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    snowcreep
    Junior Member

  • snowcreep
    replied
    I had speed wobles on the road bike in the spring. The Stans I put in the tube in the fall had formed a hard plug at the bottom of the tire throwing it out of balance. New tube = no wobble.

    I weigh 150# and I run 22# on the mtb. I pound through all kinds of baby heads....even Porc Rim in Moab mmmmmmmmm chewy. Even if you weigh 220 you shouldn't have to run more than 32#. Your bones will thank you

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  • James
    Senior Member

  • James
    replied
    ^^^great movie great ending.

    What Danno said is correct. There have been countless studies on this. I doubt there is single track trail on the planet where 40 psi would roll better. When I was cross racing someone did a study of rolling resistance on grass and psi as low as 20 pounds proved to be the fastest. Granted cross tires are more narrow but the study was on grass. I think on most single track trails the fastest would be what ever keeps the tires from burping.
    James
    Senior Member
    Last edited by James; 12 November 2013, 04:55 PM.

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  • 3PinGrin
    Senior Member

  • 3PinGrin
    replied
    40 - 45 psi seems crazy on tubes OR tubeless. On any kind of rocky / rooty terrain I would be bouncing all over the place and spinning out on the climb.
    I have been very pleased with the Bontrager TLR system and run about 25 - 28 psi.

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  • twopass
    Senior Member

  • twopass
    replied
    Originally posted by Danno View Post
    Running 40-45 on tubeless is madness.

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  • Danno
    Senior Member

  • Danno
    replied
    Originally posted by Matt J View Post
    Yeah, that was traditionally with presta tubes of course. I always felt like they rolled faster. Most tires list 65 lbs. as max so I guess I just split the difference. I was probably running 25 lbs. yesterday with the Stan's. It felt slow but grippy
    It may feel that way to you, but on even marginally rocky terrain, lower air pressure actually rolls faster. Higher pressure is only faster on smooth roads, bike paths, etc. That may seem counter-intuitive, but it's true (science!). I run tubes, and usually roll at around 35, but would go lower if I could (I have gone lower, but fear of pinch flats makes me keep it to 35). Running 40-45 on tubeless is madness.

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  • TheWheel
    Senior Member

  • TheWheel
    replied
    Max pressure and optimal pressure are two different things.

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  • Matt J
    Senior Member

  • Matt J
    replied
    Originally posted by TheWheel View Post
    40 to 45? Damn Matt! That's over the top. Most would say 33-35 is way high.
    Yeah, that was traditionally with presta tubes of course. I always felt like they rolled faster. Most tires list 65 lbs. as max so I guess I just split the difference. I was probably running 25 lbs. yesterday with the Stan's. It felt slow but grippy

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  • TheWheel
    Senior Member

  • TheWheel
    replied
    40 to 45? Damn Matt! That's over the top. Most would say 33-35 is way high.

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  • Matt J
    Senior Member

  • Matt J
    replied
    Having just moved, I hadn't been very set up to do much work on anything. I've been working on that and should have a functional bench together pretty quickly. I probably should have just bought a tube with slime in it. I did get out yesterday on a short and casual dirt ride. The tires held air for the couple of hours we were out, but I didn't air them up too much. There were a couple of fun descents and I must say I had it in the back of my mind. I need to run down to the garage and see if the tires still still have any air. I also shopped for rims a bit. It's been a few minutes since I've built a wheel, but I might just give it a whirl. Thanks again for the contributions. Like I said early I have usually run pretty high pressure, 40 to 45 lbs. I guess that comes from avoiding pinch flats and then if you miss adding air before a ride you aren't in the danger zone. It was interesting to run low yesterday. The bike does feel lighter.

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  • Quadzilla
    Senior Member

  • Quadzilla
    replied
    Originally posted by Matt J View Post
    Anyone taking sealant and a mini CO2 on the trail? I am more likely to take a tube, but that ding pin holes tubes. They hold enough air for a few hours, but eventually will lose all pressure.
    I think the new hand pumps work real well. I use to carry a CO2 to top off but my new pump can get Mt. bike tires rock hard. You probably don't want to hear this but I would try to fix that rim and of course you lose all that sealant and the mess but you really need to have the ability to change out to a tube in the field. So, take the tire off, clean project and either take the rim to a good mechanic or use a C clamp and punch out that ding. Or, if the rim is toast, replace the rim. Or, get stuck and be ready for a long walk...........

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  • Matt J
    Senior Member

  • Matt J
    replied
    Thanks again.

    The ambient has been a little chilly and I've heard the sealant doesn't gel up as much in the winter as in the summer. The spot with the ding hasn't leaked, but I guess it's possible that it's effecting the seal some where else on the rim. I'm going to mess with the cores a little and tighten up the thumb nut.

    Anyone taking sealant and a mini CO2 on the trail? I am more likely to take a tube, but that ding pin holes tubes. They hold enough air for a few hours, but eventually will lose all pressure.

    Leave a comment:

  • Quadzilla
    Senior Member

  • Quadzilla
    replied
    Originally posted by Matt J View Post
    Thanks fellas.

    The rims and tires are both tubeless ready. I can't really figure out where they're losing air. I've been putting more pressure in and spinning the wheels each time I walk through the garage. At first they were definitely leaking through the valves then the mechanic that installed the valves and rim strips adjusted them and put more sealant in and they held air for a little while. It's kind of a saga now. From slow leak to complete loss and back. I miss tubes, but I had a ding in the rim that was pinching the tube which was part of the reason I gave this a whirl. I bought sealant so I guess I can keep on adding more.
    I would fill tires to 40 and put them in a tub of water, if there is a leak it would show up there. Sometimes it takes a few days for the sealant to fully cure and leaks can go away. If it is the valve stem, make sure the valve core is fully seated in the stem but using a small wrench to tighten it. The leak may be where the stem goes thru the rim. Sometimes by having a steel washer with a rubber washer under it, this is under the thumb screw. Tighten with plyers. Of course then you need to carry plyers in your pack as if you get a flat and need to add a tube in the field you will be able to take it apart. The ding in the rim sounds like a leak potential too. IMO, tubless are great once you have them dialed in. I would never go back to tubes.

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  • Nurse Ben
    Banned

  • Nurse Ben
    replied
    Tubeless compatible means more than just whether the set up will hold air, it's whether the rim design is specific for keeping the tire bead seated in the shoulder of the rim without a tube to maintain the pressure. A tubeless rim has an improved sideall which supports the bead above (hook) and below (shelf), some newer designs even have a hook on the shelf. Tubes are not evil, they work very well, esp if you don't want your tire rolling off the rim at a bad time, like on a downhill...

    You can always run a light tube and darn near get the same weight reduction without the risk.

    I have converted a lot of rims that were not tubeless in design, it's not hard, just add a valve, tape the rim, pre-seat the tire to determine fit, then deflate, add fluid, re-inflate, check for leaks, go ride.

    To check for leaks, put the wheel in a tub of water. The valves are a common culprit.

    Leave a comment:

  • Matt J
    Senior Member

  • Matt J
    replied
    Thanks fellas.

    The rims and tires are both tubeless ready. I can't really figure out where they're losing air. I've been putting more pressure in and spinning the wheels each time I walk through the garage. At first they were definitely leaking through the valves then the mechanic that installed the valves and rim strips adjusted them and put more sealant in and they held air for a little while. It's kind of a saga now. From slow leak to complete loss and back. I miss tubes, but I had a ding in the rim that was pinching the tube which was part of the reason I gave this a whirl. I bought sealant so I guess I can keep on adding more.

    Leave a comment:

  • TheWheel
    Senior Member

  • TheWheel
    replied
    Be cautious Matt. If it won't hold pressure above 30 it won't handle a decent hit either. A role off at any speed aint no fun.

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