26" vs. 29" hard numbers?

al415

Banned
Hello.
My best Christmas present in ages is fast turning into an obsession. I’ve been playing and tinkering with my garmin 705 on everything from Hartshorne death rides to walking the dog. Something I’d love to compare is loop times on similarly geared 29” vs. 26” wheeled bikes. My 29” bike is still being brazed on a wood-burning stove somewhere in Colorado, so I don’t have the luxury of running comparisons myself. Have any of you guys with a bike in each wheel size, and a suitable GPS, made such a comparison? I don’t mean subjective “butt-dyno” impressions, I remember “thinking” I felt faster on my Mary SS vs. my 26” SS bike. Now I’d like to see real-world data from people that ride the same trails that I do. Anyone?
 

THATmanMANNY

Well-Known Member
I have learned plenty about "controlled experiments" and this is not one of them by far. Ultimately, you would just want to compare the duration of both rides but you would have to keep many things constant to see which wheel size is better. You would have to keep your grearing the same, HR the same, the exact lines you take the same, how tired you are that day the same, etc.... IMO it would nearly be impossible for you to get a conclusive result but it would be fun to try.
 

syadasti

Wet Rag
Thats really all I'm looking for!

An engineer racer did it a few years ago:

http://www.cyclingnews.com/mtb.php?id=news/2006/mar06/mar03mtbnews

Harris says that after several months of riding he worried that he wasn't gaining in performance. "As an engineer [Harris works for a Virginia-based engineering consulting firm], I needed objective evidence to support what I was feeling" Which was? "I just didn't feel that my two-niners were as fast as my Fuel. They're more fun to ride but I was getting the sense that I was going slower." Which was a paradox. "Since that went against everything everyone said, I knew I couldn't just trust my perception. Since I've been training by power for a long time, I set up a 29in inch wheel with a Power Tap hub and decided to test my bikes side by side."

Harris says that although his was not a fully-funded scientific test, he took the experiment seriously enough to set the bikes up in similar ways. "Both bikes weigh 25.5 pounds," he says. "They both have Specialized Fast Trak tires." Because a two-niner wheel has a ten percent larger circumference than a two-sixer and front and rear cogset combinations would have produced different gear-inch measurements, Harris even tried to normalize the drivetrains. "I put a smaller middle ring on the Dos Niner."

The 24 hours in the Old Pueblo wasn't the first time Harris had done side-by-side comparisons of power measurements from his two bikes. In the first test - on a relatively smooth forest service road (a constant climb) in January - he gave the Fuel a slight edge. In early February, on a 3.2-mile competitive mountain bike loop at McDowell Mountain park in Fountain Hills, Arizona, he declared the competition a tie After careful analysis of some minor differences in the power meter readings between the two bikes (recorded five days apart) after the second test, he chalked up the better readings from the Fuel as his just 'feeling' better during the Fuel test run. Old Pueblo, with its constant conditions and multiple laps of data to analyze, seemed like a better laboratory for his experiment.

...

"There were a lot of different ways to look at the data," Harris said about how he broke down the results. "But people have enough difficulty understanding power in general so I kept it simple and looked at lap time versus average power." Simply put, he wanted to kow how much power was required to drive each bike around the course and if there was a difference between the bikes.

Based on that data, Harris concluded that his Salsa required more average power to achieve the same lap times over the same terrain in the same conditions as his Trek (175 watts for the Fuel, 188 for the Dos Niner). He says that by his measure, if he rode both bikes at the same power output (presumably a limitation of his physique and fitness), Harris calculates that his two-niner lap times would be about two minutes slower. "I think I can attribute some of the difference to the power required to accelerate each bike," he says. But adds, "I can only base this on impressions. And my impression, my sensation, is that Dos Niner does not accelerate as fast as the Fuel."
 

bonefishjake

Strong like bull, smart like tractor
Team MTBNJ Halter's
a better indicator would be to do a series of rides on the same course...say five rides per wheel size. an average against both would be a way better indicator than a one ride vs. one ride comparison.
 

stb222

Love Drunk
Jerk Squad
summer time will probably be your best bet as a dry summer will yield more consistent trails conditions then winter. still, the only true measure of which is faster is who gets there first, which may include a bunch of different factors. good luck!
 

jimvreeland

Endurance Guy: Tolerates most of us.
This is going to be pretty hard to do in the woods as both bikes are good at different things, you're lap times may be about the same. But FWIW, in 2007, my fastest I could do the "Jim" loop at Hartshorne was 52 minutes. In 2008 I hit it in 48 minutes on my Fisher. The two records are probably too far apart to come down to the wheel size, and fitness increase may have a role, but it does at least prove the 29er isn't slower. But with each bike having it's own strengths, where you test may play a role as well. Somewhere like Hartshorne I don't feel favors one over the other, where as someplace like Allaire will favor a 29er.

-Jim.
 

clarkenstein

JORBA Money Launderer
JORBA.ORG
i would love for someone to do a local review. personally, i can't get enough of the 26 vs. 29 debate. in fact, i'm stuck in a debate with myself on whether to go back to 26" wheels right now.
 

bonefishjake

Strong like bull, smart like tractor
Team MTBNJ Halter's
That guy already did laps with the different bikes setup as closely as possible on the same course:confused:

yeah, i know. but switching mid-race doesn't really prove anything. you tire after laps and the wattage numbers could be a reflection of that...especially since his bikes were the same weight. i'm talking about like two weeks worth of riding at the same park on the same trails in as close to similar conditions as you could get and switching the bikes up every other ride.
 

jShort

2018 Fantasy Football Toilet Bowl Lead Technician
Team MTBNJ Halter's
support your LBS and buy both...
Then make your own decision..
 

syadasti

Wet Rag
yeah, i know. but switching mid-race doesn't really prove anything. you tire after laps and the wattage numbers could be a reflection of that...especially since his bikes were the same weight. i'm talking about like two weeks worth of riding at the same park on the same trails in as close to similar conditions as you could get and switching the bikes up every other ride.

He compared the power necessary to achieve the same lap times, not which one was faster.
 

al415

Banned
I know there is plenty of anecdotal information online on the topic. I am really interested in what local riders are finding on local trails. My own recollection, from when I still had a 29er, was that I could move at comparable speeds (to my 26”) but with less effort. Of course, that was in the pre-garmin dark ages.
 

bonefishjake

Strong like bull, smart like tractor
Team MTBNJ Halter's
i have an idea that may be able to solve this issue. i'll let you know if anything pans out.

oh, and i ain't no math wiz but if two objects weight the same, whether it's feathers or poo, shouldn't it take just as much wattage to move said objects? honestly, i don't know. put them both in 10 lb bags if you'd like.
 

jdog

Shop: Halter's Cycles
Shop Keep
650b??

Chris who works with me just slapped some 650b wheels on his C-dale Rush.

He has just one ride on it but he claimed it to be the best of both words.

I too happen to have a rush frame sitting around.

hmmm:hmmm:
 

clarkenstein

JORBA Money Launderer
JORBA.ORG
if two objects weight the same, whether it's feathers or poo, shouldn't it take just as much wattage to move said objects? honestly, i don't know. put them both in 10 lb bags if you'd like.

i'm far from a math wiz too... but i think the coefficient of friction will be the main factor in the amount work to move said poo and feathers... if one 10 lb object in a bag is sitting on 60 grit sandpaper, and the other 10 lb object is in the same bag on a surface covered in silicone, it should require less work to move the one on the silicone.

i have no idea if that applies to wheels tho.
 

al415

Banned
650b??

Chris who works with me just slapped some 650b wheels on his C-dale Rush.

He has just one ride on it but he claimed it to be the best of both words.

I too happen to have a rush frame sitting around.

hmmm:hmmm:

There is a guy on that other website that has a Bontrager converted into a really cool 650b, Pacenti tires etc. I'd be curious to try it, but to be honest, I never found 29er wheels to be cumbersome on technical terrain the way some people say they are. I'm not really looking for the last scientific word on the subject, just some observations and thoughts from people here.
 

don

Well-Known Member
650b??

Chris who works with me just slapped some 650b wheels on his C-dale Rush.

He has just one ride on it but he claimed it to be the best of both words.

I too happen to have a rush frame sitting around.

hmmm:hmmm:

I was just thinking that.

I am re-thinking my main XC/all-around rig for this year and have been seriously thinking of a Sinister Ridge or Spooky Horror Taxi and starting with a 650B up front and go from there. Mickey from Spooky has had good things to say about 650B and I've come to agree with a lot of other things he has said in the past.

I'd love to hear your thoughts about it if you build one up.
 
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