Challenge tires can help reduce shock and reduce rolling resistance, leading to an overall more comfortable, faster and longer ride!

Some of this is achieved by using a certain type of rubber compound. Challenge is lucky enough to produce there where the natural rubber drips from the trees rather than use artificially produced petroleum-based rubber or other synthetic substitutes, which obviously do not have the same properties as natural rubber. In fact, using natural rubber can increase the tire’s durability, and increases the cut, puncture and shear resistance. Another important point is the casing type used in combination with the rubber tread. A high-end, flexible casing provides:

-More grip as it allows more tread adherence with the ground.

-More comfort due to greater shock absorption.

-More speed, as its greater adherence provides lower rolling resistance.

The density of the weave of the casing is expressed in TPI (Threads per Inch of material), the greater the TPI count, the finer the thread and denser the weave.

A greater TPI count casing is actually the more supple and flexible but also stronger at the same time. Throughout time suppliers have been able to deliver higher and higher grade thinner threads which have made it possible for manufacturers using these improved threads, to go from a maximum weave of 260/300TPI to nowadays 320TPI and up. Challenge ranges from a ‘low’ of 220TPI to the higher +1000TPI.

The more supple & flexible the casing, the more comfort and most of all the more adherence and grip to the road, therefore achieving the most speed.

Challenge has maintained natural properties of the rubber and suppleness of the casing by opting for the so called “Handmade manufacturing process”.
This process avoids vulcanization (very high heat treatments) which would otherwise dry up, harden and mostly eliminate the fine properties of the natural rubber and would also stiffen the casings. The ‘Handmade’ process preserves the properties of natural rubber intact as well as the suppleness of the casings, allowing for unsurpassed adherence of the tyre, guaranteeing an optimal and confident bike handling for enhanced safety especially when cornering.

A PPS (a Puncture Protection Strip) is added for puncture resistance. Some models now have two (PPS2).

The tubular and handmade clincher become even more puncture proof when paired with our seamless latex inner tubes.
The great elasticity of latex tends to stretch and go around an object long before it puctures through, unlike butyl which punctures through very easily, releasing the air quickly to rapidly flatten the tire. Latex will be much more difficult to puncture, but even then, it will release the air very slowly allowing you to ride comfortably back, or to a point you choose, without stranding you.

The great elasticity and easy flex of the latex tube also further enhances the comfort of the ride, adherence to the road, contributing to an even lower rolling resistance = speed.

Handmade clinchers begin with being constructed with the same technology used to produce a tubular (it is the same production process of tread glued to a supple casing). They are then made into a clincher tire by folding the sides of the casing around aramid or Kevlar beads instead of sewing the sides together into a tubular with an inner tube inside. This type of beaded casing can therefore be mounted as a convenient clincher tire but, having at the same time the ride and almost the feel of a high performing tubular. This high quality performance in a conveniently mounted clincher tire, really makes the handmade clincher tire the best of both worlds!

March 13, 2019

Consumer Product Safety Bulletin

(technical clarification, following ENVE’s Consumer Safety Bulletin of March 6^th, 2019)

This bulletin is to reconfirm that Challenge Tires should not be used with any rims or wheels that do not comply with either the current 2019 ETRTO, past ETRTO or soon to be released ISO 5775 global standards for tire and wheel fit.

Challenge specifically clarifies herewith, that both old and new ETRTO and future ISO standards require a minimum 0.7mm rounded radius on all hooked rims.

It has come to Challenge’s attention that ENVE SES model carbon wheels do not comply with the above standards on the design of the rounded hooked rim radius. In fact, ENVE’s SES have two sharp (<0.2mm) radii in their hooks, that leave two parallel cuts about 0.5mm apart, around the entire radius of our (and other company’s) tires, at around 3-4mm above the bead.

Challenge has noted failures of its clincher tires, communicated by consumers and athletes, caused by the sharp edges on the ENVE SES hooks. This international design standard violation has been communicated back to the affected consumers, shops, endorsed teams, ENVE and their parent company, as Challenge has been made aware of problems. ENVE, however, continues to produce and promote usage of the said SES models, as part of their line.

Challenge has consequently been forced to list the specific ENVE SES rims as not compatible with any Challenge clincher tire models, on the website. Challenge asks that consumers do not mount ENVE SES wheels with any model of Challenge clincher tire whatsoever.

Failure to follow this warning could cause the ENVE SES wheel to cut Challenge’s quality casings resulting in explosive air loss from the tire and/or inner tube, potentially causing a crash and injury to the rider.

This bulletin also aims at providing the technical clarification, that only a precisely defined 622.0mm+-0.5mm bead seat diameter, specifically defined wall height and center channel, as described in the new above standards, will safely and easily allow proper tire and rim fit and function. Challenge has regularly been attending standards meetings and being involved for the past three years in confronting the market’s accelerated changes, such as the implementation of progressively wider rims, carbon fiber clinchers rims and tubeless and tubeless ready tire technologies. Challenge has invested time, knowledge and energy together with other elite bicycle industry companies to address and update tire & wheel fit issues with the ETRTO and ISO.

Challenge handmade tires have been produced for close to 20 years using the same handmade processes that have been proven over the past 50 years at the highest levels of racing without significant failures - if the rims and wheels comply with internationally accepted design standards. And this applies for both aluminum and carbon fiber rims.

Regarding carbon fiber rims, there had also been other periodic problems in the past with some carbon rims that had cut our (and other tire manufacturers’) tire casings just above the beads. These tire cuts were however normally caused by less than optimal QC at the factory, resulting in quality issues of improper finishing at the tire hook during production. Normally roughness at the hook was due to failure to completely remove resin flashings created while molding the rim. Proper finishing leaves the required 0.7mm min. radiused rim hook smooth, without roughness, thus eliminating a potential tire failure.

In the above cases, Challenge has routinely and successfully worked with the wheel suppliers (including ENVE) to fix the problems or replace these wheels to the consumer. However, specifically with ENVE’s SES model wheels, it is the first time that Challenge has known of a rim hook design that does not meet the above recognized design criteria, reason for which Challenge feels compelled to follow up with the release of this informative bulletin to protect its customers.

For further questions please contact local distributors or Challenge at info@challengetires.com.

• You can run them at lower tire pressures without worry of them burping or coming off the rim
• Tubulars provide a 10+% lighter weight wheel/tire combination requiring less energy to bring them up to speed, less energy to keep them at speed, provides a faster climbing system, and allows them to be a bit more responsive in changing terrain
• Tubulars don’t require rims with beads that can be damaged on rough terrain, thus less worry about your tires staying on the wheel after impacts
• The rounder tire profile, wider pressure options, and lack of beads that limit the tires movement, results in a tire that can flex better over undulating terrain improving comfort and control on longer rides and rough courses
• Can continue to ride on them after a significant loss of air which is safer when riding on higher speeds as this allows you to bring the bike back into control before stopping
• Replacements can be easier to install on the course. With TLR clinchers, you need compressed air to lock the beads against the rim and might need a second air canister or to use a pump to then set the ideal inflation level. Once you get the tubular installed, you only need to inflate once to set the desired air pressure

• As with TLR clinchers, H-TLTU (Tubeless Tubulars) allow the use of a tubeless sealant which can quickly repair small punctures while riding so you can continue to ride
• As with TLR clinchers, H-TLTU (Tubeless Tubulars) allow the use of tubeless plugs so that repair punctures that are too large for sealant to fix. Thus you can continue to ride

First Option Dry: Provided it was dry (Potentially dusty), I would start my pre-ride on the Dune. These tires are very fast and have more grip in the corner that you’d imagine. If you find you slide beyond what you feel comfortable with in the corners, try to lover the pressure, in very small increments.

First Option Wet: Hard Packed Ground when wet will usually only give you a problem in the corners and transition areas. I would first try the Chicane as these give you all of the confidence in the corners. You might even be able to run these at a slightly higher pressure, as you’ll naturally have the grip in the corner.

Other Options and Scenarios:

If the course has muddy sections due to the wet (Maybe you are in a late race and the course is already cut up), then go with the Grifo. This is a great option providing you with the best of both worlds above. You can be confident with a Grifo and they give you amazing variability when you alter the pressure.

REMEMBER: You don’t need to run the same tire tread front a back. Also don’t assume the same pressure front and back is the right option for you. Always ride what’s best for you. Don’t be influenced by those around you. Riding with confidence in your equipment makes you fast. Approaching a corner slowly because you’ve risked a more aggressive tire choice could slow your lap time down.

First Option: Grifo - When the ground is loose, you need to feel at one with your bike. You need to put your focus in pre-ride to find the best lines. The Grifo gives you the ability to move around on your bike and give you the right balance between grip and speed on the straights.

Second Option: If the course is loose, but you fancy riding in a “foot out flat out” way, try the Chicane. Maybe you’ll slide a few more inches but you can be sure the side wall grip is going to kick in and you’ll be fast on the exit as soon as you hit the straight.

Other Options and Scenarios: Loose ground can be cover to many things. If the loose sections are on up hills, you need to consider a Baby Limus rear so you can really get the power down and keep traction.

REMEMBER: Always consider the type of loose ground you on. You might want to run slightly higher pressure to avoid a flat if there are largish stones on the course. Ride with finesse and you’ll be fine. My tip would be have a slightly higher pressure on your pit bike to avoid a 2nd issue.

First Option: Whatever you would have used for the course should the sand not be there. Don’t change your race for one short section of sand. Consider the remainder of the course first and put your energy into being first into the sand pit.

Second Option: If there are multiple sand sections, try the Dune on a low pressure. This is the natural choice for loose sand, but if it’s going to neutralize the way you ride the remainder of the course then it’s potentially not worth it.

REMEMBER: You can ride sand on any of the Challenge tire options. Dry sand is loose, and often best ridden on a round tread with low side knobs avoid grabbing the sand, like the Grifo or Dune. Ride the ruts, and look forward to the exit of the sand pit.

First Option: Dune is the natural tire choice for these conditions. Think of the Koksijde world cup course as a pure sand course and you are looking to float over the sand and keep as little sand flicking all over your drive train from the tire treads as possible. Run them low.

Second Option: The Grifo might allow you to run a slightly more balanced race. If there is a little moisture in the ground, a fraction of the skill of sand riding has been taken away, and the sand will lean towards speed than balance. Having the ability to corner fast in the wetter corners could mean faster entrance to sand sections.

Other Options and Scenarios: If you have sand on one side of course and not on the other, you could consider 2 set ups if there are going to be a large number of pit changes. If you can change fast you won’t loose time and could have the best options for both sides of the course.

REMEMBER: When riding sand, steer with your eyes by being focused on the exits to the sand zones. You can ride sand on any of the tire options available from Challenge. Start aggressive and move up the grip options as you feel necessary.

First Option: Grifo - I tend to run slightly lower pressure in the front for my first lap of pre-ride and see how that rolls. Dry grass and fast transitions make for quick races, but often moisture comes out of the grass as it’s ridden over so the conditions can change slightly. Often you see this with slippery corners.

Second Option: The choice of many for grass is the Chicane. Fast in a straight line and great on camber, the chicane can give a great second option for grass races. Even with higher pressure, these are option well worth trying.

Other Options and Scenarios: The Baby Limus might give you that little more security in the corner, particularly where the grass is a little longer and you get some great hook up in the large side wall tread. Or the Dune will be ideal for those confident in a course, perhaps varying their line accordingly as a race progresses.

REMEMBER: If you are pushing things with your first option, put a more grippy option onto your 2nd bike. A fast dry course should mean no changes. A change in these conditions means potential disaster recovery, so plan for it in advance.

First Option: Wet grass means you need to be very aware of changes of condition during a race and try to predict what you might need. Things can change a lot from your last warm. I’d start with a Chicane, but be prepared to switch

Second Option: I’d have a Grifo on my 2nd bike. I’d run them nice and low to try to cover a lot of options.

Other Options and Scenarios: If you think the course could really cut up, then consider the Baby Limus. You’ll have lots of grip and it will clear very quickly on any asphalt sections.

REMEMBER: Find the limits of the tyres. Don’t change for more grip before you have experimented with your pressures.

First Option: The Limus will give you a consistent performance right the way around the course. They are faster than you think and mean you might be able to get away with no pit changes.

Second Option: Baby Limus is one step down from the Limus in terms of grip, but for a more aggressive option this could be the one. If you’re lacking grip, lower the pressure.

Other Options and Scenarios: The Grifo is a very happy tire in the dirt, wet or dry. Try it if you don’t quite feel you are getting what you need out of the Limus or Baby Limus .

First Option: Limus is your best friend in these conditions. All you need to be focused on is finding the right pressure for you, if you can be confident you can ride where others can’t.

Second Option: If you don’t have a Limus in your armory, then consider the Baby Limus nice and low. Get that tread flat across the mud and you will be amazed at the grip.

Other Options and Scenarios: You might be able to get away with a Grifo on the front and Limus on the rear. If the course has multiple long straights, you might be fine with this as it allows you to get the power down and maybe keep the speed up on the asphalt.

REMEMBER: Ride the ruts. They are faster and you can see what’s in them rather than hit hidden obstacles.

First Option: Dune will come into its own in these conditions showing its versatility. Snow means cold so the grip will be needed in the corners. You might have hidden frozen ruts so plan for slightly higher pressures when first checking out a course.

Second Option: Chicane could be your best option especially if the day is warm enough for the course to defrost mid race. It also have a little more bite in the corners if the snow is loose.

Other Options and Scenarios: You might find a Limus or Baby Limus on the rear and a Chicane on the front could be the fastest option.

REMEMBER: Frozen courses have a lot of hidden problems. Its worth an extra warm up lap to try to get the course very dialed in.

First Option: Dune would be the first option for me in pre-ride. I want as much rubber on the floor when I hit ice. Snow itself can give lots of grip in a corner so give the dune a try before scaling up your grip.

Second Option: Chicane might give you a little more grip in the corner helping you flow in the technical sections. These are really good when the course has more protected areas like in woods where less snow has reached the ground.

Other Options and Scenarios: Grifo are good in the ice. A round treads gives smooth transition free corning and therefore a smooth confident feeling.

REMEMBER: Riding in ice is a confidence thing. The more you can ride a course like you would in the dry, the better you are going to be. Try to adjust your tread choice not your riding style.

First Option: With all icy conditions I try to ride the Dune. They grip by giving me a lot of surface area on the floor, plus they keep me quick in the straights.

Second Option: Grifo is a good option on the Ice. Running low pressures they give exceptional grip and seem to be very at home in the ice.

Other Options and Scenarios: If you suspect the course will warm up and might get more slick in the corners, start with the Chicane and certainly consider this on the front.

REMEMBER: As with other conditions, set your 2nd bike up to try to predict for course changes and certainly give yourself a more secure option for a last minute change before you can get your pit crew to change your option for you.

Stronger levarage can be applied than with a standard plastic tire lever without risking it to break.

Standard tire levers are more brittle, risk not doing the job, you still somewhat hurt your fingers and can risk pinching the tube if not carefull, none of which will happen with this tool!

It is s a lightweight but strong, heavy duty nylon tool that helps to pull a tight tire bead over and seat it into the other edge of the rim.

It works by pushing against the rim wall on one side used as a fulcrum, while the other side will lift and pull the bead up and over the opposite edge of the rim.

Great for many consumers and shops to have around as an aid for more difficult tire mounts.

GRIFO

The Grifo can be used in different directions to achieve different results. If you point the arrow < < < of the tread forward the tire rolls faster.
If you turn the tire around with the arrow pointing backwards > > > the tire has more grip but added rolling resistance.

The rear tire is usually more suited to switching directions. Have fun trying different orientations for different conditions.

LIMUS/BABY LIMUS/CHICANE

For these tires it is advised to have the long arm of the "Y" pointing forward and the open V shape of the Y pointing back “ ˂ “ on both the front and rear tire.

The tire in this direction has less drag or rolling resistance. Additionally it also sheds dirt and mud better on the road, so that maximum grip is once again obtained. Using the tires in this direction on both wheels also ensures optimal grip.

You can run these the other way around with the open end of the "Y" hitting ground first if you desire more traction.
However, it will be slower when cornering.

The corespun cotton used in the TEAM EDITION and SERVICE COURSE casings absorbs more latex than our polyester casings.
We opted to include waterproof bead-to-bead coating allowing you to ride the tires as soon as they are installed, saving you the time normally required to seal a cotton tire. This new CHALLENGE sealing technology replaces the need to seal by hand with Acquaseal, Aquasure or similar sealant.
Though this may add a few grams to the tire, the combination still provides a more supple ride and higher performance than our SuperPoly tires.

Side note: all CX tires should be gently washed with mild soapy water and a soft brush, then thoroughly dried before storing. If and when the outer threads start to show through the casing the sidewall should be sealed again after it is cleaned and dried.

The longer answer is more interesting and here you will learn from the experts how to prevent a majority of these cuts from becoming a problem.

The natural latex and rubbers that handmade tires use in their casings and tread rubber are softer and stickier than synthetic rubbers and vulcanized processes used for normal clincher tires. Therefore a CHALLENGE tire may be more likely to pick-up a small sharp stone or piece of glass in the tread and hold it there for multiple tire revolutions, allowing the stone or glass to progressively cut the tread and eventually the casing. Essentially the same special soft, sticky materials that give the casings and treads incredibly low rolling resistance, cornering and traction also make them more susceptible to cuts if certain precautions are not applied.

In January 2013, the Belgian woman’s team CHALLENGE sponsors reported multiple cuts on many CHALLENGE training and racing tires. They had some similar problems with other tires and with CHALLENGE in the past, but now it seemed much worse. We felt this was strange because our second, larger (meaning both more and bigger riders), men’s Belgian team was riding the same tires and were not reporting any problems. We went to the men’s team training camp in Calpe, Spain to investigate this problem (along with having other technical discussions).

Immediately when I brought up the problem in front of team management they looked at me incredulously and said, ”What? You do not know that you need to apply vinegar to the tires before riding in this “season of the little stones”?” I could not have been more stunned.

They then patiently described (like to a child) that “everyone in Belgium” knows that in the “winter” (which in Belgium is the standard three months plus two months on either side when you can get “winter” for two hours on any give day) you need to take special precautions against tire cuts.

The state trucks that sand or grit the roads plus heavy rains that wash dirt from the fields combine to dump many small, sharp stones and pieces of glass into the roads. Cars then spray the stuff to the sides of the roads where cyclists are forced to ride through it. Average people know you need thick, heavy, hard tires on your commuting bike to keep from getting flats. Riders and mechanics for professional teams are all taught at a young age that you must treat racing tires with vinegar every two to three days during “winter” (or when “winter” suddenly reappears).

“Vinegar.” I said again, patiently, “Vinegar.” I thought they are pulling some old Belgian joke, which would be fine, but I did not want to pass along the joke before I understood I alone bore the brunt of the joke. “Yes,” they said, “You must wipe the tires with vinegar, any cheap vinegar, to clean the sticky oils from the tread and “dry out” the surface of the natural rubbers.” I know that vinegar is an astringent that will dry oils from your skin so I let them continue.

“The small sharp stone or glass may still stick in the soft rubber but after using vinegar the centrifugal force of the spinning tire will be sufficient (with the less sticky tread) to throw the sharp object out of the tire. The problem only comes when the sharp object stays in the tread and continues to cut, deeper and deeper.”

Hmmm… fortunately a mechanic walked into our meeting at that moment so I told my manager friends to stay quiet and I asked the mechanic how he kept the sharp stones or glass from cutting racing tires. He said, “Well, of course, I must apply vinegar to all of the tires every day or two before riding in the “winter” season.” Normally in Spain or Italy or southern France it is not a problem but he heard from other mechanics that this year, with winter snows heavier and further south, they needed to use the same process in these areas.

OK, the mechanics and managers were all in on the joke but I needed one more check. That night at dinner I chose one of the younger Belgian riders who came from a cycling family and asked him the same questions. He said his father taught him the same story when he was 12. Vinegar.

Long story short, if you want to have all the incredible performance - low rolling resistance, cornering and traction – that the Pros enjoy with Challenge Handmade tubulars but do not want to get a bunch of cuts or punctures, simply keep a rag handy and wipe your tires with vinegar every couple rides in that “season of the small stones”.

Challenge tires shipped by ocean freight typically come in a large square box where the tires are stored in a round state, partially inflated. Air shipments typically come in a rectangular box with the tubular tires folded. This is done to reduce air shipping volume and cost.

Due to the handmade nature of these tubular tires and the continual curing of the glues used in production, we ask that tubulars be removed from the rectangular shipping boxes immediately and inflated to approximately 20psi/1.4bar. Failure to perform this step can affect the glue bond in the areas where the tire has been folded to fit in the shipping box. Prolonged storage in a folded state can lead to tread separation at the fold and potentially also lead to the latex inner tube sticking to itself affecting the roundness and ride quality of the tire.

Ocean freight shipping box: 70x70x25cm (28x28x10in)

Airfreight shipping box: 95x32x32cm (37x13x13inch)

Do not store Challenge handmade tubular tires folded or hanging from hooks/bars.
As with the folded state mentioned above, hanging tubulars from a hook, or bar, could lead to folds that affect the juncture of the tread and casing as well as leading to the latex inner tube sticking to itself.

Do not remove tubular tires from their individual bags.
Some Challenge tubular tires come individually wrapped in a bag to help with curing and protect the tire. To inflate, the valve can be carefully pressed through the plastic and then slid back into the plastic after inflation.

Store tubulars in a dry, dark area.
Like a fine wine, Challenge tubular and open tubular tires need a dry, dark space to properly age and prepare for a long, productive life. Moist air can inhibit glue curing leading to premature tread separation and/or formation of mold that shortens the lifespan of cotton or silk casings. Prolonged exposure to UV rays (sunlight) will dry the rubber materials used in both the tread and the casing reducing the lifespan of the tire. To prevent premature cracking of the tread or casing, store tires in a dark area such as a warehouse, basement or garage, away from windows and sunlight and potentially supported by use of dehumidifiers during the humid part of the year. Do not leave your tubulars or bike with tubulars outside in direct sunlight for prolonged periods.

Artisanal products require special care.
Challenge tubular and open tubular tires are high performance products combining special materials using labor-intensive processes. Unlike the common vulcanized clincher, special care and handling is required to help the materials and the glues properly cure. Adherence to the steps and warnings mentioned above will prolong the life of these tires and provide customers with an optimal experience.