1970s drivetrain alterations

Becontreejim

Dirt Disciple
I have a 1st generation Dura Ace crankset, running 54 42 rings.

Block is 6 speed Dura Ace 13-18.

Front and rear derailleur is 1st Generation Dura Ace, including original Crane DA mech.

Given I am no longer 18, to make bike more useable for club runs and some long retro training miles, want to make gearing more user friendly.

Question for those more knowledgeable than me, I propose;

Fitting alternative chainrings, probably 130 bcd modern Stronglight 39/52. Will these fit my crank without alignment issues etc. Any recommendations - source for original D Ace or some other maker?? I am concerned about chain alignment, faffing with spacers etc.

Want to fit a 14-28 block to original Campag Tipo hubs, rebuilt onto modern Pacenti rims. Will the Dura Ace rear mech cope? I read on original DA data on velobase, it can take a 28, but anybody know the realities. Also, sjs sell 6 speed blocks with middle aged man ratios, but any recommendations.

Any particular chain needed, or any 6 speed do? I rate kmc over sram and Campag, but that’s on modern setup.

Also, I have the original dura ace bottom bracket fitted. Apparently this has a peculiar offset and taper. Whilst it’s in great condition, if I were to “save” it from punishment and fit a modern alternative, what are my options?

All advice appreciated.
 

hamster

Retro Wizard
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Swapping to Stronglight rings and the 12-28 should be fine. Generally Shimano is hyper-cautious with its recommendations so you should have no problem.

Any 7/8 speed chain should be fine.
 

Old Ned

Old School Grand Master
Not sure about this but won't a Dura-Ace chainset take a 39 tooth ring? Or is it only later Shimano that do? Crane mech should cope with at least a 26 or possibly 28t sprocket (I think!). I'm sure I used one with a 28t at one time.
 

Becontreejim

Dirt Disciple
Re:

Thanks for replies. Looking at Disraeli gears site, Crane can take a 28.

Issue is now bb. Apparently original dura ace is 112mm, but offset. Can’t just source one off shelf. Also don’t know which chainrings to fit, as don’t want to alter chain line. Any ideas? I have had issues before with bottomnenda campagnolo on winter bike. Swapped same bcd rings on Veloce from ultra to power torque and totally out. Chain falling off, chain catching, all due to width of rings.
 
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