At what speed should the landing gear be retracted during landing?

The appropriate speed for retracting the landing gear after takeoff, which typically applies in the context of transitioning from landing to climb, is indeed around 100 knots indicated airspeed (KIAS) for the ERJ 170/175 aircraft. This speed ensures that the aircraft has attained an optimal performance margin above stall speed while allowing for safe handling characteristics during the transition phase.

Retracting the landing gear at too low a speed can lead to potential aerodynamic issues, including loss of control or increased drag. Conversely, retracting it too late can increase drag and reduce climb performance, potentially compromising safe climb-out profiles. Therefore, the specified speed of 100 KIAS balances safety and performance, making it the correct choice for retracting the landing gear after takeoff.