Loads on Front Suspension?

[bwanajames]

Greetings All,

Newbie here with a packing question. I see some guys attaching loads (water bottles most frequently) to front suspensions. Is this a good idea? Wouldn't rebound be very sluggish with all that water weight attached? Any other adverse effects?

BJ

[chrisx]

I want to know the same thing?
Forks are made to go up and down.  They are not made to flex front to back.
Will an extra 5 pounds or so cause the fork to ear out to fast?

[Spec44]

I just add some air to mine to readjust the sag for the increased weight.

eta: which after re-reading doesn't answer the question so nevermind.  

eta2: but of course they are made to resist forces acting in all directions.  The front wheel doesn't only act linearly with the fork.

[RonK]

It doesn’t matter where the load is carried on on bike, it compromises the handling in some way. Load carried on the frame affects compression damping. You just don’t get sports car handling from a loaded truck.
Most bikepackers find they need to take advantage of every load carrying opportunity the bike offers, including the fork legs. How much weight is loaded there is up to you.
I carry water in a frame bag to centralise mass and put food and cookware in Anything bags on the forks.

[bwanajames]

I guess I was thinking in terms of sprung vs. unsprung weight. A lot of motorcycle forks are inverted to reduce unsprung weight and realize a more responsive suspension and better handling. 10 lbs carried on a front suspension fork will have a much greater effect on handling (and greater stress on suspension components) than 10 lbs in a frame bag.

Below are some findings with a little digging. I guess I've answered my own question. For me, I'll keep the front suspension free of gear.

Sprung weight: The complete chassis, including all the parts that are suspended above the suspension’s springs, is considered “sprung” weight. That includes the frame, engine, plastic, controls, saddle, upper fork tubes and shock body. It’s called sprung weight because springs are used to hold it up and to isolate it from the bumps that the wheels hit.

Unsprung weight: Unsprung weight is the mass that hangs below the springs (fork legs, hubs, brake calipers, rotors, spokes, rims, swingarm, linkage, tires, tubes and rim locks). Unsprung weight is more closely connected to the ground than the parts above it, because when you hit a bump, unsprung components compress into the chassis to absorb the impact.

NEGATIVE EFFECTS OF WEIGHT BELOW THE SPRINGS
Your bike’s suspension is constantly moving. If it’s not compressing, it’s rebounding. At the top and bottom of the suspension’s stroke?whether fully bottomed, topped out or somewhere in between?the wheels must change direction as quickly as possible. The less weight hanging from the suspension components, the easier it is for the mass of the wheels to stop and accelerate in the opposite direction. It’s no secret that the quicker the wheel reacts, the better the suspension will be — because the next bump is coming faster than the mechanism can respond.
It goes without saying that the less unsprung weight, the less strain will be placed on the pivots, springs and dampers. The lower the unsprung weight, the quicker the suspension reacts to bumps. The improvement is most significant over repetitious, high-frequency bumps (like braking and acceleration bumps). Why? The more weight you load on the wheels, the more the shock absorber has to struggle to bring the mass to a stop. As the damper struggles with the weight, the suspension packs, the wheels kick over the bumps and the bike becomes a handful.

BJ

[evdog]

I'm sure a bunch of weight strapped to the fork will have some impact on handling.  The handlebar, frame and seatbags will all affect handling and center of gravity too. 

For bikepacking, you're going to be riding slower than normal trail riding.  Not only does this reduce the forces acting on the bike, but it also means you will have an easier time adjusting your riding to that weight. 

For me the biggest issue with handling is not being able to drop my saddle very far, or at all, when I use a seat bag.