Just seen some 3pc middleburn racing cranks on the bay and just wanted to know wat there like and if they would fit on a 84 robby expert resto.Cheers 
Old School MTB maybe but not BMX; I don't think Middleburn were around in the early 80's and I don't recall any BMX stuff but I could be wrong.
Probably better off trying to get some SR, Suntour or Sugino alloy 3 piece cranks if you want to be era specific - try Tefore I think he had some for sale
