Well, the 29 inch wheels may be bigger and heavier (due to both a bigger wheel but also a bigger fork), which means a harder acceleration, but they do have some pretty significant advantages. They roll a lot better on rough surfaces than the smaller 26 inch tires. That is due to the attacking angles becomes lower and lower the bigger the wheels are. Below here, we have an illustration with oversized obstacles and wheels to make the understanding easier:
On the picture it’s easy to see that the 26 inches wheels will bump into the rough surface all the time, slowing down the bike. Imagine every time the bike hits one of these bumps it’s like a little parachute activates and slows you down, forcing you to accelerate a bit to get the speed up again.
Meanwhile the 29 inch wheel will roll over these bumps a lot easier, making the ride a lot more stable. That means the rider will gain a greater speed over this section, along with saving energy compared to the 26 inch wheels. Even though the difference is a lot smaller in the real world, this is really what makes the 29 inches wheels great. It will simply make you faster on rough surfaces, along with making the ride more comfortable and less bumpy.
But as mentioned before, the wheel inertia will get bigger with the bigger diameter of the wheel, so the accelerations and weight on the bike will become harder and worse. Combine that with the 26 inch wheels having a better maneuverability it will make the choice harder than it seems.
Or does it?
We have to remember, that the bigger wheel inertia also means that it keeps the speed better, so once up in speed, a heavier wheel is preferable. In addition, the bigger the wheel the better the grip it also gets, due to the bigger 29 inch wheel spinning slower at the same speeds as the 26 inch wheel. That result in the tires gets more time to “dig” into the ground, and get better traction, because they have a fraction of a second more connection to the ground at every rotation. A heavier bike also helps this.
29 inch is the winner in test
Aalborg University from Denmark has been testing a 26 inch mountainbike against a 29 inch mountainbike. Scott gave the university two identical mountainbikes, apart from one being a 29 inch MTB and the other being a 26 inch MTB. An article about can be found here and is readable in Danish, but to summarize it in English: They tried racing the mountainbikes on the same course, and all participants came to the same conclusion; the 29-inch bikes was simply better on almost all parts of the track. They all got a faster time on the same course on the 29 inch mountainbike. The advantages (and disadvantages) already mentioned above, was concluded too in the test. Along with it, they all said it was giving them a much greater downhill speed, because they were able to get more grip with the wheels, along with it not taking a big beating on bumpy surfaces as the 26 inch wheels. The 29 inch wheeled mountainbike was slightly harder to climb with due to the heavier weight, though.
Advantages of the 29 inch wheels
Therefore, as a conclusion we can say, that the 29 inch wheels have the following advantages:
- The 29 inch wheels rolls better over bumps and rough surfaces due to a lower attacking angle the wheels hits the obstacles in. That makes them lose less speed, and therefore makes you faster on such surfaces. This also helps increasing the speeds downhilling.
- The 29 inch wheels demands less work from the rider, compared to the 26 inch wheels, once they have gotten up in speed due to a bigger wheel inertia.
- 29 inch wheels is more stable due to the bigger diameter of the wheel combined with the weight, so corners can be taken with a bigger confidence, and therefore also with greater speeds. The bigger wheels also helps with more stability during downhill riding.
Disadvantages of the 29 inch wheels
There are a few occasions where the 26 inch wheels are better. These are:
- When the wheels diameter grows, the bikes weight also does. The fork has to be bigger, so does the frame, and of course also the wheels. It all adds up in weight.
- It is harder to accelerate the 29 inch wheels due to the increased wheel inertia that has to be accelerated up. Combined with the weight, the accelerations can be up to 40% harder compared to 26 inch wheels.
- The 29 inch wheels are poorer in breaking and maneuverability compared to the 26-inch wheels, due to the greater weight, making them a bit harder to change direction, and therefore entering corners, with.
So if you are riding in places that constantly demands accelerations and a has a lot of technical corners and parts, the 26-inch wheels will be preferable. On the other hand, on longer straights and tracks with many bumps and downhilling, it will be done faster on 29-inch wheels.
But what is your experience with the 26 vs 29 inch wheels discussion? You can write it below here, in the comment section.
Written by René
Read more: http://www.cyclingtipsonline.com/news/26-vs-29-inch-mountainbikes/