Twentyniner
Nearly no other current MTB trend has been discussed more intensively than the emerging 29” giant wheels. Over a long period, “Twentyniners” were generally just regarded as a marketing gag from the USA. But now, there is more and more evidence that these sportive bikes with mighty wheelsets offer many benefits when compared to their 26” brothers. At first, 29ers were often criticized for lack of agility and liveliness. Meanwhile, those disadvantages have been cut down to a more than tolerable minimum e. g. by gradual weight reduction with respect to components – especially wheelsets and tires. Since then, at the latest, 29ers enjoy increasing popularity among enthused bikers. But how can we define the beneficial differences between 29” and 26”?
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Enhanced traction
Especially hardtail riders appreciate a 29” wheelset’s larger “surface contact face”: Under same preconditions (tire pressure, profile and width), 29ers offer better surface contact than 26” versions (as shown by the thinner and longer oval “E” in Image 1). Advantage: The tire rolls with less energy expenditure while providing a wider tread/surface grip area – and therefore better traction. Uphill, this means deferred rear wheel slippage. During sharp turns, 29ers grant increased steering control due to added lateral stability.
Easy over obstacles
Every trail has a lot of obstacles – bikers are purposefully looking for thrills like tree branches, roots, rocks or cliff edges. 29” advantage: These giant wheels master such challenges more easily thanks to changing leverage. The latter results from a combination of weight force (W; downwards) and driving force (D; in direction of travel). Example: If a root is hit, the weight load on the tire (W) has to be carried over the obstacle via driving force (D). In case of a 29er, the proportionally bigger leverage (a) provides a more efficient moment of force. Thus, bike and rider experience less impact deceleration at obstacles – and keep on rolling more easily.
Rolling resistance
Thanks to its different “surface contact face”, the bigger tire manages on less flexing. Result: Reduced rolling resistance.
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