Disappointed :-(

[s7ephanie]

Decided i'd ride to sons house and back which i thought was 26k there and same back !!!
Got my distance thingy on bike and it was only 34k return, maybe justas well really, as i've got a very sore bum

 

[Gravity Aided]

Sounds like a good thing. Your son is closer than you thought. Make more visits.

 

[Rickshaw Phil]

Is your speedometer set up correctly? My brother's accidentally got reset to a smaller wheel size recently and was claiming he'd done half the distance everyone else had on the same ride.

 

[helston90]

^ check this and try mapping it on a couple of sites/ checking it in the car to be sure.

 

[Pat "5mph"]

Check it out on Google maps, enter the postcodes, it will give you the distance.
As Phil said, maybe your computer is at the wrong setting - maybe your bum is right, it was 52K you did!