The Evolution of Mountain Bike Wheels from 26" to 29ers & 27.5+
Southern California like many regions around the United States is blessed with some exceptional mountain bike trails that offer a variety of challenging trails for nearly every skill level from technical single track that stresses all your riding abilities to the less demanding rugged terrain in open spaces like parks or farms. One of my favorite warm up rides is racing over the rough cut paths in our local orange groves with its drainage canals and rolling hills that for some challenging terrain mixed with the sweet aromatic smells of the orange blossoms. A few months ago, a friend took a bike tour at one of local wineries on a mountain bike and praised the trail and the scenery, not to mention there was a chance for free wine tasting at the end to help recuperate. He rode for the first time on 29" wheels (622 mm) and was surprised at the improved handling considering that these larger mountain bike wheels were larger than his normal (26 inches) wheels and rented mountain bike was a step down from his normal ride.
Starting with 26" mountain bike wheels
Since the 1980s, most mountain bike enthusiasts equipped their bikes with traditional 26 wheels (559 mm wheels) and to change it, you needed a custom built bike or you could weld really well. Also, in the 1980s racing enthusiasts began using 29 inch wheels on the mountain bike racing circuit with legends like Gary Fisher promoting these wheels as the next big thing. Over the next 30 years, mountain bike manufacturers launched new products with these advanced wheels, but could not find a fit in the market. Demand for these larger wheels has increased and most companies today offer a line of mountain bikes that offer the 29er wheels with advanced suspension components.
Why 29" Wheels?
So, why would someone switch to 29ers from standard 26ers and yet there are even more options available today: 29, 27, and 27+ wheels. If you are going switch to the new format: be warned that this requires a complete mountain bike replacement. Because of the suspension and bike frame size you cannot simply pull the old wheels off and replace them with shinny new 29er wheels. Of course, purchasing a new mountain bike isn t the worst thing that you might have to do, because we all have a longer list of places we want to ride than bills we want to pay. So what are the advantages to 29ers over traditional wheels? Obviously, they are bigger in diameter and with the added size these wheels run over obstacles easier like sandy ruts and sharp rocks than a smaller tire. Think about how easy it is for a monster truck to run over cars with its enormous wheels compared to a normal duty truck. With the larger size tire more air will be required which translates to a smoother ride making bumps and jumps less stressful on the body. Another advantage to the larger diameter wheel is that with each stroke the distance covered will be greater, because you the rider will be generating the same amount of force turning the wheels at the same speed, but the larger diameter wheels will cover more track. Before you put your mountain bike up on craigslist, there are some drawbacks to these new wheels sizes and don t be persuaded just because most racers have adopted this format. The wheel assemblies are heavier, which means you the rider have to generate more power. How much heavier? Surprisingly, both wheel assemblies weigh about 1140 grams or 2.5 pounds. The difference between the two is in the tires, where the 29ers are much taller pushing weights up to 5 pounds from 3.5 pounds when fully assembled. It pays to shop around for options. The taller tire height also reduces some of the handling often called tire roll in tight corners where the smaller diameter 26ers perform better.
What is the difference between 27.5" and 27.5+?
There are options in this emerging market where designers are creating products to bridge these performance gaps between 26" and 29er wheel sizes: 27.5" wheels and the 27+ wheels (or plus wheels). The category of plus wheels refers to larger size tires, but not as large as a "fat bike". 27.5+ wheels with wider rims and 2.8-3.0" tires are becoming increasingly popular for their traction, compliant ride, and roll over properties. Manufacturers are phasing out the 26ers which will be relegated to department store bikes. Offering similar handling to the traditional format, the 27.5 wheels and the 27.5+ wheels perform very well in tight spaces while still giving the rider some additional circumference to absorb those deep crevices and sharp breaks than can easily defeat you. Taller tires are required which does add weight, but the longer travel suspension and extra air create a much smoother riding experience. There is also the possibility of increased speed with the larger 27 or 27.5+ wheels that require a minimal increase in power output by the rider. Choosing 27 or 27.5+ wheels may seem like the intelligent compromise, but this may be a mistake. There is more that goes into the selection equation than the size of the wheel alone. The best recommendation for any rider who wants to improve their riding experience or advance to a new level is to try before you buy. Your height, weight, riding skills and terrains you frequent are important in factoring into this decision. Ride a friends bike, ride a new bike or rent a bike, but trying one of these new sizes with 27, 27.5+, or 29er mountain bike wheels will be an exciting and rewarding one.