Weinmann LP18 Geometry Causes Flats?
12-17-17 | 08:06 AM
#51
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From: Chicago area
Bikes: Airborne "Carpe Diem", Motobecane "Mirage", Trek 6000, Strida 2, Dahon "Helios XL", Dahon "Mu XL", Tern "Verge S11i"
The thing that has not been satisfactorily explained is the *spacing* of the dimples. They look much like what would be expected if air pressure forced the inner tube through rim holes, but the spacing is wrong. Also not explained is why this same spacing occurs if the cause is "stretching" of the tube into a larger cross-section tire... random hole spacing would seem more likely.
Steve
12-17-17 | 08:36 AM
#52
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Old Boy
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From: Minnesota
Bikes: Mostly 1st-generation, top-of-the-line, non-unicrown MTBs/ATBs: All 1984 models: Dawes Ranger, Peugeot Canyon Express, Ross Mt. Whitney (chrome), Schwinn High Sierra, and a 1983 Trek 850.
I'm gonna take a shot at this. I have a pair of LP-18's as well. I have used them with 13mm Velox rim tape with cross tyres up to "35c", but with the narrow rim, it ends up closer to 31-32c. I ran those tyres at 3.2ish bars or 50-55ish psi. I usually ride on "25c" aka 23c Paselas at 110 psi, but I weigh 140lbs. I know that is high, but I have rough roads where I live and pinch punctures are a common problem.I have never had any problems with the rims, but the '80s Weinmanns that they replaced had what I assume to be a defect. On the inside sidewall of the rim, the join/weld where the rim was joined to make it round was filed flat, but didn't follow the profile of the rim. The edges were sharp-ish. I think that the combination of this along with the wider than recommended tyres are a possibility. The aforementioned pear shape of the tubes also probably play a role. The wide rim strips may be hiding the bad filing.
I didn't recall seeing this mentioned or asked - how tight are the tires when mounting? Do you always mount tires starting at the same point on the rim? Is is possible that a tight bead is pushing the rim tape over and partially exposing the nipple holes? And when the pressure is removed (by deflation) that the rim tape returns to it's intended position, hiding the cause?
I realize that this isn't what rim tape is supposed to do, but with the lack of another explanation (so far) you have to look at outliers, no?
I realize that this isn't what rim tape is supposed to do, but with the lack of another explanation (so far) you have to look at outliers, no?
I'm done messing with these wheels.
In the Spring I am going to sell them with the qualification that they are too narrow for the tires I use. I've got ten bikes rolling right now and haven't had any flats since I hung these wheels up on the wall. Life's too short to obsess over weird phenomena like this. I'll just be sure to buy the right rim width from now on.
Thanks everyone for trying to help!
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Roulez pour la joie, jamais pour la douleur.
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Roulez pour la joie, jamais pour la douleur.
USMC 1981-1991 Semper Fi!
12-17-17 | 12:20 PM
#53
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From: Upstate NY
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I can understand cutting your losses and moving on, and here's hoping that'll be the end of the problem for you, but I still disagree about tire width being related to the problem. I run 27" x 1 1/8" tires on LP18's without issue. (1 1/8" = 28.575 mm) And if your problem is occurring on the rim side, when the bike isn't moving no less, it seems the tire is unlikely to be involved.
12-17-17 | 01:26 PM
#54
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From: Kent Wa
Bikes: Kona ESATTO DDL Cinelli Zydeco
I had this same type thing happen except it was on the tire side and next to the 2 dimples was a dime size hole. I had put new tubes and tires in the night before the bike was hanging on the bike stand overnight. I pulled a new tube out inflated it a bit and saw 2 dimples and a bubble start. These were continental tubes.
I pulled a new tube out inflated it a bit and saw 2 dimples and a bubble start. These were continental tubes.
12-17-17 | 01:54 PM
#55
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From: CID
Bikes: 1991 Bianchi Eros, 1964 Armstrong, 1988 Diamondback Ascent, 1988 Bianchi Premio, 1987 Bianchi Sport SX, 1980s Raleigh mixte (hers), All-City Space Horse (hers)
I can understand cutting your losses and moving on, and here's hoping that'll be the end of the problem for you, but I still disagree about tire width being related to the problem. I run 27" x 1 1/8" tires on LP18's without issue. (1 1/8" = 28.575 mm) And if your problem is occurring on the rim side, when the bike isn't moving no less, it seems the tire is unlikely to be involved.
That said, wider rims aren't a bad idea for the 28-32mm tires the OP wants to run. Something with a 17mm inner width would be much better, and on some of the newest rims that have a 19mm inner width, a 28mm tire may puff out to 32mm anyway.
