Much of the discussion here is more focused on DD wheels that can replicate most of the actual forces, and are handled differently by rF2. So ignore some of that. Anyway:
On a Logitech wheel you're limited to about 2.5Nm torque. The Caterham here is on the low end of typical cornering forces at around 5Nm, with most cars producing more. So first thing: you aren't going to get real forces.
More force is better, on several fronts:
- More engaging, as it's more realistic and just feels better. It's a bit like music sounds better when louder, to a point.
- Greater difference in forces, either mid-corner fluctuations, understeer dropoff, or comparitive forces when judging track grip (dry or wet).
- Signal to noise ratio - gear or belt driven wheels have more inherent weight in their movement, so increasing forces will help to separate FFB effects from the wheel's friction.
So basically without exception, this level of wheel should be run at full strength in the software/driver. Reducing the force takes you further from reality and has the above drawbacks.
Avoid above 100% unless you know for sure it actually produces more force on your wheel, and isn't going to flatten the top end of forces too much.
In-game settings aren't so simple.
You have to keep in mind what you want to get from FFB. It's not just a centering spring or a heavy feel on the wheel; you want to feel variation in the forces at your fingertips, to help you understand what the car is doing. There are broadly a few different things that generate different levels of FFB:
- Mid-corner centering force, which will fluctuate with variations in tyre grip, load, angle, plus suspension geometry.
- Harsher interactions like driving along kerbs (rumble strips), grass, dirt.
- Collisions with stationary objects and sharp edges - e.g. crossing road/kerb edges at an angle.
From top to bottom those forces are increasing in magnitude. The cornering forces are by far the most useful, the second group you want to be aware of but offer little in the way of car-control FFB, while the last group will only shake your rig/desk and threaten to injure your fingers and hands if you're in a compromised position.
So, usually the best approach is to increase FFB as much as possible without losing the forces you want to feel, which are those in the first group. This is a fairly dynamic process as forces can vary with car setup, track conditions, driving style to some extent, and different people prefer slightly more force or more detail at the high end. It may be something to revisit occasionally and adjust if necessary. I prefer telemetry for this (you can identify force levels in parts of the track you actually need feedback, and ignore harsh bumps or kerbs) but Simhub can display the FFB level live as well.
If you run in-game FFB too high you'll get excessive clipping, where instead of high-level fluctuations you get a flat 100% output. Over extreme bumps or harsh kerbs you're not missing useful feedback, but if that happens mid-corner you now just have a centering spring instead of FFB.
Different cars can produce different levels as well, because the car maker can arbitrarily set the "max forces" point, and that sets the standard 100% output level. Many cars in rF2 will produce some mid-corner clipping at 100% FFB Mult (in-game), so getting more detailed FFB needs a Mult of 80% or less. Some other cars have the "nominal max" point set well above normal forces, so you can actually run above 100% without losing much relevant detail. The IndyCar is like that (130% is reasonable, but would kill FFB in most other cars) and the caterham is in this category as well - its max is set to 9.5Nm, well above the 5.5 cornering forces I've seen with some test laps. 150% or higher might be perfectly useable and make the most of your wheel's limited power.
Anyway, I usually run about 70 or 75% mult in most cars, but here's the DW-12 at 100% mult: (I believe the recent IndyCar is similar; I don't own it)
