Tires / Do you like foam?
Do you like mousse?
Most ADVers know the debate between tubeless tires, the TubLiss system, or good old-fashioned inner tubes…but what do you know about using foam inserts in your tires?
My knowledge is minimal, so I asked some questions to Mike, owner of TacoMoto.co who is himself a rider and runner; his company sponsors many Baja riders and teams as well as Dakar sensation Mason Klein.
rtwpaul: I guess I don’t know much about tire foam systems. I know the Dakar, Africa Rally and Baja guys use them for flat out but not sure which ones I should try or how to install them or history…any tips or information what would you like to share?
TacoMoto: Depending on the bike and the riding conditions, a foam can be a fantastic choice or a terrible nightmare for you. A foam is a cellular foam insert consisting of a butyl rubber honeycomb filled with nitrogen gas to control thermal expansion. This fills the tire instead of air.
This idea was originally developed in the early 80s by Michelin for the Paris-Dakar Rally, in order to gain an advantage over tube bikes, which continually suffered from punctures and delays.
The name “bib” comes from the Michelin mascot and French desert moss due to its airy composition, so the name “moss bib” is like calling a tissue a “Kleenex” no matter who made it .
The enemy of foam is heat
The enemy of a foam is heat, as it weakens the walls of the micro-pockets of air cells, causing them to fail, mixing them into larger and larger fused air chambers, which could lead to failure rampant system density and a possible flat tire. To prevent this, an installer should carefully lubricate the foam with silicone grease or thick silicone oil and the rider should avoid overheating the system while on the pavement by maintaining speeds in the 40 range. 55 mph in the summer, and possibly 55 to 75 in the winter, stopping occasionally to check rear tire temperatures.
The higher the heat load, the shorter the life, although the front tire is generally immune to any temperature/heating issues.
Although it may seem complicated and difficult, the pros far outweigh the cons with a puncture-free, trouble-free ride over any terrain or condition.
How long do they last?
A typical foam rear will last as long as one or two tires and a front for generally the same life as a tire.
Are they heavier or lighter than a tube?
Rear weight is comparable to a Bridgestone heavy-duty tube at around 4.3 lbs, but the cost is much higher and is usually between $125 and $140 (USD) for most brands.
Describe the ride/feel?
The ride feel is neutral and bouncy free and may take some getting used to, but once you get used to it most will prefer it to air and often never go back to a tube again. Densities will dictate ‘PSI’ ratings but most will be in the 8-15 psi range.
Who are they ideal for?
The ideal foam rider is:
- Any runner who cannot afford the flat time penalty.
- Any rider who wants to give up with spare tubes, air pumps and tire changing tools.
- Any rider who understands that these are a little more complicated than a tube but is willing to accept that for the benefits of these over the air.
- Any rider who wants to free themselves from the worry of flat tires, punctures, most rim damage and routine maintenance of air pressure checks.
Do not consider foam if:
- You ride mostly on pavement or you know you won’t control the speed if you do.
- You don’t want to deal with their unique installation and operating practices.
- The weight of your machine and rider is over 550 lbs. We found that to be about the ceiling of durability, unless you’re ok with shorter replacement cycles.
- You are someone who has a good background with tubes and air-based systems.
How about some foam tips and tricks?
Murphy’s soap or tire installation paste is a poor choice for long-term durability, as they are generally vegetable oil-based compounds that dry out quite quickly and shorten the potential life cycle of the suds. If you plan to change them often, you’ll be fine, but if maximum durability is your goal, go for silicone.
Unless you replace a tire and mousse with a new one after each rally stage, a rim lock at the rear is mandatory and optional at the front.
Some will run two rear rim locks; it’s a great idea, but difficult to install and not essential to get a good performance life cycle from a rear end. Spinning a tire on a rim with flabby foam is a real drag and spinning the lock saves the day every time.
To maximize the life of a foam, it must be balanced. The rim lock will be a heavy spot and the constant pressure exerted on that specific heavy spot of the foam will shorten its possible life. Do this even if you only ride on dirt.
If the cord does not settle during installation, you can try a few speed runs to sort it out. if that doesn’t work, try blowing shop air into the empty valve stem hole to push the tire into the bead. Foam that is too small to fill a tire should be avoided and can be inflated with cut sections as needed or swapped to the next larger size or run with the next smaller size tire.
How/why do they fail?
The most common cause of foam failure is not foam failure at all; it’s a tire puncture caused by a sloppy installation. Tearing the bead cords ruins the tire and it’s only a matter of time before it comes off the rim.
Once it’s done, it’s done, right?
Yes and no. Save your old foam in a trash bag and cut it into usable filler sections to re-inflate a current foam as needed to maintain a usable filler and extend its life.
How difficult are they to install?
While it’s entirely possible to install and remove foam with hand tools on the garage floor, if you’re serious about committing to a long-term relationship with foam, invest in a Rabaconda machine. or one of its clones.
This video will show you a great way to mount a mousse with little effort. There is a good rim lock tip towards the end.
Lubricate the foam and the tire, use a stiff flange mechanical brake brush to completely “paint” the inside of the tire with the lubricant, then with your hands, blot the foam with the goo. There is not too much lubricant. We use two tubes in the back and one in the front.
We buy gallon cans of SuperLube brand 5000 cSt silicone oil (PN 56501) and also use it as needed, which is as thick as cold honey.
Having used foam on all of our Baja 1000 race bikes and trail bikes for nearly 10 years exclusively, and having had the benefit of trying just about every brand and system, we have never found one that performs as reliably and consistently as the Michelins using the tips and techniques outlined above. We know that there are many people who have many good experiences with other brands and we hope that this good experience will continue for them.
Foam is not for everyone. Compared to tubes, they cost more, have a shorter lifespan, are heavier than a standard tube, and are more complicated to install and handle. But for those whose riding conditions, riding style and mechanical aptitude are a good match, they wouldn’t ride on anything else.