I have payed attention to cycle tours since 2000 more or less. A web page about Thai Tours was recommended to me at that time. If you are interested in organized group tours, you can contact thai tour operators with licence of the TAT (Tourism Authority Thailand). The booking and the payment must agree on you directly with the tour operator. For that I am following seeing to these tour operations so well and conscientiously, I am not able to assume the responsibility or liability for these events, which are passing outlying of my direct control. If bookings are made, it has to be taken care that elapse time of the visa agree with the travel dates, in particular the flight appointments. At faults series can be made of costs for cancellations and rebookings.