26 VS 29 Inch Mountainbikes

26 versus 29 inch wheels is a common discussion amongst mountainbikeriders. For many years, the pros and amateurs have preferred the 26 inch wheels, however, in the past few years, the 29 inch wheels have won more and more ground. But why is the 3 inches bigger wheels getting a bigger and bigger audience compared the standard 26 inch wheels?

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/

Cheapest way to get faster on your bike

Every single bikerider has been there, and since you are here on my blog right now, you are having one of these moments: You want to buy something that will make you go faster on your bike, but you dont have the budget to go all the way and buy a set of Lightweight Obermayer wheels. 

What to do then? You maybe have 1000 dollars to spend, which you could get some nice wheels for, which usually is the thing people tell you to buy to get fastest the best way. 
But will this be the best way to go faster for that budget? 

No it isnt. Actually, the most effecient way to go faster is buying some premium tires with low rolling resistance. Rolling resistance is actually taking a lot of the effort you put in your pedals, and there is a big difference between the tires. The German "Tour" magazine made a test a few years back, on which roadbiketires was the best. You can see it in the link right here:
[www.conti-online.com] 

According to their tests, the Continental GP4000S was the tyre with the lowest rolling resistance, and comes in with a 34,3 Watt's of rolling resistance at 35 km/h. 

On the other end of the scale, there's the punctureresistant Continental GP 4 Seasons, that comes in at 53,9 Watts rolling resistance at the same speed of 35 km/h. Thats a massive difference of 19,4 Watts! For many riders thats about 10% of their total power they could save by changing from one to the other!

Now lets turn over to the wheels. Will there be a greater resistance here? Lets turn back to Tour Magazine, who tested both lowprofile, and highprofile wheels not long time ago. A link to that test can be found here: [http://www.tour-magazin.de/services/qtr/epaper_4_2011/page104.html] (The tests starts from page 86 and forward).
In the test they measured the windresistance of the wheels, and lets try to compare a cheap lowprofile wheel against a Zipp 404, the most common high-end wheel out on the roads. 

As a cheap(ish) budget wheelset, lets take a Mavic Ksyrium Elite, which comes in at around 700 dollars. At 30 km/h, this wheel produces a total amount of 7,7 Watts of drag, which is way lower than the 34-53 Watts the mentioned tires above produced at about the same speed. 

What about the Zipp then? At 30 km/h, they produce 4,5 Watts of drag, which means these 3600 dollars wheels only saves you 3,2 Watts.. Can we agree, that at these speeds, it would make way more sense spending 100 dollars to get some very good tires with low rolling resistance (capable of saving you 19,3 Watts per tyre!), instead of bursting your bankaccount for not even 4 Watts?

But of course rolling- and windresistance changes differently. Rolling resistance increases in a linear curve compared to the speed, while if you double your speed, your windresistance has increased 4 times as much as your speed. So the windresistance increases a lot more than the rolling resistance, as the speed improves. So the higher the speed, the greater the difference will be between the 2 wheels. A lot more, than the difference between the 2 tires. But how high must the speed have to be in order for the Zipp-wheels to be a better buy than the 2 tires that costs only a 36th of the Zipp-wheels?

At 40 km/h, the Mavic-wheels produce a drag of 18,2 Watts, while the Zipp-wheels produce a drag of 11,0 Watts, so a total saving of 7,2 Watts, going at a normal racespeed. Here the difference between the GP4000S produces a total amount of 39,2 Watts, while the GP 4 Seasons produce a total of 61,6 Watts. So with the tires you can save a total amount of 22,4 Watts, or what compares to 3 times more energy saved, than going on Zipp 404's.

Well, lets say it goes a bit downhill then, and we are at 50 km/h. Here the Mavic-wheels produce a drag of 35,6 Watts, while the Zipp's are at 23,3 Watts. A total amount of 12,3 Watts are now being saved. But the difference between the 2 tires are still greater. The GP4000S produces a rolling resistance of 49 Watts, while the GP 4 Seasons are at 77 Watts. A total difference of 28 Watts, still 5 more Watts to save on the right tires, than the very very expensive wheels.
So you will have to go a little bit above 50 km/h, before it would make sense to buy the Zipp's before changing your tires to low rolling resistance, and then think about, how long time on your trainingsessions, are you actually going at this speed? Not much properly, unless you live on the top of a mountain.

Therefore, my best advice for anybody, if they want to go faster on their bike for a small budget, is, go out and buy some good tires before changing to a expensive wheels, because you get a lot more speed for your money for changing tires. I know several people who actually ride these 2 types of tires i mentioned above, and they claim they ride up to 3 km/h faster on the Continental GP4000S than the GP 4 Seasons. That is a big difference! I myself, tried changing from some Continental Ultra Race to some of the mentioned Continental GP4000S-tires, and on the very first workout, i set a new record on a 40 km-course i usually ride when I get home from University, and just have this 1½ hour before dinner is served. Clearly the tires makes a difference. So as Yokohama says about their tires; "Its the tires that makes your car", I can tell you, that the tires also makes you go faster on your bike.

But if you are doing a time trial, there are other factors that will help you a lot too. Aerodynamics are very important here, because you cant hide in a peloton. Australian bikesite  Cyclingtips.com.au have this helping table you can see below, where it gives an indication of how much you can save over a 40 km course, driven in 48 minutes as the standard. So its a lot faster than a "normal" guy could do, and therefore the difference for any ordinary rider would be lower than indicated below. But it gives a good idea of where you can get most speed for your money.

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Written by René

Read more: http://cyclingtipsonline.com/news/cheapest-way-to-get-faster-on-your-bike/