“The nice thing about standards is that there are so many to choose from.”
-Andrew S Tanenbaum Ph.D
So Dr. Tanenbaum wasn’t thinking about bikes, but his comment certainly applies. There are a few measurable aspects of a frame that can tell you how it performs. But, if everyone is measuring these aspects differently, how do we know what we are comparing? It would be great if there was one agreed upon standard so that you could be certain that you are in fact comparing an apple to another apple.
There is no such thing as a wrong or bad standard. Different standards, or different measures, will tell you very different things about a bike. Essentially, these different measures will answer different questions. Knowing how to compare bikes accurately means knowing what questions you are asking, and what question a standard is answering.
Cervélo’s mission is to make our athletes, people like you, faster or more efficient in their riding. Therefore, we base our tests on answering ‘does it make you faster?’ The performance of one frame can be compared to another based on weight, stiffness, aerodynamic drag, and rider comfort. Over the next few articles, I will try to break down why different manufacturers will come up with different results and which results paint the truest picture.
Part 1: Weight
All else equal, lighter bikes make climbing easier. And there is something to be said for that look on your friend’s face when he first picks up your R5 and can’t believe how little it weighs. Does less mass (in your frameset) make you faster? Certainly not in every scenario (downhill, anyone?), but it becomes especially important on climbs steeper than 5%. (Why 5%? Have a look at “Weight vs Aero,” aka “Col de la Tipping Point”.)
Fortunately, a standard already exists for comparing mass. Simply weigh the options you are considering and compare the numbers. However, you can’t compare a frame that you don’t have. So why don’t manufacturers just make it easy for you and publish their frame weights? There are a few reason for that.
First, the weight can vary slightly from size to size. Nothing in this world is perfect, so even two frames of the same size and model can have different weights. Slight variations are tolerated - literally, in or out of tolerance. Weight weenie? Weigh a batch and select the lightest.
In manufacturing a frame like the RCA, we measure the mass of every individual part at every part of the manufacturing process to ensure that the quality and mass of the frame is completely controlled. Because of this process, we can be confident in saying that the average weight of a 54cm frame is 667 grams.
Detailed chart of weights measured in RCA manufacturing
Second, not every manufacturer weighs their frame in the same condition. If the idea is to have the lightest frame possible, it is tempting to weigh the smallest size frame with no hardware (seat post clamp, derailleur hangers, etc.) and no paint. Size, paint and hardware can account for a significant difference in weight when you start looking at the lightest frame available. And if you were a bike manufacturer, wouldn’t you want to claim to have the lightest frame?
How we measure
Since we want to make you faster, we weigh frames with everything necessary to make that frame work. When we present a frame weight, like the 667 gram RCA, it is a weight for a fully painted frame including hardware like seat post clamp and derailleur hangers. After all, you do need your seatpost and derailleurs to ride it.
What you need to know
If you find a claimed weight, always ask what was included. Was it weighed with hangers and clamps? Does it have a seat mast? If it has a seat mast, is all of the hardware included? What size was weighed? Was it painted? When comparing two frame weights, make sure you are comparing the same effective parts. More often we are seeing frame set or ‘module’ weights. If one option includes the headset, bottom bracket, seat post including all of the hardware necessary to mount a saddle, make sure you include the same when considering another option.
If you can’t put a frame on the scale yourself, the next best thing is to look for an unbiased third party measurement. Publications like Tour Magazine, Bicycling, Velonews, and Bicycle Radar often publish weights and do their best to avoid relying on manufacturer claims.
We compiled our own list of frame weights for internal use (from the RCA white paper).
So you found some nice, light frame options. The comparison doesn’t stop there. Read Part 2 where composite engineer Will Chan discusses frame stiffness standards.