Here is a picture of the problem I have. It should tell me that I am tracking 263 miles but it says 262 instead. That means my OCD kicks in, plus some of the MPG calculations will be slightly off. (Not sure which ones!)
Fuelly is just going to ignore the first fill up odometer anyway. It gave you a 0mpg for the one mile entry. It needs a second reading entered to calculate distance. The first fill is to get the starting baseline at an odometer reading with a full tank of gas.
You are running afoul of Fuelly trying to prevent erroraneous entries. It is extremely rare for a vehicle to have 0 miles on the odometer by the time the first owner gets it and registers it here. Friend of a friend has a Grand National SS he bought new and trailered home. Still has the plastic on the seats, I've been told. Between all the moving onto and off of transports, the car still had about 4 miles on the odometer.
So you have three choices.
1. Just leave the first entry with an initial odometer reading of 1 mile. This means your first calculated fill(the second entry) is off by about 0.8mpg, but it will have less and less impact on the lifetime average overtime.
2. If you don't want that error in your data, do as Jay says and just start with the your second fill for the Fuelly profile.
3. Ask Robert or another administrator to make your 1 mile enrty a 0. A suggestion that motorcycles be allowed to have a 0 mile initial odometer reading wouldn't be a bad one.
The odometer reading will not be off if you put an initial fillup with one mile on it and zero or .001 gallons filled. Odometer logging does not add up the miles from each fillup, it just takes the most recent odometer reading.
This should probably be in the FAQ if it's not already.
I prefer the trip meter method anyway, if you skip a few fill ups it makes no difference. If you skip just one fuel up using the odometer reading, then you have to check the "missed fuel up" box and then wait another two fuel ups until your data can be calculated accurately again.