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OPINION
Aluminium frames are the work of the devil
Mon, May 02, 2022 18:00
116
Aluminium bike stress testing - credit Steve ThomasMine may well have become vaguely lost in the great mist of time, but those distant memories, the harsh realisations and promises that I made to myself many years ago have come trickling back to haunt me in recent months... namely where I said I would never ride another aluminium bike frame.
> 10 of the best British bike brands of the '70s and '80s
First things first: before all the love for this great Coke can-like material comes flooding in down in the comments section, please do note that this is an opinion piece. It's based off my own many decades of experience riding bikes made from everything from bamboo to magnesium, with a whole heap of steel, titanium and aluminium thrown into the mix... oh and of course, some metal matrix too. These are my own groans aches and opinions, and I don't expect everyone to agree!
The pre-AL era
When I started riding and racing bikes in the '70s it was about steel, all about steel. From the forks right through it was all that good old hard stuff. There weren't really any other viable frame material options back then.
Sure enough the different tubing grades and builds did make for very different rides between the various combinations available, and mostly they were of the slightly forgiving kind. Thankfully in recent times there is some form of appreciation for steel coming back, and maybe even those younger riders who’ve never slung a leg over a quality steel horse will one day try one and find out why us old fellas love them so much (or at least some of us still do), even if they have drifted out of vogue.
> Southern Steel: take a trip down memory lane with these classic 20th century bike builders
Material world order
Perhaps I was lucky that I went from riding steel straight to various forms of titanium frames, and then to carbon fibre – lucky as in there were only a few fleeting encounters with the bone shacking and wrist jarring frights without the delights of aluminium bikes. Even then those that I did ride were mostly fat-tubed mountain bikes, where much of that harshness was padded out with big tyres, suspension, cross-laced wheels and slack angles.
I did have a couple of reasonable aluminium road frames back around the turn of the century, but even then I found them to be super harsh on the lower back and my wrists, which were rattled to popping point after years of pre-suspension mountain biking.
Back then, aluminium had become the de rigeur material of choice for frame building, mostly because it was so cheap and easy to get hold of and mass produce in the Far East... and yep, just about all of the major pro road teams did ride aluminium bikes for a while, although their rides were generally tempered a little by carbon forks.
Even so, many of those frames were still very harsh in my opinion, albeit that they were compliantly rigid. For me they were just too rough and not quite ready, although perhaps my opinion would be different had I been groomed on aluminium from the start.
At around about that same time, Cipollini et al were all racing around on those gorgeous, bold Cannondales. Cipo made fat aluminium look like sex on two wheels, and so when I was offered a good price for one as an end of line clear out (by friends with a bike shop) of course I jumped at the chance.
It was a dull and dark blue in colour, and so I managed to get friends in the bike industry to spray it up in bright sparkling green. I built it up with all clean and polished Campagnolo kit, and garnished it with highly polished stem and bars. It did look the dog, even with those eyesore extended rear stays.
It didn’t take long for me to start loathing the harshness of that ride, and then the lower back troubles, shoulder and wrist ache became a regular thing. It was not a bike that I could ride for hours on end, and as much as I loved the looks of that green Hulk-like beast, it just had to go.
For a while I did get through a couple more aluminium frames, things just panned out that way. One was of the same stiff ilk and was promptly sold, the other (a Diamondback) was slightly easier on the spine, but was so flimsy that on its very first outing to Mallorca, the down tube took a huge ding in the bike bag, and so it still lingers in the back of a shed somewhere.
Grand designs?
At that time I wasn’t wholly sure whether that hard ride was partly down to the frame design (the rear stays), or whether it was simply that aluminium really had not gotten much easier on my ageing body, so I decided not to compromise again on an aluminium road bike.
As luck would have it I did get hold of a couple of titanium frames just after this: a Merlin XLC compact road frame, and a Litespeed Blue Ridge 'touring' frame. This duo added a whole new level of plushness to my ride immediately, and one that had most definitely made me a titanium frame fan boy.
Times have moved on, and I’ve shifted continents. Those titanium bikes are still around and almost as sweet as ever but, just about everything from the carbon forks to the groupsets are worn out, and being based in part of Asia where anything but pure race bikes and kit are an issue to find, and where someone six foot tall is considered to be a yeti, it’s hard to get hold of viable alternatives.
I have a couple of carbon road frames around, but they don’t really suit the riding I mostly do these days: hot and rough roads (and gravel), often with climbs that make the Bwylch y Groes seem like a mill pond.
Still shaken, and stirred
This is where the evil aluminium sneaked back into my life, just like that proverbial crazy ex from hell. On a trip to the USA I managed to mail order an aluminium gravel bike of Belgian origin. Before I’d even finished assembling it I knew it was potentially a beast of back-breaking burden, and sure enough I was soon shown to be right.
I did consider selling it almost immediately, as the discomfort was just too much for me; however, there was no way of me getting an alternative, and so I’ve stuck with it... on and off that is.
Just over a year ago I did take a trip to another region with this bike (it was the only fully functioning option at the time), which was when the wrath of the second wave of the pandemic struck, leaving me stranded with nothing but this bike for company ever since.
As much as I’ve swapped out the wheels, widened the tyres and softened the saddle, it just doesn’t cut it for me in the comfort department. Okay it is a gravel bike, but the ride is so harsh that I’ve almost 90% switched to riding it on the roads now.
My back, my ribs, my shoulders and my neck have taken such a pounding in the last year, which takes me right back to the sensation of that early Cannondale. Aluminium truly is the work of Satan Cycles Inc, at least as far as I’m concerned! Sure there are those younger riders out there who can ride on razor blades, and who have never known any different. But, one day, they most probably will.
For me, as I scour and search for ways of turning aluminium into something more rideable, I do have to remind myself not to fall into the trap of buying more of the stuff simply because it’s all I can get hold of. For now I’ll stick mostly to the hard stuff and soften the tyre pressure some more, just until I can find a ride less brutal on my old body...
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116 comments
I think looking at the frame pictured it is immediately obvious why it is a harsh ride, very steep angled rear stays directly to the short seat post and a steep angled virtually straight fork and consequent short wheel base, no doubt an agile bike, but not one designed with any concession to comfort on a long ride. Compare it with a classic touring bike frame, longer wheel base, and easier angles on fork and rear stays, much more room for the frame components to contribute to modulating vibrational loads.
Amusing but nonsense. On a fat tired gravel bike, the frame material is the problem? No it isn't. Nearly all compliance and vibration damping is down to the tyres.
There is barely and difference between riding a steel or aluminium frame with fat tyres. I'm not just saying this, there is science that backs it up.
ETA: I prefer steel but for other reasons, so no bias here.
"Nearly all compliance and vibration damping is down to the tyres."
As anyone who has ridden a cross bike with road tyres will know.
canyon ultimate al - best Alu frame ever
Better than a Colnago Dream (with fancy paint job)?
Having ridden a few mid-market aluminum bikes over the last ten years, I have to say they were darned nice. With carbon forks, they give up nothing to low- or mid-level carbon except a few grams grams. And I can lose more that that by eating a little more wisely.
Having owned steel/aluminium/titanium/carbon framed bikes over many years of riding, my anecdotal evidence suggests that the design of the frame rather than the material used has a bigger influence on comfort. Obviously tyre size/pressure has a big influence along with other components but like for like, the design of the frame makes a bigger difference than material. Many years ago I had a Cannobdale CADD5 which was very stiff/harsh, I now own a Ribble Al framed bike which is considerably more comfortable. I also have a 3T Strada carbon bike which is considerably more comfortable than the Holdsworth Mystique Carbon gravel bike I used to own, even though it had 32mm tyres on compared to 28's on the 3T. The main difference I believe is the dropped seat stays both the 3T and Ribble have which the others didn't.
A lot of the mystique of steel frame suppleness came from the traditional design of the forks. My steel framed but carbon forked bike is very stiff but lacks the lovely road imperfection absorbance that the bikes of my early adulthood had, courtesy of the traditional butted fork blades with their springing upturn just before the wheel mount.
Just an old man yapping.
Sorry i wasted time reading the first half
Considering I have 9 aluminium framed bikes I think someone is a pussy
Quite a bit of this discussion below seems to miss out the design opportunities that different materials give.
It's not so long ago that frames were straight lines. Now they are curves, they use the abilities of the material to flex - and this is where different materials have an impact. So my carbon framed Giant has very thin rear stays which allow the frame to flex while keeping the rider/power connection rigid. My ALU Kinesis tried the same with some wavey bits at the rear but ALU can't flex too much because of aluminium's tendency to suffer from fatigue (I know of 2 T2's that had failures near the BB).
Carbon allows the designer to choose rigidity, flexibility, lightness and strength, selectively through the frame. Aluminium has limits below which you cannot go, as does steel, as does carbon, but in the end fundamentally you can make a carbon frame stronger and lighter than aluminium and both more rigid or more flexible where you want it.
No, it doesn't. What you describe here is physically impossible -- one side of a triangle cannot flex alone.
As previously noted here a few times, you can test the relative deformation at home. Inflate your tires to their normal pressure. Now press on one with your finger, and see it deflect. Now try to bend your frame with your hands.
Any modern frame is stiffer vertically than all of the following components: pneumatic tires, forks, handlebars, seatposts, and saddles. You might be able to defect your frame if you bottom-out your tires, but I doubt you make a habit of that.
If you deflect one side of s triangle of course the triangle as whole has to deflect with it, but many frames deliberately have the rear stays positioned lower on down tube to increase the deflecting moment and improve the springiness of the frame as a whole.
What if your bike is non-euclidian?
Fortunately I cycle at a scale that does not need me to adjust to the deeper geometry of the Universe.
But lightly hit it with a tuning hammer and it may well ring, clearly it can deflect! A road surface will provide a spectrum of vibrational frequency to the bicycle being ridden over it, for instance a moderately rough road surface with an 8mm average particle separation would provide a vibrational input centering about 1000Hz if ridden over at about 30km/h. I dont know how the different components of the bike system modulate that input, but I suspect the answer is far from simple to model accurately.
Not completely up to speed with all the science but I owned a 2012 Specialized Allez which did seem to feel harsh resulting in aching wrists and lower back despite checking set up and fit, however, I also owned a carbon Specialized SL6 Tarmac which seemed brutally stiff resulting in a very uncomfortable ride indeed, I tried to temper it with Carbon Bars and 28mm Turbo Cottons but nothing seemed to work! needless to say like the Allez, it was sold.
All these comments and no one's mentioned Young's Modulus or Hooke's Law.
There's a reason this stuff is always described with flowery language.
Whenever someone uses words like "supple" and can't tell you how they've measured that your spidey sense should be going off.
Frame material as a source of comfort has been debunked years ago. It's Bike Industry Bullshit.
Just like wheel compliance, it can't be explained with physics.
If it was anything more than bullshit you'd be able to measure it as part of a full bike set up, just like you can with seatpost deflection or tyre hysteresis.
To feel a vibration it's got to make its way through the tyres, through the wheel, through the seat post and through the saddle.
So every bit of deflection in those other softer components will need to "bottomed out" before rider feels any flex of the frame or wheels.
Those components may have very different energy modulating properties depending on the frequency of input.
Possibly because Young's modulus and Hook's law are very crude tools for understanding the macroscopic behaviour of complex systems. Put a couple of panniers on my bike loaded up with a weeks camping gear and I can feel plenty of flex in the frame of my bike with definite ill geometric consequences for it's cornering stability, particularly on descents when braking as the frame distorts under the load! The Material properties and form have to be considered together, A round tube behaves differently to an oval one and again to a complexly shaped one.
I just want to add that I'm going out on my bike later today after work.
Modern frame engineers would laugh and cringe at all the opinions in this comment section. But none of them would ever waste their time reading it. There several scientific papers that refute all the preconceived ideas with facts.
Here's one: https://link.springer.com/article/10.1007/s42452-020-03410-w
I commend you for posting research instead of opinion, but that paper isn't relevant to the discussion -- nor even worth anything. Its authors modelled only the bicycle frame, and ignored components. In other words, they studied nothing, and just restated that larger tubes are stiffer, and that various materials have differing physical properties.
dh700, I disagree. The paper shows that comfort varies with frame design and material choice so if you were to put the same components of frames made from different material there wold be a difference in rider comfort. If you didnt read as far as the conclusion of the report it says:
"Vertical stiffness of the frame depends mainly on material and cross-sectional dimensions of tubing. Upon applying various materials to the modelled frame and performing linear FEA, considering factors such as frame geometry and material properties, it can be concluded that for better rider comfort, Aluminium 6061 will be a superior choice, in comparison to Medium Carbon Steel and Titanium."
Surprising isnt it, the research shows that aluminium will be more comfortable than medium carbon steel or titanium.
You're just wrong, unfortunately. That paper didn't study riders at all. They only studied frames, which is an insufficient approach to answering this question. Yes, it is true that a frame will eventually flex -- every manufactured item will, eventually. The point is that the force required to accomplish that exceeds that which is necessary to deflect all of the other components in the system -- and, in point of fact, it usually exceeds the capacity of the rolling stock.
You, and OP, are misapplying this study, which doesn't actually find anything relevant to the topic. In fact, it cannot possibly do so, because its design neglects everything except the frame.
Sorry, I thought the article we were commenting on was about how frame material affects the feel for the rider and the paper looks at how materials affects this. The paper does not pretend to examine the frame and rider so I think that their findings are valid. I look forward to reading your referenced work which shows how putting a rider or other components on a frame affects how the frame feels to the rider
This is the problem -- you fail to understand the paper in question. It precisely cannot do what you claim, because it is impossible to assess the impact on the rider by looking only at one component -- a component which is at least two degrees removed from contact with the rider.
Again, you are failing to understand the problem. The frame by itself cannot effect the rider. This is painfully simple. A rider does not touch the frame, and doesn't even touch any component which touches the frame. The rider is insulated from the frame by several degrees, so any analysis thereof must consider the entire system, in order to say anything meaningful about the rider's comfort.
For example, go ride a solid fat bike, with no suspension. You will find the ride extremely cushy, even if it is constructed of heavy steel tubes with a solid steel fork -- like mine is. Why? Because other components -- namely the tires -- swamp the effect of the frame material by miles.
Take a day or so and think on that, before wasting further time here.
So just to be clear, frame and fork material is irrelevant and (by implication) anyone that has spent money on expensive Ti, stainless, and carbon frames have just wasted their money? Also, by implication, there is no difference in ride quality between my Klein and Pinarello Prince on one hand, and my Colnago and Factor O2 on the other?
Come on, Chris, I think you are smarter than this, and can do better.
First off, read more carefully. Fork material absolutely does matter, as I've said. Forks are not made of triangles, and are subject to deflection. Frames and forks are different things, Chris. You should know this, and you are wasting our time here if you don't.
Second, yes, anyone who bought a frame solely hoping the material used to construct it would effect their ride comfort wasted their money. There are, however, a multitude of other reasons to choose a particular frame material -- again, as you should know. So, for example, a person who buys a carbon frame to save weight has not necessarily wasted their money. A person who buys a titanium bike because it will not rust may have similarly not wasted their money. I happen to own two titanium bikes -- but I don't delude myself into thinking they ride any differently than my other bikes with similar tires.
Finally, there may well be differences in the ride quality of those four bikes. But again, those differences are not caused by the material from which the frames are constructed. They are caused by the tires and other components which are mounted to those frames. If you were to mount ~20mm tires at 150psi, and a solid seat, you might be able to reduce the deflection of the entire system enough to discern the frame materials -- maybe. Of course, only an idiot would equip their bike in that manner. Good luck with that.
Cushy but very dead, great if you go over a tree route but laborious to cycle on normal road surfaces. With more usual 25 or 28mm tyres the frames compliance becomes very much more important in determining the feel of the bike. The vibration harmonics of even the most basic frames are clearly complex with many degrees of freedom to be allowed for.
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