Bicycle rider/mechanics

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  • LCHIEN
    Internet Fact Checker
    • Dec 2002
    • 20913
    • Katy, TX, USA.
    • BT3000 vintage 1999

    Bicycle rider/mechanics

    I'm restoring my 1975 Motobecane Gran Touring 10 speed
    which I haven't ridden for a few years.
    I've replaced the two original michelin 27x1.25" tires which were very worn and since hardened to unusability. Very hard to get off they were so stiff.
    Also replaced the inner tubes.
    One wheel holds 60-70 psi but the rear does not, leaking off to flat within a day.
    I removed the tire and the tube, checking the tube mildly inflated in a tub of water squeezing it for all I could but did not see a stream of bubbles. So
    I replaced it with another tube and it was OK for a day but also leaked off to completely flat.
    • I used correct tire irons to mount the tire so no pinching of the tube
    • I checked the inner part of the tire and the rim to make sure there were no sharp objects or splinters
    • I carefully mounted the stem to be perfectly perpendicular to the rim where it pokes through
    • I also checked and in place is the rubber strip that is placed over the ends of the spokes to protect the tube.
    • I made sure that the Schrader valve insert was tightly screwed into the valve stem.

    While its been a while, I've mounted many tires and tubes before on this and other bikes and never had this problem.
    If its leaking, it has to be leaking from the tube, how else could it escape? THe tube is held from bursting by the tires which are properly mounted to the bead in the alloy wheels.

    Have I missed something?

    PS it also has new helmet, new LED head and taillights, and a trip computer. Forgot the brake pads, they are coming next week.
    Last edited by LCHIEN; 02-27-2018, 03:17 AM.
    Loring in Katy, TX USA
    If your only tool is a hammer, you tend to treat all problems as if they were nails.
    BT3 FAQ - https://www.sawdustzone.org/forum/di...sked-questions
  • Carlos
    Veteran Member
    • Jan 2004
    • 1893
    • Phoenix, AZ, USA.

    #2
    That's really weird, and I agree, it would have to be the tube. Are you using plastic or metal tire tools? Everyone has told me to switch to plastic because metal can easily do damage you can not see. No idea how true that is. We have mountain bikes so our tubes are much tougher to start with. Did you try a spit test on the fill valve?

    Comment

    • LCHIEN
      Internet Fact Checker
      • Dec 2002
      • 20913
      • Katy, TX, USA.
      • BT3000 vintage 1999

      #3
      I checked the first tube after removal and it had no pinch damage or leaks at the valve stem.
      I have both plastic and metal tire tools; the plastic feel real flimsy to me, so I use the metal. but I have changed many tires and know the right procedure and am careful not to pinch the tubes.

      I didn't check the valve stem on the second tube yet that still on the rim. Soapy water better than spit!
      Loring in Katy, TX USA
      If your only tool is a hammer, you tend to treat all problems as if they were nails.
      BT3 FAQ - https://www.sawdustzone.org/forum/di...sked-questions

      Comment

      • Carlos
        Veteran Member
        • Jan 2004
        • 1893
        • Phoenix, AZ, USA.

        #4
        Spit is universal. Let's see what the finish will look like? Spit (or as the wife says, "Licking your wood again?" Check for leaks...spit...

        Comment

        • Jim Frye
          Veteran Member
          • Dec 2002
          • 1051
          • Maumee, OH, USA.
          • Ryobi BT3000 & BT3100

          #5
          I still ride my 1972 Raleigh Super Course that I rebuilt/upgraded in 1985. I still use QuickSticks to change tires and tubes. They work really well at helping avoiding pinches and they are fast. When you replaced the tires and tubes, did you also replace the rim strips? Probalby a good idea if the tires and tubes were that old. If not they may be the source of your leak. While you have the old rim strips off, make sure there are no spoke ends protruding with a point that could cause a leak. Often times when truing a wheel, you can end up with a spoke or two sticking out.
          Jim Frye
          The Nut in the Cellar.
          ”Sawdust Is Man Glitter”

          Comment

          • LCHIEN
            Internet Fact Checker
            • Dec 2002
            • 20913
            • Katy, TX, USA.
            • BT3000 vintage 1999

            #6
            Originally posted by Jim Frye
            I still ride my 1972 Raleigh Super Course that I rebuilt/upgraded in 1985. I still use QuickSticks to change tires and tubes. They work really well at helping avoiding pinches and they are fast. When you replaced the tires and tubes, did you also replace the rim strips? Probalby a good idea if the tires and tubes were that old. If not they may be the source of your leak. While you have the old rim strips off, make sure there are no spoke ends protruding with a point that could cause a leak. Often times when truing a wheel, you can end up with a spoke or two sticking out.

            I din't replace the rim strips. They are 40 years old. They seemed like they would do the job but... I guess they are hard and stiff..
            If the rim strips let the tubes leak I guess I better get new tubes, too.... :-(
            Loring in Katy, TX USA
            If your only tool is a hammer, you tend to treat all problems as if they were nails.
            BT3 FAQ - https://www.sawdustzone.org/forum/di...sked-questions

            Comment

            • Black walnut
              Administrator
              • Aug 2015
              • 5438
              • BT3K

              #7
              Replace the tubes! A new rim strip would also be prudent. Valve cares leak. Seams leak. If your tubes are latex they leak faster than rubber. I usually have to top off my tires every other day. On my road bike I'm running 110 psi front 115-120 psi rear.
              just another brick in the wall...

              Boycott McAfee. They placed an unresponsive popup on my pc.

              Comment

              • twistsol
                Veteran Member
                • Dec 2002
                • 2892
                • Cottage Grove, MN, USA.
                • Ridgid R4512, 2x ShopSmith Mark V 520, 1951 Shopsmith 10ER

                #8
                I had a similar problem with my 1978 Trek 515, which is is a bone rattler but still my favorite bike. Check all the spoke nipples. I had one that had a tiny sharp point on it and it would pierce the tube and I'd lose air over and over. The hole was small enough that it didn't show in a water bath until I inflated the tube to about 5 times normal size. I filed it down the offending nipple, and being a broke college student at the time wrapped the rims with a couple layers of strapping tape rather than spend a few bucks on new rim strips.
                Chr's
                __________
                An ethical man knows the right thing to do.
                A moral man does it.

                Comment

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