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I have seen more and more reference to the 650b (27.5") mtb wheel size. Whilst I don't see any need for a new standard, does anyone know of any benefit to have a 27.5" wheel over a 26" or 29"?

While I understand there are currently 650b specific frames and wheels I haven't seen forks yet.

Also can someone please make a 650b tag, I don't have the rep yet. Thanks.

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You gotta clean this up to be more specific. Currently your asking if pears are better than apples or oranges. This question is so general that the only way to directly answer it is with pure opinion. –  joelmdev Jan 18 '13 at 1:56
    
One reason manufacturers are creating more 650b aka 27.5in bikes is that it's harder to build full suspension setups on using larger 29er wheels, especially for long travel suspension setups. –  Benzo Feb 26 at 14:26
    
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5 Answers 5

up vote 10 down vote accepted

You might want to take a look a this question which discusses the advantages of 29" over 26".

650b (or 27.5") falls somewhere in the middle and therefore performance characteristics will be somewhere in the middle of the two. For instance, 650b would be faster than 26" but slower than 29" at same chainring/cog. It would also roll over obstacles easier than a 26" but not as well as a 29". Also, the weight would be somewhere in the middle.

It depends on what type of riding you are doing to determine which is the "better" platform. Also, you should consider how easy it is to find parts in your area for a particular wheel. Since 650b is only starting to gain popularity, it might be difficult for you to find the tires you want, or to find replacement tubes at your local bike store. Also, I'm pretty sure you have to have a completely different frame for all 3 options, as tires aren't really interchangeable at that large of a difference. You could possibly put smaller tires on the frame than it is designed for, if you had disc brakes, but it might look odd, and might have weird handling.

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I went from a 26 to a 29, you can go faster and the is more efficient, your wheel takes longer to turn the bigger it is making you produce less work. I would go with the 29, I love mine!

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Bigger wheels are not inherently faster any more than a larger gear is faster. The wheel size you choose ought to be determined by what best fits your frame, which should, in turn, fit you. If you're a big guy then 29" may well suit you/your bike better. See this: rodbikes.com/articles/toeoverlap.html –  James Bradbury Jan 18 '13 at 10:05
    
In addition to @JamesBradbury: Things like the change of wheel size will never have just advantages without any disadvantage. Therefore every solution you choose will be a trade-off between improvements and drawbacks. Maybe 29" was a good choice for you as the advantages overweight or you do not consider the drawbacks to be drawbacks at all. Someone else maybe will see this exactly the other way round. To be polemic: why, according to your arguments, don't all the BMX racers go on 29" if it's that more efficient? –  Benedikt Bauer Jan 18 '13 at 12:43
    
You are so right, disregard what I said. Ha. –  Seth Urquhart Jan 18 '13 at 16:13
    
@JamesBradbury "Bigger wheels are not inherently faster any more than a larger gear is faster." That isn't strictly true off-road, a larger diameter wheel allows it roll over rougher terrain without losing momentum as easily. The only reason it hasn't taken off for extremely rough terrain riding (Downhill) is that the wheels make the bikes handle less well, that's why 650b is marketed heavily for Enduro riders. –  cmannett85 Jan 25 '13 at 8:24
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Pinkbike recently did a little opinion piece it. To summarise they thought 29ers were better for open, fast XC; whilst the 26" dominated in downhill, technical sections. 650b (27.5") were considered to be poor in either domain, and not particularly liked by any of the 3 testers.

But remember it's all opinion and it really depends on what you do with a bike.

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I know you tagged your question as "mountain bike", but there is also some interest in 650b for road bikes.

Jan Heine of Bicycling Quarterly is keen on wide 650b tyres for comfort without loss of speed.

...we chose 650B because it offers the best handling with wide tires.

The other reason you'd want 650b on a road bike is if you're a smaller rider (say 5ft 5in or less), or you're keen on very low trail. In these situations, slightly smaller wheels fit a smaller frame better, when 700C wheels might result in toe-overlap or uncomfortable geometries. The details are explained here.

The downside is that 650b tyres are harder to find, especially for road bikes.

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I'd agree with what Kibbee said that the 650B is essentially "somewhere in the middle" and it really DEPENDS on the type of riding you do.

I did not test the 650 extensively, but being "better" is a very relative term. The 650 essentially is a compromise, so due to that, it is not better than the other platforms.

HOWEVER, in my opinion, 650 is closer to the 26. I measured the overall diameter of a few 650B tires, most are right at 27 (or even slightly under 27). That's only 0.5 inch difference from 27.5, but 2" smaller than a 29er really.

I made my mind up the first time I demo'ed a 29er. I ride mostly XC and wooded trails. The trails have steep drops and tight corners at the bottom, then steep climbs - essentially a lot of switchbacks along a ridge. Throw in a few flat fast sections, and even some techinal areas, these are my local trails. The 29er climbs MUCH better than my 26. It is overall much faster on my trails than a comparable 26. The only thing I would knock the 29er on is really tight twisty technical turns, but honestly it is not nearly as bad as I was lead to believe (or at least imagined in my mind). I still have my 26, but for my local trails the 29er wins hands down.

For my trails, I personally think 29er is better (i.e. faster, smoother).

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