First results of 26 vs 29 inch wheels

Note (added 2/3/06):  comments to this post have been disabled due to malicious spammers.  You know who you are.  Contact me through the "contact me" link if have something you'd like to add.  If there is enough interest, I'd consider opening a public forum for the issue. 

Note (added 2/12/06):  this test looks at comparisons for climbing relatively smooth but variable pitched long dirt road climbs.  For an analysis of rolling, twisty singletrack, check out



Which one of these are faster?  This is the question of the hour.  Every 29er fan would have you believe 26" wheels are "kiddie" wheels and also that 29" wheels are faster.  Time to cut through all the subjectivity and put some numbers on the problem.  The short answer:  for this comparison, the 26" wheels outperformed the 29" wheels, but it's not an overwhelming difference.  Then again, the margins between winning and losing are often quite small... 

I've got a Salsa Dos Niner and a Trek Fuel 110, both setup with power tap hubs.  In the past week I did the same ride twice (4 Peaks road from hwy 87 to hwy 88 and back), a 60 mile dirt road/jeep trail route with approximately 11,000 feet total climbing.  Two sections of the ride are compared:  the first climb, which is partly rolling with some steep climbs and one long climb, rising about 4,000' in the process.  The second section climbs from hwy 88 back to the high point; this climb is quite steep, climbing ~4,000 in 8 miles.  There are a few short descents.

Bike setups:  The Dos was setup with Specialized Fast Trak tires, tubeless ala Stans.  The Fuel was setup with a tubeless (plus Stans latex) Panaracer fire XC pro rear and a WTB Weirwolf 2.3 front, tubeless ala Stans.  The Dos is .6 lbs lighter than the Fuel, as measured by a Tanita scale (.2 lb increments).  I started each ride with the exact same amount of water & food so as to eliminate rider weight changes.  I assumed my weight to be the same on both days.

First off I just went out and rode the routes.  I made no attempt to ride even paces for any sections of the ride, and in fact, the latter ride (on the Fuel) was done at a more spirited pace.  I just planned on sorting out the data post-ride. 

Next, I had to come up with correction factors for the power meters.  Power taps are strain guage devices, and as such, have a small but significant precision variability.  I performed a stomp test for each power meter (including my road bike PT), here's how they turned out:

Based on the stomp test, the 29" PT measures .86% high, while the 26" PT measures 1.75% high.  This leads to correction factors of .9915 for the 29" and .9828 for the 26".

Now there's nothing left but to look at the data for each climb:

The road surface is sandy in spots, rocky in others, and fairly loose decomposed granite throughout.

Conclusion:  in this test, the 26" wheels outperform the big wheels.  The first "climb" has a lot of rolling terrain, I was interested to see how this would turn out.  In the end, though, a consistent advantage exists for the 26" wheel, whether rolling or straight up climbing.  On the steep climb ("climb 2"), one would expect a linear decrease in time for a linear power increase.  IOW, a 10% power increase should decrease time by 10%.  This is because the major resistance to overcome is that of gravity - a constant.  Yet the Fuel saw greater speed increases than linear with power increases.  I could feel this on the ride - any change in speed necessitates wheel accelerations, and the big wheels are simply slower to accelerate.  The smaller bike feels much more "lively" or "responsive".

Another interesting detail is how closely the kJ tracked for each climb.  Identical for the big climb!  This is somewhat surprising given that the Trek was .6 lbs heavier.

Clearly, a test on a dirt road is only valid for similar I'll do more tests off-road.  But I'm becoming biased now.  The acceleration issue of the big wheels is tough to overcome...I suspect they will be best suited for rocky/tech stuff.

One more data point:  at Moab, I did a lap each on the Fuel, Dos, and the 292.  I never did a lap on the 292 that was within a minute of the Fuel's lap time...

More to come!

Published Monday, January 02, 2006 1:04 PM by Dave
Filed Under: ,


# @ Thursday, January 05, 2006 7:40 AM

Hey on the 26" pay roll or somethin?

Where are the 29" descending comparisons?


Durango Dos Niner

# @ Thursday, January 05, 2006 12:06 PM

Poor test. Gearing, rolling resistance, etc all important factors that are totally ignored. I suppose it hasn't occured to you that a 29er will go faster with less power imput due to lower rolling resistance. Summary: meaningless test.


# @ Thursday, January 05, 2006 12:32 PM


Thanks for the comments. I understand the data may not be what folks want to see. However, from the standpoint of the physics involved:

- gearing plays no role in the energy requirements of climbing

- on rolling resistance, this is an unknown. However, I used tires on the 29er that are designed to be some of the fastest (ie lowest Crr) available, while I used beefy tires on the 26er (ie high rolling resistiance tires). The edge should go to the 29er.

- The 29er setup was .6 lbs lighter.

Your statement is representative of the subjective hype that my testing attempts to clarify. Objectivity doesn't always tell us what we want to hear...but at least it's objective.

Also, be sure to understand the constraints of this test: climbing relatively smooth fireroads. Clearly, this is not the whole story, and for most, it might be even pointless if they rarely ride such terrain. But it's a start.

Stay tuned, objective, and open minded.


# @ Thursday, January 05, 2006 2:10 PM

Doesn't lower power equate to better? Lower power means it took less effort to make the same climb, right?


# @ Thursday, January 05, 2006 2:18 PM

Have a read at this link:

I disagree with your comment that gearing plays no role. It absolutely plays a huge role.

Your leverage vs. tire diameter is less on the 29'er when using the same gearing and crank lengths. Thus, you will be required to expend more energy to climb the 29'er just as fast as the 26'er. Think of a teeter-totter. Long end vs. short end. My 100 lb girlfriend can out-leverage me given a long enough beam.

What I find interesting is that you spend a little less energy to climb on the 29'er. Given that the finish times correlate closely with the differences in power, it seems to me that you simply just didn't ride as hard on the 29'er. Especially since you're measuring power at the hub, not the ground. Leverage plays no part at that point.

At the point where you can increase your pedaling leverage by ~11.5% on the 29'er, you can climb at the same rate at the 26'er for the same amount of energy.

After that, I'm confident that the 29'er beats a 26'er in terms of maintaining momentum on flats, downhills and coasting.

- Jeremy -

- Jeremy -

# @ Thursday, January 05, 2006 2:29 PM

You explain that power taps are strain gauges. So it occurs to me that if you did a track stand on an incline there would be "strain" with the implication that power is being provided. But with no motion there is no energy transferred so even though your muscles would feel something there is zero power being used. From that state adding more muscle "power" propels the bike forward from zero velocity to some positive velocity. It's not surprising, it's even logical, that the velocity increase faster than a linear relationship, e.g. from zero velocity (and some non-zero strain) to some postive velocity there is an infinite % increase in velocity.


# @ Thursday, January 05, 2006 5:22 PM

Dave interesting test. I'm a 29er guy and I won't go back to 26 reguardless. I don't race and don't understand the Power Tap. I'm wondering why item F is the same on both wheels? I would think a wider tire would give a higher torque rating just like a automobile. Also would the differance in chain lenght need to be adjusted?
I understand pitting a soft-tail 29er vs. FS 26. I found the ride quality of my Dos Niner to be better than my 26 FS so the test should be equal there.
What is the weight of your Dos?
What would you ride in a 100 mile race without a bike change?
Like I stated I won't change back but I'd be interested to see your results on a 15 mile loop, where you could switch every lap.


# @ Thursday, January 05, 2006 9:07 PM

Hey y'all - many thanks for taking the time to stop by and leave your comments. I put a post to the mtbr thread, hopefully it will address most of the questions here...some I missed:

- lower power is only better if time is not lower. IOW were looking to maximize distance covered for each kJ of expended energy.

- Strain guage power meters: zero speed and force on the pedal = force, but zero power. Power is force x angular velocity.

- Item "F" is the same because it is a calculated value for what torque should read - for full details see the "stomp test" on the wattage FAQ (link in left sidebar), it is how one can check the power meter's calibration.

- I'll use the two bikes at Old Pueblo. Those race files will reveal a lot more than this test did!


# @ Sunday, January 08, 2006 4:51 PM

Go figure. I was just in New Mexico on my 26" hardtail. The three other guys were on 29er hardtails. We had a two mile paved descent back into Santa Fe. Coasting, I passed them all and made it to town by a large margin. All day, on the trail, I found the same thing happening. Strange, eh?

Before you forget your physics classes, remember that gravity affects objects of different mass equally. And if you didn't have physics class, how's this: two of the guys are lighter than me by 20-30 lbs, one is heavier by about 50. Hubs? Would it make that much difference? Chris King vs. Hugi.

So, what does this mean? My 26" wheels are better? I don't think so. I don't have all the answers. But for some reason, guys on 29" wheels seem to. Maybe I'd be smarter if I got bigger wheels?

I'm not sure why you guys with big wheels have to always act holier than thou but it gets really old. I started riding game trails 23 years ago and I still don't have all the answers. Not really sure how you guys got so smart so quick.

Dont' forget, bike position can affect power output.


# @ Sunday, January 08, 2006 6:58 PM

Scott - do I sound like I have all the answers? I don't. Your frustration is misplaced on my blog...but I hear you.


# @ Monday, January 09, 2006 10:59 AM

What color are the bike Fashion is everything, fad is substenance.


# @ Tuesday, January 10, 2006 12:01 PM

Hi Dave,

I am curious to hear about comments from your riding partners on how they think the 29er rides by watching and riding behind you. Any comments so far?



# @ Tuesday, January 10, 2006 12:53 PM

Hi Alan -

Not too many comments, but then again most of my training is solo. Descending is so much better on the 29er, that seems to be where the biggest difference is, I've had comments to that effect...