Sunday, June 28, 2015

2016 Cannondale Evo

[b]Comment:[/b] The following post is in error. The geometry chart on the Cannondale site is still the 2015 bikes. Bikerumor had an article where they described geometry changes for 2016, including adjustments to stack-reach in small and large sizes, and a general drop in bottom brackets consistent with the trend to wider, deeper tires. I'll post a follow-up post when I get the geometry chart for 2016.

Cannondale just announced it's 2016 Evo.

There's been a flurry of really attractive new bikes announced this year, including the new Madone 9 from Trek, the incredible Venge ViAS from Specialized, and the new Scott F02 update to the Foil. A common feature of all of these is increased focus on aerodynamics and comfort. Aerodynamics isn't new, with bikes going back to the Kestrel Talon and Cervelo Soloist Carbon examples of carbon frames designed for aerodynamic efficiency. However, the bikes have never been as popular as was predicted because in the end riders like feeing good on the bike, and a combination of drivetrain efficiency and vertical compliance provides a palpable advantage while the advantage of aerodynamic improvements needs to be carefully measured and is thus less obvious. But perhaps starting with the latest Felt AR a few years ago, aero bikes have received an increasing comfort focus, and it's hard to see them not finally becoming the main design used in the pro peloton.

BikeRadar photo

Cannondale's new Evo isn't an "aero" bike, but is more in the style of the Cervélo R5 which is a lightweight bike designed to be aerodynamic. The previous Evo made a nod to aerodynamics, but in a more subdued way by reducing tube diameters. This is important, but tube shape remained unchanged. That's been fixed here, with the new Evo adapting the now common "Kamm tail" approach of a truncated airfoil shape.

For "comfort", they've taken lessons learned in the Synapse. It's nothing as overt as Trek's adoption of the Isospeed linkage used in the "endurance" class (and tall-stack) Domane to the Madone 9. For example, one change Cannondale made was to reduce the seat tube diameter from the common 27.2 mm to the less common but more traditional 25.4 mm. There was a trend for a few years to make seat tubes ever fatter (my Fuji SL1 uses a mountain-bike-style 31.8 mm) but that makes little sense: propulsive torque isn't applied to the seat tube so a bendy seat tube, within reason, makes for a more comfortable ride. But additionally they've flattened the chain stays, like the Synapse, to provide more vertical compliance.

The fork as gotten an overhaul with a very light fork providing a large portion of the claimed 65 gram system mass reduction (the rest, I think, is from the seatpost). Tour magazine in Germany has been rating bikes on comfort using a combination of deflection at the seat tube and deflection at the head tube, the latter being a "fork comfort" rating which is averaged with the seat tube number. Many bikes have been engineered to score well at the seat tube deflection test but on the fork deflection test it's been common that bikes lose a lot of potential points. Jan Heine likes to emphasize the importance of fork deflection, advocating for the traditional high-rake flared out design which was common on steel bikes through the middle of the 20th century. Apparently Tour magazine agrees it's an important issue and the light, more compliant fork is a welcome modification.

One thing they did not change was geometry. I had thought with the addition of Damon Rinard, formerly of Cervélo, to the Cannondale design team that the stack-reach design philosophy would be adopted, but perhaps Rinard joined too recently for such a drastic change. Here's the Cannondale stack-reach chart compared to Trek's stack-reach-based design. Trek uses two curves, the "H1" and the "H2", for its Emonda and Madone. The special race-geometry Domane now uses the Emonda H1 curve. The Madone had a more aggresssive H1 curve but perhaps that will change with the Madone 9.

Cannondale and Trek geometry comparison

The two Evo curves are fully coincident and thus you can't see the 2015 curve, which is occluded. So the old and new Evo are the same.

Cannondale's approach includes some weirdness. For example, going from 52 to 54, the two points which are of similar reach but different stack 3rd and 4th from the left, they increase the top tube length but decrease the seat tube angle and the result is the reach stays virtually the same, the change in geometry almost all coming in the stack. Additionally the bottom bracket increases. Trail between the two is the same. I'd rather have the 3 mm lower bottom bracket so even though I could use a 14 cm head tube to avoid spacers I'd go with the smaller frame to get the same position with a lower bottom bracket and live with some spacers up front. It's just as well since the smaller frame will be lighter.

The importance of a clean stack-reach schedule can easily be overstated: either a bike fits or it doesn't and if a particular size in the Cannondale fits that's all that matters; I don't care what how the other sizes are designed. Still, I suspect this will be changed next iteration.

So this is a really cool bike. I really think 2016 is bringing a tangible advance in bike design from the big companies and my 2008 Fuji SL/1 seems more than another year older. It's more than good enough for me, however.... alas.

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