Probably not a lot, it's rare for bikes to turn into real collectibles. Your best bet is to look at craigslist/ebay or similar to see what that kind of bike is selling for.
The cast of Tandem - 1965 includes: Antoine De Rudder Christian Marin
399, includes slant 6, V8s, and tandem axles
Value of old 1965 20c english
Value of old 1965 20c english
0.01 USD. The face value.
Pre-1965 US quarters are 90% silver with a value of about $2.50 just for the silver.
25 cents.
Value is for the silver about $2.50
Face value: 10 cents.
Proof sets were not made in 1965, but a 1965 special mint set is worth $12.00 USD.
1965 to 1969 Kennedy half dollars were all struck in 40% silver and have a bullion value of about $2.00