MarTay6

Hi, All-
I'm a newbie to bicycling and in the forum here, not a newbie otherwise, though (63 years old!)...
I was reading something today that I couldn't follow up on, and that was about someone who'd crashed and was attended to by an EMT who was also a cyclist... and he asked the guy if he'd gotten any warnings or cautionaries from the bike shop about aluminum frames... of course, the guy said "No"... which didn't surprise the EMT.
Well, having an aluminum framed bike- and being new to riding (in many years!) and not particularly not wanting to overlook some basics I should be aware of, is there something I need to be aware of in riding an aluminum framed bike?
note: My current bike is an Ibex 450 Alpine mountain bike I bought about 10 years ago and never rode- but my interest in riding it has been rekindled, and I'm starting to ride it... but I'm seriously looking at a Trek 7.4 FX at my local Trek shop... I rode it, and its certainly much nicer on the street than the Ibex. That's why I'm posting here in this forum, as I think I want to end up on a Hybrid.
Thanks for any input- I hope it's not a dumb question.
Wes

no1mad 

Aluminum vs Steel vs Titanium vs Carbon Fiber.. the 'holy war' debate on frame materials...

Get the Trek and enjoy- life's too short to debate frame materials.

MarTay6

I understand that there will always be debates about materials per se... I wasn't asking "what's best". This sounded like there was something unique to an aluminum frame bike that the bike shop should have warned this guy about... which makes NO sense to me whatsoever. I was just wanting to make sure there wasn't some unique characteristic of the material in a frame that was problematic- and people needed to be aware of.
Thanks!
Wes

MarTay6

Thanks so much for your comments and encouragements via PM! Beautiful race bike... that's what I'd love to be riding if I were younger!!
I went back and did some searching for what I read earlier, and while I couldn't find the exact post, I think what I read had to do with the differences in the way aluminum fatigues over time, and to someone like me, not a major concern. It just wasn't clear in the post I originally read.
Obviously I'm not going to be fit enough to break or wear our a Trek frame!
Thanks for the replies.
Wes

4.11

Completely ridiculous to think that there is a warning about aluminum frames.

What is the warning? don't ride the bike? give me a break.

richard4993

Any frame material can fail no matter if it's carbon, aluminum or steel. If you do go with that 7.4 you have a lifetime warantee on that frame if something was to happen so its not really too much to worry about. In terms of an injury related to the frame I don't think that is too likely as usually you'll be able to notice a frame crack on an aluminum bike before it cracks in half on a downhill.

MarTay6

... And we don't have too many downhills here in NE Florida!! *grin*
Wes

SlimRider

Hey there MarTay6!

I think that what the EMT was referring to was the fact that aluminum as a bicycle material, tends not to bend in the same manner that steel does. It has a very small yield strength or yield capacity. To this extent, aluminum would prefer to break or snap upon impact, as opposed to bend. Thus, exposing the rider to greater or more extensive injury, than steel. Rather than a metal tube bending, it instead snaps and the energy that would otherwise be expended in deformation of the steel tube, goes instead, into the spearing or shearing of the unsuspecting rider, upon impact. To this extent, aluminum tends towards catastrophic faliure.

-Slim

PS.

www.brightspoke.com/c/understanding/bike-frame-materials.html

talu.com/materials.php

prathmann

In principle yes, but my personal experience with failures of steel frames and components has been that they were sudden unexpected cracks with no visible bend. One was of the steel steerer tube that led to an injury crash when the front wheel and fork suddenly parted ways from the rest of the bike. Another was a crack in a weld of the rear triangle - fortunately it didn't result in a crash. I've also had sudden breaks in a few steel components - a couple rear axles and a couple pedal spindles. None showed visible bending and one of the pedal failures led to a crash. I suspect that some of these were the result of a material defect or improper welding and therefore the steel showed an abrupt crack rather than an initial bend.

OTOH, the aluminum component failures I've had (stem, handlebar, and derailleur) announced themselves by creaking noises or a failure to stay in adjustment and I was therefore able to replace the component before it failed completely. And my only aluminum bike frame has far more miles on it than any of my steel bikes without any frame problem.

My impression is that most crashes caused by equipment failure are related to assorted components (stems, handlebars, cranks, wheels, pedals, etc.) rather than failure of the frame itself. Yet aluminum is used in many of these items even by those who seem reluctant to ride aluminum frames.

4.11

Haha, yeah because we all know that is exactly what the EMT was thinking

Let's see, no pictures or posts of catastrophic failures of aluminum frames, and many manufacturers offering a lifetime warranty on their aluminum framed bikes, let's just say aluminum works fine as a frame material (as does steel and carbon fiber).

giantcfr1

I remember many years ago when I was 15, I hit the last hump of a whoop-de-do and my cr-mo frame snapped and I ended up under the knife in hospital.
My only other frame break was on my road bike after I was hit by a motorbike. The frame was carbon but the fork crown was alloy and it cracked. Visibly the carbon appeared ok, but GIANT advised me not to ride the bike as carbon can fracture from the inside and appear ok on the outside.
Didn't stop me from riding steel frames though, nor alloy frames.

SlimRider

Hey there 4.11!

What else could the EMT be thinking?...

Ever really thoroughly examine just what a bicycle frame "lifetime" warranty actually entails?...

No doubt there will always be exceptions to the general rule of thumb, that some aluminum products will statistically outlast their steel counterparts, but that will almost always be a rarity unless you subject the steel to an oxidizing environment. That's simply what science dictates. It's out of my personal control.

Any material that will prefer to break or snap as opposed to bend, will subject the user to greater potential physical injury. Energy not employed to deform material will most likely be involved in the injury.

- Slim

markjenn

My bet is that this "problem" concerns the fatigue properties of aluminum. As I understand it, aluminum alloys continue to weaken as they are loaded and unloaded, no matter how low the stress applied in each cycle, whereas steel and carbon have a fatigue limit where, if you keep the stress below this limit, the material can be cycled indefinitely. This means that given enough cycles, any alum structure will eventually fail, no matter how lightly loaded.

This sounds alarming, but consider that everyday tens of thousands of jet airliners made of aluminum alloys are in the air being cycled continually by air loads and pressurization and de-pressurization cycles. Since they are all fatiguing and will eventually fail, how can we trust our lives to them? We do by monitoring the cycles, carefully watching for developing cracks, and eventually retiring the airplane before the material has weakened enough to be a hazard. You see photos of hundreds of airplanes being stored for parts in the desert and wonder why they're out there? Structural fatigue is a big factor with many of them.

In practice, most alum bicycles are never subjected to enough miles and high enough stresses where fatigue is a problem. But if I had a very high-mileage alum bicycle (say with more than 20K miles), I'd start doing careful periodic inspections, and I probably would consider retiring it at some point. But for 99% of bicycle riders, its a total non-issue. And as others have pointed out, all materials can have structural issues so it is not like there is any wonder material which is totally immune from problems.

Having said all this, if I were selecting a bicycle where longevity was my absolute #1 priority, I'd probably tend away from alum.

- Mark

Trakhak

Sounds like the EMT had a limited understanding of and thus a naive take on bike frame materials and design.

It appears that most people posting on BF get this: any bike frame material + appropriate engineering and design = good (and durable) bike.

Possible exceptions: carbon fiber (may be prone to catastrophic failure from specific kinds of impact), steel (lighter frames can be less durable if the material is used with a smaller margin of safety from an engineering standpoint; in fact, in frame tests simulating long-term riding stresses, steel frames fail long before aluminum and carbon).

giantcfr1

Please don`t misunderstand me as I love steel frames but I have something interesting to share.
Here in Japan we have professional Keirin riders whom belong to a governing body called NJS. NJS state that all frames raced professionally in Keirin races in Japan MUST be made of steel. An interesting point is that if a frame is involved in a crash, it must never be used in another race. The frame is replaced with a new one. These frames appear and are most probably are ok, Many fixie riders buy the old frames (stamped with NJS) and ride and abuse them endlessly with usually no problem. You`ll be able to spot these frames as they usually have a dent in the top tube where the handlebars hit it on impact. I guess the hipsters are braver than the Pro riders and the NJS.

SlimRider, you`d be in steel heaven if you came to Japan. The majority of bikes here are steel. I wish I had one but alas, no room for another bike. My hybrid already lives in the front yard.

4.11

Slim,

Don't misunderstand, I like steel plenty, I have owned steel bikes and quite frankly love the steel my Mustangs are made of. My whole gig is to make sure the newbies don't get caught up in the frame material debate.

It is more important they get a bike and get out there riding, as they get more experience they can choose different materials as they see fit.

SlimRider

A G R E E D ! ! !

- Slim

rasmith3530

Most of the bikes I've owned over the course of my 58 years have been steel, although a couple have been aluminum, most notably a higher end Raleigh mountain bike and a custom built from a Raleigh sport touring frame. In the real world, I'd be more concerned with frame quality than frame material, and Trek is certainly a maker of quality bikes, with the 7.4 FX being high enough up their model line to most certainly guarantee a decent piece of equipment.

I've recently returned to cycling after a decade long absence, and I have discovered some interesting things. I personally like the feel of good double butted Chrome Moly tubing to aluminum, but that is my personal, subjective opinion. YMMV substantially. The Specialized Rockhopper I built up a decade ago using pretty much top shelf everything is extreme overkill for how I ride today. I am a Clyde at a bit under 300 pounds, and between that and my age, flat or dropped bars are just not how I roll anymore. I'll ride upright and allow my body to act as a sail or wind brake. It's me and how I'm comfortable.

If you are looking at a new bike, by all means ride it before laying down your dollars. Money is too hard to come by these days to spend four or five hundred dollars on something that is not going to be a pleasure to ride. In my case, being the natural tinkerer that I am, I opted to buy used and rebuild the way I ant the bike to be. Depending on how mechanically inclined you are, and your access to both tools and a place which to work on a bike, that may or may not be an option for you to explore.

Remember that, even when hanging from a garage wall or ceiling for a decade, a bike deteriorates. Rubber dries out and grease gets hardened. Metal can oxidize.

I found that I much prefer the lighter and larger diameter 700c wheels of my hybrid to either the street-treaded 26" tires on my mountain bike or the 26" balloon tires of my beach cruisers. Less rolling resistance maybe, combined with more distance traveled per revolution.

Whichever route you go, good luck and I hope you find many enjoyable miles of riding ahead.

javal

All materials fail sometime. Its more about the building process than usage. There will always be badly built stuff. Alu is relatively light, stiff and cheap. I´m sure you wont get let down buying an alu-bike.

Fiery

I remember this post, though I also have no idea what thread it's from. It was something about how aluminium frames supposedly handle differently and people who'd last ridden a steel Wall-mart bike-like object years ago can get thrown off of an aluminium bike due to not being used to it.

It didn't make much sense to me at the time, and it makes even less sense now that I think back about it. I wouldn't worry too much about it.

Edit: Found it! Go to post #5. Makes absolutely no sense, as frame geometry affects handling far more than frame material. Even so, you shouldn't worry too much unless you're switching from something like a beach cruiser to something like an aggressive geometry road or track bicycle.

AdelaaR

I've got a full aluminum hybrid and I LOVE IT.
That said ... I've got a full carbon TT bike and I LOVE IT too

I'll explain to you what I know about aluminum bikes.
First off ... there are multiple typical industrial aluminum alloys that can be used for bikes ... 7005 or 6081 and several others.
These alloys come mostly from aviation technology and often use Cobalt or other rare earth metals to make them very strong and durable.
The tubes, which are made in huge factories, are very unlikely to ever fail as they are made in one piece as they are.
The weak point is mostly in the joinings of the tubes, which are made in local factories.
I'm no expert, but apparently when welding aluminum alloys it is very important to not let the welded frame cool down too fast, as this will create miniscule ruptures inside the joints and so the trick is to "post heat" the frame in a designated oven to let the joints cool down gently and let them settle in.
Therefore the problem with aluminum frames is that it's hard to know, as a consumer, whether or not your frame is actually made the way it should be made or not.

4.11

He has to be joking, either that or he hates aluminum.

This is good info, if aluminum was such a risky material A.) It wouldn't be used and B.) you wouldn't see companies offer a lifetime warranty.

rasmith3530

It should be pointed out that both 7005 and 6061 aluminum alloys have been used in the construction of supersonic aircraft. That should speak to its combination of light weight and durability under stress. Quality tubing that has been properly welded should hold up on a par with steel. Poorly assembled frames will fail, regardless of the material used in their construction.

It has been my experience that aluminum and steel do have somewhat different ride qualities, but that is subjective, just as some folks prefer one seat type over another.

In the end, buy a good quality bike and ride several different models before making your final decision.