What Are The Defining Features And Characteristics Of A 'Mountain Bike'?

Just something to ponder on.

How do we define 'Mountain Bike'? Clearly it must be designed for and suited to riding non-tarmac routes.

Can the definition be broken down to a list? For example:
1. Large volume 'balloon' tyres
2. Large nobbles on the tyres

Or are lists of defining features and characteristics counterproductive and unhelpful in defining a mountain bike?
Can the definition be broken down to a list? Not really.
Is a list of defining features counterproductive and unhelpful? Not really, either.

I don't think that you will find a single feature that all mountain bikes have that other types of bike never have. Fat tyres? No. Fat bikes, jump bikes and even the Raleigh Chopper had fat tyres. Nobbly tyres? No, CX bikes, gravel bikes and, again, fat bikes can have those. Wider handlebars? No. Well, it depends on what you call wide, but a modern hybrid or flat bar gravel bike might have relatively wide handlebars. And, in any case, some 90s' mountain bikes had their bars cut pretty short.

What about a feature that all mountain bikes have, regardless of whether other types of bike have that feature sometimes? Arguably, not even that. If I put skinny tyres on a mountain bike, I still think of the bike as a mountain bike, just one with skinny tyres. What about two wheels? Surely, all mountain bikes have two wheels. If there was just one wheel, it would be a unicycle, and if there were three, it would be a tricycle. However, it's debatable whether even having two wheels is a defining feature of a mountain bike. After all, if I see a mountain bike with a wheel missing, I don't stand there wondering what on earth this alien object is before me. I know it's a mountain bike with a wheel missing. Take away any single component, and I could still make the same type of comment However, take away all of the components and I would no longer say it's a 'bike' so much as a 'mountain bike frame' (and forks, perhaps).

So, can I define a mountain bike (or much else, for that matter) with a list of features? Not really. However, despite all the changes that mountain bikes have gone through, I can still identify a 'mountain bike' very reliably. It's not a meaningless phrase. What defines a mountain bike, then? 'Family resemblance' and 'lineage'. Although I cannot produce a list of features that all mountain bikes have, I could produce a list of features that they tend to have. If I listed ten features, I might find that bikes identified as mountain bikes have, roughly, seven of those features. They don't all have the same seven features, but they tend to have seven features drawn from that set of ten. That's family resemblance. A 'mountain bike' is not a sharply defined concept but that does not mean it's a useless concept. It's good enough for me to say that a hybrid bike has some mountain bike features, or that it is like a mountain bike to a greater of lesser extent. What about the changes in mountain bikes over time? Today's MTBs are very different from those of the eighties and nineties. That's where lineage comes in. That's the gradual development of design over time; the slow shifting of the cluster of features that MTBs tend to have. Some things are added and others are taken away from the set of features which mountain bikes will have seven (or whatever) of, just like every single atom in your body, and the way you look, will change over your lifetime but you can still be identified by your history/biography.

There you go (and thank you to Ludwig).
 
Caption / 'craption': 'Police are seeking a man who was spotted acting strangely with his hand in his pocket and holding his helmet in a public place' ? 🤨
 
I was out in the Dales today. Saw a few people riding cyclo cross bikes off road. Or were they 'gravel bikes'? Either way, people seem to have enthusiastically embraced riding skinny nobbly tyres off road. Years ago I mostly only saw that type of bike at the three peaks cyclo cross competition.
 
Except for the dozens of CX races that run across the country just about every weekend from September to Feb/March, some with ~150 starters...

FWIW I regularly run my (nearly antique!) CX bike round the local MTB trails on its UCI compliant tyres (33mm wide.) not hard going at all. Just pick better lines!
 
Surely, all mountain bikes have two wheels. If there was just one wheel, it would be a unicycle, and if there were three, it would be a tricycle. However, it's debatable whether even having two wheels is a defining feature of a mountain bike.


Bikes certainly can have there of four wheels, have you seen some of the cool 4 wheeled mountain bikes. Great things.

A bike in this context is a human powered device, could be your hands and even assisted now.
I draw the line at a motor being used without assistance, as it is a motorbike then and moves to motorcross or whatever they call them.
 
I suppose if one is to be pedantic for a minute then bike by definition has two wheels.

For me a mountain bike is just that, a bike capable of off-road and even mountain travel. Was there not an issue a while back where manufactures where labeling bikes as mountain bikes yet the frames were not up to the job and used to break?
 
I suppose if one is to be pedantic for a minute then bike by definition has two wheels.

For me a mountain bike is just that, a bike capable of off-road and even mountain travel. Was there not an issue a while back where manufactures where labeling bikes as mountain bikes yet the frames were not up to the job and used to break?
I think that was the 90s ;-)


And why is it a quad bike and not a bi bike?
I think bike has become more to mean 'cycle' now, than specifically bi-cycle and has a wider definition.

BMX is not a mountain bike, but can certainly go up and down mountains and not break.
 
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Nooooo, still have a regular turnover of snapped "mountain" bikes that have failed (literally) bouncing down a kerb.
Mainly mail order. Also, mainly overpriced by 300%.
 
Except for the dozens of CX races that run across the country just about every weekend from September to Feb/March, some with ~150 starters...
I never see any of the other cyclo cross races, because apart from the Three Peaks event, they're not run in areas I usually visit. And in any case, if 33mm tyres is the regulation for cyclo cross, quite a few gravel bikes would be disqualified. Certainly the Genesis range of adventure bikes has tyres wider than 33mm. And a 40mm tyre is not that much narrower than some of the lightweight tyres commonly used for XC races in the 1990s. What I do see more often is those things called sportives, which in my opinion are not particularly good public relations for cycling.

FWIW I regularly run my (nearly antique!) CX bike round the local MTB trails on its UCI compliant tyres (33mm wide.) not hard going at all. Just pick better lines!
Surely it depends how rough the trail is. Some trails and canal tow paths are so smooth you could take a road bike with 25, or even 23 tyres. Other off road trails would be awful on narrow tyres.
 

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