Tuesday, August 28, 2012

A Discussion On Suspension: Fat Bikes

Yesterday I discussed my thoughts and gave some background on what may make an "all-road"/ gravel road bike better when you consider tires and other means of suspension. Today I am going to turn my focus on suspension to another area where common sense seems to dictate that suspension isn't necessary- that being on fat bikes.

Suspension is rarely seen as a foolish thing on mountain bikes, but fat bikes seem to have "built in" suspension in their tires, so why on earth would anyone want to use suspension here? That and the typical low speed travel these bikes seem best for doesn't really call out for a squishy solution to rider comfort and control.

Of course, that has not prevented the tinkerers and visionaries from trying it anyway. Following are some ideas to consider when it comes to fat bikes and suspension.

While it is true that the pneumatic suspension available from using a 3.8-4.7 inch tire on a bicycle is plenty for most, there are times when suspension would be nice. Why? Well, the number one reason would have to do with damping the tires proclivity to bounce. Take any bicycle wheel out of a frame, and drop it from a foot or more in the air on the tire. You know what will happen. The wheel will bounce a few times wildly and careen out of control to the ground. This is because the energy caused by dropping the wheel against the ground is returned and until that energy is dissipated, or damped, it will bounce around out of control. Fat bike tires like to bounce. A lot. Especially when you add in speed to the equation with successive bumps.  

And the speeds do not have to be high for this to occur. Take for instance the image here which shows some severely post-holed snow. This stuff was pretty rough to ride through, making control harder to maintain, even though it wasn't frozen solid, and I was going at walking speeds. A supple front fork would have tamed the bigger hits and jarring, making keeping control and maintaining speed much easier.

Outside the box.
 Now consider that fat bikes are also being pressed into service as all terrain vehicles. The wide footprint these tires lend a rider mean more traction. More traction means you can go even faster, and with no suspension on most fat bikes, the bouncing, undamped tires become uncontrollable very quickly at these sort of speeds in off road conditions.

I was feeling this just yesterday on my Mukluk. I have 4.7" Big Fat Larrys on Rolling Darryls at less than 10psi, and hitting some ruts induced some serious arm pump to keep the front tire in contact with the trail. A suspension fork would have saved me from absorbing those impacts, giving me more control and expending less energy.

And I'm not the only one who thinks so. I have not had the opportunity to ride a fat bike with suspension, but I have spoken with a few people who have done so, and I have read others take on it on-line. The overwhelming majority of those who have tried it say something similar to what I was told recently by someone whose opinion I trust: "...it, (fat bike suspension), is game changing."  And if this is true, it will be akin to what happened when off roaders went suspended in the early 90's.

There will be detractors, and those who will cry foul, but I think in the end it will happen and become accepted. Rigid fat bikes will never go away, especially those aimed at the fullest amount of flotation on sand or snow. With the ever widening field of play for fat bikes; however, I can see a front suspension fork coming sooner than later that will accommodate wide tires and rims.


MG said...

I know you know that I'm one of "those people". Suspension fatbikes are game changers. Of that I have no doubt.

It would just be nice to be able to actually ride a bike... I'm going to be racing a fully rigid fatbike in the Dakota Five-O Sunday (instead of my full suspension 29"er). Would love to at least have a hard tail fatbike option!

S Sprague said...

Does this mean that Maverick maybe a possible fork for fat bikes? Not because it's on the prototype but it lends itself to the fat bikes with some slight modifications.

Guitar Ted said...

@S Sprague: Maverick is out of business right now. So that isn't an option, but may become one if that company is brought back. I do not know anything specific, but something tells me there is something in the works right now.