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  1. #1
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    Marathon Plus tires - problems w/air pressure too high

    Man oh man these were a pain to mount on the tires. Spent almost 2 hrs on the very first one, but after I got the hang of it I was able to get them on/off in about 10 mins.

    The problem I'm having is that once they are mounted, I can't seem to inflate the tube anywhere near the max pressure (95 psi according to the sidewall) without the tube exploding. I just blew up 3 different tubes trying to get these inflated.

    I can't understand what is going on - at first I thought I had not seated the tube properly. So I tried it again and again (taking extra care to ensure that the tube and tire were seated properly) but then I had the next 2 tubes pop on me. With my last spare tube, I finally found a pressure that would not cause the tube to explode (65 psi, just above the 60 psi minimum). However - I soon discovered that I had mounted the tires backwards (there is a direction arrow on the sidewall) . So I went through the dismount/mount process again for the 4th or 5th time but then I tore part of the tube in the process .

    I am running 700x32 tires, btw. My previous tire (Vittoria Randonneur) was also 700x32 and the max pressure was 75 psi - I was always able to run it at 75 psi or 85 psi with zero problems whatsoever.

    Has anyone else experienced this phenomenon - not being able to inflate Marathon Pluses to the same pressure as other tires? When I use the floor pump to inflate the tube with the Marathon Plus on the tire, it just feels very very tight as soon as I get to around 50 or 60 psi. Does the extra thickness of the tire create more pressure on the tube or something?
    Last edited by aaronechang; 02-25-09 at 10:57 PM.

  2. #2
    Randomhead
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    it's not the tire. The stress of putting the tire on is causing you to make some other mistake, or you have a defect in your tape. My guess is that you are trapping the tube under the bead -- this is the most common problem with mounting tires.

    Are you putting air in the tube before you put it in the tire?

  3. #3
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    When you pump, look whether the tire rises evenly everywhere. A trapped tube will be raising the sidewall abnormally. You may also pump the tire with the wheel mounted on the bike and rotate the wheel once in a while. This may make it easier to notice the abnormal bulging for a trapped tube, when you lack prior experience.

  4. #4
    Senior Member thehum's Avatar
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    heh it seems like there's a new post about mounting SMP every few days now. I had the same problem you did with my SMP 700x25s-the damned tube kept pinching shortly after i'd spend an hour wrestling to get the tire on.The solution? lubing the last edge of the tire/tube/rim with liquid dish soap-this allowed the tube to align and kept the bead from pinching it. I also lubed the two plastic levers I used to help get the last bit on. No flats since then.
    Last edited by thehum; 02-26-09 at 09:00 AM.

  5. #5
    All Bikes All The Time Sawtooth's Avatar
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    After mounting tight tires, I inflate to 20 psi, then work my hands around the wheel moving the tire back and forth laterally to allow the tube to escape from under the bead if it is pinched. I then inflate to desired pressure. This seems to work well for me.

  6. #6
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    In addition ot the above suggestions, I also keep my tubes in plastic sandwich bags. I put a teaspoon of corn starch in with each tube. The cornstarch covers the tube and allows the tube to slide up into the tire when I am replacing a tube. When I first switched to Marathon Plus's I had a similar issue with tubes trapped by the bead. I have been using the dish soap and corn starch approach for about 3 years now, and have not had a tube/bead seating failure yet.

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    Great tips - I will definitely give them a try tonight. I dropped by the LBS today to pick up some new tubes and they also suggested I deflate the tire entirely after I get the bead seated on the rim (I need to inflate the tubes slightly in order to get the tire bead seated), then push the valve stem in and then pull all the way out. They theorized that the valve stem wasn't being seated correctly - which may be right since 3 out of my 4 blowouts were all in the valve stem area.

    Hopefully I will get it right this time around.

  8. #8
    Senior Member Kojak's Avatar
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    This is a "paper" by Jobst Brandt, found on Sheldon Brown's website. I hope it helps in some way.

    Thanks.

    Subject: Tube Failure in Clinchers; Valve stem separation flats
    From: Jobst Brandt
    Date: October 13, 1997

    Riders occasionally tell about a tube that blew out with a loud bang INSIDE their tire, leaving the tube with a long slash. The tube blew out, but not as described. If there was a bang, the tube was outside the tire. That is, the tire lifted off the rim and fell back in place after the tube burst.
    Tubes do not burst inside tire casings, although they may leak, the most they can do is give off an audible hiss, assuming it is otherwise quiet enough. An un-socketed double walled rim can make a dull pop if the tube is exposed to the inner rim volume. The concept that a tube can explode inside a tire is dangerous, because it leads people to believe that tubes can mysteriously fail without apparent cause INSIDE a tire. With few exceptions, the cause is an improperly mounted tire.
    Without understanding the cause, a rider may continue to risk a blowout, without realizing that tire lift-off can be caused by the tube lying between the rim and the tire bead. In this position, the tube prevents the tire from seating properly in the hook of the rim, a condition that, under the right circumstances, will cause a blowout. This cannot occur inside the tire casing. To prevent blow-off, the tire seat must be inspected by pushing the tire away from the rim, upon which the tube should not exposed at any point around the tire.
    Valve stem separation is another common failure, but it is less dangerous because it usually occurs while inflating the tire. If it occurs while riding it causes a slow leak, as the vulcanized brass stem separates from the tube. When this occurs, the stem can be pulled out entirely to leave a small hole into which a valve stem from a latex tube of a tubular tire will fit. Stems from tubulars have a mushroom end, a clamp washer, and a locknut, that fit ideally. Such a used stem should be part of a tire patch kit.

    Valve stem separation flats
    Date June 16, 2003
    A flat caused by valve stem separation, a manufacturing flaw, is less dangerous because it usually becomes apparent during inflation. If it occurs while riding, it causes a slow leak as the vulcanized brass stem gradually separates from the tube. When this occurs, the stem can be pulled out of the tube entirely to leave a small hole into which a valve stem from a latex tube of a tubular tire will fit. Stems from tubulars have a mushroom end, a clamp washer, and a locknut, that fit ideally into the hole left by stem separation. Such a used stem should be part of a tire patch kit. Any good bicycle shop that handles tubular tires or latex tubes should have used ones if they weren't thrown away.
    Guy K. Browne

    Schwalbe North America
    USA | CANADA | Central/South America
    1-888-700-5860 | 250-598-0397 ext.105
    www.schwalbetires.com

  9. #9
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    Great news - I got the tires on successfully last night. With all of the practice I've been getting mounting these super tough tires, it took me about 30 mins. total for the two tires (mounted on Alex ACE-19 wheels).

    What I've found is that pumping up the tube slightly at the beginning (after the tube is inserted between the tire and the rim) helps tremendously in mounting the tire. Then when about 80% of the tire is mounted, I deflate the tube entirely make it easier to get the remaining 20% seated. Once everything looks good I did a once-over around the entire circumference of the wheel on both sides - lifting up the tire bead/tube with a tire lever. This is to make sure that no part of the tube is pinched outside of the tire. Then I pushed the valve stem all the way in and popped it back out.

    I'm running them at 80 psi and went for a 10 mile test ride last night. They run terrific - I honestly can't tell any difference in rolling resistance or weight. The reason I got these tires was that I'm tired of getting flats (4 of them in the past 6 months), and the Marathon Pluses are the most bombproof you can get. The ironic thing is that despite becoming very experienced at mounting these tires, I most likely won't have to do this again for a very, very long time (keeping my fingers crossed).

    Thanks again to everyone for the help.

  10. #10
    Gray Haired Commuter
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    Quote Originally Posted by aaronechang View Post
    Marathon Pluses are the most bombproof you can get. .
    I got a flat on my very first commute on a 700x32 SMP--so bombPROOF isn't the right word.
    Dave Clary
    Corpus Christi,TX
    Home: http://davidclary.com
    Blog: DaveGetsFit

  11. #11
    Fred Wannabe breakaway9's Avatar
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    One thing you may want to check, is the size of the tube I was trying to put on my marathon winters and didn't realize I was using a 25cm max tube.... it blew up also. Switch to a 28/38 tube and everything works great...

  12. #12
    nashcommguy
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    Quote Originally Posted by aaronechang View Post
    Great news - I got the tires on successfully last night. With all of the practice I've been getting mounting these super tough tires, it took me about 30 mins. total for the two tires (mounted on Alex ACE-19 wheels).

    What I've found is that pumping up the tube slightly at the beginning (after the tube is inserted between the tire and the rim) helps tremendously in mounting the tire. Then when about 80% of the tire is mounted, I deflate the tube entirely make it easier to get the remaining 20% seated. Once everything looks good I did a once-over around the entire circumference of the wheel on both sides - lifting up the tire bead/tube with a tire lever. This is to make sure that no part of the tube is pinched outside of the tire. Then I pushed the valve stem all the way in and popped it back out.

    I'm running them at 80 psi and went for a 10 mile test ride last night. They run terrific - I honestly can't tell any difference in rolling resistance or weight. The reason I got these tires was that I'm tired of getting flats (4 of them in the past 6 months), and the Marathon Pluses are the most bombproof you can get. The ironic thing is that despite becoming very experienced at mounting these tires, I most likely won't have to do this again for a very, very long time (keeping my fingers crossed).

    Thanks again to everyone for the help.
    Get yourself a Kool Stop plastic tire lever and carry it w/you as part of your tool cache. And get a set of 3 Pyramid METAL tire levers and sand down the rough edges that go under the beads. Carry a small bottle(hotel size shampoo bottles work well)of liquid dish soap in a sealed baggie. Make sure your 'emergency' tubes are no larger than 18-26mm. These additions will ALL add greatly to the ease of repair if flatting w/SMPs. I run my 28mm SMPs @ 120 psi rear and 110 psi front w/no probs. They're rated @ 75-100 psi. They can take the overinflation. Lower the psi when the weather gets warmer.

    Took me a few trys and alot of cussin' before I was able to get a mounting procedure that worked for me. Now I've got 3 sets on various bikes. Love 'em. Can't say enough good things about 'em.

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