If I were signing up for said free trial and saw a credit card request upfront, I would be suspicious. Many subscription services promise such a "free" trial a

If I were signing up for said free trial and saw a credit card request upfront, I would be suspicious. Many subscription services promise such a "free" trial and then make it difficult to back out. It also violates my model of how "free" should work to ask for credit card info, so I suspect hidden charges. That's my experience. Maybe your users are more trusting.