I would assume that bike might have been part of Decathlons first range of bicycles and seeing as that didn't launch until 1986 and they started labeling the B'twin in 1999 it must be somewhere between the two dates. Looking at the style I'd say it was late eighties/early nineties but I may be wrong.
Is it a steel frame? What make/model is the rear mech? You might be able to date it a bit closer with those details and other components. If the saddle has a moulded base it will likely have a manufacturing date stamped in.
Nice bike.
Hi, thanks for your reply.
How might I tell if the frame is steel?
It says Shimano Acera X and on another part Shimano RSX. The shifters are Shimano RSX as well (currently broken and hunting new ones if anyone knows of anything suitable!).
The saddle does have a moulded base, but no date as far as I can see!
Interesting to hear about the dates of branding, thanks for that.