Eagle 737,
The bunch I worked for used;
for the Airbus fleet... "retract the gear when the vertcal speed is postive and the radio altitude has increased"
for the B777 fleet... "retract the gear when a positive rate of climb (is) indicated on the altimeter and the RA."
On the Lear 45 I fly now the wording in our SOPs is retract the gear "at positive rate of climb on both the IVSI and the radar altimeter."
The actual wording differs between types but the intent is the same ... make sure you have two indications and then retract the gear.
best regards,
Bruce Waddington