If you can lock 4.5% for two years or 4.8% for one year, the market is implying a rate for year two that makes the two paths equal. Solving (1.045)^2 = 1.048 x (1 + f) gives a one-year forward rate one year out of about 4.20%.
Forwards are what rate traders actually trade against. Saying you are bullish rates is meaningless unless yields end up below the forwards, because the forwards are already in the price. Every bond's carry-fixed-income is a bet that the forwards do not come true.
Example: forwards imply the 2-year yield will be 3.90% in one year's time. If you think it will be 3.40%, buying the 2-year and holding is the expression; if you think 4.40%, you sell it.
Related: spot-rate, carry-fixed-income, roll-down, expectations-hypothesis