Bike the Baltic 2008 could raise £1m for the cancer care charity, which is 60 years old in 2008.
This ride will see some 300 UK cyclists set off across the Baltic States next August.
The first cyclists will ride out from Warsaw on August 16th and the 30-day cycle challenge ends in St. Petersburg on September 14th. Cyclists can choose to do the lot - a total of over 2,000km or choose any one of four week-long stages. The rides start from historic cities such as Vilnius, Riga and Tallinn.
The trips are organised on behalf of Marie Curie Cancer Care by Classic Tours.
There's more info on the Bike the Baltic website.