29er (bicycle)

For the type of skiff, see 29er.

29ers or two-niners are mountain bikes that are built to use 700c or ISO 622 mm wheels. Most mountain bicycles use ISO 559 mm wheels which are commonly called 26" wheels. The ISO 622 mm wheel is typically also used for road-racing, trekking, cyclo-cross, touring and hybrid bicycles. In some countries, mainly in Continental Europe, ISO 622 mm wheels are commonly called 28" wheels or "28 Incher".

Origins

29" and 26" mountain bike wheels

29er rims have a diameter of approximately 24.5 inches (622 mm) and the average 29 in mountain bike tire has an outside diameter of about 29.15 in (740 mm). The typical 26" rim has a diameter of 22.0 in (559 mm) and an outside tire diameter of about 26.2in (665 mm).

In the early 1980s, the size of the wheels for the emerging mountain bikes was undecided. So when English off-road cycling pioneer Geoff Apps contacted Gary Fisher and Charlie Kelly with news that he had built a prototype off-road bicycle that used 700c Nokian snow tires from Finland, they were intrigued. In December 2006, Gary Fisher, speaking about the growing popularity of 29ers, gives his perspective: “We got some tires from Geoff Apps really early on and we [Fisher and Kelly] said ‘Holy Toledo!’” But the poor supply situation of the larger diameter tires meant the fledging MTB industry stuck with the smaller wheel size." The first Geoff Apps designed 700c off-road bicycle was made in 1981 and was marketed as the Aventura by Apps' own company, Cleland Cycles Ltd , between 1982 and 1984. However production bikes used the more readily available Nokian 650b tires.

Various people claim to or are attributed to be the originator of the term "29er", the most plausible being Wes Williams of Crested Butte, CO. The US division of Bianchi Bicycles offered a line of 29" wheeled off-road bikes beginning in 1991 called the Project bikes. Their 1992 product catalog raved about the advantages of the larger wheels and showed three different bikes, the Project 3, 5 and 7. The original company Klein produced a small quantity of a 29" wheeled version of their successful "Attitude" MTB racer, and named it the Adept. It failed to find a market and was discontinued. In the mid 1990’s, Diamondback Bicycles made their Overdrive bike, and Specialized made their Crossroads bike with 700c wheels, but they were actually hybrid bicycles with frame and fork clearance for larger tires. The Project and Overdrive bikes were not a success for many reasons, primarily a lack of proper off-road tires and suspension forks competitive with the 26" offerings of the time.

A key product release, the first true 29" tire, was produced by an early supporter of the 29" movement Wilderness Trail Bikes. The company introduced the first true 29" tire, the Nanoraptor, in 1999. At about the same time, White Brothers produced the first commercially available 29" suspension forks. Before then suspension forks used were forks designed for trekking bikes or hybrids. For many years 29" frames and bikes were usually only available from small little-known manufactures like Niner Bikes. Surly Bikes introduced their 29" frameset, the Karate Monkey, in 2002. Gary Fisher Bicycles, a division of Trek Bicycles, became the first of the major manufactures to offer a line of 29" bikes. Their lines never sold well until the introduction of single-speed 29" bike the Rig, in 2004. Today most bicycle manufacturers in the US market offer at least one 29" bicycle or frame. Even companies that openly dismissed 29" as a bad idea or passing trend, Specialized and Turner, are bringing 29" wheels to market.

Tires

A tire with a tread width of less than 2.0 in (51 mm) is considered a cyclocross tire by 29" enthusiasts, even though in cyclocross, any tire wider than 1.5 in (38 mm) is not a cyclocross tire. Although they are both intended for offroad use, and typically use a 622 mm rim, cyclocross bikes and 29" wheeled MTBs also differ, in the bike's basic handling and geometry, construction methods, durability, and intended lifespan. Bikes exist that blur the distinction by combining attributes of both, however. One example of this is a Monstercross bike, with 38c-45c tires, disc or cantilever brakes, MTB or cross gearing, and the drop bars and geometry of a cyclocross bike.

Performance

A debate over the advantages and disadvantages is currently raging in the mountain bike community. Those who believe the 29" wheel to be inferior often mention added weight, perceived sluggishness in handling, and problems with fit (specifically, front wheel/toe overlap and high standover height). 29" enthusiasts respond with comments about reduced rolling resistance, perceived increased stability without sacrificing quick handling, and an enhanced ability to roll over obstacles.

One item that is often raised is tire contact patch size and shape. All else being equal, such as tire width, rim width, and inflation pressure, the contact patch of a 29" wheel has approximately the area and is slightly longer (~5%) than that of a 26" wheel.

Advantages

• Larger wheels roll over obstacles more easily due to decrease in approach angle
• The larger diameter wheels have more angular momentum so they lose less speed to obstacles and rough sections
• 29" bikes tend to offer taller riders a more "natural" frame geometry

Most of these claims have yet to be objectively investigated. Small scale, unpublished studies (including one done by Pepperdine University, reportedly at the request of Gary Fisher) exist but both proponents and detractors of 29" wheels are generally unimpressed with their scientific rigor. Long debates over how to conduct a "fair" test of the efficiency of 29" vs 26" mountain bikes have raged online, but no serious efforts have been made to conduct a large-scale, scientific study.

Drawbacks

• Increased wheel weight and rotating mass (the spokes, rim, and tire are all larger) makes the wheels harder to accelerate and harder to brake
• More force needed to change steering angle due to greater mass and longer contact patch.
• Longer spokes and decreased angle between hub flange and rim result in a more laterally flexible wheel (all else equal).
• Many types of bicycle tires, rims and forks do not come in 29"-compatible versions, though the expanding popularity of the size is reducing this problem.
• Smaller riders (i.e. less than 5'5" tall) may not be able to find a 29" bike with a geometry suitable for them. Numerous examples exist of custom bikes built for very small riders with 29" wheels, but in many cases smaller riders face significant geometry tradeoffs, especially with regard to toe overlap, handlebar height, and standover.

96 or 69 Variations

One variation is to have a 29" front wheel and a 26" rear wheel (commonly called a "96er"). Using the smaller rear wheel allows shorter and quicker handling frames, more options for rear suspension designs and lighter bicycle weight. Another variation is to have a 26" front wheel with a 29" rear wheel (commonly called a "69er"). Depending on the manufacturer, these names can be, although rarely, reversed. For example, Trek introduced a "69er" in 2007 with a 29" front wheel and a 26" rear wheel.

External links and references

• article on bicycle tire and rim sizes from Sheldon Brown's website
• Twenty Nine Inches, A 29er enthusiast site
• 29pollici.com an italian site entirely committed to the 29 inch wheels
• A 29er informational site
• Geoff Apps' company - Cleland Cycles who made a 29er in 1981
• Test data comparing 26" vs 29" bicycle wheels
• Cycling News Article comparing 26" and 29" performance
• Big Wheels or Small Wheels?, Lennard Zinn's July, 2005 VeloNews article
• Trigonometric basis for increased wheel strength at reduced spoke angles (Archived 2009-10-22)
• 29er Online – Reviews on 29er bikes and 29er parts with bias noted