drop out.
    Unsurprisngly I hit dirt hard.
    Cleat ripped off the bottom of my peddle, seatpost bent, hub came apart, disk rotor bent and rear pads torn. Tire didn't lose pressure and rim fine.

    £586 worth of repairs, or as I see it, a £50 excess!

  41. #41
    Toby Wong?
    Reputation: Tappoix's Avatar
    Join Date
    Mar 2004
    Posts
    1,307
    I've been running a WTB Stout 2.3 with about 40 psi on there....it's held just fine for a 850g tire.....wouldn't hold tubeless with stans, but fine with a tire

    a Hutch Barracuda 2.3 held fine tubeless, but the Stout rolls better (but the 'cuda rails turns!)
    lets not make it a religion, it is recreation

  42. #42
    Probably drunk right now
    Reputation: Ken in KC's Avatar
    Join Date
    Jan 2004
    Posts
    6,645

    I'm confused....

    Quote Originally Posted by Tappoix
    ok guys, you're not going to believe it......another flat

    i did a 2.4 hour ride last week and was just hammering the whole time, the tire pressure was probably 45psi and it held the whole time.

    today, with 10 minutes left on a 2 hour ride, WHOOOOOOSH, on a smooth piece of trail, the nut fell off the valve stem and there was a hole in the tube and the rear totally deflated. In fact, the valve stem retreated completely into the rim (819s) adn a Nokian NBX 2.3

    WTF is going on here, this is getting ridonkulous!

    MeanTodd at Webcyclery built my rear wheel, I'm going to have him look at it. do I really have to get some 900g tire? fack!
    Flats are part of mountain biking. Are you expecting to never flat? The hole in your tube was located where? On the outside of the tube (toward the tire? On the inside of the tube (toward the rim)? Two holes? One hole? Round hole or an elongated rip? Is it possible that you have a thorn in your tire that's causing you to flat? Have you run your hand inside your tire to feel for something sharp imbedded in your tire?

    The stem will fall inside the rim when the tire goes flat. That's normal.

  43. #43
    Underskilled
    Reputation: CaveGiant's Avatar
    Join Date
    Aug 2007
    Posts
    4,118
    Not relevant, but I actually meant ot say the cleat ripped off my shoe...far more unusual than off the peddle, they are supposed to do that

  44. #44
    mtbr member
    Reputation:
    Join Date
    Dec 2003
    Posts
    521

    On my current XC bike

    I run 2.1 Schwable Nobby Nics and Little Alberts at about 35-40 PSI. Rims are Mavic 717s. Never pinch flatted and I weigh 250+ with gear. Torn sidewall once. Since it's an XC bike the trails are realativly smooth and when I come to a rock garden I slow down and pick my way through.

    On my AM/ Six Inch travel bike I run Big Betty (2.4s) on the front and a Fat Albert (2.3s I think) on the rear both about 35-40 PSI. Rims are 819s. Never pinch flatted. Rock Gardens are taken at speed with an eye for square edged rocks, I try to avoid slamming into them or unweight a little bit to lesson the impact.

    If you want to blast your way through stuff; large volume, 35-40 PSI and a little finese would go a long way. It seems to work for me.

    Over the years my speed has gone up pinch flats have gone down. Seems like the first year or two of riding I pinch flatted every ride. Tires have improved since the early 90's, but so has my smoothness.

    One more thought; is this always happening at speed and over a stretch of rough stuff? Your shock might be packing up and need a high speed rebound adjustment?

  45. #45
    Black Sheep rising
    Reputation: utabintarbo's Avatar
    Join Date
    Jun 2007
    Posts
    914
    Would it not make sense to adjust the pressure to achieve a nearly full tire contact patch, add a few pounds, then adjust? One would think that any specific bike/rider combination will require different actual pressures.

    Apologies if this is asked & answered.
    Let the market decide!

    N42.58 W83.06

  46. #46
    long standing member
    Reputation: PCinSC's Avatar
    Join Date
    Oct 2005
    Posts
    3,093
    Quote Originally Posted by utabintarbo
    Would it not make sense to adjust the pressure to achieve a nearly full tire contact patch, add a few pounds, then adjust? One would think that any specific bike/rider combination will require different actual pressures.
    I think I agree with this, but I have a noob question. What qualifies as "full tire contact patch"?

  47. #47
    Black Sheep rising
    Reputation: utabintarbo's Avatar
    Join Date
    Jun 2007
    Posts
    914
    Quote Originally Posted by PCinSC
    I think I agree with this, but I have a noob question. What qualifies as "full tire contact patch"?
    One in which most, if not all, of the little nubblies of the tread touch the ground? Can possibly be checke by running over a wet spot, for instance.

    Disclaimer: I am a n00b myself. YMMV.
    Let the market decide!

    N42.58 W83.06

  48. #48
    mtbr member
    Reputation:
    Join Date
    Dec 2003
    Posts
    521

    Depends on the tire.

    Tires of the same size will have different shapes of carcass and tread. Think sport bike motorcycle tire vs. a dragster slick. Extreme expamle but a good one, I think.

    The Motor Raptor has a more rounded carcass that is really nice for quick left to right leaning transitions. Some of the Kenda's are more square and offer more stable upright ride.

    So if you understand the tire you might be able to get the correct pressure for that tire by looking at the contact patch. But then you'd have to account for soil inconsistency. Muddy, damp, dry etc. Dirt is not all the same. So even more variables to throw into the mix.

  49. #49
    Probably drunk right now
    Reputation: Ken in KC's Avatar
    Join Date
    Jan 2004
    Posts
    6,645

    ^^^Good Advice^^^

    Quote Originally Posted by clarkgriswald
    Tires of the same size will have different shapes of carcass and tread. Think sport bike motorcycle tire vs. a dragster slick. Extreme expamle but a good one, I think.

    The Motor Raptor has a more rounded carcass that is really nice for quick left to right leaning transitions. Some of the Kenda's are more square and offer more stable upright ride.

    So if you understand the tire you might be able to get the correct pressure for that tire by looking at the contact patch. But then you'd have to account for soil inconsistency. Muddy, damp, dry etc. Dirt is not all the same. So even more variables to throw into the mix.
    I prefer Moto Raptors (2.4) for dirt and Kenda something or others (2.3) for urban. The Kenda's wash out too much in dirt for my liking and the Motos wash out too much on pavement.

    Another thing to consider is that there's no volume standard to speak of. A Continental 2.3 is smaller than a Kenda 2.1.

  50. #50
    mtbr member
    Reputation: bikemanla's Avatar
    Join Date
    Feb 2006
    Posts
    78
    Update - - - after testing many lbs combos have ended up at...are you ready?......17 lbs in the front and 31 lbs in the rear. This works great for me in extreme XC riding here on the North Shore. I ride with about 35-65 weight distributation so I can easily jump logs and rocks!

Page 1 of 2 12 LastLast

Posting Permissions

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