To find out how many miles Josh bikes in one year, you can multiply the number of miles he bikes in one month by the number of months in a year.
Josh bikes 135 miles per month. There are 12 months in a year, so:
\[ 135 \text{ miles/month} \times 12 \text{ months/year} = 1620 \text{ miles/year} \]
Therefore, Josh bikes 1620 miles in one year.