A tall frame is also long, consider; a shorter stem ..
higher up (up angle type, or stem raiser & different length)
helps shift weight onto your saddle/backside..
your ' Motobecane ' French made ? that means parts need be French standard..
Brand name has sold off, now the newer " Motobecane " is only a name,
Bike it's applied to, is coming from Asia.. so component part switches, simpler..
.....