Bowing wheels in general
The sound of the Ekdahl FAR is just as much a product of the choice of bowing wheel as it is the choice of the string. Both the shape and the material of the wheel plays a big role in shaping the sound, certain wheels "inject" their own sound into the mix while others generally only emphasize those occurring in the string. Wheels are also consumables as they will wear down with play, this will change both the sound, playability, clarity of harmonics, the physical reach of the wheel etc.
In general, a completely round and soft wheel will inject very little "wheel sound" into the mix, but it will also emphasize the fundamental more than the individual harmonics. Adding "protrusions" to the wheel helps in emphasizing the individual harmonics more, but also injects more wheel sound. The shape and number of protrusions can set a balance in between wheel sound and harmonic emphasis. Now the concept of wheel sound is certainly not something that is objectively negative, on the contrary wheels with many protrusions (~8 or more) can add "synth like" overtones to the mix which can be pretty sweet.
The main wheels for the Ekdahl FAR are made out of soft industrial felt, harder wheels can be used to get a "sharper" sound but they tend to create distortion much more easily. The reason for this isn't entirely clear but an assumption is that as the string "slaps back" into the wheel during resonance, a harder wheel that is not as malleable will not budge as much from the strings force and will rapidly dampen the strings vibrations. Again, this isn't an objectively bad thing, one can get "natural distortion" this way which is pretty great at times.
Playing around with different wheels and even making your own is highly encouraged, it is a huge part of changing the sound of the Ekdahl FAR. But care needs to be taken because the wheels are rotating at very high speeds, up to 650 Hertz, or 39000 rotations per minute. If the wheel isn't perfectly balanced the centrifugal forces on the wheel will create loud vibrations and strain on the bowing motor, this could result in unwanted noise and worst case it could prematurely wear out the bowing motor.
Changing the bowing wheel
Changing the bowing wheel is very simple. Simply remove the bow cover and grab the wheel retainer with your index fingers and pull it off. Take care to not drop it into the case as this will be annoying to get out and be careful with the wheel holder as the nipple that the wheel retainer is on is quite fragile. Now simply remove the bowing wheel and replace it with the new one and push the wheel retainer back on using your thumbs.
When a new wheel has been put on the Ekdahl FAR, the instrument may have to go through the pressure calibration procedure again. Different wheels will depending on their hardness and protrusions have different reach of the string. If wheels need to be changed during a performance, please see the section on actuators.