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I was wondering what advantages 29" wheels give. From what I understand they are well suited to mountain biking. Are they any use on road bikes perhaps?

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4 Answers 4

up vote 11 down vote accepted

Regarding road bikes, the 29" rim size is actually the same as standard 700c wheels used on road bikes -- only the tire is different (larger).

One difference that I don't see mentioned often is that 29" vs 26" wheels change your effective gearing. If you have two bikes with the same gearing but one with 29" wheels and one with 26", the larger wheel will have a higher gearing overall because of the larger wheel diameter (one turn of the pedals move you farther down the trail). This means that the 29er can help you reach a higher top speed, but the 26er will have a lower climbing gear.

Also see the comparison on Wikipedia.

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Just to clarify, while rim size is the same, you should not use light road rims for your mountain bike, for very clear reasons. –  Papuass Feb 4 '11 at 9:06
    
@Papuass: agreed. But 700c touring or hybrid/commuter wheels could possibly work fine on a 29er mountain bike. Just as long as they're built for strength/durability. –  freiheit Feb 8 '11 at 21:28
    
Rim diameter is the same, however rim width tends to be wider for 29er rims than rims designed for road bikes. However, there tends to be a lot of leeway with rim width and what will work vs what is recommended. See tire width compatibility on sheldonbrown.com/tire-sizing.html –  Benzo Dec 6 '12 at 13:52

There is a lot of discussion about 29 inch wheels versus 26 inch wheels. I would summarize it as such:

Major advantage of 29 inch wheels: ability to roll over obstacles easier.

Major disadvantage: weight

There are other advantages/disadvantages but I think those are the main ones. Considering that weight reduction is a major focus of road bikes, and rolling over obstacles is not a great need, I don't see 29 inch wheels catching on for road bikes.

There are many places online that summarize the debate more completely, for instance. . .

http://www.mountain-bike-world.com/29-inch-mountain-bikes.html

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Currently cost is another factor. This is caused largely because 29'' wheels are the new thing on the market. –  sixtyfootersdude Dec 9 '12 at 2:11

They do roll over objects easier, if you google angle of incidence it will explain why.

They also tend to keep momentum better, since the weight is farther from the axle. That same distance is why they will accelerate slower. Think of a tennis ball on a string. short string easy to get going and stop. Longer, harder to get going but will keep moving easier.

There is also a traction advantange since the contact patch is larger.

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Contact patch is a function of tire pressure. The shape of the patch will be different (longer and narrower on a 29er), but not the area. –  jpkotta Dec 11 '12 at 0:48
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@jpkotta True - sort of. The 29er generally has a bigger tire overall volume and tread patch width. As a result, many AM/Enduro and XC riders will run the 29er at a lower air pressure. This produces a much bigger contact patch. My 2.5 Maxxis DHF on my 29er 30mm internal width rims at 20 psi have lots of rim protection, and low bounce, thanks to the larger contact patch. Just something to consider. –  Saint Hill Jun 25 at 12:12

Here is a YouTube video explaining advantage of having bigger wheels. This is only part of the answer, most important reasons were explained by darkcanuck:

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While this may theoretically answer the question, it would be preferable to include the essential parts of the answer here, and provide the video link for reference. –  freiheit May 15 '12 at 20:41
    
They come in a 36er? This I did not know. –  MrBoJangles Jul 24 '13 at 22:45
    
@MrBoJangles it must be custom made –  Papuass May 20 at 9:28

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