Rajflyboy

Ok folks. Can you help me out with this thought? Are bigger tires also like having suspension?

From my little bit of experience on + and fat tire bikes I’d have to answer yes to this. I think it’s equivalent to having a less expensive suspension.

Thoughts?

Happy Feet

No.

hillyman

I always tried to match the tires to the conditions I'm riding in. Right now it's a mixed bag of pavement, rails to trails, dirt or gravel. Whatever the exploring gives me. Continental Double Fighters do alright. I get enough suspension from a rubber saddle.

cyccommute 

I agree. But, because I’m me, I’ll expand on that. Tires provide a little suspension but it is completely uncontrolled. It’s a bouncing ball that follows Newton’s Laws of Motion. Real suspension has to follow the same laws but there are ways to control the way they work. Forcing oil through a venturi slows the rebound and makes for better control. The shock (front and rear) follow the terrain rather then bouncing off it. The tires still bounce, of course, but the suspension system slow the bounce considerably.

The difference can be substantial. On a fast rocky downhill, a suspended bike is faster than an unsuspended bike...even one with fat tires. The unsuspended bike bounces from rock to rock and the rider has to either be very good at control or has to slow significantly. The benefits aren’t limited to downhill either. On uphills, the front tire follows the terrain rather then being bounced off the line like a rigid bike does. Rear suspension also “squats” down on the ground and provides traction. A rigid (or even a hardtail) tends to bounce and not provide as much traction on climbs.

The rider’s arms and legs provide the bulk of the suspension on a bike with and without suspension but the suspension system does a very good job of aiding that human provided suspension.

subgrade

In addition to what's been said above, suspension does not affect rolling resistance.

Gconan

Yes. It adds some suspension. A small amount. A softer ride.

Happy Feet

I'm pretty sure the OP is asking if they equal suspension as in rigid / full suspension mtbs. He has brought this same thing up before in the mountain bike sub forum. Post 24 https://www.bikeforums.net/mountain-...fork-nada.html

Rajflyboy

Supercross riders like stiffer suspensions ( typically)


https://motocrossactionmag.com/bare-bones-3/

63rickert

Of course tires provide suspension. Presumably everyone knows what a pinch flat is? If a pinch flat happens you just used up all the available suspension travel. Obviously a big tire gets more travel than a skinny tire.

As long as there is travel there is suspension. Regulated travel with valves is better suspension than just a bag of air. The simple bag of air does work.

Most riders overinflate so extremely they get little suspension. Those riding current fashion are going overboard the other direction and using so little air they break wheels. But it is just not hard to get some suspension from tires.

In my experience bouncing or pogoing only happens in very specific circumstances. Much more likely with high pressure than low. Also far more likely with cheap tires than the good stuff..

Rajflyboy

this

from my experience

HTupolev

What do you mean by "like having suspension"?

Tires are literally a suspension system. They're usually very low-travel and have pretty low damping, so they're predominantly employed toward dealing with small surface irregularities.

If you're asking about the degree to which they overlap with the role of something like an MTB suspension fork, mostly not much. Those have more travel than most tires, and are set up with aggressive dampers to keep them calm and prevent bouncing. They're designed for dealing with big drops and impacts.
You can theoretically use a tire to similar effect, but it would need to be a huge tire, and putting super-high damping in a tire will add a lot of rolling resistance (since the tire is constantly actuating as the bike rolls).

FiftySix

Landing huge jumps requires it. Compare that to an enduro woods bike that has softer suspension specifically built to handle tree roots and ruts.

I had a enduro woods bike that no motocrosser of equal skill could beat me on in the woods. But that enduro bike bottomed out hard on mild motocross jumps, let alone attempting supercross jumps. And yes, if you got your butt too low and back on the seat when the rear bottomed out and rebounded, that seat would try to swat you over the bars.

FiftySix

At the right pressure, tires sure can smooth out road ripples and poorly laid concrete. Same with small rocks, acorns, etc. Don't gravel riders run wider tires and lower pressures than roadies?

HTupolev

Yes. When surfaces get rougher, people use larger tires pumped squishy to deal with the bigger surface irregularities.

Happy Feet

I have a decent quality rigid fat bike, a rigid 26", a hardtail 26" and a FS 27.5. There is a world of difference between them on technical terrain. On groomy stuff maybe not so much.

rigid 26 I have to pick my lines very carefully and go slow, hardtail and rigid fatbike are more forgiving and a little faster. FS goes over the same stuff faster with way less consideration. At first it's a little disconcerting just how much you can breeze over that otherwise would have caused concern. Particularly hitting larger ledges and/or drops. It feels a little dangerous until you get used to it. A rigid, even with fat tires can do some of the same stuff but not to the extreme and certainly not as fast.

If all one rides is rail or flow trails there may not seem like much difference in performance but as soon as you add speed and more than 6" of vertical impact you begin to see what full suspension can do.

alo

If you run fat tires at quite low pressure, there will be a lot of give, acting a little like suspension. However, if you run the pressure that low, there is increased rolling resistance, requiring more effort to pedal.

So for best performance, you need to run fat tires at a pressure where there is only a small amount of give. As a result there is not a huge range of movement. So they are not really like suspension.

If you ride on a gravel road, for example, or a road with a rough surface, you do get a slightly smoother ride.

Some benefit comes when there may be narrow holes that narrow tires may drop into, but wider fat tires get support from a wider area, and do not drop into narrow holes.

cyccommute 

The operative word there is “little”. It’s not much. There is a limit that depends on how “fat” the tires are.

I fully agree with the caveat that any suspension from the tires or even a long travel bicycle suspension is small in comparison to the suspension provided by the rider’s arms and legs.

Rajflyboy

pretty much what I have experienced as well

I would add cost into the issue as well (if you don’t have a lot of cash a fat bike or + bike may be a good option for trail riding that will work for someone)

Kapusta

If you consider an undamped spring “suspension”, then kinda yes.

But in practice it is not at all the same as a suspension fork or rear shock. Not even remotely close.

As others have pointed out, it works for relatively small surface irregularities.

50PlusCycling

Larger tires do indeed add a fair amount of suspension to your bike. The tires compress over bumps and holes just like the shocks or elastomers in a suspension system do. Larger tires at lower pressure allow for more compression, and while you do not get as much suspension travel as a suspension for or rear swingarm system, you get enough to make a noticeable difference. The tradeoff is that lower pressures increase rolling resistance. Shock absorbers add damping to the suspension, but your own body weight does most of the damping.

I used to work in a tire shop when I was younger and dumber, and many of my young and dump friends swapped out the original tires and wheels on their cars for larger diameter wheels and lower profile tires. And while we thought this looked very cool, it make the cars drive much more roughly.

HerrKaLeun

If you think pneumatic tires don't provide suspension, ride a bike with steel tire.

It is just little suspension without dampening.

Tire and frame and fork design also play a role.

All depends an your riding and skills. Arms and legs are good suspension too, but require you to maneuver around and get out of the saddle.

FiftySix

Sure thing. Just like horse buggies, carriages, and wagons with ironclad wooden wheels and springs mounted between the axles and the body of the vehicle.

Of course, not many of us would put up with that now.

AndreyT

Of course it is. Any kind of elastic structural element between you and the ground acts like a "suspension" (as long as it is not bottomed out).

But this is obvious. Which in turn makes one wonder what your question is intended to be about.

Kapusta

Yeah, I guess the title of this thread should have been "Fat Tires = Useful MTB Suspension?"

The answer to that is "no".

Rajflyboy

I guess we could add a 29er bike over a 27.5 bike. 29er rolls obstacles easier than a 27.5