# 26 vs 29. "Fueling the flame"



## preparation_h (Feb 1, 2004)

Just thought this was interesting.
http://teamhealthfx.com/blogs/dave_harris/archive/2006/01/02/309.aspx


----------



## - Jeremy - (Jan 13, 2004)

Interesting...

His data says that he expended less energy at the hub on the 29". This simply tells me that he didn't pedal as hard on the 29'er. Or couldn't pedal as hard... Perhaps 180mm cranks would give him the edge. Then again, 180mm is only 2.8% longer (per arm) than 175mm.

He even admits that his ride on the 26'er was more "spirited". I interpret that as "pedaling harder". Maybe I'm wrong, but it just seems to me that he rode harder on the 26'er. Then again, he also rode some nasty, beefy tires on the 26'er that require way more energy to roll than the Fast Trak 29's. I'd like to see him ride Fast Trak 26's. 

All things being equal in the drivetrain, I admit that logic dictates that a larger wheel with more rotational mass would take more energy to overcome inertia. That's why I advocate the use of longer crank arms and lower gearing on 29'ers. Or growing stronger legs 

If it's possible to match drivetrain and cranklength ratios to wheel / tire size, then I think that the 29'er would be at least as fast on uphills and definitely faster on downhills.

- Jeremy -


----------



## 29inch (Sep 16, 2004)

- Jeremy - said:


> logic dictates that a larger wheel with more rotational mass would take more energy to overcome inertia.


I'm not sure I agree.

There's a very slight difference in effort to get the wheel turning from a dead stop, but that's not overcoming interia. After that first 10 feet or so from a dead stop, inertia becomes your best friend, and you work to maintain it. This a portion of the reason 29ers are faster, smoother, and less fatiguing over same distance/terrain.


----------



## - Jeremy - (Jan 13, 2004)

29inch said:


> I'm not sure I agree.
> 
> There's a very slight difference in effort to get the wheel turning from a dead stop, but that's not overcoming interia. After that first 10 feet or so from a dead stop, inertia becomes your best friend, and you work to maintain it. This a portion of the reason 29ers are faster, smoother, and less fatiguing over same distance/terrain.


My use of "inertia" in this case would be by the book as "resistance to change in motion." Any motion, whether it be moving or not. And I agree, once the wheel is up and moving, that larger rotational inertia becomes your friend, which is why I believe that the 29'er would have the advantage over the 26'er only if the drivetrain and crank ratios are adjusted to match on each bike.

I think of the drivetrain like a lever. On his 26" setup, the larger end of the lever would be where the force is being acted upon (pedal) and the shorter end of the lever is where the force is acting upon (tire / ground). The hub would be the fulcrum. On the 29" setup, that pedal end of the lever would remain the same length, but the tire end of the lever grows in length. Thus, you lose your mathematical advantage while pedaling. To compensate, you'll have to increase the length of the pedal side lever by lengthening the cranks and lowering gear ratios.

Flats, downhills and coasting definitely give the advantage to the 29'er due to the greater rotational inertia and better angle of attack.

- Jeremy -


----------



## DeeZee (Jan 26, 2005)

*Intense Cycles*



- Jeremy - said:


> Interesting...
> 
> His data says that he expended less energy at the hub on the 29". This simply tells me that he didn't pedal as hard on the 29'er. Or couldn't pedal as hard... Perhaps 180mm cranks would give him the edge. Then again, 180mm is only 2.8% longer (per arm) than 175mm.
> 
> ...


I like what Intense cycles did. They compared a 26" Spider to their 29" prototype. Similar component groups and tested the two head to head. Comparing two totally different bikes is not a valid comparison.


----------



## crashing_arizona (Jul 26, 2005)

*data interpretation*

Is he interpreting the data correctly? He states that the power numbers for the Fuel are higher and equates that as being good. Don't higher power numbers mean you are expending more energy to make the same climb?

cheers,
Sam


----------



## derby (Jan 12, 2004)

*unequal major factors*

Interesting test.
Much repetition and rest between tests would be required for more valid results. But on the surface the test with lots of climbing seems to represent two major performance problems with bigger wheels.

2 big factor differences:
A. The rims and tires are heavier on the 29'er, hurting climbing speed due to the repeated outer wheel acceleration/deceleration cycles normal to pedaled climbing. You'd need to add about a 1/4 pound or so of weight to each tire of the 26'er to match the difference in rim and tire weight of the 29'er tire. The flywheel effect to maintaining momentum of the bigger wheels won't completely offset the inertia differences when climbing. The flywheel effect becomes greater as speed increases, and almost nil at a slower climbing pace.

B. The final drive rate (crank cycle to distance covered) favors easier spinning in the same ring/cog combo with the smaller wheels. The 29'er has a much higher final drive for climbing gear options. Spinning is most efficient for climbing.

A third performance problem with bigger wheels for more aggressive riding is cornering grip. Due to greater ground contact, he tires just cant don't bite into the ground as deeply using the same tread, and so they slide out sideways noticeably more easily than smaller wheels.

Overall, somewhat like bigger cars or motorcycles usually have better comfort, so are bigger wheels bikes. You may not be able to cover distance quite as quickly or energy efficiently, but the pleasure level may be much greater. If you want to race to win, then smaller wheels rule, but not too small or they won't float the bumps very well.

Larger, taller, and heavier riders may benefit more (or have less efficiency loss when climbing) than smaller and lighter riders when using bigger wheels.

I still want a 29'er.

- ray


----------



## ernesto_from_Wisconsin (Jan 12, 2004)

*ride them*

I just ride.


----------



## - Jeremy - (Jan 13, 2004)

crashing_arizona said:


> Is he interpreting the data correctly? He states that the power numbers for the Fuel are higher and equates that as being good. Don't higher power numbers mean you are expending more energy to make the same climb?
> 
> cheers,
> Sam


Yeah, Sam. He spent about 2.8% more energy on the 26'er and therefore was roughly 2.8% faster. I just think he rode harder on the 26.

If you took two identical bikes, one 26er and one 29er. Gave them the same parts spec and tires but magically made the 29er weigh the same as the 26er and also gave the 29er ~6% more drivetrain leverage to match the extra ~1.5" wheel radius. Then you slapped on some motor that spun at a constant rate which varies wattage as required and pointed them up a hill. Both bikes should make it to the top in the same amount of time and expend the same amount of energy.

I think the argument that a larger wheel requires more energy to accelerate is negated by the fact that the rotation also carries more momentum and is just as resistant to slowing down as it is to speeding up.

I could be wrong 

- Jeremy -


----------



## Cloxxki (Jan 11, 2004)

>The rims and tires are heavier on the 29'er, hurting climbing speed due to the repeated outer wheel 
>acceleration/deceleration cycles normal to pedaled climbing.
Get a wheel, give it a spin, and lift it. Stop the wheel, lift again.
29" adds 350g per bike, period.
Or do you mean the varying speed of someone pedaling too slowly on a climb? The heavier wheel will also help keep the speed once put back in. It plays even.

>A third performance problem with bigger wheels for more aggressive riding is cornering grip. Due to
> greater ground contact, he tires just cant don't bite into the ground as deeply using the same 
>tread, and so they slide out sideways noticeably more easily than smaller wheels.
I've got 100 bucks saying you can't follow me through a sequence of nasty turns when riding the 26" versions of my tires. Even though you're right, 29" tires will bite less deeply.
I'll let you in on a secret, that makes them faster! and the place where they bite, being a longer narrower contact patch, places all the pressure where you want it, down the middle, rather than spread over the sides.


----------



## - Jeremy - (Jan 13, 2004)

derby said:


> A third performance problem with bigger wheels for more aggressive riding is cornering grip. Due to greater ground contact, he tires just cant don't bite into the ground as deeply using the same tread, and so they slide out sideways noticeably more easily than smaller wheels.
> 
> - ray


I don't agree. The 29's carry a longer, more narrow contact patch. A tire of the same pressure deforms itself to the ground until an equal amount of pressure is reached on the air inside the tire. Therefore, a 29" tire has an equal size contact patch (say in mm^2), just in a different shape due to the larger diameter. So when leaning into a corner, and depending on the tire, a greater number of cornering knobs can contact the ground at the same time vs. a 26" tire. Which is evidenced by the 29" riders who swear up and down that they can rail corners with more speed and stability than they ever could on 26".

- Jeremy -


----------



## ernesto_from_Wisconsin (Jan 12, 2004)

*spreadsheet*



- Jeremy - said:


> He spent about 2.8% more energy...


What a bunch of malarky. He probably spent more energy writing the spreadsheet.


----------



## ernesto_from_Wisconsin (Jan 12, 2004)

*my...*



- Jeremy - said:


> I don't agree. The 29's carry a longer, more narrow contact patch. A tire of the same pressure deforms itself to the ground until an equal amount of pressure is reached on the air inside the tire. Therefore, a 29" tire has an equal size contact patch (say in mm^2), just in a different shape due to the larger diameter. So when leaning into a corner, and depending on the tire, a greater number of cornering knobs can contact the ground at the same time vs. a 26" tire. Which is evidenced by the 29" riders who swear up and down that they can rail corners with more speed and stability than they ever could on 26".
> 
> - Jeremy -


My triathlon bike is faster than my 29er...what's wrong with that equation? is it the un-aerodynamic knobs?
Is it the fact that my triathlon bike has aerobars and my 29er has the Midge? or that sometimes gnomes cry when poked with frozen french fries?


----------



## Nat (Dec 30, 2003)

Some questions enter my mind:

Did he account for differences in physical ability from one bike to the next, meaning how did he know if he was more tired on one ride versus the next?

Did he have the same nutrition?

Was he more dehydrated one ride than the next?

Did he take a leak or poo and weigh less?

He admits to developing bias. Was there any bias to begin with?

Was it hotter out one day than the next?

Did he wear identical clothing?

Did he get a good night's sleep?

Did his tires track on exacctly the same line each ride?

Did his chain have less lube in one trial than the other?

Despite all our efforts to control the machinery and mechanical factors, I've never seen how we can eliminate the human influence on a small sample size. I think you'd have to have a study with a research group of LOTS of participants to see if there's a pattern.

Or, you'd need a machine to propel two bikes with unwavering output, and the two bikes would have to be identical in every way except for wheel size. It would be a dynamometer for bikes. Even then, what machine could adapt to technical terrain and know when to pop a wheelie to most efficiently get over a log? What machine knows how to unweight the rear tire just enough to keep it from slipping under power when crossing a slippery, wet root? Finesse gets us up and down a trail as much as does efficiency.


----------



## richwolf (Dec 8, 2004)

derby said:


> Interesting test.
> Much repetition and rest between tests would be required for more valid results. But on the surface the test with lots of climbing seems to represent two major performance problems with bigger wheels.
> 
> 2 big factor differences:
> ...


I think a bigger contact patch is preferable and gives better traction and grip while cornering. Why do downhill racers go to bigger tires?? Following you logic, 1.5 inch tires or even 1 inch tires would grip better but nobody uses them for serious off roading.

I think the real answer of 26er vs. 29er will come on the racing circuits. If a 29er rolls better and is more efficient then why would a racer not use it?? If I spent hours and hours training and watching my diet and beating myself up to compete at a high level, why would I dismiss equipment which would get me to the finish line faster?? Racers are fanatics and will do anything to be number one.

I think people who get 29ers are a lot like anyone who gets a new bike. "Oh it is so much better, so much faster, so much more efficient" and on and on. Usually a lot of the differences noted are due to superior forks, different wheels and tires, nicer components and the fact that new stuff usually works better than old stuff plus the justification factor.


----------



## jugdish (Apr 1, 2004)

wow, this thread takes all the fun out of riding. can't you all get back to using your big brains for evil purposes and let us get back to the joys of biking?


----------



## Nat (Dec 30, 2003)

jugdish said:


> wow, this thread takes all the fun out of riding. can't you all get back to using your big brains for evil purposes and let us get back to the joys of biking?


This happens every winter.


----------



## jugdish (Apr 1, 2004)

Nat said:


> This happens every winter.


 sure `nuff.


----------



## RobW (Jan 18, 2004)

derbyA third performance problem with bigger wheels for more aggressive riding is cornering grip. Due to greater ground contact said:


> I call BS on this one. You gotta spend more time on one. Mine hooks up in the corners like velcro compared to my (now gone - sold to finance another 29er) C'dale...


----------



## Cloxxki (Jan 11, 2004)

Last SS race I did, I won, on a 29" bike 
I made the real difference in the endless left-right twisties, 200 real corners over a good 4-mile lap. Simply a higher pace there than any 26" bike could follow. My tires weren't real rollers, but the 26" bikes had to work hard to keep closing gaps in the short straights.
I like these discussions. People get to tell me how much my bikes suck, and next summer they'll to comment it from behind me


----------



## ernesto_from_Wisconsin (Jan 12, 2004)

*I just...*



Nat said:


> This happens every winter.


I just ride in winter.

I really don't own a tri bike. I was being sarcastic. I only have a Rock Lobster SS 29er and a Surly Pacer a la ENO/fixed. I just ride even if its 0 outside.

Cholos.


----------



## ozlongboarder (Jan 12, 2004)

The truth is in the riding. No amount of graphical analysis can make up for what you feel during a ride. Test one yourself then make your mind up. Dont forget that tires can make a huge difference to how ANY bike feels. 

Is this tester biased towards the 26" wheel as he does not like the "kiddie wheel" comments so he feels he has to defend them against the growing numbers of 29er converts? Maybe maybe not. If you want to try one get on the 29er forum and find a bike in the loaner thread and have at it, feel the differences for yourself.


----------



## - Jeremy - (Jan 13, 2004)

richwolf said:


> I think a bigger contact patch is preferable and gives better traction and grip while cornering. Why do downhill racers go to bigger tires?? Following you logic, 1.5 inch tires or even 1 inch tires would grip better but nobody uses them for serious off roading.


No go, because the smaller tire requires higher pressures to keep from deforming too much to equal the contact patch size of the larger tire.

e.g., why 2.5" downhill tires are run at sub 20 PSI and road tires are run at 120 PSI. That's not to say that they have the same size contact patch... Just a similar amount of deformation vs. stability and control. Different results for different applications.

Ah hell, we might as well just ride on flat tires  Who needs PSI!?

- Jeremy -


----------



## redxj (Oct 17, 2004)

richwolf said:


> I think a bigger contact patch is preferable and gives better traction and grip while cornering. Why do downhill racers go to bigger tires?? Following you logic, 1.5 inch tires or even 1 inch tires would grip better but nobody uses them for serious off roading.
> 
> I think the real answer of 26er vs. 29er will come on the racing circuits. If a 29er rolls better and is more efficient then why would a racer not use it?? If I spent hours and hours training and watching my diet and beating myself up to compete at a high level, why would I dismiss equipment which would get me to the finish line faster?? Racers are fanatics and will do anything to be number one.
> 
> I think people who get 29ers are a lot like anyone who gets a new bike. "Oh it is so much better, so much faster, so much more efficient" and on and on. Usually a lot of the differences noted are due to superior forks, different wheels and tires, nicer components and the fact that new stuff usually works better than old stuff plus the justification factor.


That is the biggest load of crap I have ever heard about the "new bike" syndrome. I have bought a new bike in the past and hated it. I kept that bike around longer than I should of. This summer I took a chance and bought a used SS 29er. It had cheap budget parts, a rigid fork, and I know for a fact it had more miles/wear and tear than my 26 FS bike. I had almost 5X times the amount of money into the 26 than I did in the 29er. After a few weeks of riding both bikes there was no question as to which bike was better. On the same trail a few days apart I rode both bikes and was a couple of minutes faster on the 29er. I sold both of my 26 bikes after that and haven't thought twice about it. Now only 6 months later I have two 29ers and a third will be on its way this spring.

Racers wouldn't use a 29er because their sponsor does not make one. Sponsored racers use what the sponsors give them. This years SSWC was won on a 29er. There are a number of endurance racers running/winning on 29ers right now. If I were a betting man (oh wait I am), I would bet you will see a lot more 29ers in racing in the future.


----------



## MTBNate (Apr 6, 2004)

Hey racer types... 26" bikes are WAY FASTER!

No need to change to the faddish 29ers because you can beat them everytime. If 29ers were 'all that' EVERYONE would be on them but they arn't so please continue riding your super-accelerating, super-fast 26" wheeled hardtails.

Nothing to see here.. its all HYPE.


----------



## AndyN (Jan 12, 2004)

Cloxxki said:


> >
> I've got 100 bucks saying you can't follow me through a sequence of nasty turns when riding the 26" versions of my tires.


Typical 29er comeback, overly defensive and lacking any credible data.

Have you ever ridden with Derby?

If not how can you possibly know what he is capable of.


----------



## Go Kart Motzart (Jan 2, 2004)

derby said:


> A third performance problem with bigger wheels for more aggressive riding is cornering grip. Due to greater ground contact, he tires just cant don't bite into the ground as deeply using the same tread, and so they slide out sideways noticeably more easily than smaller wheels.


I think I'll mount up some 18c road tires for max grip!!


----------



## rryyddeerr (Oct 4, 2005)

*????*

you know, when you read about what everybody loves about 29ers they always come back to the word "momentum". Now, I dont know about you, but i dont carry much momentum up a hill. It takes a constant motor to get up a hill. momentum usually goes along with flats and downhills. And he said he climbed dirt roads. Not many obsticles on the dirt roads around here. Another thing ive heard folks talk about is how well 29ers ROLL OVER things. If there was nothing to roll over, and no momentum to keep, then why was he using this test? Maybe he should have used a power tap mounted on a cross bike. Maybe he would have announced that as the new mountain bike revolution.


----------



## richwolf (Dec 8, 2004)

redxj said:


> That is the biggest load of crap I have ever heard about the "new bike" syndrome. I have bought a new bike in the past and hated it. I kept that bike around longer than I should of. This summer I took a chance and bought a used SS 29er. It had cheap budget parts, a rigid fork, and I know for a fact it had more miles/wear and tear than my 26 FS bike. I had almost 5X times the amount of money into the 26 than I did in the 29er. After a few weeks of riding both bikes there was no question as to which bike was better. On the same trail a few days apart I rode both bikes and was a couple of minutes faster on the 29er. I sold both of my 26 bikes after that and haven't thought twice about it. Now only 6 months later I have two 29ers and a third will be on its way this spring.
> 
> Racers wouldn't use a 29er because their sponsor does not make one. Sponsored racers use what the sponsors give them. This years SSWC was won on a 29er. There are a number of endurance racers running/winning on 29ers right now. If I were a betting man (oh wait I am), I would bet you will see a lot more 29ers in racing in the future.


Boy, I don't know who is more touchy the single speed crowd or the 29er crowd??? Oh ya I know the SS 29er crowd 

Hey I am not dismissing 29ers, far be it for me to do that since I have never ridden one, but I still think it will be shaken out in the next few years on the XC race circuits. The excuse that the sponsors don't make the 29er bikes does not really cut it because many many racers are not sponsored by anyone but themselves. A lot of what is said about them rolling over rough terrain better or having a bigger contact patch for superior traction does make sense to my little feeble mind.

New bike or new gear syndrome does occur. I have had it myself numerous times. Years and years ago I bought this killer wheelset and I could swear that I was faster on them. Then I went to weigh them vs. my old set and found out my old set was lighter and the bearings were just as nice.
Every new bike I get is so much better than the old one until a few months go by and I get back on the old one.


----------



## hairball_dh (Aug 7, 2005)

*wow. Y'all are riled!*



Nat said:


> Some questions enter my mind:
> 
> Did he account for differences in physical ability from one bike to the next, meaning how did he know if he was more tired on one ride versus the next?
> 
> ...


Dave Harris here, author of the test under scrutiny. More than a little hesitant to poke my nose into this ring 

First off, I didn't advertise this test on this board, or the 29er board, mostly because I didn't think anybody would care about an almost imperceptible difference, but also because I didn't want to get embroiled in something like this thread. I did post to the endurance racing board since *racers* do care about small differences. Well, here we are, so...

The beauty of the power meter is that it measures power (surprise) from which energy expended can be calculated. So, all the human factors can be eliminated. It doesn't matter that both rides weren't paced exactly the same (although damn close). What matters is weight, wind conditions, and rolling resistance. IOW, the external factors that create forces to be overcome by the rider. Gearing and crank length will affect how it *feels* to pedal the bike, might even make the difference between cleaning and not cleaning certain sections. It will not, however, affect the amount of energy needed to raise bike+rider to the top of x climb. Anyone remeber F=ma?

In the tests, both days were windless - and if there was a significant wind differential it would have been borne out in the results, as the two climbs are in opposing directions. Weight was controlled for - the 29er was .6lb lighter. Rolling resistance was not: but the tires were chosen such that the 29er should have had a decided advantage.

In the end, it appears the 26" bike has a very small advantage *for me* climbing dirt roads. If you don't spend much time climbing dirt roads, or don't care if that climb takes you 30 seconds longer (or whatever), this test is likely meaningless to you. Its also possible that you could generate opposing results - these results might be due to my pedalling style, or ? If you race, it's food for thought, but still not very illuminating. Climbing dirt roads happens in races, but it isn't going to be the strong suit of the 29er - anyone that's ridden one knows how good they feel on descents, through techy sections, and how you can rail corners with them. I plan to test such conditions as well - but in the end, all I hope to do is figure out analytically which bike is better for what *for me*. The results may or may not apply to anyone else, and you'll have to read said results (if at all) with that in mind.

It is good to see so many folks thinking about it, though. That is a good thing.


----------



## - Jeremy - (Jan 13, 2004)

Hey, Hairball. Didn't realize you were the suspect on trial 

Now I can see your reasoning. It's not to prove that 29'ers take less or more energy to climb or 26'ers are faster or slower... It's to prove that a bike, regardless of type, can have a (more or less) psychological effect on the rider. If the Fuel made you FEEL like you wanted to pedal harder, then you pedaled harder. Which is what I suspected all along, but your original article made it sound like you were comparing efficiency rather than psychology.

And MTBNate is right. Racers shouldn't ride 29'ers... I'm only getting one because I'm already too fast and I need to make it easier on my competition... *ahem* 


- Jeremy -


----------



## hairball_dh (Aug 7, 2005)

*Am I that unclear???*



- Jeremy - said:


> Hey, Hairball. Didn't realize you were the suspect on trial
> 
> Now I can see your reasoning. It's not to prove that 29'ers take less or more energy to climb or 26'ers are faster or slower... It's to prove that a bike, regardless of type, can have a (more or less) psychological effect on the rider. If the Fuel made you FEEL like you wanted to pedal harder, then you pedaled harder. Which is what I suspected all along, but your original article made it sound like you were comparing efficiency rather than psychology.
> 
> ...


I gotta work on my writing style...I honestly have no idea how you came to that conclusion based on what I wrote. I AM comparing efficiency of the two bikes - more specifically, my two bikes. The reason I rode a little harder on the Fuel test was my training plan - not the test idea. The power meter was used to sort out the gory detials post ride. But neither climbs were pinned...

I'll be doing Old Pueblo with these two bikes. There will be plenty of opportunity to compare race pace files from the two bikes on identical 15 mile laps. Should be fun.


----------



## - Jeremy - (Jan 13, 2004)

Hmm... Well I guess I'm confused, then.

If that's the case, then the only difference I see is that the Power vs. Time isn't linear like it should be. So it seems like the Fuel is more efficient by 0.7% on the first climb and 0.65% on the second climb.

But that's where I'm confused. Those readings are entirely within the margin of error for the hub (+/- 3%). The "stomp test" was a good effort, but one stomp isn't enough to calibrate vs. 1 - 1.5 hours of climbing. 

Also, and more importantly, you assume that your body weight was the same on each day. Did you weigh yourself? Before each ride? Body weight can fluxuate up to 5 lbs on a daily (or hourly) basis. It all depends on what you ate the day before. Lots of sodium, low sodium, lots of water, no water, lots of training, no training, lots of food, no food, etc. I weigh myself every morning. My weight easily changes by large amounts depending on how much water or food I'm retaining. Example: I literally weigh 2 lbs. less this morning than I did yesterday morning. A 0.65 - 0.70% difference in weight on a 160 lb. cyclist is only 1.04 - 1.12 lbs. Add in the 0.6 lb. difference in the bikes and you could have weighed 1.64 - 1.72 lbs more on the day you rode the Dos.

You could easily be right. Perhaps your 29'er is ~0.70% less efficient. It just seems far more likely to me that other factors influenced this number.

Anyway... Thanks for your post and thank you for making me think a little bit. Laying in bed thinking about the efficiency of a 29'er is a ripping good time 

Woo!

- Jeremy -


----------



## hairball_dh (Aug 7, 2005)

*Yes!*



- Jeremy - said:


> Hmm... Well I guess I'm confused, then.


Aren't we all 



- Jeremy - said:


> If that's the case, then the only difference I see is that the Power vs. Time isn't linear like it should be. So it seems like the Fuel is more efficient by 0.7% on the first climb and 0.65% on the second climb.


Bingo. That is my premise.



- Jeremy - said:


> But that's where I'm confused. Those readings are entirely within the margin of error for the hub (+/- 3%). The "stomp test" was a good effort, but one stomp isn't enough to calibrate vs. 1 - 1.5 hours of climbing.


Good point. The stomp test reveals the accuracy of the strain guage. Hang a weight off a crankarm and take a torque reading, compare with what that readiing should be (calculated) and you have an error estimate. This error estimate is a constant for a properly working PT - it doesn't drift (OK maybe a little in severe cold...). So it really is a good measure of the accuracy for any duration.

For example, a friend has 3 power meters - 2 PTs and an SRM. Her threshold power is different for each PM, something she has to account for in her training. But, it is consistent across any one of the power meters.


- Jeremy - said:


> Also, and more importantly, you assume that your body weight was the same on each day. Did you weigh yourself? Before each ride? Body weight can fluxuate up to 5 lbs on a daily (or hourly) basis. It all depends on what you ate the day before. Lots of sodium, low sodium, lots of water, no water, lots of training, no training, lots of food, no food, etc. I weigh myself every morning. My weight easily changes by large amounts depending on how much water or food I'm retaining. Example: I literally weigh 2 lbs. less this morning than I did yesterday morning. A 0.65 - 0.70% difference in weight on a 160 lb. cyclist is only 1.04 - 1.12 lbs. Add in the 0.6 lb. difference in the bikes and you could have weighed 1.64 - 1.72 lbs more on the day you rode the Dos.


My weight was the same each day. The Dos was actually the lighter bike - and it had the smoother tires. I was more than a little surprised with the results myself. If I go put some fast traks on the Fuel (probably will), y'all are gonna HATE the results!



- Jeremy - said:


> You could easily be right. Perhaps your 29'er is ~0.70% less efficient. It just seems far more likely to me that other factors influenced this number.
> 
> Anyway... Thanks for your post and thank you for making me think a little bit. Laying in bed thinking about the efficiency of a 29'er is a ripping good time
> 
> ...


Hey, bunny hopping fences is better'n counting sheep jumping them, no? Just keep these results in perspective. Without more testing on more common MTB terrain, this doesn't say too much...and your point is well taken that the results are tight enough that they could we swayed by other factors.

Thanks for putting some serious think time in!


----------



## Nat (Dec 30, 2003)

hairball_dh said:


> Dave Harris here, author of the test under scrutiny. More than a little hesitant to poke my nose into this ring


 Don't take this personally Dave, but if you're trying to put forth scientific research then you have to be able to handle criticism. The reason you came up with your test in the first place was because you were critical of some other premise, right? So don't act surprised if you get people riled up; that just means you asked a good question.
.
.
.


hairball_dh said:


> The beauty of the power meter is that it measures power (surprise) from which energy expended can be calculated. So, all the human factors can be eliminated.


 I don't see how the power meter can possibly eliminate all other human factors. We use double-blinded tests because it's hard to control all human factors. If you can show me how you or the hub accounted for all the questions on my list then I might be convinced, but otherwise it looks anecdotal.
.
.
.


hairball_dh said:


> In the tests, both days were windless - and if there was a significant wind differential it would have been borne out in the results, as the two climbs are in opposing directions. Weight was controlled for - the 29er was .6lb lighter. Rolling resistance was not: but the tires were chosen such that the 29er should have had a decided advantage.


If you chose tires such that one bike should have an advantage, then that sounds like poor design.
.
.
.


hairball_dh said:


> Its also possible that you could generate opposing results - these results might be due to my pedalling style, or ?


 If results can vary due to pedalling style or what-not, then you haven't succeeded in controlling human factors and the test is poorly designed.
.
.
.


hairball_dh said:


> I hope to do is figure out analytically which bike is better for what *for me*. The results may or may not apply to anyone else


 If the results apply only to the tester and to no one else, then it's anecdotal and therefore not really scientific.

Can you revise your test design such that results apply to everybody and is repeatable?


----------



## preparation_h (Feb 1, 2004)

Kind of sorry I got you into this mess but from reading your past archives I kind of knew you were really into your dos...and then this. So coming from someone who loves his 29er it was good to see you were so objective. 

Thanks for responding.


----------



## hairball_dh (Aug 7, 2005)

*keep it in context*



Nat said:


> Don't take this personally Dave, but if you're trying to put forth scientific research then you have to be able to handle criticism. The reason you came up with your test in the first place was because you were critical of some other premise, right? So don't act surprised if you get people riled up; that just means you asked a good question.


Like I said before, there are good reason's I didn't post to either this or the 29er boards. Furthermore, I'm making no attempt to put forth scientific research. I'm just a guy who like to ride & race bikes, but am also technically inclined. I'm not funded for this...I have no monetary interest...it's simply a passion - much the same I imagine as anyone reading this.

I'll continue to do more testing and will share the results - it will be left to the reader to understand and assess the validity of my conclusions, and also the applicability to their own situation. I hope it helps the reader in some way, but it isn't of the one size fits all variety.

Not taking anything personally - but I was surprised to see this thread pop up. Thanks preparation H 



Nat said:


> I don't see how the power meter can possibly eliminate all other human factors. We use double-blinded tests because it's hard to control all human factors. If you can show me that how you or the hub accounted for all the questions on my list then I might be convinced, but otherwise it looks anecdotal.


A lot of folks see this test and think about human performance factors. That's not what I'm investigating - I'm looking into the mechanical efficiencies of the bikes. Jeremy mentioned using an electric motor for a test - this is actually similar, except that I'm the motor. Power is variable, but it doesn't matter because it is all accounted for by measuring the output.

I can't make it any plainer. I'm looking at the physics of motion, not human performance.



Nat said:


> If the results apply only to the tester and to no one else, then it's anecdotal and therefore not really scientific.
> 
> Can you revise your test design such that results apply to everybody and is repeatable?


I've asked the 29er board for suggestions on test design. Didn't get much.

As for designing a test that applies to everyone...nope. From the physics involved, I'd think this particular test translates well across individuals, but when the tests start to involve bike handling, that goes out the window. On this test, I'd surmise the difference in energy expenditure is due to the reapeated accelerations/deccelerations - and that is going to occur for any bike regardless of the rider.


----------



## hairball_dh (Aug 7, 2005)

*Thanks*



preparation_h said:


> Kind of sorry I got you into this mess but from reading your past archives I kind of knew you were really into your dos...and then this. So coming from someone who loves his 29er it was good to see you were so objective.
> 
> Thanks for responding.


I think 

Yep, I love the Dos. It kicks some booty. Who knows? I may find that it does better than the Fuel on a singletrack loop where the begin/end elevation is the same.

I *feel* that the 29ers work better for some terrain than the 26ers...but my aim is to quantify it for some common scenarios. For the serious racer type, it's all about using the best tool for the job.

I'll say this out loud: if I didn't race, there'd be no question. I'd ride 29ers and never look back.


----------



## derby (Jan 12, 2004)

*Fuel's optimized pedaling bio-pace*



hairball_dh said:


> I think
> 
> Yep, I love the Dos. It kicks some booty. Who knows? I may find that it does better than the Fuel on a singletrack loop where the begin/end elevation is the same.
> 
> ...


H-ball,
There is another significant performance factor difference in your test.

Rear suspension has a bio-pace reaction factor that is peculiar to each design. Some just suck energy (much less now with the addition of platform shocks on the more average designs, those that fight good handling when hard pedaling and bob a lot), some better optimize pedal input more than others. Your Fuel is very optimized for racing performance pedaling, few designs are more highly optimized for racing performance, maybe only VPP and DW-link are really much better designs for XC racing performance than the Fuel design.

We will likely see rear suspension in road races soon if rules allow.

Bicycle rear suspension is just beginning to be optimized for maximum performance levels. I don't see much bicycle racing. But all the pro men leaders of last year's Sea Otter short track were on full suspension. The quickest starter was a privateer on a VPP Spider (he wasn't a full time professional rider and could have ridden any bike of his choice), a Fuel either won or was very near the front at the end. Hardtails were at the back of the pack with rare exception.

Comparing a hardtail 29'er to a very similar set up 26'er hard tail might show a much different performance comparison.

- ray


----------



## pacman (Jan 16, 2004)

*Fooling the Flame*

The test has too many variables to be meaningful. I'd like a test in which you cover a section of trail at the same speed for each bike and then announce the energy expended over that section.

So you were more spirited on the Trek? You expected a proportional decrease in time for an increase in power? The important factor is where you used the extra power (energy). You may have instinctively applied the extra effort where it would do the most good for the overall time, i.e. peg the meter on some climbs and recover on the easier stuff.


----------



## teamdicky (Jan 12, 2004)

*I need "Physics for Dummies"*

I can't figure out what to believe, but I think what you are doing is interesting. I also agree that the tests would seem more accurate with two rigid bikes or two similar suspension types, but since I only took one physics class in college (13 yrs ago) I wonder if I am off on that assumption. I don't know how different bikes would effect actual power readings. I read "Lance's War" and I somewhat grasp the concept of "watts" and "power". I think that it is a tough nut to full grasp.
Forge on Nutty Professor


----------



## Nat (Dec 30, 2003)

hairball_dh said:


> I'll continue to do more testing and will share the results - it will be left to the reader to understand and assess the validity of my conclusions, and also the applicability to their own situation.


That's exactly what all this feedback is about. We're commenting on what we see as the lack of validity and sharing back.



hairball_dh said:


> I've asked the 29er board for suggestions on test design. Didn't get much.


Well, I gave my suggestions above:
" I think you'd have to have a study with a research group of LOTS of participants to see if there's a pattern.

Or, you'd need a machine to propel two bikes with unwavering output, and the two bikes would have to be identical in every way except for wheel size. It would be a dynamometer for bikes. Even then, what machine could adapt to technical terrain and know when to pop a wheelie to most efficiently get over a log? What machine knows how to unweight the rear tire just enough to keep it from slipping under power when crossing a slippery, wet root? Finesse gets us up and down a trail as much as does efficiency."


----------



## hairball_dh (Aug 7, 2005)

Nat said:


> That's exactly what all this feedback is about. We're commenting on what we see as the lack of validity and sharing back.
> 
> Well, I gave my suggestions above:
> " I think you'd have to have a study with a research group of LOTS of participants to see if there's a pattern.
> ...


Your objections have been duly noted and appopriately filed


----------



## hairball_dh (Aug 7, 2005)

pacman said:


> The test has too many variables to be meaningful. I'd like a test in which you cover a section of trail at the same speed for each bike and then announce the energy expended over that section.
> 
> So you were more spirited on the Trek? You expected a proportional decrease in time for an increase in power? The important factor is where you used the extra power (energy). You may have instinctively applied the extra effort where it would do the most good for the overall time, i.e. peg the meter on some climbs and recover on the easier stuff.


Hmmm. More spirited was 2% higher power. Do you have a feel for what difference that is? That's about half of the power losses due to friction in the drivetrain - an imperceptible power level. From a power perspective, the rides were nearly identical.

If anyone would care to see the power files, just say so and I'll make them available. You will need CPsoft to analyze them, and a good understanding of power files in general.


----------



## shiggy (Dec 19, 1998)

pacman said:


> The test has too many variables to be meaningful. I'd like a test in which you cover a section of trail at the same speed for each bike and then announce the energy expended over that section.
> 
> So you were more spirited on the Trek? You expected a proportional decrease in time for an increase in power? The important factor is where you used the extra power (energy). You may have instinctively applied the extra effort where it would do the most good for the overall time, i.e. peg the meter on some climbs and recover on the easier stuff.


 There are (at least) two valid ways to measure the efficiency:

1. Maintain a steady speed and measure the power difference.

2. Maintain a steady power output and measure the speed/time difference.


----------



## Nat (Dec 30, 2003)

hairball_dh said:


> Your objections have been duly noted and appopriately filed


Nice one.


----------



## gdunha (Sep 10, 2004)

*Missing Something???*

Maybe I'm missing something?? Independent of tires, framesize, suspension system, measuring how much power is needed to do a ride factoring in speed and time is a farily simple measurement of how much power you would have to exert to go a certain fixed distance. Now in order to attribute the power difference to any one factor you would have to have as many variables the controlled as possible. So runnning a 26 vs a 29 with very similiar equipment will tell you which one requires more power to complete a ride. This would be for any rider, as long as the bikes fit the rider. 
So I think you need to get two custom frames set up with your custom geometry and then equip them the same and redo the test. 

Iterested and wating for more.

Gary


----------



## frankenbike (Mar 17, 2004)

Excellent post Nat. My thoughts exactly.


----------



## mcd (Jan 12, 2004)

*hey hairball...*

Now the money question....which bike left you fresher feeling afterwards? which bike could you have pushed to a faster pace???? I think you did a great job with your test...i read it and was able to remember that it was done by you for you and your equipment...therefore it is a valid test for you which is great. It will be interesting to see long term tests if you are able to run the power tap on bunches of different trails on each bike, then you could come up with some decisions regarding which bike for which situation...keep on going. and definitely post results here.


----------



## hairball_dh (Aug 7, 2005)

*Easy question*



mcd said:


> Now the money question....which bike left you fresher feeling afterwards? which bike could you have pushed to a faster pace???? I think you did a great job with your test...i read it and was able to remember that it was done by you for you and your equipment...therefore it is a valid test for you which is great. It will be interesting to see long term tests if you are able to run the power tap on bunches of different trails on each bike, then you could come up with some decisions regarding which bike for which situation...keep on going. and definitely post results here.


Funny you should ask - cause I just rode the same route on the 29er again and was surprised how tired I felt afterwards compared to the Fuel.

This I think is a result of the gearing on the Dos compared to the Fuel. Both have 22/32/42 x 34/11, which of course puts the Dos gearing 10% taller due to wheel size. Almost all the climbing is done in the middle ring on the Fuel, but it's a stretch on the Dos (I'm a high cadence guy). I didn't ;notice this at all on my 292 - it had 20/30/44 gearing, which worked flawlessly at Moab.


----------



## LyndaW (Jul 22, 2005)

Hey Hairyball,

How about putting your 26" wheels on your Dos and riding a 20 min climb at 90 rpm and say 12mph and then repeat with the 29" wheels on board? I suppose you can't put the 29ers on the Fuel.

Just an idea if you want to see what the wheels are doing ..


----------



## Padre (Jan 6, 2004)

The entire test is pointed in the wrong direction.

Let's test going DOWN hill! 

I'll take a rigid 29er over a 3" travel 26"er!

On the uphill, I'll make up the 2.8% power loss with the extra turbo-boost provided by the fun I'm having and the stability downhill.


----------



## nonoy_d (Jun 27, 2005)

*The age old debate...with nothing accomplished*



preparation_h said:


> Just thought this was interesting.
> http://teamhealthfx.com/blogs/dave_harris/archive/2006/01/02/309.aspx


C'mon guys, and gals. This is an age old debate. It is like evolution vs. intelligent design, it also reminds me of a lot of medical research studies just having to focus on one outcome of benefits/success discounting other outcomes (i.e like quality of life after treatment)! Maybe we can place another outcome other than just which was faster but also which ride was more enjoyable. I hope it will end the debate.


----------



## richwolf (Dec 8, 2004)

nonoy_d said:


> C'mon guys, and gals. This is an age old debate. It is like evolution vs. intelligent design, it also reminds me of a lot of medical research studies just having to focus on one outcome of benefits/success discounting other outcomes (i.e like quality of life after treatment)! Maybe we can place another outcome other than just which was faster but also which ride was more enjoyable. I hope it will end the debate.


Oh come on! Debate is what forums are all about. Now what is your take on 26er vs. 29er??


----------



## MTBNate (Apr 6, 2004)

So wouldn't 24" tires be even faster?


----------



## JAK (Jan 6, 2004)

*a worthless debate.*

We are not machines.

it does not factor in this



Padre said:


> extra turbo-boost provided by the fun I'm having


That is a common yet hella different variable betwixed all of us.

AAhh the beauty.

Hit that ****!


----------



## Rivet (Sep 3, 2004)

Padre said:


> I'll take a rigid 29er over a 3" travel 26"er!


You have officially lost your mind. I might buy into some of the other 29'er propaganda but to say a couple inches bigger wheel works better than 3 actual inches of suspension travel is ridiculous.


----------



## - Jeremy - (Jan 13, 2004)

Rivet said:


> You have officially lost your mind. I might buy into some of the other 29'er propaganda but to say a couple inches bigger wheel works better than 3 actual inches of suspension travel is ridiculous.


He's not alone. Nearly everyone that rides 29'ers agrees with his statement. You always hear variations like "3 inches on a 29'er feels like 5", etc. Even JHK has something to say about the smoothness of the 29'er in this artice: http://www.fisherbikes.com/happenings/news.asp?id=163

A hardtail 29'er may not be as smooth as a 3" 26'er on drops and jumps, but I bet it smooths out a rough trail in a similar fashion.

- Jeremy -


----------



## Nat (Dec 30, 2003)

- Jeremy - said:


> He's not alone. Nearly everyone that rides 29'ers agrees with his statement. You always hear variations like "3 inches on a 29'er feels like 5", etc. Even JHK has something to say about the smoothness of the 29'er in this artice: http://www.fisherbikes.com/happenings/news.asp?id=163
> 
> A hardtail 29'er may not be as smooth as a 3" 26'er on drops and jumps, but I bet it smooths out a rough trail in a similar fashion.
> 
> - Jeremy -


I'd also grab the 29er before the 3" 26er just because I like the steering dynamics better. Besides, 3" travel is minimal. If I were going to ride, say, Porcupine Rim with its numerous delicious high speed drops sometime this spring between March and April, I'd look for a bike with 5" travel or more, whether it be 29 or 26.


----------



## Padre (Jan 6, 2004)

Rivet said:


> You have officially lost your mind. I might buy into some of the other 29'er propaganda but to say a couple inches bigger wheel works better than 3 actual inches of suspension travel is ridiculous.


Funny, I didn't say that at all! (Now who's lost their mind?)

Here is what I said.....


Padre said:


> I'll take a rigid 29er over a 3" travel 26"er!


My statement was clearly about preference.

Keep the propaganda to a minimum, eh Rivet?


----------



## nonoy_d (Jun 27, 2005)

*My take?*



richwolf said:


> Oh come on! Debate is what forums are all about. Now what is your take on 26er vs. 29er??


_________________________________________
26 X 2.35, and 2.1 for studded tires.


----------



## Nat (Dec 30, 2003)

nonoy_d said:


> [nothing]


Well, you had nothing to contribute to this thread but at least you got to do it twice!


----------



## hairball_dh (Aug 7, 2005)

*supplying my own noose this time around*

For your consideration: http://teamhealthfx.com/blogs/dave_harris/archive/2006/02/10/510.aspx

Something for everyone this time around...not too controversial. It does go to illustrate the tricky nature of comparing 2 different rides.


----------



## edoz (Jan 16, 2004)

*My scientific test.........*

My face after riding my 26er  
My face after riding my 29er


----------



## edoz (Jan 16, 2004)

*Possible Enzyte ad?*

Bob's got some new wheels
really big wheels
he's so much happier
his friends can't believe the change
and he's got a big hew swing of confidence
and some much deserved respect
not to mention a VERY happy Mrs. Bob at home!


----------



## asv (Jan 24, 2011)

This is an old post but I had to reply to it.

Reading forum after forum where the 29er subject is present makes me think there is a kind of mass marketing propaganda going on and some of the guys that post in the forums are just hired by Gary Fisher. 

Funny how the 29er guys attack everyone that thinks different. If you enjoy your bike, then let it be, there is no need to criticize Dave for his study just because the numbers didn't meet your expectations and come up with excuses that could change those numbers in your favor. I bet that if those number favor the 29er bike many of the guys here will support Dave and be happy with the way he performed his tests.

I prefer to ride a 26" to keep up with the pace of my other cyclist companions than ride a 29er and worry about them having to wait for me at the top of the hill. The same goes for competitions, the psychological effect of thinking I am riding a heavier bike (the 29er) will affect my performance more than the actual effect of riding 2lbs more of weight uphill.

Some bikes are just not for everyone and there is no need to slam somebody that just doesn't think like you! Enjoy your 29er and don't worry so much about the result if you don't race!


----------



## Mikecito (Jun 2, 2007)

You should get a time machine to go back to 2006 and let them know how you feel :thumbsup:


----------



## asv (Jan 24, 2011)

Mikecito said:


> You should get a time machine to go back to 2006 and let them know how you feel :thumbsup:


lol, yeah, they are probably riding 39er now and would not care


----------



## natrat (Mar 20, 2008)

so whats the deal now that 5 years have gone by. Are races being won by people on 29ers? that seems the only way to judge . Probably depends on the terrrain


----------



## Vespasianus (Apr 9, 2008)

natrat said:


> so whats the deal now that 5 years have gone by. Are races being won by people on 29ers? that seems the only way to judge . Probably depends on the terrrain


They actually are.


----------



## PAmtbiker (Feb 2, 2005)

And also... who cares? It's been half a decade. Just ride your bike...


----------



## 53119 (Nov 7, 2008)

29nation, gary fisher is your parade marshal. dress up however you need to follow him and just get yourself down the trail all happy style


----------



## wannabeRacer (Feb 9, 2004)

I ride both, I'm upset as to whats going on between 26" and 29" arguments. If it makes you smile then thats all you need 

Also, if these two doesn't satisfy you then I recommend 20", though not off road unless your on funniest home video


----------



## PeterMarv (Jan 14, 2011)

just saying...


----------



## scrublover (Dec 30, 2003)

Christ on a unicycle! 

Ride what wheel size puts a smile on your face, and don't get your panties in such a wad about what wheel size other people are riding.


----------



## 53119 (Nov 7, 2008)

most importantly raise your kids to be bmxicans. they're guaranteed skills to rock ANY wheel size for life. chances are if you didn't learn it on 20s.. you can't.


----------



## PolishExperiment (May 14, 2011)

We've had 1 world cup win on a 29er. The argument of 'racers can't ride 29ers because sponsors don't make them' is largely moot now as all major manufacturers make race 29ers. Seems that the majority of the time 26ers are faster in a WC race setting.


----------



## SeaBass_ (Apr 7, 2006)

Yawn........


----------



## Leopold Porkstacker (Apr 21, 2010)

26 + 29 = FATBIKE!!!










Here's a "half fat" shot to compare a 29er wheel (rear) to a 26x3.8" fat front (Surly Larry tire):


----------



## AllisonWunderland (Jun 7, 2011)

Larger diameter wheel has less rolling resistance over uneven terrain -- because of the arc radius of the larger wheel. This is why they put large diameter wheels on 4WD off-road vehicles. 

That's my story, and I'm sticking to it . . .


----------



## 53119 (Nov 7, 2008)

like i said they want their own parade.


----------



## PruneJuice (Jun 22, 2011)

Hrmm this makes me want to try a 29er...


----------



## beagledadi (Jul 18, 2004)

I ride a 29er and love it!

Hi hairball_dh 

Matt


----------

