Kapton Kaution
 

I went to ride my Gitane yesterday, only to find the front tire flat. I pulled the tire off, inspected the tube, found a pinhole on the side nearest the rim (and the spoke hole closest the valve hole). Looking at the rim, I saw the Kapton tape had “failed” allowing the spoke tip through.

This is the first bike, IIRC, that I used Kapton on, in 2021. The choice of tire (GP5000 TdF) and the rim (no name, I must have lost any label during polishing) made mounting the tire just about impossible, and it was suggested at BF to remove the Velox tape in favor of Kapton because it is thinner. I used two layers, and I was pleased enough with the product that I use it on all wheels. This is the first I’ve seen of trouble.

(a) Is this a common occurrence? Does the product have a service life, and is a “consumable”? Not sure if three layers, instead of two, would make a difference.

(b) The tip of the spoke sticks up above the head of the nipple, made 1/8” but still down in the recess in the rim. With the old tape off, I see they all are. Should I be concerned and, if so, now what? I got out my Dremel, and put on a tiny stone bit, cylindrical and small enough to fit in the rim’s recess. Going in vertical, I tried, but made no progress on the spoke — but “drilled” a nice hole in the flat end of the stone. Just now, I checked Park Tool’s website and they do not list a STN-01 Spoke Tip Nipper to get down in there. Is there an alternative tool/method?

Perhaps I should ignore all this and just replace the tape, and ride and then expect to be notified of tape failure by a puncture flat every couple of years?

Replace the tape of course, you may need to nip, or grind, the spoke end to prevent future issue. I used a dremel the last I needed to perform the task

tiger1964

You may need to use a burr or find a very hard stone, if they're that hard it may be a challenge to not hack the rim. :twitchy:

I’ve used a dremel for that purpose. It was a PITA.

Yeah, after posting it occurred to try a burr, and I might be able to go in at an angle -- and not run the rim. 36 spokes (and I have not demounted the rear tire yet :cry:)

I checked my collection of Dremel stuff, the only burr I have is loaded up because I tried it on aluminum so I probably need to do some shopping.

No idea how old the wheels are, or who built them. One might suspect that selecting spokes 2mm shorter would have spared me some grief.

You may need more power and or speed, if you have a compressor this is the thing to use, way better than a dremel. :twitchy:

https://www.amazon.com/Neiko-10649A-...89090595&psc=1


You could also try using the edge of a cutoff wheel.

wouldn’t it be easier to just return to Velox or similar ?

( I survived below install with Velox and also more challenging combinations )

https://cimg8.ibsrv.net/gimg/bikefor...5c85da1a4.jpeg
wouldn’t it be easier to just return to Velox or similar ?

A Knipex flush cutter might be an option to trim exposed spokes ?

( probably not due to rim / spoke holes )

https://cimg5.ibsrv.net/gimg/bikefor...5de13b9d5.jpeg

Although I did not think the Dremel's motor was the shortcoming, I do have an old, 4HP 20gal compressor. That might be a fun toy!

I should go dig up my old topic from 2021 (?), I was getting nowhere at all trying to install the tires. I'm certainly used to Velox and have some in my stash, but...

So, it's just me.:(

If they had one with a tiny tip to fit down in the hole in the rim, sure. I was only half kidding about a Park Tool STN-01.

They work amazing, once you get the hang of it, control is key. Not sure a small compressor would get you there put could be worth a try.

It has saved my azz countless times with less drama than most anything else.

You live not far from me in NoVA, and we go through some pretty drastic heat/cold cycles. I store my bikes indoors, but if you use a garage or space not climat comtrolled, you could be stretching and relaxing the tape each cycle, degrading the adjesive and resulting in a slightly relaxed tape tension. Also possible that since this was the first set of wheels you used Kapton on, your K-Fu was deficient and the tape was not wrapped tightly enough.

If that wheelset is using spokes 2mm too long (how much pokes up above the nipple?), you might want to consider disassembly, shortening the spokes, and reassembling.

Or, like you said, maybe it’s just you. Probably not, but hey, you brought it up!

Yeah, too big. I do have some small tools of unknown origin, one pair of diagonal cutters and one pair shaped like a tiny pair of that Hozan tool, flush cutting. Jewelers' tools? I suspect it would take forever to grind down the head until the remains fit through a 10mm (??) hole.

Small compressor? Now, I had neighbor with 5HP 55gal one, a beast but it took forever to charge up when you switched it on. Anyway, I'll have the small carbide burrs shortly, try that first, the air tool is Plan B

Stored in an unheated basement; mid winter it might get to 55F down there. Not wrapped tightly enough? It's supposed to be under tension?

Had not considered unlacing the wheel. Let's call that Plan Z.

I don't think you should blame the tape if your spokes protrude beyond the tops of the nipples. I consider punctures an eventuality in that condition. If you can't get a dremel or cutter in that space, take a file to the spokes. I've done this. It's even more annoying than it sounds, but it will work. Once I had a wheel like that (on an old 3-speed), and I tried to hire my local bike shop to do the job. I left the wheel there, and the owner/mechanic gave it back to me because it was too annoying. I can't blame him.

So these are single wall rims? I wouldn't use kapton tape on single wall rims where spokes poke thru.
That setup seems like it's a sure failure, just a matter of when.

Heck yeah. If it’s not under tension, the pressurized inner tube will press into whatever space is available. EG, the holes above the spoke nipples.

A file with the wheel in a wheel stand is easier.

Double wall rims, so the nipples and the tips of the spokes are rather recessed. Yeah, if I had finally bought a truing stand to hold the wheel, this would be a good time to use it. Regardless, the Dremel bits are here, let's see if I can solve the issue.

BTW, this tape does not seem to want to stretch during application, I'll again try to keep it taut but... tension?

Tight is fine. Just keep it under tension while wrapping.

I had a problem on my Colnago right after I got it. The wheels are 70's Super Champion , which I have multiple sets , 700c , never had a problem. This set of wheels were a struggle to get the wire bead tires( Pasela , just like my others) on and off to repair flats I switched the Velox tape which is what I always used , to the stuff that Trek bike store sells . It looks like narrow electrical tape ( I think it comes in different widths) . I took the time to go around the wheel and carefully file down the holes over the spoke tips ( burrs) , cleaned the old Velox tape residue and it worked! I don't have to panic when I get a flat while riding . I can pull the tire off , replace the tube , and be on my way. I used be on the side of the road going through the alphabet of bad words while hoping not to break a plastic tire lever.:troll:

Double? Oh wow, yeah those spokes need to be cut down then.
I figured single wall was why the spoke head was sticking out.

Beet of luck!

Thanks for the encouragement. I should clarify about the spokes. They stick up above the spoke nipples' heads, but still below the "valley floor" of the double-wall rim. The Kapton stretched down into the round holes in the rim until the spoke tip pierced it, and the tube had a tiny bulge when I removed it, projecting down into the recess created. Contact!

Yes -- I should have taken a photo when I started. I did not anticipate the complexity of what I was facing.

If only a few spokes at issue, I have created a short leather washer approx 4x12mm to build up the area under the rim tape. These were on used wheels, they are functional and on the list for rebuilding. I will call the above a “field service” level solution.
if all or one side … best to rebuild with proper length spokes.

The pack of carbide burrs, affordable and from Amazon, arrived. The first one I tried is tulip-shaped, the end was flat so I could go straight down on the spoke tip. No control, immediately gouged up the edge of the 10mm hole (dressed with a jeweler's file later). The second one was egg-shaped, and I could go in about 60 degrees from the vertical. Bracing with both hands, much better control. A few second per spoke, stopping frequently enough to check how much I was removing, did the job and I could move on to the next spoke. I wanted down to the surface of the nipple, I definitely removing a tiny bit of metal from each nipple but I want that at a minimum. Lots of fine metal dust, I expect some is in between the walls of the rim -- I need to see if I have one of those blow guns for the compressor, before I put on the fresh tape.

What I need to do is try to remember this topic, and if when I next get a flat on this wheel, I should check tape condition and report back. My hopes are that the Kapton is not at fault, and by now most of my bikes have it.

Yikes -- that sounds like a massive amount of work, for 36 (or 72?) spokes. A creative solution, however! :thumb:

note I wrote to begin, “if only a few spokes…” the problem reads as one side or all the spokes are too long.
shorter spokes required.