Originally Posted by
John E
"...I would give a smaller inner chainring a shot. You will need to confirm this, but your inner ring appears to have the 3-bolt BCD which was popular on cottered cranksets. If so, a TA Professional ring will fit, a will various Nervar or Stronglight units."
Looks exactly correct to me. I'd wager that has a 116 mm BCD and chainrings of 36t were once extremely common - often found on many 3-arm cranks, first on cottered cranksets and later alloy as well - as John E. suggested, this was very common on French bikes.
Originally Posted by
divineAndbright
"... the front derailleur could never handle the tooth difference between the big and small."
I don't see a problem at all with the front derailleur AND just a smaller inner ring. There seems to be plenty of room below the chain where it is now resting on the smaller chainring. I have one bike set up with a 32x51 rings and just a basic old double front derailleur... it works just fine - seriously, it's only nudging that chain over a few millimeters to the left or right. In fact, Campy actually specified their standard "double" front derailleur for my Nuovo Record Triple crankset (with 36 to 54 teeth), and that derailleur was definitely designed for racing and not for small chainrings.
The main issue with the cranks on this bike that I can see would really be the rather minimal usefulness of the larger chainring for your Dad. Higher gearing which he'd use less than a 48t outer ring. However, if you really wanted to keep the existing crankset, there is no reason that he would ever really have to use his smallest rear cog (highest gear) anyway.
I really wish I were there to break the bike down and work on it myself.
You'd really be amazed how sweet any old and long neglected bike can run with just a pretty basic - but, unfortunately labor intensive overhaul [which is costly at a bike shop] and a replacement of some rather basic items like a chain, cables, cable housings, brake pads, and such will take MANY years off a bikes age.
Having myself returned to active daily cycling in my late 40s after a long absence, I think it would be a wonderful thing for your dad. Although I'll warn you, he'll discover the long implanted old memories of his effortless former cycling days will likely be a real shock to him with his now unfamiliar, aged and stiff body. Quite a rude awakening! So, I'd definitely recommend a modern long cage derailleur mated to a wide range freewheel (at least 14-28 or preferably 14-32 for a hilly area) as a very good way to start him back riding with minimum of frustration... and pain!
I would also consider a taller stem or at very least raising that one as high as possible... yes, and that's without even seeing the bike! ... You'd be amazed how those damned things can miraculously shrink over time while sitting unused, and can make a once agile body with limber back and neck suddenly "seem" dismally old, stiff, and out of shape
