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Is anyone able to provide evidence that a 29'er is faster than 26/27.5 in cross country racing? I am curious about whether this is a fact, or something people hear so they assume it to be true. "Feels" is a word often used.

I guess the type of evidence would be numerous lap times in similar conditions, at a similar fitness? Obviously it could vary course to course between smooth buffed courses and extremely choppy loops with lots of rocks and roots, etc.

Thank you, in advance, for sharing any thoughts you have.
 

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I'm assuming that most of the WC XC pros have done testing and determined that 29ers are faster. Nino ran the 27.5 for a while and eventually moved to the 29er.
 

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Elitest thrill junkie
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You should ride 26”.
 

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Isn't that somewhat of an unfair question for today.

Can you by a nice XC bike on 26" wheels right now? If no.....you can't really compare a new bike, regardless of wheel size, against the older counterpart.

Slight tweaks over the years have improved the riding experience, for most people anyway.

My 2016 Stumpjumper FSR is faster than my 2000 Stumpjumper HT. The new bike is not XC focused like the old bike was. I don't blame the increased speed to the wheel size alone.

What exactly are you trying to determine, or are you asking for sake of conversation?
 

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A couple of weeks ago a guy got top spot in Cat2 on a ten year old-ish high end Giant XTC 26er. I ride 26 a lot, the bike is kind of heavy but not a bad bike, I've done enough on Strava, and measuring how fast I am riding with the same guys to convince me that I'm faster on 29, mostly due to the faster/smoother wheels on rougher terrain where the 26 gets really pitched around. We had a ten minute segment (maybe it was shorter, it felt long) in a race a few weeks ago that was very flat, and was cut out of Salal over what must have been small loaf of bread sized rocks, it was such a pounder even on my 29er fs bike. It was hard to imagine riding it on a 26er, I finished before my kid started and I put him on my fs instead of his hardtail. It was a good/tough trail for racing, but I can't imagine anyone choosing to ride it for fun. - A very smooth trail will not favor the 29 very much, but as you get to the really choppy stuff the 26 could be quite a bit slower. I want to say that a 26 would be just as fast on smooth ground, but we don't see very many road racers on 650b, and didn't some TT bikes used to have a smaller front wheel?, -you'd think the TT guys would have tested and settled on smaller wheels if they were faster on smooth ground.
 

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Mountain bikes have progressively gotten better since the early 1990s, but every advancement has been heavily debated, and lightly tested.

Comparing a "classic" Klein with modern MTB of today, there is quite an apparent difference:

In my opinion, the biggest, most recent advance was simple, but strongly resisted because it didn't look "pro." In the '90s, the "roadie fit" influenced super-long 140 stems, short top-tubes, and terrible handling "because it weighted the front on climbs." ...Not to mention the godawful 1.8" tires.

Your modern XCO bike should fit you with plenty of reach on a 35-60mm stem. If it doesn't, your bike's top tube is too small and you need a larger frame.
https://intensecycles.com/collections/intense-sniper
 

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Mountain bikes have progressively gotten better since the early 1990s, but every advancement has been heavily debated, and lightly tested.

Comparing a "classic" Klein with modern MTB of today, there is quite an apparent difference:

In my opinion, the biggest, most recent advance was simple, but strongly resisted because it didn't look "pro." In the '90s, the "roadie fit" influenced super-long 140 stems, short top-tubes, and terrible handling "because it weighted the front on climbs." ...Not to mention the godawful 1.8" tires.

Your modern XCO bike should fit you with plenty of reach on a 35-60mm stem. If it doesn't, your bike's top tube is too small and you need a larger frame.
https://intensecycles.com/collections/intense-sniper
Total thumbs up on that comment. I've posted in multiple times in forums with a great article on bike setup that references in the MTB setting the stem length is used as a bike handling tool, not a "fit" item. People always push back thinking that stem length needs to be the same as their road bike or you shorten/lengthen it to get your torso angle the way that you want it. That is not the case. You use stem length to correctly set up the bike to handle appropriately. I can't believe the number of people I see with 120mm stems (especially pros) on a mountain bike....totally crazy.

When I went to a 70mm stem the front wheel wasn't wandering or wheeling up climbs, I just adjusted my position on the bike. Anyway, great comment.

BetterRide Mountain Bike Skills Tips
 

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Yes there is, here is a scientific paper made by the swiss, of course.

https://www.researchgate.net/public...s_National_Team_cross-country_mountain_bikers
Interesting data. Over 0.6 KM, there is a 7.5 second speed difference(2.4%). If 27.5 is a half the difference, assume 1.2% slower than a 29.

What is interesting about that paper is that they clearly show that with the 29" wheels, you are faster with the same power output, which makes it a no brainer.

Nice find TDLover.
 
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