Is Aluminium alloy good for nothing?

Aluminium alloy frames aren't getting a lot of favours these day. On the top end, carbon seemed to be taking over everything, while at the lower end, people complain about the harshness of ride and suggest CrMo as a better material choice.

So is there anything left for Alu frames in the future? Is there anything that'll keep it around when carbon starts to filter down to mid-range bike frames? Apart from price, would anyone take an Alu frame over carbon?

 

I have a healthy distrust of carbon left over from my sailing days, so I would take an ally frame over a carbon one.

Of course, there is only one material for a bike ...... steel is real baby, steel is real.

 

I go through alot of road bikes and aluminum is inexpensive and lightweight. Need another bike? Just order a cheap, custom sized, alum road frame and build your components around it. ChroMo good but a little heavy. Never had one of the real euro steel frames so don't know the contrast.

 

I ride an aluminum road bike and though it may not be as forgiving as steel, carbon , or ti, it is a lot less harsh than the aluminum bikes 10 years ago (the last time I rode an aluminum road bike). It also is quite comfortable to ride, something I thought I would never say about an all aluminum frame. I also am skeptical about carbon filtering down to the masses. It is still an expensive material to manufacture with few companies doing it. I doubt aluminum is going to go away because it is inexpensive and abundant.

 

I like Al for lightness, but see the long term benefits of CrMo.

Carbon fiber reinforced plastic bikes, well, maybe they have their place as a single use (TdF) item, one race and then throw it away!

 

Yes, I am also concerned about carbon bikes and the risk of failure following an accident. Not a great thought despite the minimalist weight.

 

7 series Al is not known for good failure properties either, though it may not be as bad as carbon.

roadies like 110 psi 23mm tires but if you ride anything much bigger you'll not notice the frame material much.

 

Just reading the Orbea catalog today, they make CFRP and aluminum bikes and state that both have their places. The lightest frame they make is aluminum, a "climbing" bike at 950 g, made from 6000 series. They say it's lighter and stiffer than their lightest carbon frame, which is listed at 1020g. The Orca is marketing as a top-line "all around" bike, for century-long comfort, at 1070 g, while the Opal at 1050g is said to be stiffer and made to race. Also claim that for the pro teams they sponsor, riders will ride both CFRP and aluminum, depending on the event or stage.

Could be some marketing hype at work, but obviously Orbea feels aluminum is not dead. Appears for their frames at least, aluminum beats CFRP for lightweight stiffness.

 

While it might be true that the TdF bikes are disposable, the carbon fiber tubes on the bikes that are sold to the general population are twice as thick and four times as strong as those used on the pro tour. Carbon fiber frames are no more likely to fail than are CrMo or aluminum. Under the right (or wrong) conditions, any frame will fail, regardless of the material. There is no evidence that carbon fiber or aluminum frames are more likely to fail than are modern CrMo frames. A CrMo frame that weighs the same as an aluminum or carbon frame will be weaker than the aluminum or carbon fiber frame. A CrMo frame that is as strong as an aluminum or carbon fiber frame will be heavier than either of the others.

 

The difference is in the way it fails. You can substantially weaken a carbon fiber part by crashing it and not see any external signs. Then, when you hit your next big bump, it will suddenly give way completely.

The same goes to a lesser extent to 7 series aluminum especially if you don't inspect your frame for cracks. You may see a crack start in an aluminum frame (then again you may not) but it won't have any give to it. It will just pop.

Good old steel can be counted on to bend before it breaks though. Medium carbon chrome moly steels have good toughness and exceptional failure characteristics. Cracks will propagate slowly and are not likely to spread completely through the material all at once. Plus, you can just weld them up if they crack.

You can't just laminate a few extra layers of carbon roving over a damaged carbon part because you can't always tell where it's damaged. You can't just weld up an aluminum frame unless you have an oven to heat treat it in, or the area around the weld will be "7005-0", not "7005-T6"; or in other words, weak as hell.

 

So has anyone had the misfortune of getting a crack in their Alu frame? One that came without some significant accident or abuse.

 

My 2001 Raleigh M50 is going strong; it is made of 6061-T6.

 

Says who? Have you looked at the crop of bikes these days? Not only are there plenty of AL frames out there, but so many great rides are a blend of AL and carbon. I personally just built up a Cannondale CAAD8 which is one of the hottest frames around and rides oh so sweet. The "Aluminum gives a harsh ride" is an urban legend. It all comes down to quality and frame design. Wishbone seatstays and ovalized tubes have done a lot to smooth out the ride over straight guage tubes. Not sure what you are basing you information on, but based on sales and what I see people riding AL frames are as popular as ever.

 

Worth pointing out that wheel and tyre choice will make just as much difference to ride quality as frame material - maybe more.

 

The problem with your comparisons about ultimate yield strength is that not many frames are made of "good old steel" anymore, just because it's heavier than most of us want to ride on the road. EG, my 30 year old Raleigh Gran Sport 531 frame and fork. It got some handling abuse years ago, bending the fork. The LBS was able to straighten it by "cold setting" (bending). Certainly can't do that with CFRP.

But, it's probably a 7-8 lb frame/fork, which to my way of thinking makes strength comparisons a bit meaningless. How many people want a heavy steel fork anymore, even if they can take abuse and be straightened? Believe the weight and stiffness advantage of CF forks are preferred by most roadies today. EG, a buddy here spent big bucks to upgrade and lighten his fine old steel Merckx frame, and said switching to a good CF fork was the most cost-effective ($/gram saved) single update.

To get down to a weight anywhere close to aluminum or CF, a modern steel tubeset will have ultra thin walls and less ultimate yield strength. The crazy tensile strengths of the latest super steels allow for these very thin and light tubes, but you've sacrificed a good bit of the advantage in terms of denting and bending for handling and crash damage. Personally, I'd love to have an ultralight steel frame of S3, Ultrafoco, 853/953, etc, but not because it could handle abuse or crashes.

Bottom line, buy what you like, ride it a lot and don't worry. A heavy steel fork and frame would still be a great choice for "heavy duty" requirements far from an LBS....like extended loaded touring over unpaved roads. But other than those kinds of applications, the lightweight, stiffness and strength of aluminum and CF is hard to deny.

 

JFTR I would not use a contradiction in terms like "ultimate yield strength! "

My point is that aluminum and carbon make a nice bike if properly executed but have their drawbacks. It is good to discuss costs and benefits.

For example,to say that Al or carbon has worse failure properties than steel is not to assume they are too short lived to be worthwhile.

In aluminum's corner, someone has pointed out that technology has erased some of the drawbacks of aluminum, with the wishbone seatstays. Also, low-end, heavy Al frames are not butted and the thickness would contribute to stiffness, but this problem would not plague all the mid-range bikes built with quality butted Al tubing.

 

I'm a bigger guy (6'1" 200lbs) and I ride a CAAD 7 Cannondale AL and have had no complaintsin almost 2 years of riding it... cost was certainly a factor in my choice; Carbon was just too expensive (and still is)

 

Let me share with you my experiences with carbon fibre parts versus ditto aluminum/alloy parts.

I'm a rower and be racing at the world champs four times now, so I think I know alittle about boats now. (use road cycling for x-training, by the way!).

During the last 5 years, carbon fibre parts have become more widespread that aluminum/wooden parts in rowing. If you compare two equal top boats with aluminum riggers and carbon tube riggers, they are about equally stiff and costs about the same. So really no diffrence in performance. I've only seen prototype boats, pure carbon fibres that are stiffer than regular racing boats, but they were not light enough to be used for racing.

While parts that suddenly break in rowing are not acceptable, it is in road cycling. We have to use the same boat and oar set for an entire season and cannot risk something that breaks during a race. In road cycling, faliures are more acceptable during races, because you can always get a new wheel etc. Theres always a service car right behind you (if you're good enough ).

This year we got a new type of oars, pure carbon fibre. The oars we had before them had wooden handles. Good wood is extremly stiff aswell, but these new oars were extremely stiff. Really nice oars. As the season progressed, we had some issues with them. Out of 20 oars 3 broke. And I mean broke as breaking into two pieces. I've never seen a new oar with wooden handles do that.
Also at the world cup, I saw a favourite boat from Japan suddenly break a rig during a race. Resulted in the japanese guy had to take a swim. Boat was new - only a couple of months old tops.

What is my point is, if you compare good aluminum parts with its carbon counterparts, they are really equally stiff. Aluminum almost never breaks and it doesn't break just because you accidentally gave it a tiny little knock in the wrong place. Carbon parts cost hell of a lot more than alu parts.

Unless you do races and you're almost pro on a level where you -need- CF parts to take you further, I don't see why you would want carbon parts.

There are good alu parts out there. Good alu frames and alu everything. Go alu!

 

Great info!
I treasure input from real experience like this.
Cannondale looks better than ever!

 

I feel I left some info unsaid, by the way .. to continue my last post - here it goes.

Basically carbon fibres have two major advantages when it comes to part used in cycling (well also every other use you might find for it).

First thing is that it's ligther at same strength/stiffness, which is the obvious. The other thing is that you can precisely control how stiff something has to be and what better is that you can adjust the stiffnes/flexibility in diffrent directions. In rowing boats you do this first of all to ensure optimum force transfer from water through oars to the boat hull. Then you have directional layers of carbon fibres to control how it feels when the boat rocks from side to side. A top level rower like me want to have maximum sideways stiffness, so I can feel through the boat what the other rowers do and react to that and have to boat immedately respond to my slightest movement. An intermediate rower might want to have a more flexible (sideways) boat that won't punish him/her for poor rowing technique while still being stiff enough to transfer all the power into movement..

This is also true for road bike parts. By controlling the fibres, its possible to precisely control how flexible, say, a fork is or stem or whatever part we're talking about. This is often done to ensure more comfort or extreme stiffness or even both at same time in advanced products (expensive ).

You can do the almost the same with any metal. There are diffrent grades of metals. There are stiff aluminum types, flexible aluminum types, durable types, less durable types and so on. These have originally been invented in major industries such as aviation, automotive industry, space industry and so. The technology behind it is very well described and dates back to about the '70 I would guess. That's why there are aluminum parts that are so good on the market. Still, they can't compete with top level carbon fibre products in terms of lightness and precise contol of flexibility/rigidity. But really, if you want a top end product that is better than any metal type product, be prepared to pay the cost.

If it was my all day ride and I wouldn't want it to break down, I'd choose an aluminum frame over a carbon fibre frame anyday.
Then if I was really good at cycling, I would of course use carbon fibre parts for competitions.

EDIT: Also because a bike is meant to bump on the road occationally, your bound to stress your carbon parts in the way that is baddest for carbon fibres. Especially in parts that -will- touch the ground, should you crash your bike. I'm talking about handle bars, crank arms, seat post and so on. If you crash, you don't know if they've been damaged.