As for the sweaty delivery guy,in my experience no one cares how the parcel got to them as long as it was on time!! I wouldn't push the "We use bicycles" bit until you have a firm client base.The most important thing is to stop the ever decreasing company bank account when first starting up,market yourself like any other messenger firm then when your making money re-market as bicycle messenger firm pointing out how brilliantly fast you are and what fabulous clients use your firm.Or something like that!!!