Introducing The New Cobalt, Iodine, And Opium Wheelsets From Crankbrothers

When the founders of crankbrothers, Carl and Frank (get it? Carl + Frank = crank), first began developing a wheelset back in 2005, they wanted to create a wheel that had a more thoughtful design. In order to make something that is either stronger at the same weight, or lighter at the same strength, you have to use materials in a better, more efficient way. Carl and Frank wanted to completely pair up the spokes because paired spokes form a triangle, and triangles are the strongest geometric shape. This thought process lead to the design of the iconic and unique ::twinpair spoke wheelset, which was originally launched in 2008. Since then, we have continued updating the wheel design based on athlete feedback. In 2010, the 2nd generation wheelsets were launched with a new freehub design. Now, we are excited to share the newest generation of crankbrothers wheels.

Introducing the new cobalt, iodine, and opium wheelsets from crankbrothers.

Over the last two years, the engineers at crankbrothers have been focused on improving our wheel collection by redesigning the rim profile. With a design focused on strength : weight, the new rim profile is tuned for durability, lateral stiffness, and vertical compliance. We partnered with some of the world’s best athletes during our development and testing process to ensure that our wheelsets will exceed the demands of the most discerning and aggressive riders. With the addition of a 27.5 diameter, reduced prices on level 2 and 3 wheels, and full axle compatibility, the crankbrothers wheelset collection is an ideal upgrade to any mountain bike. As Hans Rey says, “crankbrothers wheels have been my loyal companions on many rides in the most remote corners of the globe.” Where will crankbrothers wheels take you?

“When we test new wheels, we train, practice, and race on the prototypes in all kinds of real world situations. The wheels get used hard, maintained, and replaced, so we can see where the weakest points are and report our findings and feelings on performance. The original MY 2008 opium wheels were pretty good for entering the DH wheel market for the first time. There were a few flaws with the freehub bodies, but those issues were resolved in the next generation hub. The MY 2010 opium wheels had the hub figured out, but the rims were too weak. This lead to a total redesign of the rim for MY 2014. Everything was considered: rim width, shape, height, material, joining, etc. With the redesign, we wanted a better seal for tubeless, more stability, a black option, as well as a rim that wasn't so hard and stiff it would flat, but that it could also hold up in rocks and big hits. These wheels have held up amazing with both tubes and tubeless, on a wide variety of terrain at speeds and under pressure. I think crankbrothers found a balance with the stiffness and width that takes impacts really well.”
- Jill Kintner, Norco International DH Team

Over the last 2 years, the engineers at crankbrothers have been focused on improving our wheel collection by redesigning the rim profile. With a design focused on strength : weight, the new rim profile is tuned for durability, lateral stiffness, and vertical compliance. We accomplished this by focusing on three key design elements in the rim profile: 1) internal lateral widths have been increased by 2mm on each model, 2) all sidewalls are 1.7mm lower, and 3) all rim depths have increased. We also focused on reducing weight in four key areas, including removing the original central I-beam, tapering sidewall thickness, reducing bead hook width, and reducing sidewall height. The reduced bead hook width and sidewall height, along with the curved tire well and non-perforated tire bed, also make the wheels incredibly easy to setup tubeless. After thorough FEA stress analysis, extensive machine testing, and hours of ride testing, we are certain that you can have confidence in the new collection of crankbrothers wheelsets.

Tech Specs

Wheel size facts Part 3... Contact Patch and Tire Factors

Banshee sent along part 3 of their tire/wheel series today check it out below....

In this post, I'm continuing with the wheel size theme, but looking at tire related factors such as contact patch, tire pressure and tread. Check out Part 1 and Part 2 of this mini series for some other wheel/tire things to consider. In Part 1, small wheels beat big wheels, but in Part 2 big wheels fought back... so which, if either, is going to come out top for you?

Here, I  discuss contact patch and related factors across the 3 common wheel sizes. Once again I will be taking the wheels and tires from Part 1 for consistency.

Contact patch:

What is the contact patch, and how does it effect grip and rolling resistance?

The contact patch (shown in fig.1 in blue) is essentially the footprint of the tire that is making contact with the ground at any instant in time. For any given tire, it will change with tire pressure, as Pressure=Force/Area. So the lower the pressure, the more your tire will deform to the contours you are riding over.

A larger tire contact patch area represents more rubber on the ground, which increases friction and therefore grip (good). However, the larger the contact patch area the greater the rolling resistance (bad). So, as with most things, there is always a compromise, and you just have to pick the right balance between grip and rolling resistance to suit your needs.

Shape and area:

For this section on contact patch shape, let's look at a basic representation of each wheel size (no tread, and no tire stiffness) each with 2.3" width , based on 50kg of weight (assuming 50:50 weight distribution, and bikes + rider = 100kg), and 2Bar (about 29PSI or 200,000 N/m²) of a perfect gas on a flat surface for all wheel sizes. Since the pressure is the same in each tire, the contact patch area will be the same for this scenario as Pressure=Force/Area. This is not very realistic as pressures will change a bit with wheel size (I will go into that later), so this is just to give an idea of patch shape.

 

In Fig .2 you can see the 3 wheel size contact patches overlapped for the same tire pressure and loads: the bigger the wheel size, the longer and narrower the contact patch. But the variation in shape is probably much smaller than you'd expect, or have been made to believe. So let's look at this slightly differently...

One way of measuring optimal tire pressure is actually as 'tire drop', which is a percentage of original tire height (a little like suspension sag) as seen in Fig.3.

pressure, as well as contact patch shape and area for each wheel size.

As you can see in Fig.4, the contact patch area and lengths change as tire pressure changes, but the width remains the same due to same tire carcass width and cross sectional shape. So for the same tire drop of 6% the 29" wheel has a 2.7% bigger contact patch than 650b, which in turn is 1.85% larger than 26". The difference in contact patch area and shape is far less than most marketing would have you believe, but it is present.

This also shows that the larger the diameter wheel, the less tire pressure is required to achieve the same tire drop. Therefore you can get away with running lower tire pressure on bigger wheels if you wish. That said, the volume of the tire is the more significant factor, so the width of the tire will have a more significant impact on required tire pressure than wheel size.

These factors are the reason that mountain bike tires are wider than road bike tires. For road cycling, traction is less important than minimising rolling resistance (and weight) and so they run narrow low volume tires at high pressure. Mountain bikes run lower pressure, larger volume tires to increase traction as well as shock absorption. It's a case of picking the best tool for the job, by optimising what you want, and compromising on factors that are not as important to you.

Tire tread and compound:

All this marketing chat about contact patch actually ignores the most important factor. Tread patterns are massively relevant, because in reality, none of us ride around on fully slick tires. So when talking about contact patch, we really should be considering actual contact patch of the top of the treads on the surface, and also considering the extra grip provided by the edge of the treads biting into soft ground. Tread pattern and rubber compounds make a bigger difference than contact patch area.

The tread pattern changes the contact area far more than wheel size will!

So when thinking about grip, rather than think too much about wheel size and exact tire pressures, you'd be better off spending that time and effort picking the best tire tread pattern and compound for the riding conditions and experimenting with different tire pressures.

A softer rubber compound (lower durometer) will not only deform more to 'grip' the ground, but will also help damp the ride by compressing more easily under impacts. If you use a new soft compound tire you will be able to brake later, accelerate faster, and corner harder because the tread will bite into the ground with nice sharp edges, and the soft compound will have a higher coefficient of friction, and absorb the shock to stay in contact with the ground better.

For you to consider:

From all the information above, you can see that a bigger wheel will offer a slightly larger contact patch area due to the fact that you can run a slightly lower tire pressure. Therefore, a larger wheel will offer a bit more grip than a smaller wheel with same tire drop, but the increase in theoretical traction of larger wheels is probably less you were expecting.

With the larger tire contact patch comes more rolling friction, and efficiency is reduced. So smaller wheels are more efficient than larger wheels in this area for same tire drop. On a perfectly flat surface with a slick tire, smaller wheels with equal tire drop will lose less energy when rolling along than bigger wheels.

But let's be real... mountain biking isn't about just rolling along flat surfaces and we certainly don't use slick tires! It's about carrying speed through rough sections, cornering hard on the edges of tires, finding traction when climbing steeps and many, many more fun things. For most of these things, tire tread pattern and tire rubber compound are FAR more important than wheel size when it comes to grip. So my advice to you is not to get too lost in these wheel size numbers, instead pick a good tire choice and just enjoy riding your bike!

PROJEKT ROAM: Landscapes Vol. 2

If it wasn't for the colorful and diverse landscapes that decorate and geographically define our country, where would we ride? Landscapes is a film series that celebrates and depicts the fruit of the earth's time and toils with the elements that have helped to create and shape the terrain we mountain bike across today. Volume Two of Landscapes showcases several sides of the multi faceted trail systems found in Durango, CO. This elevated, mountainous country provides a plethora of variation and trail options for any mountain bike adventurer to explore.

Situated at 6,512 feet above sea level in the lush Animas River Valley, Durango, Colorado is a town that is as rich in culture, history, and outdoor recreation as the surrounding ore laden San Juan Mountains. The former mining town has it's own quirky, laid back vibe; an eclectic mix of mining town meets mountain town meets the west.

With a long standing reputation as a bicycling mecca, Durango turned out to be an optimum choice for us to spend time exploring on two wheels. Spiraling outwards from the hub of downtown, the countryside is magnanimous.

The ever present contour of rugged mountain peaks that define Colorado's high country seem to be synonymous with the horizon in nearly every direction.

The riding found in the higher elevations can be grueling with arduous ascents, sometimes leaving you thinking that your oxygen just might have been stolen from you like a thief in the night. But it doesn't really matter, because the descents and the surroundings, along with the whole experience, completely overpower those minute grumblings. Especially when you blast down the mountain with an ear-splitting grin while your entire focus and being are trained on the trail as it flashes by before you and still winds downward thousands of feet below you.

We spent some time wandering through the high country in the outlying mountain passes sprawled around Durango, it was as if you're taking a step back into time.

Abandoned ghost towns, ripe with dilapidated wooden buildings, endure the harsh winters and picturesque summers slowly succumbing to the inevitable forces of nature and time.

Old abodes, equipment, mines and mills in various stages of decomposition are often in view, blending in with the natural surrounds, silent and weather-beaten monuments of a time passed.

These artifacts of a different era made for remarkable, exploratory stops during our adventures in the high alpine single track wonderland.

Many of Durango's different riding areas provide trails that make their way through twinkling groves of aspen and meadows stippled with an abundance of flowers that range from every colour under the sun. This scenery is definitely more noticeable when you stop for a ride regroup.

There are numerous trailheads and trails to be found scattered everywhere about the city, it seems. An added bonus is that all of these different, local riding locations are unique unto themselves.

Rocky terrain and scrub brush dominate the landscape with clay coloured earth cushioning the tires' tread in some of the trail riding regions.

One of the things that makes this mountain biking haven stand out was the ability to spend a day on a trail that carried you through stands of pine passing an occasional crystalline lake if that is what you were in the mood for.

Or if you wanted a completely different ride the next day, it wasn't a problem to hit up a trail with manmade features including jumps, drops, and berms.

We happened to be in Durango during the summer months in which monsoon season dictates the weather pattern. Once this tumultuous weather hits, many a trail day can turn into an electrifying adventure.

A ride would start out with perfect, textbook weather. Over a matter of a couple hours, our senses would become bombarded with brilliant flashes of light accompanied by the sounds of roaring thunder.

The thunderheads sometimes brought moisture that turned the dirt into tacky trail heaven, or on other occasions, completely saturated us and the trail completely with torrents of rain. Whatever the ensuing weather brought, we knew we were always in for a thriller, hair-raising time.

Whether it's after spring snow melt, during the warm, sunny months of summer, or in the autumn, Durango is definitely a place with a genuine multitude of trails to ride and enjoy on a mountain bike.

 

Projekt Roam was founded by husband and wife, Colt and Jessee Maule in 2010. It has been their mission to travel North America in search of places that celebrate the unparalleled beauty and freedom of not only the bike, but the terrain we ride as well. Plan your own trip to Durango, CO and check out more photos, film, and riding locations throughout North America at www.gravityrideguide.com.

Thanks to our sponsors for some great product and to all of our new friends who have helped us out along the way, ride on.

Words: Jessee Maule

Photos/Film: Colt & Jessee Maule (Filmed May 2013)

Riders: Colt Maule & Jessee Maule

Wheel Size Facts Part 1-Dimensions, Weight and Strength

The boys over at Banshee Bikes sent this along today it is a good read on wheel size.

"You may have read certain online and printed marketing startegies which talk about wheelsize with a significant bias towards one size. The size they promote will always be either the only size that the source company produces, or the size that they want to push. Intentional marketing spiels are often very misleading and can skew the purchaser's judgement.

I feel it is my duty to set the record straight by writing a series of blog posts that kick off with this one, which addresses two key components of wheel size: weight and dimensions (and little bit of strength thrown in for good measure!). I plan to give unbiased information that you may find useful when deciding what size hoops you want your next purchase to be.

I can offer nonpartisan information (actual facts, rather than marketing blurb) as here at Banshee we offer all 3 mountain bike wheel sizes. We let the customer decide what they want rather than force it upon them, so have no reason to promote one over any other.

Every wheel size has its pros and cons, so picking the best wheelsize for you really comes down to personal preferance. The main things to consider when picking wheel size are your riding style, riding purpose (style or speed), the terrain you ride, and rider height, but there are also many other factors. I'll try my best to cover the main ones.

The following camparisons for this whole series are based on using Maxxis High Roller II 2.3" tires on each wheel size with same rim width for all sizes.

Any comparison I do will be relative to 650b wheels since they are the middle wheel size and so it makes the % change figures clear and consistant.

Dimensions: (Outer tire dimensions taken from official Maxxis 3D files)

Straight away this table is likely to cause some confusion... because as you can see, none of the rims or tires match up to their name sake. You can find out why this is the case by reading from a master of bike knowledge Sheldon Brown.

However, one point to notice is that while 650b is marketed as 27.5", it is only 1" larger diameter than 26", and 1.5" smaller than 29", so it is significantly closer to 26" than 29.  The 650b tire (often marketed as the 27.5") does not actually fall equally between the 26" and the 29" tires, so the characteristics of the 650b are far more similar to 26" than 29" wheels.


Weight:

Static weight

Obviously, tire and wheel build weights can vary significantly for all wheel sizes. So I'm sticking with 2.3" wide High roller II 3C/EXO/TR. For the wheels, I will use Stan's ZTR Flow EX wheels for each size.

Static weight (the weight of an unrotating wheel) is often emphasised by marketing teams. But it only really matters when you lift the bike on and off a rack or carry it on your back. However, static weight does have an effect on the...

Moment of Inertia

Moment of inertia is resistance to angular velocity change about an axis of rotation. Basically, the higher the moment of inertia of a wheel the harder it is to accelerate (and decelerate). This is far more significant than static weight when riding a bike.

Moment of inertia is related to both radius and mass, as Moment of Inertia (I) = Mass x Radius². A low moment of inertia results in a fast accelerating wheel (easy to start spinning). The flip side of this is that a high moment of inertia is harder to decelerate (harder to stop spinning), and so the wheel will carry the speed better once rolling if all other factors are equal.

The below table shows approximate moments of inertia by using the BSD as the effective rotational radius for all wheel sizes. 

What these numbers illustrate is that if you ride flowy trails that do not require lots of braking and accelerating back up to speed, then a larger wheel might be a better choice. However, if the trail demands regular braking and pedaling up to speed again then a smaller wheel might be better suited.

If using the same effective components, then as the wheel size increases the weight and inertia increase accordingly (as you would expect)... but because inertia increases at a rate that is proportional to the radius squared, it goes up more steeply than weight as the wheel size increases.

Strength:

A factor that is strangely often overlooked by marketing teams is that of the strength and stiffness of the wheel. I find this particularily strange as wheels cost a lot of money, and are subject to a lot of abuse, and personally the lifespan of a wheel is a significant factor to me when chosing what set to invest in.

If comparing like to like wheel builds (same rims, hubs etc), smaller wheels will always inherintly be stronger than larger wheels. This is due to wider gaps between spoke eyelets and poorer spoke triangulation etc. So strength to weight ratio is something that will always be won by smaller wheels.

It is however easy enough to compensate for this by getting stronger and stiffer wheels, but they do generally either weigh, or cost more. So something has to give.

It doesn't stop there....

Weight, dimensions and strength are obviously very important factors to take into account when considering what wheel size to choose. But... there are other factors too! And if this mini-blast of physics chat hasn't put you off too much, stay tuned for future blog posts about topics where bigger wheels have the advantage."

George and Neko Both Finish Top 15 at World Cup Finals

Perfect sunny conditions prevailed for the final World Cup race of the 2013 season here in Leogang, Austria, where Trek World Racing’s remaining uninjured downhill riders Neko Mulally (USA) and George Brannigan (NZL) had solid qualifiers Saturday. Neko had a career best qualifier coming in 7th place, and George had top 10 splits on his way down the hill, but 400m from the line had a crash which cost him time. However both riders went into the finals today knowing they had top 10 pace.

George went off about 1 hour before Neko and had a great run going. His run put him into the hot-seat as fastest rider at that point but only after unclipping his foot on the approach to the same corner where he fell in qualifying, crushing the family jewels.

“Yeah that was a pretty uncomfortable way to finish the run, but overall it was going well until then. I’m sure I lost a few seconds and even though I’ve ended up 13th for the day, I was having a solid top 10 run until that mistake. Considering I also hurt my shoulder in the crash yesterday and it wasn’t that good today, I do know the speed’s there and I feel 100% back to my best now”, said George shortly after leaving the hot-seat, where he sat for close to an hour.

Neko was on a great run as well and would have slotted into 3rd at the end of his run, and a guaranteed top 10, but lost 3 seconds in the final sector after making an error while pushing hard.

Neko said: “I knew I was having a great run, perhaps my best ever in World Cup racing and as I got towards the lower section of the course I made the conscious decision to keep pushing. Sometimes it’s easier to back off when you’ve had a great run for most of the course, but really great runs only come when you push the whole way. It can be riskier and unfortunately for me I did make that one mistake, but I’m glad I pushed for the result rather than be conservative. Finishing top 15 overall for the season was my goal, and today I achieved that”.

Team Owner Martin Whiteley summed up the Downhill season. “Injury definitely played a big part in our 2013 season. Aside from George’s knee recovery which we were aware of coming into the season, Brook’s shoulder injury before Andorra had a big impact for us. Then with Greg fracturing his collarbone and separating his shoulder in South Africa, it made for a tough time. Having said that, we have an awesome group of riders and there is strong team unity, and for me that’s very positive. Neko and George have done a great job these last 2 World Cup races and I know we’ll be back very strong in 2014.”

Next month Neko and Greg are planning to race in Mexico at the Taxco Downhill, and some other events may be announced in the coming days.