# durability of scandium frames



## rodar y rodar (Jul 21, 2006)

Just wondering: how does scandium compare to aluminum in terms of lifespan? Is it actually a form of aluminum? I don`t understand why the sc. frames are so cheap (relatively) for their weight. There must be some catch and I don`t see it. Forgive me if there has already been a huge thread on the subject here- I tried a search but didn`t find it.


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## DeeEight (Jan 13, 2004)

Scandium is just an element being added to a high zinc content 7000 series aluminium (its widely assumed to be 7075 used as the base alloy) which has the effect of making an otherwise unweldable high-strength alloy weldable. The zinc enriched 7000 series alloys are essentially the strongest of all the aluminium alloys, yet the high zinc contents of many of them also prevent their being welded easily into structural components (7005 and 7020 are basically the only two as yet ever used in welded bike frames previously). Adding scandium to the alloy improves the grain structure of the final product and makes it easier to weld at the same time. The only other way to make a frame with these alloys is to bond them together (as trek used to do in the late 80s/early 90s for example) with tubes and lugs. The problem with that method is you cannot easily just switch the geometry from year to year because you need to not only produce new jigs to set the frames up in during assembly (as with welding) but also you have to manufacture your lugs and tubes to new dimensions. That's why companies like Trek went away from bonded construction to Tig Welding (which is faster and cheaper), which unfortunetly also meant switching to weaker alloys. Companies like Miyata and Trek which made frames that way used to advertise how the epoxy used to bond them together was actually stronger than the tubing itself, and that you'd be more likely to break a tube (which at around 80,000psi was more than double the strength of the alloy Cannondale was welding frames out of) midspan than at the joints.


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## jmtbkr (Jan 15, 2004)

I've been riding a scandium frame for 6 years with many horrific crashes and the frame is still straight and there are no dings on any of the tubes.

Oh yeah.....I weigh 225lbs


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## rodar y rodar (Jul 21, 2006)

Okay, so if that alloy is stronger than 60 series, they should be able to get away with thinner walls, therefore less weight. Is that how it works? Where did you find all that good info? It `s certainly interesting.
jmtbkr- glad to hear your frame is hanging in so well. To tell the truth, I`m not really looking at a new frame in the near future, but if I eventually do, I`ll think seriously about those Salsas and Kulas. For now, I`m pretty happy to putt around on my semi-tank (30 lb Kona Blast).


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## jmtbkr (Jan 15, 2004)

Scandium is alloyed with other metals besides aluminum. As D8 said, it alighns the structure better and makes a stronger alloy.
The Rissians discovered this years ago. They wanted to be able to launch sub based ICBM's thru the ice pack, but the titanium they used didn't have the shear strength to withstand the pressures of cutting thru the ice, and would shear the stablizer fins off the misslies. Along came scandium, which when alloyed with the Ti, permitted the fins to remain intact. But then the Soviet empire collapsed, they ran out of money for the program and began selling the stuff off to the rest of the world. 
So we, as bikers, benefitted from the Russian misslie programs of the cold war, with some of the worlds best metals. The largest deposits of titaniun and scandium just happen to lie beneath the Russian soil.

I've been on my Rocky ElementSC for 6 yrs with no problem. Yes, the tubes are drawn thinner than standard aluminun, therefore the weight savings. But I think the scandium makes for a definately stronger frame.


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## DeeEight (Jan 13, 2004)

Not thinner so much as a return to the smaller diameters that were typical of Al frames 15 years ago, yet in the same wall thicknesses as done today. Net result, less weight (the frames back then used thicker tubing) and a more forgiving ride because the main reason Al frames are considered overly stiff by everyone except racers is that you need larger diameters of the stuff to be stiff, and resist flexing during usage. 

Why do they have to be stiff ? 

Since the Al alloys used in bicycle frames have no defineable fatigue limit, EVERY single time the frame flexes regardless of how much of a load it was, takes it one step closer to a fatigue failure, and there's no magic number as to exactly how many times that will be. This is why frames ended up being built really stiff (Cannondale was really the first to do frames that way and everyone else followed suit eventually) with massively oversized tubing and thin walls. So in terms of impact "strength" alone, they're roughly equal to how frames made from Steel or Titanium would be, but in terms of fatigue strength, they're much worse off, but still adequate to last several years. Ti and Steel on the other hand does have defineable fatigue limits (where they can withstand near infite numbers of flexing cycles as long as the load is below a certain known point) which is why you rarely see a Ti or Steel frame developing fatigue cracks (though it can still happen). 

Case in point... I own a 1995 Manitou FS-DH frame... its made from Easton 7005T6 aluminium, and I first noticed the cracks developing in its headtube in 2003. That's 8 years of usage from an aluminium frame, which is rather good. My 1991 Alpinestars Ti Mega frame which is made from US Grade 3Al-2.5V Titanium alloy only just had a fatigue crack develop last month.... that's 15 years of usage.


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## froze (Feb 5, 2011)

DeeEight said:


> Not thinner so much as a return to the smaller diameters that were typical of Al frames 15 years ago, yet in the same wall thicknesses as done today. Net result, less weight (the frames back then used thicker tubing) and a more forgiving ride because the main reason Al frames are considered overly stiff by everyone except racers is that you need larger diameters of the stuff to be stiff, and resist flexing during usage.
> 
> Why do they have to be stiff ?
> 
> ...


Sorry I know this an old post but I was doing some research on Scandium for another forum when I came across this.

Anyway, I had a Ridley Scandium bike myself I bought back in 2004, the ride quality was horrible like I was riding on bricks, which I didn't really detect on a short test ride I did, it wasn't till later after trying to do a 75 mile ride that around the 20 mile mark I realized this bike rode badly.

But I didn't have the bike long because about 5,000 miles and less then a year later I discovered a crack forming from the top of the headtube radiating down from the headset about a 1/4 of inch, long story short, Ridley refused to warranty it saying it was due to fatigue!

But I find it interesting that people are willing to accept a bike frame failing after 8 to 15 years, why do I find that interesting you scream while pelting me with rocks? Because I have a few steel bikes, one of them I use to race about 1/4th of its initial life, it has over 150,000 miles on the frame and components, it was purchased new in 84, it's still very much rideable today I only retired it due to the excessive miles and I was more concerned about component failure while riding then I was about the frame. I have other bikes too with quite a few miles, nowhere near 150,000 but in excess of 20,000.

I did buy an 13 Lynskey Peloton which is titanium, it's 6 years old with no cracks. So needless to say when someone says they got good use out of a 8 to 15 year old bike and find that failure rate to be acceptable I sort of cringe because decent bikes aren't cheap and I expect at the least the frame and fork to hold up to many years of use like my 84 steel bike has done.

I hear people all the time on forums replacing their bikes because it has 15,000 to 20,000 miles on it, and I'm thinking the bike isn't even broken in yet and they're dumping it? but I guess that's what needs to be done with aluminum and carbon fiber bikes?

I do have a carbon fiber fork on my Lynskey, a Enve 2.0 which I decided on the slightly heavier fork vs the 1.0 because it had a rider weight limit of 340 or 350 pounds, while the 1.0 had a limit of 240 pounds, even though I only weigh 175 pounds I figured the more heavy duty fork over engineered for my weight should last the rest of my life...I'm going to find out!

Anyway sorry to dig up an old post but I found this reply interesting so I felt I needed to respond.


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## zerodish (Jun 17, 2006)

I asked my dad who was an engineer with ALCOA about the alloy when it first showed up. He said it had a tendency to catch on fire while they were making it. I think that's where the high cost came from. Obviously they have worked out that bug. Santana Tandems likes the stuff and they never use any thing that is not durable.


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## froze (Feb 5, 2011)

zerodish said:


> I asked my dad who was an engineer with ALCOA about the alloy when it first showed up. He said it had a tendency to catch on fire while they were making it. I think that's where the high cost came from. Obviously they have worked out that bug. Santana Tandems likes the stuff and they never use any thing that is not durable.


Well my scandium frame never caught fire so that wasn't the problem with it, the problem a crack started in the head tube which was a flaw in probably the thickness of the wall, because it cracked at the front top of the head tube not the rear where the top tube would have been welded to it.

Sc I've heard since then is more brittle then just aluminum, but I'm not sure if that was because they used too much Sc back then mixed into AL, the odd thing is that in todays modern higher end AL bikes they mix in a little bit of SC but they don't mention it, and I think that's because the amount their mixing is less then what it was in SC labeled bikes, but it does help those higher end AL bikes to last longer.

bike blog or die: What Ever Happened to Scandium Bike Frames?

MTBers were having issues with SC frames snapping under rough use, Kona had issues with their SC frames too and I found out from writing this post they didn't warranty them either! Another cracked 3 Kona's, he doesn't say if they replaced them under warranty. Also an Air 9 failed https://singletrackworld.com/forum/topic/what-ever-happened-to-scandium-frames/

So I really don't know because overall they are getting good reports on the internet now, but back when mine broke they were getting bad reports on the internet, so not sure what's changed between then and now.


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## Jayem (Jul 16, 2005)

IMO, it was a gimmick. You could use a bit thinner-wall aluminum with some Sc mixed in, but durability took a hit and it was difficult to get the fatigue properties you wanted for anything other than a one-season race bike. Ti has largely been a gimmick too IMO, lots of people forking over mega $$$ for frames that are more apt to crack at the welds due to brittleness. There was all sorts of craziness going on back in those days, steel frames around 3.5-3.7lbs that were absolute noddles/unacceptably flexy. Sc was a marketing gimmick for a short period of time. Being able to hydro-form complex designs was far more important to aluminum frame progress.


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## edubfromktown (Sep 7, 2010)

Jayem said:


> IMO, it was a gimmick. You could use a bit thinner-wall aluminum with some Sc mixed in, but durability took a hit and it was difficult to get the fatigue properties you wanted for anything other than a one-season race bike. Ti has largely been a gimmick too IMO, lots of people forking over mega $$$ for frames that are more apt to crack at the welds due to brittleness. There was all sorts of craziness going on back in those days, steel frames around 3.5-3.7lbs that were absolute noddles/unacceptably flexy. Sc was a marketing gimmick for a short period of time. Being able to hydro-form complex designs was far more important to aluminum frame progress.


Agree that Scandium was more marketing hype than anything earth shattering on the technical side of the house. I never owned one but sure remember a lot of folks riding Niner Air9's back in the day. Not sure what to say about Titanium brittleness. Only frames I've killed were aluminum.

I've ridden 29er's since 2009 of primarily aluminum and steel frame varieties. Added a carbon FS to the mix in 2018 and also a titanium rigid SS MTB mid-last year, just for fun.

I still ride a 2009 aluminum hard tail with a nice 8+ year old rock impact dent in it not far above the BB shell. I've shaken welds loose on two other aluminum frames- one full suspension and one hard tail. The weld cracks both developed at the top of the seat tube- one: where the seat stay meets and the other where the top tub meets. Can't tell if that brittleness or just plain old fatigue.

I recall a number of friends who snapped steel Niner SIR 9 frames mid-way along the chain stay or at the rear axle interface. The rigid SS one that I beat the snot out of for 4+ years (before selling it) had a few dents, but no cracks.

I have not cracked welds or snapped bits on carbon, titanium or steel frames thus far. I do shake rear axles loose with regularity- 12mm axles, Chris King Fun Bolts, DT's similar bolts, Halo's, etc. That may be an indication of how much rattling the frames sustain on gravel, dirt, road, rocks, roots, staircases, etc.


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## christexan (Jun 1, 2004)

Old thread but for anyone coming across this discussion... 
I had a Scandium road frame (Easton provided /Scattante OEM frameset)... loved that road bike (although it was a bit jittery compared to my old steel bike, wasn't quite as confident on hard high speed cornering)... anyhow... 
Bought in 2005... broke at the rear dropout/axle interface in 2018 or thereabouts. So 13 years... in that time, thousands of hard miles (at times I weighed in the 250# range, but overall probably averaged 220# in the life of that bike)... 
Bunnyhopped 3ft potholes... had crashes that broke the saddle, skidded 30ft across intersections, had 2 riders "ride over" during a paceline crash. The final failure was "just riding along" noticed shifting was getting really rough and drivetrain noise, thought a cable had shifted or something, eventually after a couple of stops to try and adjust, I spotted a slight "shift" in the frame at the axle when moving the bike around and found the actual breakage (it was so stiff overall that it was rideable for probably 10 miles with just occasional glitches/funny feeling. The rear triangle was carbon seatstays with aluminum chainstays, just for reference purposes. Total frame weight (size 60) around 2.5#.  
Because this was an Easton provided and rebranded (and thus optimally engineered/built by them) frameset, the top tube was swaged down to 0.4mm wall thickness in the middle section. Literally only about 3-4x thicker than the walls of a soda-can (do not clamp in a bike stand by the top tube!!!!!).
Those saying "why do Scandium (or any aluminum applies)" frames break. It's a material properly of aluminum versus steel, nothing to do with the Scandium specifically. Steel does not work-fatigue or harden. So long as you don't exceed deformation points, properly made/manufactured/assembled steel will ALWAYS return to normal with no harm done when flexed. One time, on thousand, one billion, does not matter. If a steel rod is extending out freely (environmentally controlled, not including chemical/environmental impacts, just physical characteristics), and youand everyone who walks by "sproing" it every day so that it oscillates back and forth freely within it's safe range, it will not break, ever. 
Repeat that with aluminum. Aluminum DOES work fail... always. The only question is when. Repeat the rod experiement, at some point someone is going to flick the rod and it's going to break somewhere along it's flexible length (most likely near the secured point of course where the degree of flex is most severe, but COULD be anywhere). Might not be today, might be 10 years from now, but it will break eventually. 
This is a fundamental characteristic of aluminum. It's why airplane airframes have a "lifetime"... a steel airplane, would not need a (solid structure) lifespan so long as it's maintained corrosion free forever. (wearing/moving surfaces, maintenance access points wear-and-tear, etc would obviously impart some finite lifetime, but structural fatigue would not be the limiting factor). 
Engineers statistically engineer aluminum items based on anticipated lifetimes. Obviously the more repeated stresses applied, the sooner the failure will happen. 
Bike makers know this. The other problem with aluminum vs steel is welding/joining frames (also a problem in steel of course)... the difference between failures is that steel, typically fails IN the weld... the welding material and/or interface is harder or more brittle due to the process, than the tubing, and thus the welds often break. Tubes CAN break ,but it's typically in the weld area caused by the process driving imperfections into the surrounding materials, but more often it's simply the weld material or interface breaking. 
This is where Scandium suffers/ed the most. ScAl is "not your fathers aluminum"... in general, aluminum welds break "in the tubing" not the weld itself. 2 things happen.. .one, the bulk of the weld increases the stress locally at the edge of the weld (a strong "stress edge") Second, the heat of the welding for aluminum is much more distressing than it is for steel (steel being much more heat tolerant and manufactured/tempered at temperatures much higher than aluminum would vaporize at, LOL)... 
So welding aluminum, "typical" alloys, on a good day, is always going to cause a stress/fatigue zone from the force concentration and the heat transition zone. This means most (any good ones) aluminum welded frames must have very special "heat soaks" performed to destress the heat of welding and crystallization structures formed, back into a more homegenous form (leaving only the physical stress zone ideally, but obviously this is far from perfect)... 
With ScAL, you MUST use the proper ScAl welding rods. Then you have to follow a VERY particularly rigid heat treatment procedure. This is because if you use the non-ScAL rods to weld it, you drive out the Sc in that region during the welding process, and the 2 materials do not "mate" well at all due to differing compositions. Quite a few "quick-and-dirty ScAl bandwagon" frame makers made this error, and/or did not follow the full heat treatment process (not easily done outside industrial environs), they didn't last long making them, typically by year 2 they were done with at least Sc if not out of business. 
Super-long story short... even done properly, the best most perfect job, ANY aluminum, will eventually break. Most often it'll be in the tubing near/at the heat transition zone, not within the weld itself (obviously any bad weld can break directly also). Unlike steel, you are unlikely to get weld separation from the tubing itself, the melting and heat transfer is too fast in aluminum so they are very well fused instantly unlike steel where a "cold weld" can happen. (Thus chipping hammers, that can chip off poor welds in steel or iron). 
Pretty much every ScAl story of a broken frame is "in the tubing along a weld line"... basically you are following the "temper" line where the welding process realigned the structure of the base aluminum from "in weld zone" to out of weld zone, and that difference, plus the increased stress in that region from the much more inflexible welded region, is where it's most likely to break (reality, any aluminum frame can break anywhere, anytime, just something to keep in mind).


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## Jayem (Jul 16, 2005)

christexan said:


> Repeat that with aluminum. Aluminum DOES work fail... always. The only question is when. Repeat the rod experiement, at some point someone is going to flick the rod and it's going to break somewhere along it's flexible length (most likely near the secured point of course where the degree of flex is most severe, but COULD be anywhere). Might not be today, might be 10 years from now, but it will break eventually.
> This is a fundamental characteristic of aluminum. It's why airplane airframes have a "lifetime"...


Well, kind of. If the frame is designed for how many ever thousand or million of cycles of stress, it should not fail before that unless it's being over-stressed. If it fails before that without being over-stressed, it'll fail wherever the bike was flawed, either in terms of design or production. Common areas include chainstays yokes, dropouts, weld junctions, etc. It does not necessarily correspond with the most flex, the movement of a longer part or tube may be more than a shorter part, but well within what it can take, vs. forces being directed into an area that exceed what it can take, with little to no "flex", it'll still break. Some aircraft are life-limited, some are not. They do require inspections. It is exceptionally rare for a bicycle to fail due to outright cycles. They usually fail due to an overstress event or design/manufacturing flaw. In this sense, steel, titanium, carbon fiber, they all react about the same here, They all break...and they break most often because of this reason, including aluminum.

Now, if you make your aluminum light enough, the number of cycles it'll put up with will be lower, so with the raciest frames produced out of aluminum, the racing-team type stuff, they did have shorter limits. This was rarely an issue for production stuff, as there are probably significant liability concerns with a "one season frame".

Just wait till you learn about titanium welds...


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