Wednesday, August 27, 2014

Tour magazine test of "under 800 gram" frames

Tour Magazine did a web feature from an article in the Dec 2013 printed magazine "Lieichte Rahmen unter 800 Gramm." This featured 8 bikes, all exceptionally priced, which presumably get under the challenging 800 gram mark for a bike frame.

Now 800 grams is hardly new. For example, Ruegamer showed a custom frame under 700 grams at the National Handbuilt Bike Show 6 years ago, and that frame is still ridden a ton by weight weenie legend Don Becker of Berkeley. Spin, a company in Germany, was also around the same mass at that time.

But production bikes tend to be overbuilt due to the need for mass production margins and since sometimes the fattest riders buy the lightest bikes, irrationally. It's not a good thing if a 100 kg rider snaps his 51 cm frame after hitting a pothole on his 3 mile bike commute. Additionally, 1500 watt sprinters may perceive an extra few mm of flex in a super-light frame, causing irrational fear that precious watts are being squandered. So the game has more often then not been to claim lower weight by changing the protocol (for example, without paint, without derailleur hangers, even in the case of Pinarello without bottom bracket shells.... I'm still waiting for a company to leave out the epoxy and just weigh the carbon fibers). Cannondale, for example with the Evo, used an "equivalent" mass attained by adjusting for various design features on the frame, on the basis they could have made it that light had they designed the frame differently.

Despite this, big US media almost always report the claimed mass of the frame. After all the claims are from advertisers, and it doesn't do well for advertising revenue to indicate any lack of trust in their claims. It's been said "the customers of magazines are the advertisers, the product is the reader; they deliver the product to the customer."

The German magazine Tour, however, ruthlessly weighs every frame they review, and that includes the frames of complete bikes, which obviously requires disassembling it. They weigh not just the frame, but also the fork and bearings, reporting each separately and rating the bike on the combined total. This is important, because usually everything else on a bike is replaceable, and in any case there's almost always various component options for each frame, so a "fair" comparison comparing like-to-like with different companies becomes impossible.

I say "ruthless" because while it's common to report the lower mass associated with smaller-sized frames (the most infamous case of this might have been the Guru Photon first shown at Interbike, a tiny custom), they target a "medium" frame, medium by German standards, which is typically what is called a 56 cm to 58 cm. The other difference is they are willing to use a white version of a bike, and since white paint needs to be applied generously to fully occlude the black background, white frames tend to be heavier, especially relative to a clear coat option. So the numbers are often on the high side. The result is if you come out light in the Tour magazine tests, that says a lot.

So back to the "800 g" article. They measured the following:

  1. Cannondale SuperSix Evo Black, a personal favorite of mine. I test rode a Cannondale Evo back soon after they first appeared in a local SportsBasement and it was very nice.
  2. Cervélo RCA: the famous $10k frame described in Cervélo's white paper. This is a wonderful combination of light, aero, and optimized stiffness but with an anomalously tall head tube which calls for a relatively long, -17 degree stem to get a racing bar position.
  3. Corratec Mauro Sannino Prima: I've heard of Corratec, but don't really know anything about them.
  4. Focus Izalco Max 0.0: Focus has always been a practioner of the "fatty down tube" style of frame design, which I don't like. But they do claim low masses.
  5. Neil Pryde Bura SL: Neil Pryde made big claims about this frame, but in the end, it wasn't particularly light compared to competition. I suspected this wouldn't do as well as some of the others like Cannondale, obviously Cervélo, Simplon, or maybe even Trek (with its expensive vapor coat paint).
  6. Pasculli Altissimo: I don't think I've ever heard of Pasculli.
  7. Simplon Pavo 3 Ultra: Simplon is one of the frames that perennially competes for the top spot in Tour's ratings. The frames are very light, but like the focus, designed with the fatty downtube philosophy which results in poor aerodynamics.
  8. Trek Madone 7.9 H1: Trek historically didn't brag much about weight, at least until the latest Emonda "fatty downtube" design, but the top-tier Madone with vapor coat does very well. Trek always comes through with a really light, super-priced top-end frame, then they beef out frames lower in the range which are sold at a consideraly lower price.

Here's the results, ranking the bikes by total mass:

modeltotalframeforkbearingsstackreachSRratio
Cervelo RCa1082704323555763871.48837
Simplon Pavo 3 Ultra1113717324725593941.41878
Cannondale Evo Black1123760303605593961.41162
Focus Izalco Max1164802293695654021.40547
Pasculli Altissimo1203789336785593941.41878
Trek Madone H11204786379395454041.34901
Corratec Mauro Sannino Prima1209783336905474041.35396
Neil Pryde Bora SL1241802374655623901.44103

Tour goes beyond mass, also measuring stiffness (good and bad) to come up with an overall score. I'll leave the stiffness scoring to them: check out the German article.

One thing which pops out here is that despite the title of the article, two of the frames are over 800 grams: the Focus and the Neil Pryde. The Focus makes up for it to a large extent with its exceptionally light fork: the only fork under 300 grams, something which used to be fairly common back in the mid naughts but which is rare now due to increased safety standards. Note the Cervelo fork is 323 grams, well above 300, despite its expensive micro-think nickel coating for strength. The Neil Pryde, on the other hand, complements its 802 grams with the 2nd heaviest fork in the group, only the Trek Madone heavier and just barely. The Trek Madone, however, has the lightest headset bearings by a decent margin.

On average, these bikes have the following masses:

avg bearingsσ bearingsavg forkσ forkavg frameσ frame
6614.3701333.528.4912767.87535.4663

Interesting here is that the difference (as reported by the standard deviation σ) in bearing mass is around 40% the difference in frame mass, and the difference in forks is around 80% the difference in frames. So just looking at frame mass, fairly common, doesn't tell nearly the whole story. And there's only a weak correlation among these frames between frame and fork mass. So you really need to consider both, unless you're planning on replacing a heavy fork.

The total mass has an average of 1167 and a σ of 52.4 grams. This σ is larger than you'd expect if the three mass componts were uncorrelated: the uncorrelated result would be 43.4. So there's a positive correlation among components.

On the specific results: the Cervélo wins on total mass (it's also the most aerodynamic, I'm fairly confident). The Simplon and the Cannondale are close behind, trailing by 31 and 41 grams. The Simplon frame is impressively light at 717 grams, only 13 grams more than the Cervelo and 43 grams lighter than the Cannondale. The Cannondale scores strongly with the light bearings and the light fork.

By the way, even though the Cervelo RCa "won" on total weight, the frame weight is higher than Cervelo claimed for even the heaviest of the size 56's. Did Tour include something with the frame that Cervelo does not? The Cervelo number includes "hardware":

Here's rankings by sub-class: frame, fork, and bearings.

modeltotalframeforkbearingsstackreachSRratio
Cervelo RCa1082704323555763871.48837
Simplon Pavo 3 Ultra1113717324725593941.41878
Cannondale Evo Black1123760303605593961.41162
Corratec Mauro Sannino Prima1209783336905474041.35396
Trek Madone H11204786379395454041.34901
Pasculli Altissimo1203789336785593941.41878
Focus Izalco Max1164802293695654021.40547
Neil Pryde Bora SL1241802374655623901.44103

modeltotalframeforkbearingsstackreachSRratio
Focus Izalco Max1164802293695654021.40547
Cannondale Evo Black1123760303605593961.41162
Cervelo RCa1082704323555763871.48837
Simplon Pavo 3 Ultra1113717324725593941.41878
Pasculli Altissimo1203789336785593941.41878
Corratec Mauro Sannino Prima1209783336905474041.35396
Neil Pryde Bora SL1241802374655623901.44103
Trek Madone H11204786379395454041.34901

modeltotalframeforkbearingsstackreachSRratio
Trek Madone H11204786379395454041.34901
Cervelo RCa1082704323555763871.48837
Cannondale Evo Black1123760303605593961.41162
Neil Pryde Bora SL1241802374655623901.44103
Focus Izalco Max1164802293695654021.40547
Simplon Pavo 3 Ultra1113717324725593941.41878
Pasculli Altissimo1203789336785593941.41878
Corratec Mauro Sannino Prima1209783336905474041.35396

Geometry in this review is primarily parameterized by stack-to-reach ratio. A bigger number is a more upright bike, a lower number is a more aggressive, lower or longer geometry. Here's that ranking:

modeltotalframeforkbearingsstackreachSRratio
Trek Madone H11204786379395454041.34901
Corratec Mauro Sannino Prima1209783336905474041.35396
Focus Izalco Max1164802293695654021.40547
Cannondale Evo Black1123760303605593961.41162
Pasculli Altissimo1203789336785593941.41878
Simplon Pavo 3 Ultra1113717324725593941.41878
Neil Pryde Bora SL1241802374655623901.44103
Cervelo RCa1082704323555763871.48837

The Trek and the Corratec are the most aggressive, each at 1.35. Then there's a pack at 1.42: Focus, Cannondale, and Pasculli, and Simplon. This seems like a good numberto me. Then there's the Neil Pryde at 1.44, and in a class by itself, the Cervelo is 1.49.

Geometry is plotted here, where each bike's point is at the center of its label:

image

Adding spacers (assuming a 73 deg HTA) moves you up the near vetical blue dotted lines. Adding a longer stem (0 degrees) moves you along the near horizontal lines to the right. A +6 deg would move you at an upward slope relative to these lines, a -6 deg would move at a less steep slope. The spacing between lines is 1 cm.

The result is that it would take around 3.5 cm of spacers, and a stem 1 cm longer, to match the position of the Madone or Corratec on the Cervelo.

Which of these do I take? I'll eat the SRratio and go with the Cervelo. It wins on mass, it wins on aerodynamics.

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