I’m new to characters, rigging, and poses. If anybody has tips on how to fix the shoulders and lower back deformations, I’m all ears. The shoulders in particular really cave in at the top between the traps and collarbones.
I found this rider model on Mixamo. The vehicle is my design and model.
Does the rig include shoulder bones? If not, it should include them, and they should be used as a part of the pose. If the arms are stretched foward, the shoulders would move too and would be responsible for part of that movement.
In other words, your arms have one more joint than is immediately obvious and it’s important not to forget it when rigging and posing a character.
For the lower back, it looks like you have placed the pelvis upright and made the spine curve forward? If that’s the case, try tilting the pelvis so it’s more in a straight line with the spine.
If the pose is already correct and realistic though, you might need to do corrective shape keys. That’s what is done in an animation when the rigging of a character cannot do a pose perfectly: you can make a shape key that exists just to fix that specific pose.
I like it, but I would reccomend adding some wear and tear to the kart, helmet, tires, and suit. Additionally, I think an asphalt texture would benefit the overall render adding a little more detail.