It is a known fact of life that anyone bitten by the motorcycling bug will eventually waste an inordinate amount of time searching for the bike. That one machine that satisfies every desire and fulfils every practical need. The two-wheeled Swiss Army knife. The ride to end all rides. But see, this is impossible. Not impossible as a figure of speech: mathematically impossible. I am not saying this. Science is.

The fantasy is always the same. One bike that can do everything well. Comfortable enough to cross countries, fast enough to make the long way home an actual choice, and cheap enough that the bank does not start sending handwritten letters. A bike for touring, commuting, errands, holidays, bad weather, good weather, and the mysterious category known as “just popping out for twenty minutes”, which no motorcyclist has ever completed in under two hours.

Manufacturers know this fantasy well. They sell it constantly. Every few months a new machine appears with expandable panniers, adjustable suspension, riding modes, red brake calipers, a ludicrous “starting from” price, and a clean, crisp press photo taken somewhere mountainous. The implication is clear: this time, finally, the compromise has been defeated. It has not. It has just been given a price tag that would short-circuit a polygraph.

In computer science (those who bit the motorcycle bait, please bear with me, it’ll be over soon) there is something called the CAP theorem. In its popular, dangerously simplified form, it says that a distributed system cannot have all desirable properties at once; when conditions become hostile, something must give. In the world of business, the same principle is known as “good, fast, and cheap: choose two”. Well, it turns out that the CAP theorem applies to motorcycles too: a bike may be comfortable, affordable, or performant. It may even be two of these. It can never be all three.

This is not a moral claim. It is not even a matter of taste; mind you, taste is how we got into this mess. The point of the theorem is that each of these properties can be made precisely measurable. Let’s break it down.

Comfort is the degree to which a bike can support a long trip without requiring a chiropractor on retainer. A comfortable bike can be used instead of a car for a long journey without sacrificing more than your love of bikes can justify. The car may still be quieter, warmer, safer, and better at carrying furniture. That is not the point. The point is that the bike has enough weather protection, luggage, range, ergonomics, and amenities that choosing it remains a reasonable option rather than an act of stubbornness.

The Comfort index is scored out of five points:

  • wind and weather protection (tall windscreen, full fairing, or equivalent): 1 point
  • upright or neutral long-distance ergonomics: 1 point
  • fuel range of at least 300 km: 1 point
  • integrated luggage (panniers, factory-supported, fitted or optional): 1 point
  • cruise control: 1 point

Each item is a simple boolean: one point if the bike has it, zero if it does not.

A top case is not integrated luggage. Even Vespas have a factory-fitted top case. The true mark of a bike made for travelling is the pannier. A manufacturer that does not offer them at the point of order is telling you, in no uncertain terms, not to consider any serious distance on it. Similarly, the omission of the pillion seat in that list is not an oversight. It does not make a motorbike more comfortable for the rider; there might even be an argument that it makes for a less enjoyable trip when occupied, but this is beside the point. Even superbikes provide a small upholstered apology where a passenger might theoretically, ill-advisedly try to accommodate their derrière. That most pathetic piece of hardware is painfully, if figuratively, wailing: “Do not sit on me! I am barely a seat, if at all.”

Pardon the slight detour, back to science. The formula is:

$$C = \dfrac{\text{comfort pts}}{5}$$

If $C \geq 1$, the bike is comfortable.

Performance is also quantified, with only a forgivable amount of fraud. A performant bike does not merely produce torque in spades, but has the architecture to support it. It must have enough power relative to weight, enough cornering clearance to be able to steer the bike, suspension that can keep the tyres usefully attached to the road, and brakes that can bring the whole enterprise back from optimism. Otherwise, you might as well be sitting on a freshly-fired cannonball.

The Performance index is:

$$P = \dfrac{hp}{(m + 80) \cdot 0.26} \cdot \left(\dfrac{\theta}{43}\right)^2 \cdot \dfrac{(1+s)(1+d)}{4}$$

where $m$ is the bike’s wet weight in kilograms, ${\theta}$ the maximum lean angle in degrees, and $s$ and $d$ are boolean flags for inverted suspension and dual front discs. The $80$ is a standardised 80 kg rider. The constant 0.26 HP/kg is not a calibration choice: a system accelerating uniformly to 100 km/h in 4 seconds requires, at that final speed, power $P = m_{\text{total}} \cdot a \cdot v_f$, giving $P/m = (100/3.6)^2 \div (4 \times 745.7) \approx 0.26$ HP/kg. A bike scoring $P \geq 1$ meets that threshold at 43° lean with full hardware.

If $P \geq 1$, the bike is performant.

The lean-angle 1 The lean angle used here is a shortcut. A principled measure would be derived from cornering physics: the minimum lean required to clear a known reference corner at a defined speed, computed from the centripetal constraint $v^2 = rg\tan\theta$. A hairpin at a given pace imposes a known geometric constraint; the lean angle at which a bike can safely meet it would be the actual threshold. The maximum achievable lean angle serves as a proxy on the reasonable assumption that a manufacturer designing for performance builds in the clearance to use it. factor is squared in the formula, with 43 degrees as the reference point—roughly where a performance-oriented naked or sports bike naturally sits. A comfort-focused adventure bike at 37 degrees scores 74% of the reference lean factor; a cruiser at 33 degrees scores 59%; one at 28 degrees scores 42%. Track-oriented machines, which might lean to 55 or 60 degrees, are rewarded accordingly. The reference was set here deliberately: 43 degrees is not a lean angle you reach while focused primarily on comfort or cost.

The hardware 2 The hardware flags are themselves a shortcut. A rigorous measure would use actual stopping distance from a reference speed, and lateral load capacity from suspension data, each normalised against a defined threshold, scoring 1 if the bike meets the mark, above or below accordingly. Inverted forks and dual-disc front brakes serve as stand-ins: manufacturers who specify this hardware are signalling performance intent, and the inverse holds. A bike with a large single-disc and a quality radially-mounted caliper might stop shorter than one with dual smaller discs; the proxy cannot see this, but a measured stopping distance would. modifier is multiplicative: each component independently halves the score if absent. A bike with both keeps the full score. A bike missing one loses 50%. A bike missing both loses 75%, which is the theorem’s polite way of raising an eyebrow at the manufacturer’s priorities. The reason the modifier exists is that their absence is rarely accidental: inverted forks and dual brakes cost money, and a manufacturer optimising for affordability will cut them first, confident that the target customer will be distracted by the colour options. A bike with a good power-to-weight ratio but no inverted forks and no dual discs is telling you something about its priorities. The index listens.

Affordability is the part where everyone starts lying to themselves. The proper measure would include tyres, servicing, fuel, insurance, tax, depreciation, accessories, finance, parking, and the domestic diplomacy required by yet another garage neighbour. Unfortunately, calculating that accurately across countries would turn this article into investigative journalism, and nobody came here to read a tax report with handlebars.

So the Affordability index uses a portable proxy: inflation-adjusted new purchase price, normalised against local GDP per capita. Second-hand bargains are not allowed, because the index can be defeated by a suspicious listing 300 km away with “minor electrical issue” in the description and “’tis but a scratch” in the one blurry picture.

The formula is:

$$A = \dfrac{0.25 \times \text{GDP per capita}}{\text{adjusted price}}$$

If $A \geq 1$, the bike is affordable.

A bike is affordable only if its new price is no more than a quarter of local GDP per capita. A Honda SH125i clears this in Spain. A Honda SH350i clears it too, barely. A Moto Guzzi V7 is cheap compared to its BMW or Ducati equivalents, but it is not a cheap bike.

With these three 3 Every other property that might be assigned to a motorbike can be reduced to one of these three. I have discovered a truly marvellous proof of this, which this margin is too narrow to contain. firmly established properties, the ineffable power of huge swathes of anecdotal data1, and the righteousness of combinatorial mathematics, we are faced with eight ($2^3$) possible combinations. Let’s label them: 0, C, P, A, CP, CA, PA, and CAP; and unpack each carefully.

  • 0: There are zero-properties bikes out there, but we did not gather here to embarrass anyone, so they shall remain unmentioned.
  • C: Luxury tourers and some heavy cruisers that look after you beautifully while treating performance as a dangerous obsession and affordability as a shameful habit populate the comfort-only category.
  • P: Serious sports bikes and exotic machinery that prioritise speed so completely that comfort and affordability are asked to wait outside can be found in the performance-only category.
  • A: Small scooters and commuters, those noble machines that cost little, ask little, and deliver exactly the proportionate amount of excitement and amenity, are classified as merely affordable.
  • CP: Comfort and performance are the province of fast tourers, which also happen to be expensive: BMW RTs and K1600s, Ducati Multistradas, S1000XRs, and similar machines that can cross whole countries quickly while protecting the rider from most of the consequences of doing so, save for those involving the continued safekeeping of one’s driving licence. They are comfortable, sometimes even plush. They are fast, sometimes ridiculously so. Therefore, they are not cheap to buy, and the ownership experience is unlikely to be confused with public transport.
  • CA: Comfort and affordability are the hallmarks of the sensible yet boring machinery: Honda NC750X, CB500X or NX500, Suzuki V-Strom 650, old Deauvilles, and the better maxi-scooters. These bikes can do long days without cruelty and can be bought without having to trade in vital organs. They may move well enough, but they do not defy physics.
  • PA: Performance and affordability define the territory of excellent, regrettable decisions: the Yamaha MT-07, and the lighter end of the naked and sports-bike world. These bikes are quick, sharp, entertaining, and attainable. They are also not the obvious choice for a cold, wet, luggage-heavy day, let alone touring two-up. The Triumph Trident 660 shares this spirit only in the United Kingdom; at Spanish prices, it sits on the wrong side of the affordability line. The Suzuki SV650 and Kawasaki Ninja 650 miss it from the other direction: genuinely affordable and close to the performance threshold, but their modest hardware specification tells the story, and the formula concurs.

The one conspicuously missing combination is where all three properties converge: CAP. The conclusion at which you, O brightest of readers, will surely arrive is as follows:

  1. A bike that is comfortable and affordable cannot be performant
  2. A bike that is comfortable and performant cannot be affordable
  3. A bike that is performant and affordable cannot be comfortable

Every candidate that claims all three is quietly grading at least one axis on a curve. Comfortable for a sports bike. Fast for a tourer. Affordable for that brand. These are not lies, exactly. That does not make them true either.

This is why the perfect bike does not exist. The idea of a machine that is comfortable, affordable, and performant at the same time is now debunked beyond any shred of doubt. Not because engineers lack imagination, or because manufacturers are lazy, or because motorcyclists are impossible to satisfy (though that last one is most likely true). It does not exist because the requirements fight each other. Comfort adds weight, volume, equipment, and cost. Performance demands power, chassis, brakes, tyres, clearance, and usually more cost. Affordability resists all of it.

So how many bikes are enough?

If you need to cover all three bases, you need more than one bike, and you do not need more than two. This is not indulgence. It is compliance with mathematics. It is abiding by the laws of physics.

Yeah, Mr. White! Yeah, science!

– Jesse Pinkman

  1. The anecdotal data ↩︎