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Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

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Old 09-25-06, 08:58 AM   #1
NRRider
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Spoke-induced flats

Just posted re this in the Road Cycling forum (Wheel Woes (Reynolds Alta Race)--Help?, but this is probably a better place.
Bottom line is my spokes on my Reynolds Alta Race wheels keep causing flats. I have rim tape on there. Is there anything I can do or are these wheels just not for me?
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Old 09-25-06, 09:30 AM   #2
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Those are double wall rims, so the spokes should not be coming anywhere near the tube. I think you have been getting pinch flats caused by hitting bumps in the road with too low tire pressure. If you are running tires 23 or 25 mm wide, the pressure should be over 110 psi at the back and close to 100 psi at the front. If the rim tape wasnt fitted right, the punctures could have been caused by the tubes being forced against sharp edges on the holes at the base of the rim.
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Old 09-25-06, 09:32 AM   #3
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How do you know the spokes are causing the flats?
How are they getting through the Velox? This doesn't seem credible.
Are you sure the holes in the tubes are on the rim side?
Are you indexing the tires so that you can align the holes in the tubes with the location of the tires?

Running low pressure will not help and can cause more problems.

Al

Last edited by Al1943; 09-26-06 at 04:36 PM.
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Old 09-25-06, 09:34 AM   #4
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It is not clear to me that it is a spoke problem. Have you felt around inside the tire and rim for any debris or burs stuck in the carcass of the tire or on the rim? Is the flat happening at the same place in the tube over and over?
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Old 09-25-06, 09:41 AM   #5
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Check your rim tape. It has to completely cover every single spoke hole. It the tiniest crescent of spoke hole is exposed, air pressure will force the inner tube into that space and eventually cut the tube. It's best if your rim tape is wide enough to completely span your rim from flange to flange but rims come in more width sizes than does rim tape.
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Old 09-25-06, 10:22 AM   #6
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To answer all the questions:
I felt around inside the tire; nothing. I just pulled the tire off in the comfort of my house and the tire's perfect. No puncure, no debris.
The puctures occurred in different places in the tube, but each time on the inside, facing the rim. I just checked my last patch and it's right over a spoke hole.
I had another flat after I put the Velox tape on, though I think it was because the tape was pushed to the side. Stupidly I bought the 1cm Velox as opposed to the 17mm. I had the original rim tape wrapped around the Velox, but they look like they were both pushed to the side. When I got my next flat (number 7), I put the second roll of Velox on the same rim, so I had 3 layers of tape--2 Velox and the original tape (which was the more elastic rubbery stuff). That's also when I decreased the tire pressure. After that, no flats.
I'm pretty confident that inflating the tire to a high pressure contributed to this problem, since I flatted much more quickly when the tires were fully inflated, and once I dropped the pressure down way low I had no more flats.
I also checked for burrs, and nothing significant, though I suppose there is a VERY slight burr around some of the holes. How should I smooth those out?
Looking at the wheel again it does seem like it would be very odd for the spoke to be causing this problem. They are far from the tire.
I don't think they were pinch flats since I've had those before and none of them had the tell-tale "snake bite" holes. They were all single hole flats. Plus, I had 7 of them, and there's n way I'd have 7 pinch flats in 60 or so miles.
It was not happening inthe same place each time, which also puzzled me.
This is pretty wierd. The most logical explanation is the holes in the rim were causing the problem, but I've never had this happen before.
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Old 09-25-06, 01:09 PM   #7
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Quote:
Originally Posted by NRRider
The most logical explanation is the holes in the rim were causing the problem, but I've never had this happen before.
This is actually very common. With high pressure tires the tube will extrude into the spoke hole and will fail.
It's important to have the correct width Velox.
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Old 09-25-06, 02:45 PM   #8
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I have had 3 flats on the 17 mile ride to work due to bad rim tape leaving holes partially exposed. You can remove sharp edges from the holes with a Dremel, or by running an oversize drill in them slowly by hand. Then use rim tape that covers the bottom of the rim from wall to wall.
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Old 09-25-06, 05:18 PM   #9
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Are there little "blow off" holes on the inside of the rim near where the vertical part meets the horizontal part? Often times if these little holes are present and depending on the quality of the tube they can be the fault. (Sorry for the weird description) If this is the case cover those holes with a wider tape or change to a heavier weight tube.
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Old 09-25-06, 05:35 PM   #10
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Quote:
Originally Posted by humble_biker
Are there little "blow off" holes on the inside of the rim near where the vertical part meets the horizontal part? Often times if these little holes are present and depending on the quality of the tube they can be the fault. (Sorry for the weird description) If this is the case cover those holes with a wider tape or change to a heavier weight tube.
I'll have to check that when I get home. You mean right where the sidewall of the rim meets the part that the rim tape is applied to (sorry I don't know the correct names either)?
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Old 09-25-06, 07:28 PM   #11
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Quote:
Originally Posted by Al1943
This is actually very common. With high pressure tires the tube will extrude into the spoke hole and will fail.
It's important to have the correct width Velox.
I have also had this happen with the stretchable plastic rim strips, the strip went right down into the hole enough that the tube was stretching down into the hole too much. Only at 130 psi. Not at 125.
I fixed it with Velox.
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Old 09-25-06, 07:34 PM   #12
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Originally Posted by 2manybikes
I have also had this happen with the stretchable plastic rim strips, the strip went right down into the hole enough that the tube was stretching down into the hole too much. Only at 130 psi. Not at 125.
I fixed it with Velox.
Very interesting. This may be what happened. The Road Morph pump that I use seems to inflate to a level higher than indicated on the guage, so it's possible that I was overinflating, though the first flat was on a wheel inflated using my home pump, which should be accurate. I still think it's something like this, or perhaps a combination of this and rough edges around the holes. Should stick with Ksyriums and I wouldn't have to deal with this nonsense.
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Old 09-26-06, 01:28 PM   #13
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Follow-up: Stopped at the LBS and picked up some 17mm Velox yesterday, installed it last night, filled the tires to 110 psi and rode 30 miles this morning. No problems. Hopefully that solved the problem. Thanks everyone for your help. Now if I could only eliminate that clicking in the BB. Time for a new thread....
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