The 29er topic reached Roland Abächerli through racing. Abächerli works for Komenda AG, the Swiss Giant importer, and built up the Giant Swiss Team for this employer, which is now active as an elite professional team under the name Giant Swiss SR Suntour Team. "When I rode the Mountain Bike World Cup in 2000, athletes suddenly turned up on 29er bikes from Gary Fisher. We just looked at it critically and didn't pay much attention to what was happening. The Fisher riders didn't ride to any notable results on these bikes either. In 2005 and 2006, Sven Nys switched from cross-country racing to bike racing and took to the track on a 29er. Then the first rumors started doing the rounds in the bike scene that the big bikes make you fast," says team manager Abächerli.

First: the disappointment
It was not until 2010 that the 34-year-old Abächerli gained his own experience with the new wheel format. The first test rides were not very positive, "I am used to race hardtails weighing just under 9 kilograms, the first 29er aluminum hardtail was modestly equipped and with over 11 kilos on the really sluggish side. My first riding impression wasn't good at all, but I hadn't compared apples with apples".

And then the aha moment
Something light was needed to test the new format properly: in 2011, Abächerli built one of the first Giant 29er carbon hardtail frames with lightweight wheels. "This 9.3-kilo bike was the aha moment, it was surprisingly good, I felt perfectly comfortable. I felt comfortable in the bike, not on the bike, the riding position and feeling were so harmonious."

Equipped with these impressions, the 29er newcomer wanted to know about the history of these bikes: "In 1999, the accessory manufacturer WTB produced a large-volume bike tire that could be mounted on a 28-inch rim. However, there were currently no sufficiently stable rims or suitable frames such as forks for this tire to give the lugged tire with its large circumference a run for its money off-road. On touring bike rims, this wheel clearly had limits in terms of stiffness on hard terrain, but it was already recognized that a larger wheel could bring advantages off-road. Gary Fisher - after his role as a bike pioneer in the seventies - also got a taste of fresh air very early on with the 29er and started to produce frames for this new standard. At the turn of the millennium, however, it was still far too early for the 29er to make a breakthrough. Gary Fisher set a major milestone in 2005 by convincing Rock Shox to produce a 29er Reba fork. This brought the first high-quality suspension fork onto the market and the USA took on a pioneering role, as the 29er format was gaining ground in the hardtail sector there. According to current market estimates, 29er bikes achieved a market share of over 70 percent of hardtails in the USA in 2011".

And Abächerli knows the developments in the racing sector: "In 2011, the breakthrough of the 29er was celebrated in racing, Jaroslav Kulhavy climbed to the top of the podium for cross-country bikers at the Mountain Bike World Championships in Champéry on a 29er fully bike".

Roland Abächerli, why did the breakthrough of the 29er take so long?
Yes, it took at least ten years, from 2000 to 2010. The market simply wasn't ready for it yet. For a long time, the new standard lacked lightweight and stable wheels, suitable tires, optimized frames, suitable suspension forks and the right gear ratios.

Why the name 29er?
If you look at the so-called Ertro standard designations, the dimension 559 refers to a 26-inch rim with a rim shoulder diameter of 559 millimetres. A 28-inch rim on a road bike, for example, has the Ertro dimension 622 - and shares this dimension with a 29er rim. This means that a 28-inch and 29-inch rim have the same rim shoulder diameter of 622 millimeters. However, with a large-volume bike tire mounted on a 29er rim, which is actually a 28-inch rim in terms of diameter, this results in a significantly larger wheel circumference compared to a 28-inch wheel with road bike tires, for example. The overall diameter and circumference of a large-volume mountain bike tire on a 28-inch or 622 rim is so large that it has been generously rounded up to 29 inches. This measurement does not correspond to any mathematical or logical exactitude, but has become fully established in biker jargon. In addition, the actual wheel circumference can always vary slightly depending on the rim, air pressure and rider weight.

It is still possible to mount a 28-inch Schwalbe Marathon everyday tire on a 29er rim, for example. However, if you want to mount narrow tires on a 29er wheel, you need to clarify how much pressure the rim can withstand, but theoretically a racing tire can be mounted on a 29er wheel.

What are the benefits of larger wheels?
Larger wheels roll over obstacles more easily. The roll-up angle is flatter with the larger wheel. If I go into the forest with my daughter on the Like a bike balance bike, roots are big obstacles for her, whereas my adult bike simply rolls over them. This is also the ratio between 26 and 29-inch bikes, the impact angle is more favorable on the 29er bike. You could also say that bigger wheels make obstacles smaller.

And: Larger wheels and therefore tires have a larger contact surface with the ground. And this results in more traction. The tire grips better, both when accelerating and braking, even when cornering. Rolling resistance is also lower due to the larger wheel circumference.

The following is important for downhill characteristics: Larger wheels speed up the descent. The larger wheels provide more downhill stability due to the greater rotational mass. The smoother ride is particularly noticeable on gravel roads, but also on rough descents.

Is there an ideal 29er frame?
The advantages of large wheels come into play when the distance from the ground to the center of the bottom bracket in the bike frame is identical to the 26er bike. Due to the rider's anatomical requirements, the distance from the center of the bottom bracket to the top of the saddle is identical to the 26er bike. Thanks to the large wheels, the center of the bike does move upwards, but the equally low bottom bracket gives the rider a central position within the bike - a low center of gravity in relation to the larger wheels results in an interesting riding experience that conveys a great deal of confidence both uphill and downhill. In addition, a well-designed 29er bike is characterized by a short wheelbase, which is only slightly longer than a 26er bike. A bike "inflated" from 26 to 29 inches, on the other hand, cannot function satisfactorily, as the bottom bracket area would then also move higher.

Do 29ers have disadvantages?
A 29er bike is simply heavier, as there is "more meat on the bone" due to the larger dimensions - the extra rubber on the tire alone makes the wheel heavier and more sluggish. The fork is also "longer" and therefore heavier and usually slightly less stiff. The result is a higher overall bike weight due to the extra size. On narrow, angled routes that require a lot of pedaling, a sluggish wheel can be a disadvantage as it requires more energy to accelerate.

Are 29ers only for tall riders?
At 1.90, Jaroslav Kulhavy is certainly predestined for a 29er bike. But for me, wheel size has nothing to do with body size. The only thing that matters is the construction of the frame and how comfortable you feel on a frame, regardless of body and wheel size. With small frames, in small or X-small dimensions, the designers are challenged to accommodate the large wheels. Short head tubes are particularly important for small frames to prevent the steering center from growing too tall. Small women in particular often ride 29er bikes in the XC World Cup.

Which gear ratios are suitable for 29ers?
Due to the better rolling behavior and higher traction, the rider puts more watts on the bike. In the Giant Swiss SR Suntour team, we therefore use identical gear ratios for 26 and 29er wheel sizes (28/40 x 11-36). Outside of racing, it is important to adjust the small cogs on the 29ers by two teeth. A cassette with 36 teeth fits perfectly with a 2x10 crank with a 24 or 26 tooth small chainring.

How important is the wheel weight?
Whether an XT or SLX groupset is fitted to a 29er is not as important as lightweight wheels. After all, lightweight wheels are extremely important for the riding fun of big wheels. The lighter the external rotating mass on the wheel, the more lively and fun a bike rides. This is the case with 26-inch bikes, but this rule seems even more important with 29ers. A specialist dealer can clearly stand out from the competition if he offers special wheels and thus added value. In our team, we have had very good experiences with NoTubes wheels. We ride 29er wheelsets with a weight of 1430 grams and the wheels are extremely stiff. There are now also 29er rims available for heavy riders that are sufficiently stable.

For which areas of use are 29ers not suitable?
In downhill and freeride, these wheels are currently too big to design a bike with more than 140 millimeters of travel. But the engineers are not asleep, because 29 and 26 inches divided by two equals 27.5 inches... In the long-travel sector, this format is a big topic in the thinking and development departments of manufacturers.