Technical FAQ with Lennard Zinn: More thoughts on sealants, tires and rims

Lennard fields readers' questions and comments regarding recent columns.

Q. Dear Lennard,
My son has a latex allergy. Liquid latex is a major instigator of a potential reaction and potential anaphylactic shock. So, my question is, are there non-latex tire sealants out there? Am I better off just using the tube/tire/carry-a-spare method in order to avoid potential exposure? I’ve read about latex squirting around when applying and or blowing out a tire. I don’t race and typically haul my son (he’s four) around on a trail-a-bike. I have a nine-year-old Trek Fuel with Bontrager rims that may be set up for tubeless. I don’t know if it’s a good idea to go tubeless without some kind of sealant in the tire.
— Tom

A. Dear Tom,Caffelate
Caffélatex has no latex in it. The company owner is fond of saying that the only latex in Caffélatex is in the name.
— Lennard

Q. Dear Lennard,
In reading your response to questions on sealants, I read the following quote from Alberto of Caffelatex:

“Sealants work at their best with tubeless systems, while their maximum-damage sealing properties are limited with tire-and-tube systems. It has to do with the way inner tubes deflate/move (a tube has no inherent strength; it just holds air and is much more flexible than a casing: the puncture hole geometry is changing constantly as pressure changes) and by the movements at the casing/tube interface (they are rubbing one against the other, tending to mechanically remove the patch).”

I myself have used both Stan’s and Caffelatex in road clinchers. I have found that the Caffelatex seems to stay liquid and last longer (as explained by Alberto in the column as well), and that the Stan’s seals quicker and stronger ─ especially with the larger holes.

But Alberto’s comment got me to wondering ─ I’ve heard all sorts of theories about why you should dust/powder a tube before installing it. And most seems to have to do with avoiding snakebites, blowouts, or ease of installation ─ but primarily to keep the tube from sticking to the inside of the tire. But when using a sealant, if you have a puncture, some of the sealant gets out, between the tube and tire, until the leak is sealed. The sealant that has leaked out mixes with the powder, makes a mess, and tends to create a glue that all but guarantees the tube is stuck to the tire.

So what I am wondering is, why not forgo the powder and try to get the tube to stick to the tire as much as possible? It seems like this would avoid a lot of the aforementioned mess. And it seems that if the tube is stuck to the tire, then a leak and the escaping air would create a small section around the leak where the tube/tire would not be stuck together, the sealant could get between tube and tire, and help the overall sealing process.

I would be very interested in hearing your thoughts on this.
— Steve

A. Dear Steve,
Makes sense to me. In fact, although I recommend it in my books because it’s the way I was always taught, I never use powder myself and actually prefer having the tube stuck to the tire. And I generally have good success with sealant in my inner tubes. Maybe there’s a connection.
— Lennard

Q. Dear Lennard.
I was doing some Aqua Seal touch ups to my Dugast Rhinos and while checking the glue job I noticed a small section of base tape had separated from the tire approximately one-inch long by a-quarter-inch wide.
What type of glue to you suggest for base tape repairs?
— Mike

A. Dear Mike,
That’s an easy answer: Barge Cement.

Barge cement was originally developed as a handy means of repairing shoes, but it’s a strong contact cement. When working on base tape — especially when dealing with long sections or reattaching the entire tape after a repair — be careful about wrinkles and work to keep it smooth.
— Lennard

Q. Dear Lennard.
I read the “Limits of Sealant” Technical FAQ column today and was intrigued by the reference to latex/silicone tubes by Lennard. I have been in cycling for almost 30 years and I have to admit this is a new item to me. Where would one find such tubes and who makes them?
— Alan

A. Dear Alan,
I asked Dugast if they sold them individually, and received this answer: “No, I’m sorry we don’t sell the inner tubes. They are made for tubular tires and that means that they are a little shorter than normally, so it’s not good to use them with a clincher.”

I don’t know of any other source for them.
— Lennard

Responses to last week’s column

From the founder of Stan’s NoTubes:
RE: Dear Lennard,
I was just reading on VeloNews about sealant.

“Dugast, producer of some of the finest tubulars money can buy, are very concerned about latex inner tube/sealant interaction. Over the years they have received several warranty claims for tubulars where the tube had been cooked by the ammonia found in natural latex based sealants.”

My sealant has less than 0.1% ammonia this is less than one small drop / 2oz. Less than one tenth of one percent.

I cannot speak for other sealants but my sealant has almost no ammonia. So little in fact it does not need to be listed on the MSD.

My sealant is completely different than the sealant I started out with 11 years ago.

In a tubular my sealant after a few rides will maintain much better air pressures. Seems like the more you ride it the better it holds air.

We have many top tubular rim designers using my sealant in tubulars with great success and no cooked tubes.

Look at it this way if you have a $100.00 tubular all glued on and it has a hole in it you have nothing to lose by putting in a 2oz bottle of sealant. I have a set of tubulars we use for puncture tests that have been mounted for the past three years. These tubulars have hundreds of holes in them and I can still ride them.

A few things about sealants:

1. Any sealant that will inject through a valve core will seal almost nothing. My sealant will seal a valve core with one drop.

2. Foaming sealants do not work. One of my first sealants was a foaming sealant. I thought it was a great idea but once you take two of three ounces and whip it into foam it leaves no liquid to seal a puncture. I would go on a test ride with my foaming sealant. After a few miles I would stop and puncture my tire. Nothing would come out except air. While removing the tire, I found the inside of the tire was filled with my foam leaving nothing to flow to the puncture. At that time 11 years ago I realized foaming sealants would not give me the performance I wanted.

3. Sealants must be thin to flow quickly to seal a puncture. It they are thick they will never give you good performance.

4. It’s easier to seal tires with no tubes. Tubes stretch making sealing them much harder.

5. NoTubes sealant will seal tubulars better than any sealant I have tested.

6. Sealant that will freeze will not last very long.

— Stan Koziatek, Stan’s NoTubes

On all subjects in the column:
RE: Dear Lennard,
Before throwing that Tufo (which has no inner tube) or other tires in the garbage because the hole is too large for sealant to close, try a needle and thread and some glue. I’ve successfully ridden on Tufos and tube-type MTB tires with sewn/glued sidewalls (I’ve no experience with UST or road-tubeless). Worth a shot before tossing a $100 tire in the garbage.

On extenders … if the original tubular valve stem is the type with a removable core (as in Tufo) remove it and use an extender that then moves the valve at the end of the assembly so it functions as normal. The extenders that leave the valve buried in the rim are a PITA. Then if the valve or extender becomes clogged it’s an easy matter to remove the core and either clean it (or replace it) or ream out the extender with a long 1.5 or 2mm Allen.

My experience with Caffelatex reflects the other writer’s experience. While using Caffelatex in a Hutchinson Bulldog tubeless-ready tire (with no tube) I got a thorn puncture. The Caffelatex did a good job of spraying me and my rear triangle with sealant, but not sealing the tire.

I went back to using Stan’s and accepting that I have to perform some regular maintenance to refresh the sealant. Haven’t used sealant in a tubular. When I tried Caffelatex in my MTB tires (Kenda non-UST, no tubes on a Stan’s rim) sealant leaked and bubbled for a long time and was a pain to get completely sealed. Again, once replaced with Stan’s my MTB tubeless setup was much better. Again I’ve not used latex sealant in tubulars with tubes or in MTB tires with tubes but I’ve never had tire failure issues due to Stan’s sealant in clinchers sans tubes.
— Fred

More on the sidewall cut:
RE: Dear Lennard,
I’ve heard that in Tufo tires the butyl tubes are vulcanized to the casing. So, couldn’t the fellow with the small cut thoroughly clean the area and patch it with a tube patch kit on the outside? I’ve seen it done successfully on a (Dugast) Rhino before. That might hold if he did a good job??? Worth a try anyway!
— Tre

Stybar's rainbow front wheel
This one's for dry days.

Regarding deep rims:
RE: Dear Lennard,
I read with interest your recent write-up on the advantages of aero’ wheels for cyclocross.

There was also a recent write-up on Zdenek Stybar’s bike a little while back.

He’s not running deep rims.

— Brian

A. Dear Brian,
It depends on the conditions. You’ll notice that in this photo, his mud setup has deep rims.

Stybar's rear triangle Asper-Gavere
This one's for mud.

Incidentally, I just found another reason for deep-section wheels in cyclocross. I have wide-profile cantilever brakes (TRP Euro X Magnesium) on one of my bikes, whereas I’m used to low-profile brakes.

A couple of times when dismounting, I’ve kicked up on the right cantilever arm when swinging my right leg off.

If it’s a deep-section wheel, there would be no problem, but with a 25mm-deep rim, I managed twice to kick the brake hard enough that the pad went underneath the rim. One time I kicked the cable end out of the arm as well and had to stop and re-install it. The other time, when I heard the telltale rapid ticka-ticka-ticka-ticka-ticka of the pad banging the spoke nipples, I just pulled the arm back down and continued riding, as the cable had not become disengaged.
— Lennard

RE: Dear Lennard,
I thought I would let you know that Kinlin recently released a 38mm-aluminum rim. I use the Kinlin 27mm rims and am very happy with them.

There is more information on the rims at
— James

Regarding the post about whether low tire pressure makes wheel stiffness imperceptible:

RE: Dear Lennard,
The proof offered is only half complete. While the spring rate consideration is addressed, it stops short of addressing actual efficiency. For simplicity, consider the two part system of frame and tires: If the frame is ideally stiff, the tires will displace X amount under an applied load and there is no displacement in the frame. If the frame acts as a spring in series with the tires, yes the total spring rate is lower and therefore the total displacement is greater (Hooke’s law) under the same applied load.

Yet, the displacement of the tire spring component will be the same in each case because the force on each spring within the series is still equivalent to the applied load. The total displacement is only greater because of the addition of frame deflection. To complete the proof, energy stored in a spring is 1/2kx^2. Because of the squared relationship to displacement, there will be more total energy transferred to the springs in the (softer) system with two springs in series. The above can be shown mathematically.

Now take into account that none of the springs in the system are ideal, meaning less than 100 percent of the energy transferred into the springs can be recovered. To complete the argument, for two bikes with the same rider weight and same tire pressure, the system with the stiffer frame is still more efficient by the relative extent to which the frame is made stiffer. Though the assertion that the tire spring becomes the dominant term in total system efficiency is correct, the efficiency gained by the stiffer frame is still efficiency gained. In practice, the other comments re: torsional stiffness, handling precision, etc. are relevant, as would be taking into account that most of the “springs” in the system exhibit varying degrees of nonlinearity with respect to rate and damping characteristics.
— Nick

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