26 vs 29 singletrack shootout: tie

Well now, (AHEM!), looks like I jumped the gun yesterday in revealing results.  That's what I get for seat of the pants analysis.

The testing of 29er vs 26ers continues on.  Quick recap:  the first round of tests looked at how climbing on the Dos 29er compares to climbing on the Fuel 26er.  Those results showed a small but repeatable advantage to the Fuel for climbing dirt roads.  That wasn't a big surprise to me, however, many took it as a direct attack on their lifestyle ;)  We're just talking about a slightly larger wheel size, right?

This round of tests was done on a 3.2 mile singletrack loop in McDowell mountain park outside of Fountain Hills, AZ.  If you've done the Mesa NORBA nats, you've ridden this trail.  Swoopy, twisty, fast in spots, steep rollers, bad braking bumps in spots, a few very tight turns.  It starts with a ~ 3 min big ring climb, finishes with a more rolling but trending downwards section of whoops and twisties.  I call the latter section the "descent" in this analysis.

I did the rides on 2 different days separated by a 5 day period.  The first ride tested the 29er, the second ride tested the Fuel.  The results for each test are broken down by overall time, average power, and normalized power.  Here's how it turned out: 

Other relevant data not reported in the above sheet:  energy expenditure was identical across bikes and runs at 185 kJ & 184 kJ for the Dos, 185 kJ and 182 kJ for the Fuel.

At first I thought based on average powers that the Fuel was significantly faster on the descent portion - which is completely non-intuitive.  The Dos felt like it held speed better in turns, so I expected the Dos to be faster on the descent.  If we just look at average power, that conclusion would stand.  However, normalized power comes to the rescue.  Normalized power was just enough higher in the Fuel tests to indicate I had a bit more snap in the legs on that day.  In rolling terrain, it is very important where you put the power down, and how much at a time.  On the Fuel's day, I just had a bit more to give on the steep ups, and rested more on the descents.  The averages were the same, but Pnorm tells all...another factor that may have attributed to faster times on the Fuel was that I got 3 runs in on the Dos 5 days prior, so I was more familiar with the trail.  The Fuel did feel faster in the tightest terrain, oh wait, that's subjective, nevermind.

Here's a chart showing how the distribution of power changed between the two rounds of tests.  There's a considerable shift to the right for the Fuel's test, which simply means I was feeling better that day. 

As for the climb - look how tight the data is between the first run on the Fuel, and the second run on the Dos.  Looks identical to me.

Round 2 conclusion:  it's a tie. 

So what's next?

One test will be similar to this one, except at a much more relaxed pace.  These runs were at a XC like pace, far above that of an endurance race.  What happens if power spikes are much lower & most of the riding is in the saddle?  Will the bigger wheels conserve energy somehow in the twisty/rolly stuff under those conditions?  

How about some pure downhill runs?  There aren't any around here I can think of, that'll probably have to wait until late-spring back in Colorado.  The great thing about a bunch of downhill runs means I get to do a bunch of climbing :)

Signing out for now, fire away, but keep it civil.

Published Friday, February 10, 2006 6:23 PM by Dave
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# @ Saturday, February 11, 2006 8:48 AM

Looks like you've been having some fun. I think it would be interesting to perform some tests like this on a novice rider. To see then if the bigger wheels help a beginner with speed and power, or if the 26ers are more beneficial to someone learning how to ride and handle a mountain bike.

Anyway, have a good week, hope to see down at OP next week.

Adam Lisonbee

# @ Sunday, February 12, 2006 6:55 AM

HI Dave,
Sounds interesting and those CPS power dist. charts maybe are of some use after all :)

Don't mean to ask too many questions but do you have any specific recommendations for a moutain bike PT setup for me? I have two road PT Pro setups (one well-used and one only ridden on the trainer). I also have a couple of extra harnesses and computers. It was suggested that I could perhaps modify my old PT Pro wheel for m/c spacing.

Conditions are down to -5C + windchill, wet for sure, grimy (road sand), sometimes salt ...

I've recently looked at just how many rides I was estimating based on Avg. HR and geez it's a lot. This year I've been getting out weekly for a long ride (sometimes two) and that's about 300 TSS and perhaps 1/3rd of my weekly load.

If I were to buy a new PT PRo built into a rim, what would you recommend. I'm 6' and 185 lbs BTW. Usage is mostly road with a modest amount of logging road, railway bed trails...

You can email offline if and when you have the time. Hope the taper isn't driving you crazy ;0


p.s. We had 2-4cm of forecast snow end up as 36cm by 0800 Sat. morning. No riding in that.


# @ Sunday, February 12, 2006 7:12 AM

See Rick, that's why I'm a snowbird ;)

The taper is a blast actually - in my world taper's aren't that easy until the final 2 days...I'll hit OP at CTL 123 and TSB 138...330 TSS ride on the books for today. Funny how the ride that used to kill me has become a taper ride.

I think you can use one of your existing PTs by getting a 135 mm axle kit from cycleops. I haven't done that though, you'd have to ask them, but the only difference between the MTB and Road PT hub is 5 mm of spacing.

As for rims: go with ceramic braking surfaces, whatever you get, otherwise you'll be replacing rims every year due to brake wear. I'm running a Mavic 717 ceramic and it's been bulletproof thus far. Lots of racing on it. On the 29er, I'm running an Open Pro Mavic Ceramic, and it too has been bomber. I've crashed it through numerous white rim rides and a bunch of other stuff, still holding strong, but I'm not a linebacker either (remember the Fridge, that 380 lb football player from the 80's? That's how I envision you...).

Get some skiis man!


# @ Sunday, February 12, 2006 8:05 AM

thanks Dave. With about 20,000km on my old PT PRO - I'm ready to sacrifice it.

32 spoke of course is all I ever use and usually a deep chunky rim.

Linebacker -- well seeing I was a 'natural' 215lbs in college days (no weight training but no aerobics either) I guess I would have fit the bill. I hit 245 when I weight-trained a lot in the early 90's so 185 (190 right now) is positively svelte for me :)

Skiis -- not specific enough. But I do some x-training when walking the dog by jogging UP all the hills. And darned shovelling too ... but hurt my back a bit last week when I had 2hrs and 4.5 hours on Wed/Thursday (50cm of snow and 100 kph winds). Yesterday was only 2hrs ...

Did you really mean TSB 138? How can you do that on CTL=123 :) +38 sounds good.

Hear what you're saying about the 300+ days not being *that* stressful. I did a 225 and 300 back-to-back last weekend (temps -3C and -2C but not much wind). And I felt quite 'normal' on my Monday rest day.

Good luck on race day if we're not talking ...



# @ Sunday, February 12, 2006 10:45 AM

Doh! Yep, that's 38, not 138.