Tuesday, June 29, 2010

Equipment - Selecting A Tubular Tire

Over the past decade or two I've used a lot of tubular tires. I've tried a bunch, prefer a few, and, like many other things on the bike, settled with what I consider to be a good combination of cost, performance, and durability.

Although I used to feel like gambling the race on equipment choices, like using super thin, super light 17 mm tubulars in a crit, in my "old age" I've come to appreciate equipment that works long enough to get me to the finish.

Cue in the maxim:

"To finish first, you must first finish."

It's one thing to drop out because the race was too fast or you attacked really hard and blew up or something where you stop because you're exhausted.

It's another to drop out of a race (or even stop on a group ride) because you dropped a chain because you removed your front derailleur to save weight (or just dropped it), flatted an already-iffy tire, or broke a 90 gram saddle.

So, for now, let's forget about finishing first. Just finishing in the pack can be a triumph, and it would really suck to make the effort to train, get a license, drive to a race, start said race, and then drop out because of a mechanical.

Racers like using tubulars for a bunch of performance-related reasons. They don't pinch flat except in extreme conditions (I've never pinch flatted one), they feel super consistent in turns, they tend to be lighter for a given durability, and the rims weigh less (since the tire holds in the pressure, not the rim).

The latter is really the key. You can lose a good pound off of a pair of clincher wheels by using a tubular equivalent, meaning rim profile ("aero-ness"). Yes, you can get really light clinchers, but they're not that aero. And even aero tubulars end up very lightweight. Case in point - my 60 mm tall tubular rimmed wheelset weighs less than 1400 grams.

Of course the tire makes a difference too.

This brings us to tubular tires, and specifically, which tires you should use. Although this all relates to racing, it does so in the "to finish first you must first finish" maxim. These tubular tire guidelines make for, first and foremost, a reliable set up.

Yes, it's fast. Yes, it's light. But it's durable, probably as durable as tubulars get for a given width. You could easily use the recommendations below to pick out your training tubulars, but, for me, I find that it ends up a bit cost prohibitive.

Here's why: A decent tubular tire costs about $80. Run over an errant tack, skid a bit in a turn, and you just had an $80 flat. Most tires last a good 1500-2000 miles, so you'll go through at least a rear tire in a reasonably conservative two months. If you're piling on Pro type miles, maybe a month. Multiply that by three or four for a front tire.

That's a lot of tire dollars.

Clinchers cost less to replace regularly. That's why a lot of racers like clinchers for training.

So... without any further ado, let's look at three tires I grabbed from my pile of tires. I was gluing up a pair of wheels and after examining the two "nice" tires, decided on the Racer X Lite Pro. You'll see why in a bit.

Top: Bontrager Race XXX Lite
Center: Bontrager Race X Lite Pro
Bottom: Clement Futura

Round versus Flat Casing

The first order of business is to see how the tire is made. Since tubulars are round (duh) you want the tire to start life as a round thing. Clinchers are molded in nice round shapes, that's why they look round when you get them. The tread doesn't fold flat because you can't fold a rounded thing flat without wrinkling it somehow.

Therefore, you should see if the tubular folds flat.

If it does, you probably don't want it. I mean, yeah, it may hold air, it may work for you, but if you're going to get tubulars, get good ones. Otherwise stick with good clinchers. It's not worth getting the Ferrari with decrepit old tires. Stick with the Lotus and put some good tires on the thing.

See, flat folding tubulars are made from a tube of cloth ("casing").

Think hot dog.

Hot dogs don't roll up into circles real well (you ever try to bend a hot dog into a loop?). Neither do straight casings. When you inflate a flat folding tubular, it turns into a double hot dog for a while, desperately trying to straighten out. At some point it pops into a circle, but only because it has to, not because it wants to.

Good tubular tires start off on a circular mold thing; the casing is sewn together on a rounded form. This means that the tire wants to be circular and round at rest - the casing has no weird stress raisers due to transitioning from a straight piece of casing to a circular one.

Therefore, the first thing you should look for in a tubular tire is one that looks like a deflated version of its mounted self. It should resemble a tire, not a 2x3 block of wood.

My favorite vulcanized tire - the Clement Futura. The Kevlar belt under the tread made a big difference, but the tire weighed a bit more (close to 300g). In the dark days of bad clinchers, these were my favorite training tires. I can't believe I still have one.

Vulcanized versus Glued Tread

The next thing you need to check is usually related to casing construction. You want to see if the tread has been melted onto the casing or if it's been "glued". With the aforementioned flat casing, the tire is laid out in some flat manner.

That's because the casing is straight like that - it's like ironing the tire - you don't iron it when it's all wrinkled. You iron stuff when it's flat and smooth. Flat-folding casing is happy when it's flat. You know, deflated.

Then the tread gets attached. Because it's cheaper, it's usually molded on, i.e. melted onto the tire.

Vulcanized.

The tread is happy at this point, and works really well. It's securely fastened, it's nice and consistently thick, and it's secured well to the tire.

Problem is that unless you ride your tubulars with no air in them, that's not how the tread is when you're on the bike.

No, you inflate your tires before you ride, right?

This stretches out that happy, flat casing until it pops, unwillingly, into a circular cylinder.

The tread stretches out too. Little cracks appear. The rubber stretches, somewhat inconsistently. You end up with little fractures in the tread everywhere. They pick up pieces of glass nicely. Eventually, relatively quickly, the cracks become big enough to see.

Put it this way. You ever try and put tape on a balloon? There are two ways to do it - one is putting tape on it when it's inflated. (As a party trick, if you stick a pin through the tape, the balloon won't pop, so if you use clear satin tape, it looks like the balloon got shot with the pin).

The other way to tape a balloon is to attach the tape when the balloon is deflated.

Imagine what happens when you inflate the balloon. The tape tries to retain its shape. The balloon tries to stretch it out. You end up with a deformed balloon.

At a much smaller level, vulcanized flat casing tubulars do the same thing.

So how do you fix that?

You glue the tread onto an inflated circular casing. Typically at room temperature a properly molded tread is attached to the tire like so. The tread is happy, consistent, and unstressed when the tubular is inflated. This is much better than the stressed, stretching, cracking vulcanized flat casing tubular.

The gluing used to be done with meticulous care in Italy, probably by Italian grandmas adept in such fine motor skill things. Now it's done in Thailand for some companies (including Bontrager and Vittoria). Okay, Veloflex still does it by hand in Italy.

Do I think there's a difference between the Italians and Thailand-ians?

No.

The tires work great. I've used Vittoria CXs forever. The Thailand Vittoria EVO CXs, which I happen to have on my race wheels, work as well as the Italian Vittoria CXs. The Bontragers come from the same Thailand facility so that's why I'm trying them now.

Casing Trueness

One of the big claims you'll see on tubulars is the "hand made" part.

To me, except for the artistic, non-mass produced things, "hand made" means "inconsistent". After all, if you made everything perfect by hand, it would look... mass produced.

Now, for whatever reason, gluing treads seems to be a manual job. Making the casing, not so manual.

Hand made casings seem to make for inconsistent shapes, due to the variances in the sewn part of the tire (under the base tape).

The Bontragers used to illustrate this post both boast "hand made" on the label, but one is so much more hand made than the other.

How do I know?

Just look at it.

"Hand made" usually means "Inconsistent". Note the Racer XXX sidewall wrinkles and base-tape "meandering".

The "Hand Made" Racer XXX casing doesn't hang straight. It's "Hand Made".
Note the almost perfectly straight looking Racer X Lite on the floor.

The more "Hand Made" Racer XXX sits above the less "Hand Made" Racer X Lite. Note that the Racer X Lite sits much more... straight than the Racer XXX.

The Racer X Lite seemed so much better that I glued them up first. The Racer XXX will wait for... I dunno what, maybe for some truly traditional box section type rimmed wheels. I want a pair for rainy bad weather races.

Tread Trueness

Another factor in selecting a tubular tire is its tread trueness. This is closely related to the casing shape and trueness. The absolute worst offenders I have ever seen or experienced are the Continental tubulars, the nicer ones. They have lumpy casing and the tread zig zags in a drunken manner. Granted, they are tough tires, but when riding rollers ends up a vibratory experience... yeah, not for me.

(As an aside, I plan on using up my Contis by gluing up some heavy box section rimmmed wheels training on them. Long rides, bad weather. Flahute. Gotta love it. Well, first I have to get my Flahute-ness back. Then I'll ride long rides in bad weather.)

The Bontrager Racer X Lite has a pretty straight tread. It must be similarly made to the Vittoria EVO CX (which, if you recall, is made in the same factory) because both tires sit relatively straight and spin nice and round. I have yet to ride the Racer X Lites but I glued them up the other night. Very easy, a little bobble around the valve (that's pretty common), straighter than not.

Tread

I joke with people who ask about tread that Contis have a file tread (i.e. no direction, no lines) because it's harder to tell how much a file tread wiggles. If there were any straight lines the rider would be horrified every time they glanced down at their wiggling front tire.

The Bontrager Racer X Lite has lines (two tread types) and smooth tread. The Racer XXX has the classic Clement Criterium tread, a herringbone type set up.

One doesn't work better than another, at least not for me. I tend to think that no tread works the best, but any tread on a bike tire is so fine that I can't tell the difference.

Tire Pressure

A huge part of a tubular's durability comes from the fact that the tire holds its own pressure in and that glue holds the tire to the rim. There is no wall on the rim holding in literally thousands of pounds of pressure, nor are there any super-tight beads cinching the tire to the rim.

With a properly glued tire, you can run pretty low pressures, especially off road. I haven't ridden too much off road, but I have gone a few hundred yards down a grassy field at close to top speed on my road bike (intentionally, at Rocky Hill, not like Lance in the Tour). I had my tires at normal pressures.

I run pretty high pressures (120/130 psi front/rear) - I like the sharp response and I feel like the tires grab better in the dry. I have to experiment in the wet because I've avoided racing in it for so long that I no longer know how to corner aggressively in the wet. I imagine a wider tire with lower pressure would work fine.

Width

You can easily mount wider tires, reducing the amount of pressure you need to run (to protect the rim).

You'll see some weird widths when checking out tubular tires. You won't see the ubiquitous "23c" tire markings. Instead you'll see 21 mm or 22 mm (typical all-purpose racing tires), 19 mm (time trial or track), and wider tires for durability (Paris Roubaix or general training).

I'm not sure why but tubular tires still get measured in mm. I buy the 21 or 22 mm tires.

Note: Bontrager has taken to the clincher type sizing numbers, so their tubulars are marked 700x23. If they were Vittorias, they'd be 700x21.

Tubes

There are two types of tubes in this world, other than the "no tube". TUFO is a brand that lines its casing with a tube-like material (seems to be butyl) - it has no tube. I'm not a fan of them - for whatever reason I had quick and multiple failures with that construction type.

Continental and many cheaper tires use butyl tubes. They're the black tubes you use with your clinchers. They're heavier, hold air overnight, and cost a lot less. I don't care either way for them - I use butyl tubes in my clinchers because they're cheaper, but I have a huge stash of lightweight ones (thinner wall tubes), so they're close to latex in weight.

Right, latex.

The nicest tubes are the latex ones. They're super thin (you see latex condoms, not butyl ones), they stretch pretty well (allegedly resisting punctures better), and they're light. They do not hold air overnight and they cost more. Vittoria's CXs usually come with them (I remember a batch that mysteriously held air - apparently Vittoria used butyl tubes for a short time for whatever reason).

Latex tubes force you to check the air pressure every time you ride because the tires are basically flat the next day.

Conclusion

So what tire should you get? Well, if I were buying tires for me, I'd get a set of circular casing tires with tread that is glued on when the casing is round. I want a round casing, one that's not lumpy, one that doesn't make my bike bounce up and down on the rollers or trainer. I also want a tire that's reasonably durable, so if I have to ride over glass in a crit I won't necessarily flat right away. I'd prefer a latex tube just because I know it's lighter, and if the tire is the same weight as a butyl-tubed tubular, I know there's extra material in the tread or casing. Finally I want a reasonably priced tire. For me, that means anything under $100 a tire.

The tires that fit this description?

At full retail, the Bontrager Racer X Lite, at $79.99. A great price for a tire that you should be able to order or buy at any Trek dealer in the US. That makes it probably the widest available tubular. I have yet to check out the traction and such, but I have full confidence that it'll be good (I have other Bontrager tires and they are fine). For a first tubular tire I think this would be a good one.

My favorite remains the Vittoria EVO CX. Street price is similar to the Racer X Lite, lower if you can find them. It has a protective belt under the tread, which the Racer X Lite may or may not have. It rides well, is round, smooth, and durable. I just removed tires I raced on for a year so I could glue on the Racer X Lites - and the tires, other than looking a bit dirty, look fine.

2 comments:

Kawika said...

Could use some advice on tire selection. My rim doesn't have a center channel for the Vittoria Corsa Evo CX II "hump", under the tape, to sit in so the tire kind of rocks and there's a 1-2mm gap on some edges.

Advice I received was to either build up some extra glue on the edges, which I completely furbar'd that and have to start over, or use tires without the hump in the middle like Continental, Veloflex or Challenge.

Do you have any suggestions on a tire from these manufacturers or alternative solutions? Thanks -- kleinboogie

Aki said...

I've always had good results using a bit extra glue, rolling around the glued tire/wheel assembly while inflated to about 20-30 psi, and then letting it dry overnight. Once it's dry and you inflate it, you should have pretty good edge of tire "seal". If you can't remove the tire by hand when it's deflated you'll be fine.

This applies to the older standard box section aluminum rims, none of which had the groove for the basetape lump (the stitching lump). These rims include various Mavics and Campy rims.

I don't have much experience with Conti (not keen on them, they're not very straight but they are reliable and durable, prob had 6-8 of them); Veloflex (seems like I had bad luck with the 6 or 8 I had). Bontrager seems nice (made in same place as Vittoria), I'll be gluing up a set shortly and ordered 2 more sets. Evo CX I've had probably 30-40-50+ tires, from the Italian days to the current one.