Writing to companies for sponsorship

Hi,

Please help me,

A colleague and i are going to ride cycles approximatley 2,250 miles in 14 days, with three rest days, to raise funds for a charity.This means we will cycle about 200 miles per day for 11 days. We also have a support team of 2, a medic and a cycle mechanic.

We need to write to companys with the aim of getting financial sponsorship and have prepared a pack to go with a covering letter by i have no idea what to put in the letter as the prepared pack contains details of the project and the charity but we still need to grab there attention.

Any ideas would be greatly apreciated.

Charlie Stanbury