That's a bit harsh. I think most people would struggle to do Palace Pier to the Amex in under 25 minutes.I live in Coldean and cycle from town regularly and you have to overcome a heap of traffic lights (22 I think, between the pier and the stadium), the traffic and pedestrians frequently...
I've been cycling to the Amex since it opened and never had any problems. Used to cycle to Withdean too and forgot my lock once - even unlocked, it was fine