I bought the 1991 BumbleBee basket case without speedometer. The pieces of the bike don't look overly abused, just cruddy. I'm trying to determine the ballpark mileage. The steering head bearings felt very smooth and upon disassembly reveal no visible wear marks. I see no marring or other indication that they've changed out. Can a mileage ballpark be determined from this? What would be the envelope?