Ask HN: Required credit cards during registration?
Question: Should you ask for a credit card during sign-up and give the user a 7 day trial before charging the card?
Whether the increased conversion rate overcomes the reduction in signup volumes is the big question. I suspect it's different for everybody, and the only way to find out is to test.
One thing that'll affect your decision, is what the cost to you of "freeloading" no-credit-card signups is, and whether it's worth forgoing them to concentrate on the more-likely-to-convert signups who are prepared to put their CC number down. If you're offering a SaaS or Pass thing where the incremental cost for each new signup is extremely c heap (like cents or less), then it's much easier to justify a totally free non credit card trial than if whatever you're selling has incremental costs in the dollars or tens of dollars range.
(And, the flip side to that, if you want to build an Uber style "grab all the market while supported by ever increasing VC round funding and profit after you've collected all the underwear" business, then don't ask for CC numbers up front. Or even at all... And hope you can flip $700mil of shares before your Uber-but-for-office-space business crashes down around everybody...)