Dating campagnolo chainrings
The worst-case scenario is that you will be riding along with the bike in its highest gear (large front, small rear) and then for some bizarre reason shift down in front before downshifting in the back.(There is no shift pattern in which it is reasonable to shift in this sequence.) [Not with a 9- or 10-speed cassette, to be sure -- John Allen] If you do shift this way, there's a small chance that the chain might "skate" over the edges of the teeth for maybe half a turn.
The only problem you might run into is that the chain will be more liable to rub on the inside of the bigger chainrings in the small/small crossover gears, gears you shouldn't be using in any case.Once you have done this, you'll also need to re-dish the wheel to bring the rim back to the centerline.You may need to re-space the frame if you have added spacers to the axle. Shimano 5-speed and 6-speed shifters are made to index with the 5.5 mm spacing between sprockets on older 5- speed and 6-speed freewheels (or even, some new freewheels made as replacements).Different seat-tube angles and chainwheel sizes also may require different front derailers. There's considerable interchangeability among hubs . If you're upgrading from a system with fewer than 8 rear sprockets to one with more, you may need to concern yourself with the frame spacing. The freewheel threading on these older hubs is generally interchangeable except for some very old French units.See my Front Derailers Article and Derailer Adjustment Article for more detail. If you go from a 5-speed freewheel to a 6- or 7-speed freewheel, you will usually need to add some spacers to the right end of the axle between the cone and the locknut.