My gym does not have a seated calf raise rack or a smith machine. They have kettlebells but they only go up to 40lbs. Does know another way to do the exercise?
Do them straight leg on a smith or press machine ! When seated you don't use more soleus, you just use less gastroc ! The soleus still works as hard as possible when standing, you just have the gastroc to help it (so you can go heavier hehe).