Saturday, August 16, 2014

Trek Madone, Scott Addict, Cervelo R5, BMC SLR01, Swift Carbon geometry comparison

More bikes added to the stack-reach plot I showed last time. It's tempting to add more and more but I run out of colors, and humans have only 3 color receptors so there's contrast only between so many...

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Again the mostly vertical blue lines indicate points which can be matched to fit with the same stem but with more spacers on the lower stack, longer reach frame. Spacers reduce reach and increase stack. I additionally added mostly horizontal blue lines, which are spaced by 1 cm spacer height apart, again assuming a 73 degree head tube. These lines would correspond to points which you could reach with the same spacer height, but different length of 0 degree stem. Of course stems aren't typically 0 degrees 6 degrees, 10 degrees, and 17 degrees are popular, and these can be flipped positive or negative. But the spacing between these lines is the key point.

For small riders, Cervelo and Swift rule, Swift providing less stack, the Cervelo geometry at this size only relatively unchanged from the 2008 Cervelo. For big riders there's several contenders: Cervelo, Trek, BMC, with Trek providing the lowest stack. It would take around 2.7 cm of spacers to bring the Trek up to the bar height of the Cervelo.

In the mid-range, Trek is the low-stack king of this group, with Cervelo the big-stack leader by far. Note the difference between the Trek and the Cervelo here is around 5 cm of spacer. This is why among the pro riders you see so many slammed Cervelo stems with riders on small frames.

Cannondale clearly is not designing to stack-reach. Personally I don't care: I only need to fit one bike, so for a given point on this chart which would be my best fit, all I care about is which bike is closest. The shape of that bike's curve doesn't matter. If I were fitting a team or running a bike shop I'd feel differently. In contrast both Swift and Cervelo are clearly designed to stack-reach: their ranges form essentially perfect lines on the plot.

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