Most trainers are built very well. I wouldn't sweat it, unless you're looking at one of the $99 magnetic trainers, and then it's more a stability issue.
( Not to mention noise!)
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. “He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you.”- Fredrick Nietzsche
"We can judge the heart of a man by his treatment of animals." - Immanuel Kant