tyrion

I just had an idea and wonder if it makes sense:

Take a tubeless fat tire wheel, put an air reservoir device close to (or encircling) the hub, and an air tube connecting the rim with the reservoir. There will be a valve in there that lets air move from tire to reservoir quickly, but return slowly. The goal is to have the tire absorb shocks with less rebound.

The whole mechanism would be within the wheel, so a simple wheel replacement would give a suspensionless fat bike a plusher ride. The valve could be tunable to suit a given terrain.

Could this work? Has it been tried?

Darth Lefty 

Offroad R/C car tires can sort of be tuned this way, but they're not constructed like bike tires at all. They're not pressurized, instead they contain a foam rubber donut. The beads are glued to the rim and the rim has holes in it so the tire is flat and the weight of the car squeezes the foam. You can cut the donut to make it softer, stuff in a bigger donut to make it stiffer, and there are stiffer foams available. You can drill out the holes in the rim to reduce the damping. All these things are very fast wear items in racing so are sort of disposable to play with.

Oh hey also, remember you are getting a lot of damping from any tire just because the tire is viscoelastic rubber and not a pure elastic spring.

Here's a sort of example

osco53

Schwalbe's Pro-Core system is similar in execution.. It adds 200 grams to each wheel on normal MTB wheels..

Your Idea has merit IMO but would take a already too heavy fat bike tire to the extreme side of fat/heavy..I.E. slower..

Show me some weight numbers....

osco53

Supporting an R/C car is far different than a 200 plus pound fat guy on a fat bike......

Centrifugal force of the very high RPM spin of the very small diameter r/c car tire has a lot to do with the foam supporting the tire..

Your foam would need to be more dense...more poundage...

Darth Lefty 

@osco53 I wasn't suggesting it, just giving an example.

dminor 

Kinda like having a monster truck, then worrying about improving it's performance on a road course, isn't it?

Darth Lefty 

If you had an inner tube with baffles, you could get damping from air moving from one cell to the next. Or maybe we can come up with some other way to slow the air moving around.

@dminor this is about adding more adjustment knobs to fine-tune the system.

FrozenK

Suspension wheels are the closest thing I've seen to this idea. And there are reasons why we use suspension forks instead of suspension wheels.

Fluent wheel may not be shocking, but it is shock-absorbing

If you were to do what the OP suggests you'd be lowering the pressure on your tire under impact. That doesn't sound like a good idea to me. Can you limit the volume (pressure drop) so that you won't bottom out and still let enough out to be able to control rebound?

And unless you use a two-chamber setup this will have problems if you use sealant. So it won't be tubeless compatible.

You will then need some kind of charged piston or something to push the air back into the tire. And that piston will have to be equalized to the tire pressure. To me what the OP proposes seems awfully complex when you can go and buy a Bluto fork.

Shimagnolo

Cool. I learned about something new today: Schwalbe // PROCORE

Darth Lefty 

Well, it might be an ok idea, because it's working like a suspension. That's an ok goal. I don't think the idea is fully baked but we can play with the dough

FrozenK

You can play all you want, it won't change physics.

dminor 

So . . . we are talking about adding 'fine-tuning knobs' to the stone axe of bicycles?

Darth Lefty 

A full-zoot shock absorber has five adjustments (preload and high and low speed compression and rebound damping) even without replacing any of its parts. I don't think we are talking about anything that complicated in this thread.