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Old 08-06-10, 10:04 AM   #1
rjn3100
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flats on aero rims? psi too high?

OK so a little while ago I bought a new to me Fuji (next 3.0) with areo type rims, they are Alexis (sp?) anyway I am getting flats at the spoke holes. when I take out the inner tube you can see the dimples where the holes are.

I plan on getting thicker rim tape, tonight, right now the original rubber band type rim band is on there.

Also I never really looked at the tires they have an inflation of 85 psi, of course I have been inflating to about 100, because of my other bike with regular old fashoned rims. To me 85 psi seems kind of low and might feel weird to me. I was planning on changing the tires next year, can I go to a tire with a higher psi? Or am I limited by the rims?
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Old 08-06-10, 10:23 AM   #2
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Get some good cloth rim tape and that should solve it when you change the tape also take a look and make sure spokes are not sticking up past the nipple inside
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Old 08-06-10, 10:31 AM   #3
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You didn't mention what size tires these are. If they are 28's for some reason then 85 is more in line with the sort of pressure you SHOULD be running. On the spoke puncture issue I'll just echo a healthy "DITTO" to JT's suggestion to ensure that the spokes are not sticking up past the nipples and rubbing through the rim tape. Also the one time I had a rim tape failure and the tube flatted at the spoke hole it was a very explosive experience complete with a mini "BANG" as the tube herniated into the spoke eyelet cup on that rim. If you're "only" getting little pinholes then go around the rim and remove any burrs from the edges of the spoke nipple holes so they can't worry their way through the rim tape such as what you're suggesting.
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Old 08-06-10, 10:32 AM   #4
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Replace rim tape with non rubber, high PSI rim tape. End thread.
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Old 08-06-10, 10:34 AM   #5
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The rubber band type rim strips are utter crap. Replace with Velox cloth tape and your problem should vanish. As for the tire pressure, if you have 77cx28 tires, 85 is probably adequate, unless you are a clydesdale. If they are narrower tires, I would probably replace them with something that has a higher recommended inflation pressure.
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Old 08-06-10, 10:45 AM   #6
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I would think that you should be able to go higher pressure with out a problem ONCE you have solved the rim tape issue. Just get a higher quality rim tape of the proper width for your rim or Velo plugs. I just solved a rather nasty spoke hole rim tape issue on my bike. The bead was EXTREMLY hard to get on the rim and it would push the rim tape off the largish spoke holes on this narrow rim, causing frequent flats, velo plugs solved this problem. GEEEE there were no posts when I started typing and when I posted there were 6 ahead of me. You could stop reading at operator if you wanted to.
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Old 08-06-10, 10:49 AM   #7
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The tire size is 700 x 25.

I checked the Alex website and I don't see a reason why I cant go to tires that might require a higher pressure.

Thanks. Confirmed what I thought, de-burr the spoke holes and better rim tape tonight.
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Old 08-06-10, 10:54 AM   #8
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I also think that the issue is your rim strips. I don't think that it's the dimples so much as the location of the rim strips. It is important that the rim strip cover the tiniest little arc of every single spoke hole. Otherwise the air pressure pushes your inner tube against the raw metal edge and eventually will cause it to slice. Ideally your rim strip should completely cover the rim from flange to flange. I generally prefer Velox but, on some rims, the 17 mm Velox is a bit narrow.
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Old 08-06-10, 11:20 AM   #9
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Velox

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Old 08-06-10, 05:43 PM   #10
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Guys, I had something similar happen an hour ago. I have been running 700x28 armadillos at 110-115 Psion, the are rated 100 max. Got tired of hoe slow they were and wanted to experiment so I put on my 700x25 nadhbar primas that I bought for a project. The vintage project bike was going much faster and the lower wheel weight seemed to be it. The prima are also rated 100psi and I inflated to 115 rode around the block and all of a sudden. Boom! Explosive failure. What is it about a tire that makes its psi rating? Why did these same tubes work fine in the armadillos at that pressure but blow up in the prima? My only guess is the softer compound on the prima means the tire expands more and a larger volume of air is needed to achieve that same pressure. I have a pair of pasela tg 700 x 25 that are rated at 115.
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Old 08-06-10, 06:45 PM   #11
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Boom! Explosive failure. What is it about a tire that makes its psi rating? Why did these same tubes work fine in the armadillos at that pressure but blow up in the prima?
Tires are typically "rated" at 1/2 their maximum pressure before self-destruction, that is, if it holds 230psi before it rips apart, then they'll rate it at 115psi.

From what you describe, I bet you had a bit of the tube caught under the tire bead when you changed it. It held while you inflated it and when you went out around the block, but then the tube pushed the tire off the rim and blew out. Been there, done that, my ears are still ringing.

Next time, inflate the tire to 20 or 30 psi and verify that the tire is seated on the rim evenly all the way around. If there's any place where the tire is hopping or dropping, stop, deflate to 10 psi, fix it, and start inflating again.
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Old 08-06-10, 07:31 PM   #12
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The only time I had this problem was using Michelin plastic rim strips, with 160psi tires. Bought and installed Continental High Pressure (220psi) rim strips, and have not had another problem with them.
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Old 08-06-10, 08:10 PM   #13
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Originally Posted by Jeff Wills View Post
From what you describe, I bet you had a bit of the tube caught under the tire bead when you changed it. It held while you inflated it and when you went out around the block, but then the tube pushed the tire off the rim and blew out. Been there, done that, my ears are still ringing.
That's exactly what I was thinking.
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Old 08-07-10, 10:16 AM   #14
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Thanks guys. I kinds thought that too, in switching over tires yesterday I effectively unmounted and remounted 4 of them and prob got a little lazy in checking. I'm going to try running them up at the higher pressure I.prefer again and see hoe it goes.
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Old 08-08-10, 06:31 AM   #15
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https://www.adventurecycling.org/res...SIRX_Heine.pdf
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Old 08-08-10, 11:39 AM   #16
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seen that article a thousand times, its helpful but I guess i was just wondering if any catastrophic failure happens when yo inflate over recommended psi. I'm pretty confident it was just a case of me getting the tube pinched, i went back up to 110psi with no issues.
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Old 08-09-10, 09:32 AM   #17
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I've never seen that article, thanks it makes a lot more sense than just blindly pumping to a max pressure...

I de-bured all the spoke holes in both rims, the front one was really bad, I'm surprised I wasn't getting flates on the front tire. I used a thicker rim tape, and inflated to 90 psi.
I didn't do too much riding this weekend, got about 25 miles in yesterday and a few miles the day before. So far no flats, hopefully that will solve the issues.
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