Getting Tubeless Tyres Seated
Morning all. A short post today, to share a tip on making some MTB rims a bit easier to work with when setting up a tubeless tyre.
But I thought they were all easy...
...well, that would be nice, wouldn't it? Fact is, when you're getting your tubeless tyre set up for the first time, some rims will be very easy to get that initial seal, and some will be difficult bordering on impossible to get the initial seal. All rims are not equal...
Here's two rims I've used recently, one easy and one difficult.
Difficult
First, the difficult one:
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| WTB Laserdisc profile |
This is the cross section of a WTB Laserdisc rim. You can see that this rim has a deep "well" in the centre, and the sides of the well are slightly higher than the bead hook area (there is a small "lump" for the bead to get over). This is what will make it extremely difficult to get any tubeless setup sealed. When you first put the tyre on (not yet inflated) the tyre's bead will be located in that well. You then face the seemingly impossible task of getting it to stretch up and over the steep edge of the well, before it is located nice and snug, by the bead hook, using only air pressure delivered through the valve.
Once the tyre bead is on, great - it is very secure. But that's not going to happen very easily.
Easy
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| Sun Estate profile |
And this is the cross section of a Sun Estate rim. This rim was extremely easy to get the tyre sealed. You can see that this rim has a shallow dip and not a deep "well". This rim will seal easily. There is no "lip" to prevent the tyre popping into place. As the tyre bead is gradually pressed outward by any air pressure, it will "self seal" on this rim as the bead becomes tighter and tighter on the rim. It's almost like this rim was designed with tubeless in mind.
On the minus side, this particular rim doesn't have a flat bead seat. Without a rubber rim strip (cut inner tube or stans conversion kit style) it will be prone to burping.
"Official" Tubeless Rims
Just for to make the point, the cross section of a Stans Crest rim is like this:
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| Stans Crest profile |
Which, on the face of it, looks like it has a well, but, the well has smooth sides to it. There is no "lump" at the edge of the well. It has a flat bead seat area.
And a Pacenti tubeless rim:
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| Pacenti TL28 profile |
Again, fairly shall well with smooth sides, no "lump", flat bead seat... spotting a theme?
Get to the Point, man!
Ok, how do I fix a problem rim? The answer is to build up the "well" until it is level.
What with? This stuff:
Cheap foam insulation tape. Any DIY shop will have it. Also available for peanuts on Ebay. Try and find some that is about 1mm thick.
All you do is run a length or two of this tape around the rim, in the well, until the well is full (edit - or part full - if you fill it completely it may make it very difficult to get the tyre on the rim in the first place). It might take several times around. After the foam tape, put your usual rim tape over the top before carrying on as normal with the tubeless setup (for ghetto conversions or stans rim-strips, you can forget the rim tape - the spoke holes will be covered by the foam tape). Easy!
Give it a try if you're stuck and can't get your tubeless tyre inflated.
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