Thanks for the info... These guys were definitely wearing brown overalls, 3 sleds in a row, no whistles, horns or anything. They were on the inside of a turn on switchback (kind of understandable the way insides become outsides on that trail). I understand about needing to get some get-go uphill, but it honestly was startling seeing them pop out from nowhere... I guess that's just a bad trail for them to be on.