DIY costs

Others will probably be able to advise you on the availability of French threaded components - or, more likely, the non-availability! - but I can give you the technical stuff. It affects the headset and the bottom bracket.

The headset has no compatibility at all with others, so if the headset is worn out and there's no French threaded replacement available you're looking at new forks. The bottom bracket is actually a close enough thread to an English threaded bracket for the adjustable cup to work, but the fixed cup is right-hand threaded. It's easier to find something that will do the job for the bottom bracket compared with the headset.

The Routier you're looking at is a really interesting old bike, but the keyword here is old! With its French threading and components which are before even my time it's not going to be a very practical bike. I know you've set your heart on it, and I can understand why, but that second Peugeot from the late 80s / early 90s is a MUCH more practical option, will almost certainly give better service, and is going to be a lot less hassle when bits need replacing.

Anyway, good luck with whatever you decide upon!

...and I should have added that the stem is also smaller diameter, because of the headset. (Not the 'bars - they're probably 25.4mm). I'm writing from memory now, but I think French steerers were 21.8mm instead of 22.2. Both those could well be wrong, though - it's a long time since I've needed to remember those!

I had a Peugeot road frame in the 80s which must have been one of the last to be made with French threads; it was a right pain. Even then, I couldn't get a stem to fit the bike (although I didn't have www.retrobike.co.uk to help me!) and ended up having to grind off some of an English-type stem (which isn't a great idea, really). I eventually changed the forks.

Simon,

Thankyou so much for taking the time on these two posts - I think I get it now, will save for reference.

The one in ebay is lovely but I'm going to try and remain sensible and patient for now. I do need something practical as it's going to have to see me through three years of uni-based poverty, that said I do hope to get something that I can add to every now and then and eventually treasure.

Peugeot, 501/531/Vitus or similar frame, mid-late eighties, 54-56cm,. I do make things difficult for myself!

No problem - I think you've been sensible, TBH. Good luck with your search!