Wednesday, February 17, 2016

The Idiot's Guide to Latex

Latex tubes. They're one of the "mystic" arts around cycling and triathlon, feared by many, used by some, understood by few. Most of the people I talk to about them dismiss them immediately. "Too much work," "I can't install them," "I don't want to get a flat" or just the classic "They're expensive" are some of the most common immediate responses I get.

Slightly erotic imagery?

So first, the why. Why should you be running latex?
First, the easiest answer for most of the people reading this... they are faster. Tests have proven (more than one, but BTR is a good safe one) that you are looking at somewhere around 4-5 watts for free just from running latex as opposed to butyl. That's about a half second per km. There are a lot of Time trials out there that finish the podium within 20 seconds of each other. Over something longer it's in the minutes of time saved... for tubes!

There are other reasons as well, although less sexy admittedly. For many years the argument of using tubulars over clinchers was how much better they "felt." Well... when you cut open a tubular guess what's inside? (Admittedly not ALL tubulars, but almost all the ones that you would be gluing) That's right...latex. That's where your "magic" feel and robustness came from, not glue, or heaven forbid tape.

Another benefit is actually flat protection! What's that you say, you heard latex was more likely to flat. Simply not true when properly installed. In fact, I challenge you to find a case where latex tubes flatted due to "snake bites" (when you run too low air pressure in your tube and it bottoms out, causing the famed snake fang style holes in your now useless rubber) which are one of the more common types of flats.

The astute among you may point out that I flatted on latex last weekend. Indeed. However, that can be pinned on some user error (along with bad luck and a very old tire) which is, as I'll get into later on, the primary cause of flats using latex. That's my second flat since I started using latex in 2011 ... not a bad record (especially considering I'm lazy and often run latex in my tires when I'm not racing) fwiw the other time I flatted I ran through a broken beer bottle at Rev3 Knoxville. I'm pretty certain that would have flatted a gatorskin ;)

All that said, latex isn't all roses. They leak air, pretty constantly. You don't get to "set and forget," and if you do, you're going to be asking for trouble. It gets more annoying if you don't understand the right way to install valve core extenders on your deep section rims, as you may well find it nearly impossible to keep a steady, relatively high amount of pressure in your tube. You also can't just completely get rid of butyl. If you flat, trying to replace a latex tube with another latex tube on the side of the road is just asking for trouble... you'll need to keep a good old fashioned butyl in your spare kit at least.

Also, before we go any further, let's get the "they are expensive" thing out of the way. You better be showing up on your 80's model Nishiki you bought on craigslist for $25 before you start that. 5 watts for $20 and they're too expensive? Excuse me, your Aero helmet cost how much? What about those Zipps? Hell, ceramic bearings can cost hundreds of dollars and they *can* *maybe* save you a fraction of a watt... but people think that stuff is gold. Without any doubt or argument, latex tubes are the best bang for your buck for going faster out there.

Final side note (probably) - Pick good tires to go with them! Another bit of low hanging fruit is smart tire selection. I won't go into it here, but seriously, Tom A (Bikeblather and a much better blog than this one - although I assume that's because he goes for quality over quantity.) has taken up the charge of doing this from BTR, and there is a ton of info to help you make smarter, faster choices. Gatorskins are not race tires!

Alright, so I've convinced you that latex is the way of the future, (and present, and past) great, so now you say... how do I install them without destroying a $10+ dollar tube and scaring the crap out of myself (blow one up at about 90psi and you'll understand what a heart attack probably feels like.) Fear not, I've got you a crash course in latex installation!

(Of course let me preface that my way isn't the only way. Lots of guys have success with other methods, this is mine that I feel is cheap, readily available and not too much hassle.)

Cover + 404 = Disc!

Here's what we are starting with... my older Zipp 404 (narrow rim) disc cover installed. You'll notice on the stool I have some packing tape. Yep, nothing special, just packing tape. And here is one of the major things that will determine if you have a successful installation with latex.

- YOU MUST have a smooth surface rim bed that doesn't allow the tube to "sneak" into a spoke eyelet or slightly jagged part of the rim (usually where the rim is bonded) Regular rim strips are good enough for butyl tubes because they are much less likely to blow if you get it slightly off. Latex WILL blow if it sneaks into an eyelet. So, how do you fix that. There are a few solutions, but the ones I use are packing tape and (on my H3 - which btw doesn't have spoke holes) electrical tape. I've also seen many people use STANS rim strips (the tubeless setup kind) with success. Anyways, packing tape is cheap and most people have it in the house already so that's what we'll use.
*worth noting I leave my rim strip on, it won't hurt anything (it might make seating the tire a little tougher is all) and can help.

So, start right past the valve stem and start running the tape around the rim bed. It doesn't need to be perfect, just get a good cover over the bed. I line one side of the packing tape up where I want it to be and let the other side run off (see picture below) we'll get rid of that later.

When you get back to the valve stem opening you should end up with something like the above. Notice the overhang of tape. Obviously we need to get rid of that. Enter the scalpel (or whatever sharp knife you have handy.)

My method is pretty simple here. I start right on the inside of the brake track and just follow it all the way around with the point of the knife. There should be a straight cut all the way through at this point.

Now it's really just as simple as peeling the excess off the rim. It should easily separate and leave you with something resembling an ugly brown rim strip. It's fine if it's not pretty, and you'll undoubtedly have some air pockets and folds, but as long as you get coverage you are all good.

Now your rim should be sufficiently sealed to protect you from snares that would come from the rim itself. The reason you cover the rim strip again is because of the potential for the strip to move when installing the tube, something you can't really see to account for. Note that I don't recommend Velox despite the fact that it sticks to the rim bed because over time latex tubes will "seep" into the fibers of the tape, which will make it impossible to uninstall without damaging. Velox also has a bad habit of getting pinched and moving when using tire levers in my experience.

Regardless, if you used another method to seal the rim (Stans, etc) or just skipped it because...YOLO... we're ready to move on to the next important thing.

Baby Powder.
Most latex tubes come with some small amount of talc powder already on them, but not nearly enough. You want that thing to look like a 1985 Yuppie's nose on a Saturday night! I keep a small bowl (with lid) with a little baby powder in it and then just throw the tube in and shake. That gets a liberal, even coating without making *too much* of a mess. This will make the tube unbelievably easier to get seated under the tire later on. Skipping this step will lead to some headache down the road, I promise you.

So, finally we are ready for the install process. I start by adding just a tad of air to the tube (one pump or a good blow of the mouth if you don't mind tasting baby powder.) and installing it like a normal butyl tube. Next, get your tire on but stop before inflating the tire.


This is where probably 99% of people screw up their latex tube installation, especially people new to installing them.

So you have your tire on, next step is to inflate it, right? WRONG.

This is the biggest difference between latex and butyl. A latex tube must not be caught under the rim of the tire or it will pop when inflated. A butyl tube will almost always push itself back under when inflated before it gets to the point where it explodes, but latex will not. So, slowly and methodically you need to "push back" the tire and look for the latex tube peaking out. (See below for example) It can help to slightly inflate the tube (again, like a pump or two) to get it underneath. This is where you will be glad latex tubes come in bright colors and not just black. It will be very easy to spot.

The pink you see in the picture above is tube caught under the sidewall of the tire. This is bad. So, how do you get it back under the tire? The main method is called "flicking" the tire. This is accomplished by pushing the tire opposite of the side that latex is caught under (same as picture above) and letting it go. It'll make that "flick" sound... repeat until tube disappears. Again, it can help immensely to have a small amount of air in the tube and to have used a liberal amount of baby powder. Go around both sides of the wheel until you are satisfied that the tube is completely seated and not caught under the tire.

Now inflate to desired PSI. You'll know at about 80-100psi whether you got it right or not.

Congratulations, you successfully installed latex tubes! (or you screwed it up and scared the crap out of yourself when it exploded... sorry, you almost certainly got tube caught under the tire)

Some side things to consider when it comes to latex

- Removable valve cores. This is something you should look for when buying latex even if you don't plan to have valve extenders installed on them, and is essential if you are. They are also required to run sealant. The difference between screwing an extender on top of a valve normally and just leaving it open and removing the valve core and then replacing it at the top of the extension (warning when buying valve extenders... not all, including ZIPP ones, have threads that will accept a valve core... choose wisely. Silca and Enve are safe choices) is huge. You will find things much easier (and your tires stay inflated longer!) when you install the cores at the end of the extenders.

- Sealant.
Greg Kopecky did an excellent write up about this on Slowtwitch, which you can read here. (There is also a part 2) I'll not rehash everything in this post, but the takeaway is that you can run sealant in your latex tube and have an added level of flat protection, all while slightly helping your rolling resistance.  Considering most bottles of sealant are very cheap, there is very little reason NOT to be using it.

So, here is the first post of this type. I hope to make this kind of thing a regular part of the blog, so fingers crossed!

Until next time, thanks so much for reading, I really appreciate it!

- Christopher Morelock

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