Lowest Cog Ratio. Use this filter to eliminate bikes from your report that do not have a low enough gear. The way the low gear is calculated is just a simple ratio between the smallest ring on the chainring and the largest cog on the wheel. For example, the Surly Long Haul Trucker comes with a 50/39/30 on the front and an 11-36 on the back. So the lowest gear is 30 divided by 36, which is 0.83.
In general, for Vancouver my rule of thumb is you want a lowest gear less than 1 to 1.
From the document: Form Help for Bike Lister