Marcus,
This is how we got bikes today that have 9 or 10 cogs on the back, even with quite narrow ratios. The Small ring with the small cog is a duplicate ratio, as is the big ring, biggest cog ratio. So even if you shift into all the combinations, (bad idea) you don't get different ratios!
12 13 14 15 16 17 19 21 23 * * * * * * * * * 53 * 119 110 102 95 (88) 84 75 71 (62) 39 * (88) 81 75 70 66 (62) 55 50 46
Grant McLean
Toronto.Ca
(hope that chart posts on the CR list in a readable way!!)
> I know most of the literature says don't use the small-small or big-big
> combinations. Doesn't this generally refer to triples and/or modern bikes
> with wider spacing? I would think that on bikes in the CR timeframe, with
> double chainrings, cross-chaining would not be as big of an issue, unless
> the chainstays were really short.
>
> I only have 12 speeds, I'd like to use them all.
>
> Marcus Helman
> Huntington Woods, MI