What brand of cards do you find best for card warp? I use bikes for everything, and my older ones for card ward. Lately however, the have been breaking during the routine. I usually roll the crease in to avoid this from happening, but this last deck seems to bo particularly brittle. I'm wondering if it's my technique.

I've found this to be true due to the age of the card. Very old bikes are likely to tear when you put a hard crease in them. I don't believe it's an issue with the brand per se. I would just use slightly newer cards and not use cards discarded a long time ago.

I use cheap cards ,they work the same way

Thanx
I have some dollar store cards around. I'll give them a try, but I'd rather use the old bikes than bring in a different backed deck.

In general, if I plan on doing this effect, I take old bicycles from decks I no longer use and I have never had a card break on me. I've probably used cards that were at least 4 years old.

I have a stack of bikes that come from broken decks that I use for practice decks. All different ages. Some work fine while others are as brittle as a soda cracker. I also find that the newer decks I buy, (at Costco), seem to be more brittle, and although it might be my imagination, they seem to handle differently than what I'm used to. The difference n feel might well be due to arthritis that I recently developed in my hands, but that wouldn't effect the brittleness of the cards.

I don't think it's your technique, as I often have the spectator fold one of the cards and don't have an issue with cards breaking. I have been performing Card Warp for 20-plus years and the only issue I see is using older decks / cards. As the cards "dry out" over time, the paper does become more brittle and I know exactly what you are talking about. At about $4 per deck for bicycle cards (cheaper if you are buying in any kind of bulk), I would just use newer cards. You will get 26 performances of Card Warp out of a deck (13 if you do it with a Do-As-I-Do theme). That's about $0.15 for every performance.

Best of luck and let us know if you are still having issues with cards breaking.