Paul, One possibility would be to extend the derailleur cage. Something I can easily imagine the Taylors doing. Some of their custom work showed very "out of the box" thinking.
I've extended front derailleurs to cover ranges as wide as 20-60. I
don't have any photos of modified Suntour or Campi, but here's a shot
of a Shimano. http://bikesmithdesign.com/
A friend of mine was shifting 16-32-42-45 with a modified NR FD with custom longer paralellogram arms. BTW His crank was also NR, with a custom adaptor carrying 2 Suntour cogs, years before the Mountain Tamer adaptors. In the rear I made him a custom 14-38 7 speed ProCompe freewheel, shifted by a 3 pulley DuoPar.
At 3/27/2006 09:37 PM -0500, email@example.com wrote:
>When building up my latest project, a '76 Jack Taylor, I discovered
>that my plan to use an NR front derailleur was not going to work
>with the 52/44/28 crankset as the cage is just not long enough. I
>had used it with a 52/47/36 in the past but maybe that is the limit
>(unless you go to a smaller big ring). Since I planned on using
>Suntour Barcons and Suntour freewheel I was thinking that I might as
>well use period Suntour derailleurs as well. I have 3 or 4 V-GT and
>V-GT Luxe rear derailleurs and they do shift nicely but other than
>that I really don't have much experience with vintage Japanese
>components. What would be a good Suntour front derailleur to look
>for to match the V-GT rear, perhaps a "7", a "Compe-V", or
>"SL"? Further questions:
>1. Did all Suntour front dr's of the era ('75 to '80) use the funky
>pull for low scheme?
>2. Did they all have adequate throw for a triple crankset?
>3. Are the cages longer than the NR to allow the 28T chainring to be
>used without chain drag?