At high bypass ratios (and thus also high radius ratios) the rotational speed of the LP turbine and compressor must be relatively low, which means extra compressor and turbine stages are required to keep the average stage loadings and, therefore, overall component efficiencies to an acceptable level.

However, some energy will be lost as heat in the gear mechanism and weight saved on turbine and compressor stages is partly offset by that of the gearbox.

[1] A large part of the noise reduction is due to reduced fan tip speeds.

After considering a geared design, General Electric and Safran decided against it for their CFM LEAP due to weight and reliability concerns, postponing its use for a future application, when Pratt & Whitney began development of the geared PW1000G.

[5] Rolls-Royce's latest engine design for large turbofans (25,000lb to 110,000lb thrust), the UltraFan[6] includes a Powergear rated at a new high of 64MW (87,000hp) and has demonstrated this full power during testing in 2021.