icemilkcoffee 

My son has been riding a MTB with 26" wheels and I've had to patch his tubes 3 times already since school started. I am thinking of changing to a tubeless setup. The rims in question are not TLR, but they do have 'shelves' under the beads. The shelves do slope slightly down towards the center of the rim though. If I convert this to tubeless, is there any danger of the tire beads coming unseated if the tire pressure runs down? Can you build up tape to form a 'ridge' so the tire bead doesn't get unseated?

FBinNY 

It takes very little pressure to push a tire outward against the sides of rims. That's what keeps it trapped on the shoulders. That property is the same with or without a tube.

The air pressure does the work. The tube only holds the air, and doesn't make a difference to the tire.


FWIW if your concern is flats, you can get the same or, at least, very comparable benefit with tubes and liquid sealer.

icemilkcoffee 

Right. My question is what happens when that pressure runs down? Say I let the bike sit unused for a few months and the pressure runs down, will the tires unseat?

FBinNY 

Like everything in life, it boils down to the details.

If the pressure only runs down low, odds are it'll be okay. However, if the pressure goes to zero, especially if the bike is on the floor, then there's a greater chance of the tire unseating.

In that scenario, a fluid-filled tube might serve you better because it won't require the high flow burst of air to reseat the tire.

Barry2 

Using non-tubeless wheels as tubeless, is so common they have a name for it... Ghetto Tubeless
I personally won't do this (safety concerns), but many do.

Barry

redcon1

Ghetto tubeless was very prevalent BITD for the MTB world before manufacturers made tubeless-ready wheels. The link posted above is a good starting point. I did it BITD using the split tube method. Gorilla tape method was also popular.

cxwrench

Does it matter? No. Pump them back up.

FBinNY 

-s

With respect, it might.

While conventional tires can be pumped from zero with a typical hand or floor pump, that isn't the case with tubeless.

First of all, a flat tubeless tire sitting on the floor for a long time might lose sealant. The other issue can be inadequate air flow to re-seat the tire, and establish the seat so it'll hold air. Of course, these aren't insurmountable, but can be inconvenient. I assume the OP is thinking about that factor in asking his question.

icemilkcoffee 

with ghetto tubeless , most likely it will be a struggle getting it to seat every time.

cpach

I would generally recommend against it, and will not do it for customers as a professional mechanic. This can obviously be made to work OK with relatively low offroad pressures, but generally takes some experimentation to see how much the rim bed needs to get built up to get a good tolerance fit between the bead and the rim and is still more prone to failure.

The most practical option (particularly if the bike is mostly a commuter and not used very much for actual mountain biking) is more puncture protective tires.

Sorcerer

Hi,

Since I have a lot of experience trying to use various 26" and also mainstream tubeless conversions and using tubeless tire systems I think I can offer some good suggestions.

First of all, if the tires are not manufactured to be used as tubeless tires they might not be suitable for a tubeless conversion to begin with. In this case the cheaper heavy casing tires are better because the high end tires which are built to be lighter will not hold air due to the thin casing and typically higher thread-count.

That said, if you want to try anyway, there are methods.

However in the case of getting a kids school commuter bike to not get flats, going tubeless is probably not a good idea because of the installation and maintenance an unorthodox conversion will require. Instead running a Slime innertube and maintaining tire pressure is a good idea. Alternatively a tire liner is often a good tactic against thorns, wire, and fasteners (nails,staples, screws).

In the case of caltrops or goatheads, going tubeless is a good idea.

You didn't describe the type of puncture or flat tire causes. This information could be important. For example pinch flats come from riding low pressures and hitting hard edges like rocks and curbs.

My favorite way to go tubeless on non-tubeless rims is to use UST tires. I use this on mountain bikes that see real heavy duty use on dirt trails. I use sealant and tubeless valves and maintain wet sealant inside the tires and keep the tires aired up. If the tires are ridden with too low a pressure the beads will come unseated. Unfortunately these UST tires are no longer manufactured and remaining NOS stock is pricey with few choices.

Ghetto tubeless and it's drawbacks have already been mentioned.

This brings me to the system that is excellent: fattystripper.com

These are latex ribbons which stretch over the rim. There's a hole for the tubeless presta valve stem. There are also tubeless schrader valve stems on the market if needed. Rather than trying to explain the system in detail I'll refer you to their website and at the bottom I'll paste in a quote. I've been using this system on a couple of 29" non-tubeless rim wheelsets for two years. One of the key features to this is that it facilitates inflating and seating the bead.

From the website:

"
2 pairs SkinnyStripper Latex Bands$10.00
75mm wide version of the FattyStripper bands for use on 24, 26, 27.5 & 29/700c rims up to 50mm wide. SkinnyStripper bands provide a more reliable tubeless solution for CX, Enduro and DH wheels when lower pressures are desired for traction but the off-camber and technical nature of the trail tends to encourage "burps". The latex will bond with the tire's bead after a week or two to create a "tubular-like" solution. This is "burp insurance" for your CX and DH wheels! 22g/band before trimming... or ~10g for a CX rim & ~15g on a 30mm DH rim after trimming."

tFUnK

Been said twice already so I'll say it a third time: on a 26" fat tire (low pressure I assume) I would just add sealant to the inner tube. BITD Slime was the goo of choice. I'm not sure about modern sealants in terms of in-tube applications but I assume they've only gotten better over the years.

Eric F

I'm running 26 x 2.1 Panaracer FireXCPro TLR tires on 20-year-old non-tubeless Mavic rims. The rims were wrapped with a layer of electrical tape and a layer of tubeless tape. Even after they go flat from non-use, I can get them to re-seat and inflate without an issue, using just a floor pump.

tFUnK

Nice. The key here is your that tires are tubeless ready.

Eric F

Correct. That is an important part of the equation for my setup. It was an experiment with non-tubeless rims that paid off very nicely.

Inusuit

Weight weenies will object, but I haven't had a flat since installing "thorn resistant" heavyweight tubes. Also don't need to pump up the tires before every other ride.

veganbikes

This could be a good help:
https://theradavist.com/vintage-mtb-tubeless-wheels/
https://theradavist.com/an-update-to...h-more-photos/

oldbobcat

If you're looking at ghetto tubeless for performance reasons, you know the risks now, so go right ahead. If you're doing it to make your life easier, you're barking up the wrong tree.