Indurain's Lungs
Legend of Garry Nelson
Thanks for all your help so far. Help has come from a somewhat unlikely source, too. My Dad - who rode a similar bike back in the '80s. He has given me a few hints and tips - I'll watch the video from Stat Brother too. The more I think about it, the more I am determined to have a go myself. After all, the gears are already knackered - so it isn't as if I can ruin anything! (famous last words...)
Now it's been a good 25 years since I did it but I think downtube shifters are simpler than bar ones.
If it's old enough then the gears won't even be indexed so its just a matter of getting it tight then moving the lever to adjust. Adjustment is likely by similar means on the rear mech itself.
I wonder if you'll have an issue with getting the right cable to fit into the lever.