After six months (plus) of on-again/off-again work, I finally got the Raleigh Lenton Grand Prix finished!
Gave it an 11 mile debugging run this afternoon and, happily, everything works. Of course there the occasional noise from the mudguard scraping the tyre. Which I can't duplicate on the stand. The mudguards are in rather close, so I'll get an occasional momentary rub when I hit a bump in the road.
It's definitely relaxed geometry (by today's standards). Seems to be comfortable, but I'll know more about that during the coming weekend, once I get 50-100 miles on the bike.
One thing's for sure, it's no climber. Chainwheel is 46-48, freewheel is 14-16-18-20. Which means I'm running 62-92 gear inches. And have yet to get past the 46-16 combination.
Yes, the wheels are wrong. I got the bike from Poguemahone minus wheels so in the interim I've come up with a rear wheel that is period correct (Sturmy-Archer hub on German steel rim), and a front wheel that is totally wrong (Normandy hub on Mavic alloy rim) just to get the bike on the road. Hopefully I'll at least come up with a matching front wheel, if not the catalog correct pair sometime in the future.
The derailleurs are fascinating, and were my biggest challenge since I've never worked on something this early previously (back in my days at the shop, I saw one Schwinn Continental with a rod front derailleur, never saw a Cyclo Benelux Mk. 7 before, except in pictures).
Much to my pleasure, the rear works a lot better than I expected it to. Admittedly though, this is a touring, not a racing, derailleur. You make your shifts gently and deliberately with a bit of foresight. And having it work in reverse from modern convention makes a lot of sense. Need the lowest gear possible? Just shove the lever forward, all the way. Done. I found that setting up the side to side travel is rather critical, starting with whether or not you use a spacer on the freewheel. The derailleur's travel is that limited. There's no way you'll ever get it to work with a fifth cog.
The front, I'm still attempting to figure out. It works fine on the bench (you don't hesitate when changing freewheels, or you'll get the chain stuck between the two rows of teeth - guess how I know?) but I'm going to need a few days getting comfortable with the frame to become efficient with it. With a two tooth difference in the chainwheels, though, I'm definitely not going to be shifting as often as on a more modern (say, 70's) bike.
As to vintage: For the moment, I'm guessing it's a '61. The serial number is high in the range for the 58-62 model years, and so far every Lenton GP I've run across that's claiming to be a '58 is gold in color. If anyone has any input on dating the machine, I'd be very interested in hearing your ideas
OK, my skills are feeling sharp. Now, it's time to start studying and looking for my next project . . . . . . . . . something pre-WWI.