Drum roll please...as you look at this plot, keep the following in mind:
- This compares a Trek Fuel 26" wheeled bike and a Salsa Dos Niner 29" wheeled bike
- Bikes were similarly equiped - near identical weight
- Identical tread pattern, Specialized Fast Traks all the way around
- I changed the crankset on the Dos to accomodate a 30T middle ring to more closely match the Fuel's gearing
The data is the result of daylight laps at the 24 Hours in the Old Pueblo race. When I say race, I mean it was full on...see the OP race post if interested. The upshot of this was that I did everything possible to go as fast as possible, within the limits of the event. No prior subjectivity could have skewed the results. The displayed lap times are the time on the course. Pit times are not included. I threw out the night laps for publication because of the eyesight issue - the 9th and 10th laps are extreme outliers due to extenuating circumstances.
OK...giving this a minute to sink in...each point represents the x, y pair of average power and lap time. In other words, the dots in blue show the relationship between power and lap time when riding the Fuel. More power = faster laps. Make sense? The black lines show a linear regression (done by MS Excel) to illustrate a trend, or predicted values. The two pink squares show what happened on the Dos Niner.
I added the red rectangles to show the "what if" scenarios. Consider the case where average power over a lap is 188 watts. Based on this data, a lap time of 67 minutes would be predicted for the Fuel, while the predicted time for the Dos is just under 69 minutes. Looking at it from another angle, for a lap time of just under 69 minutes, I'd have to average 175 watts on the Fuel but 186 watts on the Dos.
So there you have it. It's cut and dried in my mind. The 29ers in my testing have lost in rolly, twisty singletrack, and also on climbs. They might fare better on downhills, and almost certainly in sand and maybe even rocky stuff...but right now I'm losing interest fast.
Anyone interested in a tricked out Dos Niner with a Power Tap hub?