help with repeated flats....
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  1. #1
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    Question help with repeated flats....


    Can someone advise me on how get correct tire pressure? I have a bike pump that has a gauge but I don't think it is correct. My wife's bike had a flat so I replaced the tube, that tube went flat while sitting in the garage, not in the same spot. I checked the tire and rim again for anything that could be causing the whole, but nothing was found. I replaced the tube again and we went riding. While riding the tube popped again, this time in a different spot. The first time it happened I thought it could be due to an old tube, the second time I thought it could be a bad tube, but 3 in a row?

    What I'm thinking is my gauge is wrong and I'm putting too much air pressure in the tire. The tires are supposed to be inflated to 120-125psi but when I'm pumping them up once I get to around 100psi on the gauge it gets difficult to pump them up. Could this be the problem, if so is there a way to check tire pressure or a way to know if you have about the correct amount? Both my wife and I are recreational riders so we don't have to have the "exact" amount, I'd rather had a little less so I don't have to keep replacing the tubes. Is there a rule-of-thumb to go by?

    Thank you!

  2. #2

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    kinda doubt....

    ...overinflation is your problem, but I could be wrong.

    What do the holed tubes look like? Are the punctures two little holes fairly close together? If so, you might be experiencing pinch flats caused when you get a bit of the tire bead pinching the tube against the rim and causing a puncture (also sometimes caused by too little tire pressure when the tube gets pinched when it hits something on the road).

    Failing that it's quite possible you have something sticking in the tire from the first puncture that could be causing the repeats. Remove the tire and very slowly and carefully feel all along the inside, any small protrusion that could be easily overlooked visually, could be causing the flats (I had one of these recently, a small point of a goathead thorn remained in the tire, took me nearly 20 minutes to find and then I had a devil of a time pulling it out).

    Good luck!

  3. #3
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    Are the holes in the tubes on the rim side or the tread side? If on the rim side you probably need to replace the rim strips with Velox. This is a common problem with new bikes.
    ~Al

  4. #4

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    Seeing that the tube flatted in a "different spot" leads me to believe you do have some sharp object imbedded in the tire as suggested by torquecal. Why, because although you put a new tube in, which is always "indexed" by the valve stem, you prob remounted the tire in another position in relation to the valve stem.

    Always put the tire on the rim with someway to index the tire to the stem. This may be some word on the tire, a small marking pen dot you can place on the tire, etc. When you take off the tire and tube, overlay them to see exactly where the tube puncture and tire position are. This is very helpful in determining if there is a foreign object in the tire in relation to the puncture, besides the old feel around the interior tire casing method.

    As Al1943 [1943 birth date?, me too] stated, interior tube flats are most always due to rimstrip either too thin or the protruding spoke end or rough un-deburred metal still existing in the pre-built wheel rim holes. You need to test this too.

    Nother thing is to always run "full sized" tubes for the tire size. Light weight tubes that are on the limits of tire size will thin out and be more susceptible to puncture, for example running a tube for 23mm tires when your tire size is 25mm. One can see that in this example a 25mm tire is 109% over-volume to a 23mm tire [ (25/23) squared = 1.09 ] and will thin out the tube.

    Get a Schrader/ Presta adapter from your local LBS if you are running Presta tubes and check the press with a digital auto tire gauge. If you pinch the aired up tire and it hardly gives, you are prob not getting pinch flats, esp. if you are not running over any pot holes, RR tracks, cattle grates, etc.

    As far as tire press goes, it's a personal choice and somewhat determined by tire size. Bigger tires, say 25mm Vs 20mm gives you more leeway to lower the pressure by 20% or so and avoid rim-pinch flats. I run about 90 psi in the front, 110 psi in the rear for my 25mm Contis as a comfort zone. If 23mm, would have to run them a tad higher, etc.

    Let us know what you find.

    Cheers,
    -WK

  5. #5
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    Quote Originally Posted by Wade Kelly
    Nother thing is to always run "full sized" tubes for the tire size. Light weight tubes that are on the limits of tire size will thin out and be more susceptible to puncture, for example running a tube for 23mm tires when your tire size is 25mm. One can see that in this example a 25mm tire is 109% over-volume to a 23mm tire [ (25/23) squared = 1.09 ] and will thin out the tube.

    Cheers,
    -WK
    Good advice overall, but I found difficulty with the wrong tube size thing. You could have super thick thorn proof tube and as soon as the air goes into the tube under high pressure anything sharp will eventually make a hole in the tube anyway. I ran smaller tubes for years and never had an issue; in fact back in the 70's and 80's when I raced, the weight winnes (myself included) all ran the smallest tube they could find (when running clinchers). I been using an 65grm ultralight tube size 700x18-23 in a 25 tire for years and never had a flat issue.

    The real problem with the reoccuring flats is to find what's causing it. And that advice has been given real well so I won't puke it again. An easy way to index the tire as Wade mentioned is to simply line up a letter in the make of the tire (usually center of label) with the valve stem then you know exactly where the tire is at and can tell if the flat is occuring in the same spot.

    It's highly unlikely the flats are caused by a faulty rim strip or a rim burr since the tube remains in the same place all the time due to the valve stem in relation to the stem hole in the rim, and your flats have been moving around. Therefore there's something in your tire. Run a cloth around the inside of the tire and see if you can get the cloth to snag on something, otherwise index the tire, watch where the flat occurs by removing the tire while eyeballing the index, then check the tire at that spot where the flat occured and see what the problem is.

  6. #6
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    Quote Originally Posted by Wade Kelly
    As Al1943 [1943 birth date

    Cheers,
    -WK
    Yep, My father was in the Seabees on the island of Attu. He asked his C.O. for leave time to travel home for my birth. The C.O. told him that he was there for the "laying of the keel" and didn't need to be there for the "launching".

    ~Al

  7. #7
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    Quote Originally Posted by Wade Kelly
    Seeing that the tube flatted in a "different spot" leads me to believe you do have some sharp object imbedded in the tire as suggested by torquecal. Why, because although you put a new tube in, which is always "indexed" by the valve stem, you prob remounted the tire in another position in relation to the valve stem.

    Always put the tire on the rim with someway to index the tire to the stem. This may be some word on the tire, a small marking pen dot you can place on the tire, etc. When you take off the tire and tube, overlay them to see exactly where the tube puncture and tire position are. This is very helpful in determining if there is a foreign object in the tire in relation to the puncture, besides the old feel around the interior tire casing method.

    As Al1943 [1943 birth date?, me too] stated, interior tube flats are most always due to rimstrip either too thin or the protruding spoke end or rough un-deburred metal still existing in the pre-built wheel rim holes. You need to test this too.

    Nother thing is to always run "full sized" tubes for the tire size. Light weight tubes that are on the limits of tire size will thin out and be more susceptible to puncture, for example running a tube for 23mm tires when your tire size is 25mm. One can see that in this example a 25mm tire is 109% over-volume to a 23mm tire [ (25/23) squared = 1.09 ] and will thin out the tube.

    Get a Schrader/ Presta adapter from your local LBS if you are running Presta tubes and check the press with a digital auto tire gauge. If you pinch the aired up tire and it hardly gives, you are prob not getting pinch flats, esp. if you are not running over any pot holes, RR tracks, cattle grates, etc.

    As far as tire press goes, it's a personal choice and somewhat determined by tire size. Bigger tires, say 25mm Vs 20mm gives you more leeway to lower the pressure by 20% or so and avoid rim-pinch flats. I run about 90 psi in the front, 110 psi in the rear for my 25mm Contis as a comfort zone. If 23mm, would have to run them a tad higher, etc.

    Let us know what you find.

    Cheers,
    -WK


    Everyone,
    Thank you for the advice. I took the rim and tire to my LBS and he looked at it. He said the tired was old and was worn down on the inside exposing part of the stiff lining. He said I need to replace the tire. He said he mounted a tube on the tire/rim and watched this spot, over time the tube started rubbing on the weak spot on the tire and eventually popped. So I have a replacement tire/tube on the way. Thanks again for all your help.

    Gus

  8. #8
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    Quote Originally Posted by Al1943
    Yep, My father was in the Seabees on the island of Attu. He asked his C.O. for leave time to travel home for my birth. The C.O. told him that he was there for the "laying of the keel" and didn't need to be there for the "launching".

    ~Al

    That is quite possibly the funniest thing I've heard all week!!

  9. #9

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    Al1943,
    pretty good story!

    We have sim stories to tell:
    My real name is PFB, and the "F" is Furlough[!] based on the simple fact my dad was in the Army from 1942 to 1945, and only got home once in that time frame.
    Lab Worker should get a smile at of that too.

    Cheers all,
    -WK
    [Wade Kelly is the main character in my bike novel (in progress) "Olympia 2025". Kelly of course honors the great Sean Kelly]

  10. #10
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    Quote Originally Posted by Lab Worker
    That is quite possibly the funniest thing I've heard all week!!
    Glad you and Wade Kelly enjoyed the story, it is true.
    My father was 39 when he volunteered for the U.S. Navy in 1942. Because of his building skills, and experience he was put into the newly formed Seabees ("C"onstruction "B"atallions). Due to his age he was considered non-combatant, but this was war and he was shipped out to Attu, the U.S. station closest to Japan. The Japanese bombed Attu on a routine daily basis. After the war he remained in the reserves for another 32 years.

    I'll be looking for Wade's new book.

    ~Al

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