
Jim’s Tech Talk
By Jim Langley
Thanks so much for the assist with Chuck’s question last week. He asked for your recommendations for inner tubes and puncture prevention. I’m sure your tips helped him and other readers with the same question.
Because flat tires are by far the most common breakdown, today I want to share a couple of your comments and answer a few related questions that were asked.
Latex versus Butyl Tubes
Let’s start off with Ray Bourne’s comment because he’s clearly done his homework!
“I cannot comment on the TPU tubes, but I’ve done a significant amount of testing over the years on butyl vs latex; specifically Continental “Race 700” butyl and Michelin “Air Comp” latex. I run Continental Grand Prix 4000s II tires (Haven’t “graduated” to the 5000’s because I have a good stash of the 4000’s!) I generally get about 2000 miles out of a rear tire before I send it to recycle and swap it with the front. Then I put a new tire on the front.
The Michelins have a greater resistance to puncture and will deform around a pointed object for some time before rupturing. Whereas the Conti’s will rupture almost immediately on contact with the entering point (be it glass or metal, it doesn’t matter).
The ride quality of the Michelins IS definitely superior to the Conti’s. I liberally talc all my tubes before use so I’m assuming the ride quality issue is due to the better flexibility of the latex. Although I ride with latex, I keep a butyl in my seat-bag for the unusual instance that I do puncture the latex.
When I get going after a flat repair with the butyl spare installed, the ride feels “Harder” (or stiffer) than with the latex. Then when I get home and repair and replace the latex, my ride quality returns to “Normal.”
And speaking of repairs, a REMA patch works on both butyl and latex although the latex cannot be buffed so I just use some IPA to clean the surface before applying the glue. It works for me and I’ve never had it fail. I usually stop after three patches just because the tube will then be about six years old!
Latex does leak down MUCH more rapidly than butyl. However, I don’t find that to be a problem because I check and pump my tires before EVERY ride to the pressures given by the Berto equations. And I’ve NEVER had a pinch flat with latex whereas, when I got lazy with butyl, I’ve had a few.
I realize this treatise is limited and totally subjective, but I wanted to share my experience from over the last 12 years as suggested by Jim.”
My answer
What a great tube comparison and review Ray. I appreciate you sharing this very much.
Patching TPU (thermoplastic urethane) tubes
Next up is “Bigborb” who asked
“Can you patch these TPU tubes – either with latex or butyl patches? That would be the deal-breaker for me. A $30 tube that cannot be repaired is just not worth the lump in my pocket if so.”

My answer
Yes you can patch some TPU tubes with Park Tool’s GP-2 Pre-Glued Super Patch Kit https://amzn.to/3D7Dv5o . Park says these patches are compatible with Butyl and Schwalbe Aerothan TPU tubes. However, they do not specifically say it’s compatible with other brands of TPU tubes. It’s also not compatible with latex tubes.
Park says that for Aerothan tubes you don’t need to sand the area with the puncture but you do need to clean it. They don’t say what to clean it with but I would use isopropyl alcohol (“rubbing alcohol”) since it should get off any oils from your hands and will evaporate quickly.

Sealants for bicycle tubes
Regarding the idea to put sealant inside inner tubes, “Charles” wrote,
“Muc-Off now makes an inner tube sealant: https://amzn.to/43mJXzY I didn’t see any information about using it with TPU tubes.”
And Brian Nystrom weighed in with,
“I’ve used sealant in clinchers with tubes since ~2010 and prior to that, in tubulars for a decade or so. I’ve had zero issues with either one and the only real caveat is that you need tubes (or tubulars) with removable valve cores (there’s actually a way to use sealant in tubes and tires without removable valve cores, but it’s way more hassle than most people will want to deal with).
I’ve primarily used Stan’s regular sealant https://amzn.to/3JRLuXM and it works so well that I’ve never had any reason to change.”
My answer
Thanks Charles and Bryan. As Bryan pointed out, not all Presta tubes have removable valve cores. Those that do have wrench flats on them, that’s the telltale sign. It’s helpful to have a valve core removal tool like this: https://amzn.to/44B9KWd If you don’t have the tool you can use a tiny adjustable wrench or pliers but be very careful not to damage the valve if you use those tools.

If you’d rather not mess with sealant, you can also buy inner tubes with sealant already in them from Slime and they’re available in quite a few sizes with Presta and Schrader valves. They’re called Slime Bike Inner Tubes with Slime Puncture Sealant: https://amzn.to/43cMFIk.
Using Nitrogen to Inflate Bicycle Tires
John Thomas asked,
“I’m wondering if anyone has ever inflated their latex tubed tires with nitrogen. The last 2 cars I bought came from the dealer with nitrogen filled tires, and I was amazed that I didn’t have to top them up for more than 3 months. From a cost/benefit perspective, probably not practical. Just asking out of curiosity.”

My answer
If you want to give it a try John, you’re in luck. Prestacycle sells the equipment to set yourself up to be able to inflate your bicycle tires with nitrogen. On this page they show their products and give reasons why you might like to use nitrogen as many car tire shops have:
https://www.prestacycle.com/product/prestacycle-6061-t6-aluminum-nitrogen-cylinders/
If you go for it, please let us know what you think. But maybe you might want to see if your friendly local car tire place would be willing to fill up your bicycle tires with nitrogen first to see if it’s worth the expense.
Thanks again everyone!
Jim Langley is RBR’s Technical Editor. A pro mechanic & cycling writer for more than 40 years, he’s the author of Your Home Bicycle Workshop in the RBR eBookstore. Tune in to Jim’s popular YouTube channel for wheel building & bike repair how-to’s. Jim’s also known for his cycling streak that ended in February 2022 with a total of 10,269 consecutive daily rides (28 years, 1 month and 11 days of never missing a ride). Click to read Jim’s full bio.
A thought on nitrogen in tires. Since oxygen permeates through the tube faster than nitrogen (it’s physics, baby) over time the N2 concentration in your tire should slowly rise as you pump in fresh air as needed. In theory, this should mean you have to pump your tires less and less if you don’t get a flat. I guess I must get flats often enough for this to not be the case because it always takes 3 strokes of my floor pump every week to bring my tires back to their original pressure.
This may not be the place for this question but….isn’t air mostly nitrogen anyway? I can understand convenience and purity (no water vapor or other (?) stuff). But do we know nitrogen is better or is it sorta “not really a thing”? Thanks 🙂
Joe
I agree with Joe. Air is 78% nitrogen. Is it really that big of a difference?
No, not in reality. The difference in leak-down is insignificant. The claimed “longer tire life” is irrelevant to anyone who rides (or drives) a decent number of miles per year, as tires wear out long before any oxidation-related issues can occur. The biggest threat to tire life is UV from sunlight, not internal oxidation. Back when I worked in a shop, I can’t say I ever saw a tire or tube that failed from the inside, despite some being decades old. The tread may have been cracked and brittle, and the gum sidewalls melted, but the casing would still be intact.
The cynic in me says that nitrogen in tires is just another way for car dealers to make money, without any practical benefits. Using it in bike tires? Come on…really?
About the only positive thing I can say about it is that it does no harm to anything other than your wallet..
Any comments here on using CO2 to fill latex tubes? I’ve read in some places that the cold when inflating can make the latex tubes brittle and fail. I suppose you might be able to fill more slowly and possibly avoid but just wondered if latex users here had experience with CO2.
My question is, will the Park glueless patches used on those Aerothan TPU tubes make a permanent repair, or just a repair to get you home?
If the Park patches are temporary then that means you will have to throw away an expensive tube.
The Slime Extra Strong tube weighs about 210 to 220 grams, a lot of weight for a tube, wouldn’t it be better weight-wise to get an ultralight tube under 90 grams, and some sort of sealant, like the Muc Off that will only add 20 to 40 grams to a tube?
On a 700 mile tour in Oregon the last two weeks one wheel had three flats in two days puzzling us as to the cause. We inspected the tire carefully each time and were puzzled by what we thought was a tube failure on the rim side of the tube each time. We wondered if the rim tape which was sliding around and had a sharp edge could be the culprit. (Why was the tape not staying in the center of the rim?) The engineer among us pointed out the blowout was at a spoke hole each time leading him to conclude that the tube was forced into the hole and the sharp edge of the hole cut the tube. We replaced the rim tape with three layers of electrical tape and that wheel rode another week without another flat.