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, therefore this type of bicycle is called 28er there.

Origins

A 29" and 26" Mountain Bike wheel

The term 29er or two-niner is a little misleading. The rims have a diameter of approximately 24.5" (622 mm) and the average 29" mountain bike tire has an outside diameter of about 28.5" (724 mm), though tires exist with diameters of over 740mm. The typically 26er rim has a diameter of 22.0" (559 mm) and an outside tire diameter of about 26.2" (665 mm)

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. Bianchi made an early attempt (in the mid 1990s) to build an off-road 29" bike, called Project X. At about the same time, Diamondback made a bike that was very close to a 29er, called the "Overdrive". The Project X and Overdrive bikes were not a success for many reasons, primarily a lack of offroad tires and suspension forks competitive with the 26" offerings of the time.

Other early supporters of the 29er movement were Wilderness Trail Bikes (which introduced the first 29er tire, the Nanoraptor, in 1999), White Brothers (who built the first commercially available 29er suspension forks), and Independent Fabrication. Small, little-known custom manufacturers, however, were the backbone of the 29er market until recently. Currently Gary Fisher bicycles is the largest major bike manufacturer in the US market that builds 29ers. Other mainstream companies producing 29ers include Niner, KHS, On-One, Surly, Salsa, Dean, Moots, Titus, Ventana, and Lenzsport, among others. The trend seems to indicate that more major manufactures will begin developing and marketing mountain bikes with 29” wheels in the future, though the ultimate portion of the mountain bike market that will be dedicated to 29" wheel bikes in the future remains unknown.

Tires

A tire with a tread width of less than 2.0" (50 mm) is considered a Cyclo-cross tire by 29"er standards. This differs from the standards of cyclo-cross racing that consider any tire wider than 1.5" (38mm) as not a cyclocross tire. Although they are both used offroad and typically use a 622mm rim, cyclocross bikes and 29ers differ in many ways, specifically with regard to toptube length (most cyclocross bikes are about 2" shorter when built for a similarly sized rider), tire clearance, chainstay length, ability to run a suspension fork, bottom bracket height and brake setup, among others. Bikes exist that blur the distinction by combining attributes of both, however.

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.

Advantages

• Larger wheels roll over obstacles more easily due to decrease in approach angle
• Larger wheels have a lower rolling resistance for the same width tire
• 29”er wheels are less prone to sinking in soft material such as sand and mud
• Larger wheels are less prone to pinch flatting
• The longer contact patch increases cornering traction - rumors that the contact patch of a 29er tire is "larger" are incorrect; the surface area in contact (assuming a flat surface) is equal, with the 29er tire having a longer and narrower point of contact.
• 29"er bikes tend to offer taller riders a more "natural" frame geometry.

It is worth noting that most of these claims have yet to be objectively verified one way or the other. 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 lack of 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.
• Many types of tires, rims and forks do not come in 29"-compatible versions, though the expanding popularity of the size is reducing this problem.
• Longer spokes and rim result in a theoretically more laterally flexible wheel.
• Longer spokes and decreased angle between hub flange and rim result in theoretically weaker wheel.
• 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 in order to ride a 29er, especially with regard to toe overlap, handlebar height, and standover.

Social Aspects

Proselytizing

Some 29er enthusiasts spend lots of time raving about 29er advantages hoping to convince more riders to switch from 26” MTBs. This is likely part altruism and part attempt to increase the market presence of 29er items. The 29er market still suffers from a smaller choice of frame designs, suspension forks, tires and wheels, though the rapid growth of the sector is attracting more mainstream manufacturers.

On-line debates

The debates regarding 29”ers can be viewed at many places, especially on-line forums such as those on Dirt Rag Mag and Mountain Bike Review. Usually many insults are traded on-line as people feel less restrained than in conventional social forums.

Variations

Trek Bicycle Corporation is introducing a 69er for 2007 with a 29 in front wheel and a 26 in rear wheel.

Carver Bicycles also has, what they call a 96'er, with a 29 in front wheel and a 26 in rear wheel.

External links

• Sheldon Brown's article on bicycle tire and rim sizes
• Twenty Nine Inches, A 29er enthusiast site
• 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
• Theoretical comparative wheel strengths based on hub flange / rim angle