The promenades are wide in Mablethorpe, there are tracks that are good to cycle on once past the promenades. The sand does accumulate but there is plenty of width for cyclists and walkers
the ride from mablethorpe to huttoft beach is quite a good run along the east coast shoreline, promenade paved all the way. once you get to huttoft beach theres refreshments like coffee and cake but if your impatient there the new colonade at sutton sea for a pitstop too