Originally Posted by queerpunk

Funny. Somebody just said to me, "You know, you told me I was riding a gear that's too big for mass start races. I went down and everything started locking in to place." I told him, "Go down two more inches. In fact, go down until it's DEFINITELY too light, then go back up an inch or two."

It's really easy to feel crap in a mass start on a too-big gear (especially the smaller the field, which likely means a lower average speed and likely greater variation between average speed and attack speed in the race). Basically, personal factors aside, I'd think about expected field size, average speed, and speed variance (each ranging from low to high) to determine my gearing: low to high corresponds across the board.

Personal factors are, of course, what works for you - and you in the context of the race. If you don't expect to be tested by the field - if you are confident that it will stay together until the end, and that you won't have to work to match accelerations, chase attacks, or close gaps - then larger might work.

But honestly, I hear "100 for a master's scratch race" and my eyebrows go way up. FWIW I race UCI elite races on a 96-98.