Why do mountain bikes all have thin tires?

Weird, my mountain bike have big fat tires. While the road bikes I owned had always thinner tires. Each type of tire has been adapted for the surfaces they ride on. A firm thin tire on the asphalt surface won't flatten much. The less the tire flattens out on the bottom, the less surface area is in contact with the road. Less contact in this case means less friction, and more speed. This is why keeping tires properly inflated is so important.

Wide and fat mountain bike tires in the other hand, flatten out more on a hard asphalt surface. However, on a dirt trail, a mountain bike tire "floats" on top of the rough surface. A thinner road tire would cut deep into the dirt, forcing the cyclist to pedal the way out of a hole.

They don't. I don't know why you think they do. If you are learning and don't know, why did you assert knowledge of something in your question? Especially when what you asserted was incorrect?

I think the true fact is ironic. It's completely opposite. Mountain bikes have the thick tires for the perfect grip. I have bought many mountain bikes and I noticed that these bikes have much thicker tires than the road bike. Thick tires increase the friction and hence, the grip.

I'm begin to think that maybe the OP isn't really a cyclist and is struggling to post material on a subject he/she doesn't actually understand.

It may also be that the OP was looking at hybrids or flat bar road bikes. These will have narrower tires that ordinary mountain bikes. A simple misunderstanding is my guess.

WTF?

Thin tires on MTB? The next thing will be men in women's restrooms. The world is going to hell.

hades_leae said:

I wonder about this a lot. You don't find mountain bikes with thick tires like you would on a 20 inch bike for an example.

I still don't even know if you put air in them, are they just like a thin rubber tire that doesn't need air?

I wonder because I want to learn why they are designed the way they are, so please don't call me stupid for not knowing, I'm just learning.

I ride BMX bikes just so you know, that's why I don't know this.

On the off chance that YOU are referring to the tire's sidewall ...

[INDENT]More expensive bicycle tires tend to have thinner sidewalls which allow them to be more flexible ..

[INDENT]THAT is a characteristic which is especially prized by MTBers who prefer to run fairly low pressures and thereby they can ensure the maximum tire contact with the ground.[/INDENT]

Less expensive tires have stiffer sidewalls.

I believe that ONLY poly-/urethane & solid rubber tires do not need some air.

[/INDENT]

I'm not wondering anymore. After reading some of the OP's stuff in other topics and across other forum sites I'm convinced he isn't a cyclist. He is just trying to hit a post count (rules wont let me say why) and doesn't really understand what he is talking about.

[USER=271079]@sharkantropo[/USER], [USER=263644]@Jcycle[/USER], [USER=271714]@warrengeb[/USER], [USER=269904]@Gnufrau[/USER], [USER=97464]@CAMPYBOB[/USER], [USER=20681]@jhuskey[/USER], [USER=93709]@alfeng[/USER],

Just clearing my question up.

OK, so I had to do some research because I couldn't get an answer to my question, I looked it up, and it turns out that my question was not distinct enough.

Some of you might not know who Lance Armstrong is, he is a Triathlete, and I was talking about the tires on the bikes that he rode when he won his championships.

The bikes those athletes use don't have the standard fat tires on them...I was not distinct enough when I said mountain bikes because I thought everyone knew what I was talking about, seeing as this is supposed to be a community of bikers, but that was my fault for assuming.

I know that mountain bikes have fat tires, I used to own one, and got rid of it because I like single gear, BMX bike, and I literally use those to travel to my job, I'm not into the big hefty bikes, they are heavy and take up too much space. I still like to learn though.

I was talking about the skinny ones that you can clearly see are not fat if you were to go type in Lance Armstrongs Bike on google and look at the tires on his bikes from the past.

Some of you mention someone as "OP" , who were you talking about? I have no choice but to assume it's me, but those aren't my initials.

[USER=263644]@Jcycle[/USER], who are you talking about?

OP means Original Poster. That is the person who started the thread. Lance Armstrong was not a triathlete, but a road racer. The narrow tires on those bikes are to reduce rolling resistance. The bikes used in road racing are very lightweightand fast. Not heavy at all. Mountain bikeshave wider tires in order to grab the surface of a dirt trail without cutting into it.

Gnufrau said:

OP means Original Poster. That is the person who started the thread. Lance Armstrong was not a triathlete, but a road racer. The narrow tires on those bikes are to reduce rolling resistance. The bikes used in road racing are very lightweightand fast. Not heavy at all. Mountain bikeshave wider tires in order to grab the surface of a dirt trail without cutting into it.

Lance Armstrong started off as a triathlete as a teenager ! He was The National Sprint-Course Triathlon Champion in 1989, 1990, and 1992. He then join the road bike world wit Motorola.

What am I talking about? You are just here because you are [CENSORED] and not really knowledgeable of the subject or interested in it and it shows. The rest of us [CENSORED] at least stick to topics we have an interest in or know something about.

LA rode road bikes. A road bike remains a road bike even if it's used (on roads) in the mountains. Mountains figure greatly in the big Tours - Tour de France, Vuelta de Espana, Giro di Italia - of which LA is closely associated with TdF.
Road bikes have thin tires, for aerodynamics, rolling resistance and weight.
The big thing about mountainbikes isn't that they're ridden in mountains, but that they're meant to be ridden off-road. Tracks, trails and paths. Maybe a logging road or two.
MTBs have wide tires. For traction, suspension and "float" on loose surfaces.
Tire sidewall thickness is a separate feature.
Both MTBs and road bikes can have either thick or thin tire sidewalls. Depends more on the price and intended purpose of the tire. Cheap tires and/or tires meant to be durable usually have thicker sidewalls than more expensive, "race" inspired tires.

FWIW ...

[INDENT]Just to reinforce what dabac observed by re-phrasing his observation ...

[INDENT]Bikes ridden on mountain roads tend to be thinner than those used off road because the additional stability and/or 'flotation' which a fatter tire would provide on unpaved surfaces is not needed on a paved surface.[/INDENT][/INDENT]

FYI. Thinner tires can be installed on a Mountain Bike (MTB). Here is one of my old MTB frames reconfigured with a Road fork + 700c wheels & tires:

[CENTER]:[/CENTER]

BTW. Tires larger than 700x28 cannot typically be installed in a typical Road frame that was made after 1990.

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