Rob Penn on "Why Steel? (and not Carbon fiber)"
Excerpted from "It's All About the Bike" (The Pursuit of Happiness on Two Wheels)
There were few sure things about this bicycle at the outset, but one of them was the frame material: steel. It’s been the backbone of the bicycle for over a century. Until the mid- 1970s, it Was the only real option. Even in the early 19905, the majority of high-quality bikes still had steel frames. Today there are many materials on the market: aluminium, titanium and carbon-fibre reinforced Polymers are common, but you might prefer your personalized steed to be made from moulded plastic, magnesium, beryllium (a toxic chemical element found in minerals and used in rocket nozzles), hemp, Wood and bamboo. In fact, bamboo is emerging as the new material of choice for socially entrepreneurial Frame-building projects in Africa, though it was first used to make bicycles a century ago.
I’ve tried all the major frame materials. I’ve had aluminium road bikes with carbon forks, steel mountain bikes, aluminium mountain bikes, a steel touring bike, a titanium road bike, a fullcarbon road bike and an aluminium mountain bike with carbon seat stays. So which material, or combination, provides the best overall ride? I have my opinions on all the bikes I’ve had but l know they are affected by my personal experiences riding them: how long I had the bike, Where I rode it, who I rode With. Objectively, I’d be pushed to say which material provides the best overall ride. I know from reading about it that frame materials do have different properties: in fact, some people eulogize profusely about the ‘ride characteristics’ of this material over that. Vm not so sure. Such things are very subtle, and only measurable with sensitive engineering instruments.
There is much nonsense passing as wisdom about materials for bike frames. The reality is that a good bike builder can make a good frame out of any of the materials mentioned, with any desired ride qualities: if the diameter of the tubes, the thickness of the tube Walls and the geometry of the frame are right, the bike will be right.
The poppycock really piles up when people talk about the stiffness of a particular frame material: this property of a material is measured by something called Youngs modulus or elastic modulus. A frame transmits the impact of every pebble and nick in the tarmac directly to the nerves in your gluteus maximus, that is, your bum, While a flexible frame absorbs the shocks. Most people who have ridden both aluminium and steel frames would say that aluminium frames are stiffer. Actually, steel has a much higher`~ Young's modulus than aluminium it is stiffer. It’s just that aluminium tubes tend to be much larger in diameter than steel, and as a tube’s diameter increases, its stiffness increases to the third power of that number.
In reality, the tyres, the Wheels, the seat posts and the saddle proper absorb the bumps. The frame itself contributes little or nothing to shock absorbency. It’s also important to remember that two frames made from different materials would not be made to the same tubing dimensions, making a relative comparison impossible. The frame feature that does have some bearing on comfort is the design of the rear triangle - the triangle formed by the seat post tube, the chain stays and the seat stays.
The most deceptive aspect of modern bike frames is Weight. The frame of my newest road bike is carbon (Toray SC carbon, if you must know). It Weighs under 1. 5 kg. It's light. People who aren’t familiar with modern road-racing bicycles pick it up and actually go, ‘Phiwoarrr’. Unquestionably, the lighter a bike is, the easier it is to pedal uphill. But the industry has become obsessed With making bikes lighter when, for the Vast majority of riders, the paramount consideration is not weight, but that a frame should not break in use.
Carbon fibre is currently the most popular frame material for elite professionals, largely because it is so light. If your absolute priority is having the lightest bike possible, because you’re a professional cyclist and you need to shave seconds off the time it takes you to climb a 20 km mountain in the Pyrenees, to give you a competitive advantage, make a living and put food on the table for your children, then you must have a carbon frame. Por the rest of us, it's either an indulgence or We’re victims of a conspiracy. Or both.
Yes, even the bicycle industry has a conspiracy theory. It goes like this: the manufacturers of mass-produced bicycles spend a fortune on R&D to ensure that the top professionals they sponsor ride the lightest, fastest bicycles, and Win races. The manufacturers need to recoup this expenditure while reducing the costs of production, so they throw everything at marketing to the public the same, or similar, elite bikes as the pros ride.
My dream bicycle will be made from steel. Here’s why:
1. Steel is very strong. High-quality steel has a very high yield strength 0r elastic range the point at which it bends permanently rather than bends back to its original shape - making it durable and less likely to bend in a crash. This means that steel tubes can be thin, with a small diameter, making steel frames light and sufficiently flexible. As people like to say: ‘steel is real’.
2. Steel has a long life. When I visited Argos Cycles, a well establishecl frame-building workshop on an industrial estate in Bristol, l was shown several dozen steel frames dating back to World War II. There were frames made by some of the great names, such as Hetchins and A. S. Giìlott, hanging on the wall, awaiting restoration Work. They were about to be realigned, shot-blasted, rubbed down, primed and resprayed. Further along the Wall there were several fully restored, gleaming frames Waiting to be collected. They looked brand new. ‘Years of riding left: in them,’ Mark, the Workshop manager, told me. ‘We have a near constant supply of steel frames in for restoration. Many are over fifty years old. A carbon frame simply won’t last anything like that long.’
3. Steel is not prone to sudden failure: despite recent advances, carbon still is. Steel is also easily repairable: aluminium, carbon and titanium are not. In fact, a small crack in the chain stay on a carbon frame often means the whole frame is destined for the bin.
4. Crucially, steel can be repaired anywhere in the world by a man with a blowtorch and a Welding rod. I know this, because I bent a steel bike in northern India, when I was riding around the world. I was slipstreaming a tractor on the Grand Trunk Road near Amritsar. We were going downhill at a lick when I rode into a pothole the size of a hot tub. There was no time to react. I had what American mountain bikers call a ‘yard sale’. The bike, panniers, sunglasses, water bottles, tent, pump, map and I were strewn across the tarmac. l lost a lot of skin but the bike took the brunt of it: the top tube and the down tube were both bent, leaving the front wheel shunted backwards, rubbing against the underside of the down tube. I wondered if my round-the-World ride was over.
_
There were few sure things about this bicycle at the outset, but one of them was the frame material: steel. It’s been the backbone of the bicycle for over a century. Until the mid- 1970s, it Was the only real option. Even in the early 19905, the majority of high-quality bikes still had steel frames. Today there are many materials on the market: aluminium, titanium and carbon-fibre reinforced Polymers are common, but you might prefer your personalized steed to be made from moulded plastic, magnesium, beryllium (a toxic chemical element found in minerals and used in rocket nozzles), hemp, Wood and bamboo. In fact, bamboo is emerging as the new material of choice for socially entrepreneurial Frame-building projects in Africa, though it was first used to make bicycles a century ago.
I’ve tried all the major frame materials. I’ve had aluminium road bikes with carbon forks, steel mountain bikes, aluminium mountain bikes, a steel touring bike, a titanium road bike, a fullcarbon road bike and an aluminium mountain bike with carbon seat stays. So which material, or combination, provides the best overall ride? I have my opinions on all the bikes I’ve had but l know they are affected by my personal experiences riding them: how long I had the bike, Where I rode it, who I rode With. Objectively, I’d be pushed to say which material provides the best overall ride. I know from reading about it that frame materials do have different properties: in fact, some people eulogize profusely about the ‘ride characteristics’ of this material over that. Vm not so sure. Such things are very subtle, and only measurable with sensitive engineering instruments.
There is much nonsense passing as wisdom about materials for bike frames. The reality is that a good bike builder can make a good frame out of any of the materials mentioned, with any desired ride qualities: if the diameter of the tubes, the thickness of the tube Walls and the geometry of the frame are right, the bike will be right.
The poppycock really piles up when people talk about the stiffness of a particular frame material: this property of a material is measured by something called Youngs modulus or elastic modulus. A frame transmits the impact of every pebble and nick in the tarmac directly to the nerves in your gluteus maximus, that is, your bum, While a flexible frame absorbs the shocks. Most people who have ridden both aluminium and steel frames would say that aluminium frames are stiffer. Actually, steel has a much higher`~ Young's modulus than aluminium it is stiffer. It’s just that aluminium tubes tend to be much larger in diameter than steel, and as a tube’s diameter increases, its stiffness increases to the third power of that number.
In reality, the tyres, the Wheels, the seat posts and the saddle proper absorb the bumps. The frame itself contributes little or nothing to shock absorbency. It’s also important to remember that two frames made from different materials would not be made to the same tubing dimensions, making a relative comparison impossible. The frame feature that does have some bearing on comfort is the design of the rear triangle - the triangle formed by the seat post tube, the chain stays and the seat stays.
The most deceptive aspect of modern bike frames is Weight. The frame of my newest road bike is carbon (Toray SC carbon, if you must know). It Weighs under 1. 5 kg. It's light. People who aren’t familiar with modern road-racing bicycles pick it up and actually go, ‘Phiwoarrr’. Unquestionably, the lighter a bike is, the easier it is to pedal uphill. But the industry has become obsessed With making bikes lighter when, for the Vast majority of riders, the paramount consideration is not weight, but that a frame should not break in use.
Carbon fibre is currently the most popular frame material for elite professionals, largely because it is so light. If your absolute priority is having the lightest bike possible, because you’re a professional cyclist and you need to shave seconds off the time it takes you to climb a 20 km mountain in the Pyrenees, to give you a competitive advantage, make a living and put food on the table for your children, then you must have a carbon frame. Por the rest of us, it's either an indulgence or We’re victims of a conspiracy. Or both.
Yes, even the bicycle industry has a conspiracy theory. It goes like this: the manufacturers of mass-produced bicycles spend a fortune on R&D to ensure that the top professionals they sponsor ride the lightest, fastest bicycles, and Win races. The manufacturers need to recoup this expenditure while reducing the costs of production, so they throw everything at marketing to the public the same, or similar, elite bikes as the pros ride.
My dream bicycle will be made from steel. Here’s why:
1. Steel is very strong. High-quality steel has a very high yield strength 0r elastic range the point at which it bends permanently rather than bends back to its original shape - making it durable and less likely to bend in a crash. This means that steel tubes can be thin, with a small diameter, making steel frames light and sufficiently flexible. As people like to say: ‘steel is real’.
2. Steel has a long life. When I visited Argos Cycles, a well establishecl frame-building workshop on an industrial estate in Bristol, l was shown several dozen steel frames dating back to World War II. There were frames made by some of the great names, such as Hetchins and A. S. Giìlott, hanging on the wall, awaiting restoration Work. They were about to be realigned, shot-blasted, rubbed down, primed and resprayed. Further along the Wall there were several fully restored, gleaming frames Waiting to be collected. They looked brand new. ‘Years of riding left: in them,’ Mark, the Workshop manager, told me. ‘We have a near constant supply of steel frames in for restoration. Many are over fifty years old. A carbon frame simply won’t last anything like that long.’
3. Steel is not prone to sudden failure: despite recent advances, carbon still is. Steel is also easily repairable: aluminium, carbon and titanium are not. In fact, a small crack in the chain stay on a carbon frame often means the whole frame is destined for the bin.
4. Crucially, steel can be repaired anywhere in the world by a man with a blowtorch and a Welding rod. I know this, because I bent a steel bike in northern India, when I was riding around the world. I was slipstreaming a tractor on the Grand Trunk Road near Amritsar. We were going downhill at a lick when I rode into a pothole the size of a hot tub. There was no time to react. I had what American mountain bikers call a ‘yard sale’. The bike, panniers, sunglasses, water bottles, tent, pump, map and I were strewn across the tarmac. l lost a lot of skin but the bike took the brunt of it: the top tube and the down tube were both bent, leaving the front wheel shunted backwards, rubbing against the underside of the down tube. I wondered if my round-the-World ride was over.
_
