Every once in a while, some brilliant new idea comes along that leaves you wondering why someone didn't think of it sooner, like narrow wide chainrings. Yes, I'll say it, SRAM actually had a good idea for once. Narrow wide (alternating tooth profile) chainrings are so elegantly simple and so efficient at cutting down on chain drops, it was an idea just waiting to be stumbled upon. Seriously good thinking, guys. Not lining things up with the requisite patent offices so that you could retain exclusive rights to the new technology wasn't so brilliant, but I digress.
This is not one of those brilliant new ideas:
The Kingdom HEX AM275
Legit build kit, legit geometry, legit suspension design, but $20 says this bike sucks.
It's made of titanium. For some unknowable reason, the guys at Kingdom (is that a bike company? Really?) built a long-travel, full suspension mountain bike out of titanium, in the modern era. Why?
It's not like no one knew about titanium, as if the guy's who designed the bike pictured above were the first guys in the bike industry to discover that titanium exists. There are lots of materials you could make a long-travel full suspension mountain bike with, but there's a reason that 99.999999% of bikes are made with carbon or aluminum.
In absolute terms, titanium is heavier than aluminum, but less stiff than steel. It's also a really expensive material to source and to work with, and it limits what sort of machining you can do.
In terms of density and weight, steel is heavier than titanium, which is heavier than aluminum. If you made three bikes with steel, titanium, and aluminum using the same tube profiles and shapes, you would get a steel bike that's unconscionably heavy, and a titanium bike that's conscionably heavy. Anyone who's ever played with fancy aftermarket bolts to save weight already knows this. Ti bolts weigh less than steel bolts. A lot less. Aluminum hardware weighs less still, but you don't see aluminum 4mm stem bolts because...
Aluminum is less stiff and less strong. Compared to steel, aluminum is about 1/3 the weight and stiffness, and about half the strength. So for small bolts and other things that can break your face off, we rely on steel. Titanium is, again, somewhere in the middle. Ti is roughly as strong as steel, but half as stiff. Going back to our identical bikes example, the steel bike would be twice as stiff, but it would also be twice as heavy. And the aluminum bike would be the lightest of the three, but would be 100% un-f-ing-rideable because it would have all the confidence-inspiring stability of cardboard in the rain.
But fortunately for aluminum, frame designers aren't married to simple, straight-gauge small diameter tubesets. You can have a huge effect on frame stiffness by playing with tube shapes, diameters, and profiles. In fact, other than changing materials, tube diameters and shapes are pretty much the only way you can change the stiffness of a bike. Basically, a bigger tube is stiffer than a smaller diameter tube.
So while a small diameter, thin-walled straight-gauge steel tubeset can make a stiff and strong frame, it takes a much thicker, much larger-diameter aluminum tubeset to equal the stiffness and strength of steel. But when you make the tubes really big, you encounter a problem. If you make the tube diameter bigger but don't make the tube walls thinner, than you are dealing with way more material and the tube gets really heavy. If you try to compensate by decreasing wall thickness, eventually you will have paper thin tubes that dent and deform easily, and you will not have enough materials at the joints to weld properly. If your welds are too thin, they will crack.
Aluminum necessitates large diameter tubing because it's less stiff than steel, but it's also much lighter than steel, so you can still have thick tube walls that are strong and good for welding without sacrificing weight. This is basically why steel bikes look like steel bikes and aluminum bikes look like aluminum bikes.
Steel tubes. Smaller diameter.
Aluminum Tubes. Bigger diameter. And a way sweeter paint job.
Aluminum bikes took over in roadie world in the 90's because they could be built lighter than steel. That's pretty much it. Any argument about "aluminum is stiffer than steel" is basically just a discussion of tube-profiles vs. wall thickness. Steel bikes couldn't be built any stiffer or lighter, i.e. bigger diameter or thinner-walled tubes, without sacrificing welds or strength.
But mountain bikes are way cooler than road bikes, because we have full suspension and pivots and shock mounts and way way way more design constraints than a standard double diamond road frame. Building a good full suspension mountain bike is the design equivalent of stuffing ten pounds of shit into a five pound bag. Just ask anyone who's tried to design a long-travel 29er with short chainstays. Not easy. If you have to pack a whole bunch of shit in a small space, that means you need to design and build some really weird stuff, and join together a bunch of CNC stuff with forged stuff with tubes. Aluminum is soft, so it's quick, easy, and cheap to machine. Drill bits and tooling are expensive, and aluminum is pretty easy on both. Plus you can hydroform and hollow forge and use monoque tubes and do some really cool shit.
If you had to do all of that with steel, you would spend $250,000 per frame or have a bike with rivets and bolts that weighs 100 pounds. That's not the only reason that mountain bikes are made of aluminum, but that's probably 90% of the reason. For brevity's sake, I'm not even going to bring up carbon fiber here.
So where does that leave titanium? Well, it turns out someone's already played that game. Titanium is pretty similar to steel in terms of strength, and it's lighter. The only real design constraint is that it's less stiff. So a bunch of guys in the late 80's had the bright idea to build road bikes with a basic steel frame design, then stick a big tear-dropped downtube on it to mask the flex, and sell it to people who couldn't really tell the difference, using the pitch that "it's lighter, and your slightly shittier-riding bike will last forever because it's made of titanium."
And Litespeed Bicycles was born:
And Litespeed Bicycles was born:
Titanium isn't inherently bad. It's just less good at everything. You know how the 27.5 wheel is supposed to be the perfect compromise between 26 and 29, distilling the best qualities of each while skirting around their major drawbacks? Titanium is sort of like that, except it sucks.
You could offset the decrease in stiffness by making the tubesets really big, but then they would have to be prohibitively thin and they wouldn't weld nicely. Unless you want it really heavy.
Practically speaking, steel and titanium are so hard and so expensive to work with that you can't build a full suspension mountain bike out of steel or ti without taking some big design shortcuts. Unless your name is Brad Watt or Phil Wiering, in which case everyone else is dumb:
Still, it took Brad and Phil a really long time to build that bike. No company could ever manufacture that bike in a cost-effective way while retaining the bike's awesomeness. And even if you wanted to manufacture a long travel full suspension bike with a material other than aluminum, you'd pick steel every day. It's twice as stiff as titanium. With titanium you have the choice between light or stiff, but you can't have both. So really, it's a choice between heavy or flexy.
People have tried making titanium full suspension bikes. They sucked then, and they suck now.
Even with 142x12 axles, oversized head tubes, and a better understanding of suspension designs and geometry, you're still just polishing a turd.
The only reason that titanium "Enduro" bike even exists is because people cannot and will not accept the fact that things exist the way they do for a reason. Of course mountain bikes aren't "perfect" right now, whatever that means, but if you study your history they're a lot better than they used to be:
I could put up a thousand different pictures to make this point. Realistically, that one's pretty tame.
Most big innovations, even the huge, exciting, earth-shattering ones, are just a combination of existing technologies, anyway. People started playing with steel around 400 BC, aluminum started to be used as a structural agent around 1825, and titanium showed up in manufacturing around 1910. People way smarter than you and I have been studying these compounds, optimizing them, and trying to use each for specific applications for over a hundred years. In the case of steel, thousands. The only world-leading example of R&D to come out of the bike world was when Shimano developed hollow forging, and they had to build robots to do that. Shimano was the first manufacturer in the world to hollow forge, and even NASA came to Shimano trying to figure out how they did it. Other than that, every single innovation in mountain biking is just borrowed from another industry that did it 20 or 200 years ago. I can almost guarantee you that the narrow/wide chainring is just borrowed from some other industrial or automotive application. If you want to develop a new alternative technology for bikes but you can't show me an example of that alternative that's currently in use SOMEWHERE outside the bike industry, there is a 0.000001% chance that your new product isn't going to suck. And if your name isn't "Shimano," there's a 0% chance. If you can't show me your "new" idea at work somewhere else, you have no idea. You just have a dream.
"I dream that one day titanium mountain bikes won't suck,
so I'll just start making them until they stop being terrible."
But no one in the whole bike industry wants to talk about this, so everyone who rides bikes just gets dumber. It's like no one in the whole world wants to hear that incremental progress, while less sexy, actually results in a better long term product. People want so desperately for things to change, but instead of learning about how and why we do things the way we do and focusing their energy on how we can incrementally make the things we already have better, they would rather throw the whole thing out and start over again, just so they can feel like "We're doing something different! This is progress!"
And that's why this Russell Brand video is retarded.
Most of the technical talk about frame materials is straight from the one and only Master Jedi, Sheldon Brown: http://www.sheldonbrown.com/frame-materials.html