It's a material world

Was in a bike shop the other day and heard a sales person tell a potential customer that they shouldn't buy a Cannondale because "aluminum is stiff and will beat you up."

You hear and read this a lot in the bike business. Too bad it's not true. It amazes me how much misinformation is propagated by ignorant bike shop employees and bike magazines. I guess this is what happens when companies are run by marketing people instead of engineers. Like "waterproof breathable rain gear" this is yet another example of where marketing people seem to act in complete defiance of the laws of physics and most consumers are too ignorant to know any better.

Didn't any of these people stay awake during science class in high school? Heck, let's put down the textbook for a second and just focus on the bike world and ask ourselves a couple of simple questions:
1) If aluminum is stiffer than steel why are track handlebars (where stiffness is of paramount importance) preferred over aluminum?
2) If aluminum is stiffer than steel why don't we have aluminum ball bearings, hub axles, BB axles, etc?
3) If aluminum is stiffer than steel why were the aluminum Alan and Vitus frames of the 90's criticized for being too flexible?

The reality is aluminum is softer and more flexible than steel (assuming same dimensions). That's not an opinion but rather a fact of science. This also explains why it's lighter. A lighter material has a lower density. A lower density means lower weight. You can see the pecking order by busting out the periodic table of the elements (yeah, the one from the high school chemistry class that most marketing people seem to have slept through):
Iron (the main component of steel) is # 26
Titanium is # 22
Aluminum is # 13
Carbon is # 6

The lower the number, the lighter and less dense the material. The lowest numbers on the periodic table are the gases hydrogen (# 1) and helium (#2) - which have both been used in balloons and blimps because they're actually lighter than air. At the other end of the scale you have tungsten (# 74) and uranium (# 92) which are used to make the armor piercing rounds fired by tank cannons. Anti-tank armor piercing rounds actually have no explosives in them, they're simply solid darts of tungsten or depleted uranium that rely on their high density and extreme velocity to penetrate the armor plating of their target (I spent several years as a M-60A3 and M1-A1 Abrams tank crewman). Gold, well know for its heft is also pretty low down on the list at # 79.

What makes most (though certainly not all) aluminum bikes so stiff isn't the aluminum at all. Rather it's the diameter of the tube. In a nutshell, the larger the diameter the more resistant to twisting. A great example of this is to ride a Klein or Cannondale and an old Vitus or Alan. All four are made from aluminum but the Klein and Cannondale feature massively oversized tubes while the Vitus and Alan feature tubes not much larger than conventional steel tubes. As a result the Klein and Cannondale are almost impervious to flex making them excellent bikes for climbing and sprinting at the expense of comfort. The Vitus and Alan on the other hand are notoriously flexible and were prized for their smooth ride and all day comfort.

The next time someone in a bike shop or bike magazine tries to tell you aluminum is stiffer than steel tell them to go back to school and learn some basic science.