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Thread: Clincher tyre tubes and pressures

  1. #1
    Join Date
    Jan 2003
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    England
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    Default Clincher tyre tubes and pressures

    Dear All, a customer just made it 300 yards down the road before both tubes blew out on his newly restored 1927 Harley J model, running 3.85 x 20 clinchers. What tubes and pressures should he have been using?

  2. #2
    Join Date
    Jan 2007
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    Corvallis, Oregon USA
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    87090 28X3 TR-4 MS CYCLE TUBE $12.95
    89200 17" - 22" RIMSTRIP $2.99
    From Coker. I run at 35psi.
    Bill Gilbert in Oregon

  3. #3
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    Sep 2005
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    Sarasota, Florida
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    Those are good questions Steve. I ran 50 p.s.i. in my Series 20 Excelsior with 3.85 x 20 Clinchers with no problems. As for inner tubes. I ride a bicycle every day and have had at least 40 flat tires in the past 5 years. Without sounding xenophobic, all I can find are Chinese inner tubes and they are junk. I've looked on-line and cannot find quality tubes. For what it's worth, I now slit old tubes and wrap them around the new tubes to give some more protection.
    Eric Smith
    AMCA #886

  4. #4
    Join Date
    Nov 2009
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    201

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    35 PSI sounds low to me. I run my 28X3's at 50 psi, never had a problem. The whole design of the clincher relies on high pressure to keep the tire on the rim.

    Gene Harper

  5. #5
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    Aug 2006
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    Agree with Eric and Gene, been told the Chinese tubes are not any good at all. Try for Japan or Europe for tubes, that's what Rotten Richard told me, good luck.

  6. #6

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    Hi guys. i race at davenport every year and what the race guys do is to take electrical tape and tape the inside of your rim around the area were the spokes are. in other words the center of the rim. use a good tape and go around it several times at lease 8 to 10 times.. next use the correct tube for the tire . 28/3 clincher. or what ever tire size it is for. i know that some of the guys use the harley tube for a 21/3 tube. i guess that works just fine.. and they use about 50 pounds of air. if your useing a tube from a china or elsware you will want to put at lease 50to 60 pounds of air. most important is that you clean the rim and tire with a good soap and water . and make sure that you dry it well. this works very well for us on the race track.i hope this helps you out. thanks John Mertens . board track racer #24 #21 #23.Mertens race team.

  7. #7
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    GA
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    Imagine going into a sweeping curve at about 40-50 MPH and having your tire come off your rim....It's never happened to me but I think about it alot when riding a clincher rimmed bike. I would not run any thing under 50 psi.
    Louie
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  8. #8
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    http://occhiolungo.wordpress.com/201...allation-tips/

    I'm not an expert on clinchers, but ran across this article by Pete Young on the Occhiolungo web site. I found it interesting, hope you do too....Rod

  9. Default

    I'm not an expert either, but I'll never run super high pressures. I've seen too many clincher tubes pop like a balloon at high pressures. The books in the old days recommended medium pressures, like 5-10 psi more than drop center tire pressures. It depends on the size of the tire and the weight of the bike/rider/passenger. But mine work ok at 42psi. I've had a few go flat, but it was a gradual loss of air, not a sudden pop! Some old timers run less psi around 35-38, even though they are bigger guys. The most important thing is to check them often. And to install them well. And to prep the spoke heads. I guess that's three important things.

    Regards,
    Pete


    Quote Originally Posted by Rod K View Post
    http://occhiolungo.wordpress.com/201...allation-tips/

    I'm not an expert on clinchers, but ran across this article by Pete Young on the Occhiolungo web site. I found it interesting, hope you do too....Rod

  10. #10

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    This is a HUGE safety issue - so pardon me for going on for a sec...

    Clincher tires use - and are DESIGNED - for high pressure to hold the tire on the rim, and keep it from slipping on the rim. If you run low pressure, you will likely blow one out from rimcutting and/or valve shear... The rule of thumb is 20 PSI for every inch of width... so for a 28x3, the "proper inflation" is 60 PSI.

    Remember, we're talking about *clincher* tires... Saying that - normally, "balloon" tires end not in a fraction (27x3 1/2, 28x3, 31x4 1/2 etc) but in a decimal (20x4.25, 22x3.875, etc.) - they are not clinchers the rim, if you took a slice out of it, would look like the letter "C") but either drop centers or on cars splitrims (looks like a "U")... and they run slightly lower pressures... saying that, they considered lower pressures 45 PSI in the day, something to think on... It's why racing bikes run rim locks - to keep those tires from spinning themselves flat.

    If you are running 28x3's and only have 30-35 PSI in them, you're riding on pure luck. When those tires go flat at speed, they are really likely to come apart quite quickly and not in a nice way... In an old car, I've seen them wrap an axle in lickety split time, locking up a wheel and doing some van-dammage to the car. (and yes, it's because the driver was running 32 PSI on a 3 1/2" wide tire - which specs 70 PSI...)... on a bike, they'll rap the rider on the road. The Van-dammage would be somewhat greater...)

    Think of it as a technological thing. Just like you wouldn't put modern 0w20 oil in your pocketvalve motor...(or 60 wt in your Subaru Forester)... Clinchers are a different technology, and work differently, than "modern" tires.

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