Among other changes that I am making to my Bombadil, I am converting to my favorite triple gearing: a half-step plus granny. The idea behind a half-step plus granny is that the two large chainrings on a triple are close in size so that you can split the difference (half-step) between any two sprockets on the rear. The inner chainring on the front is a small bailout or "granny" gear. This strategy works best when you have a limited number of rear cogs - fairly unnecessary when you have 11 or 12 rear cogs. The rear cogs should maintain as constant of a % difference (step) as possible - this means that the number of teeth difference between cogs will increase as the cogs get larger.
I had a Sugino triple on the front - I kept the stainless steel 24t granny and used TA Zephyr 39 and 42 middle and outer chainrings (from Peter White). The 7 speed freewheel is an NOS Suntour New Winner 12-14-16-18-21-26-34 that I bought a few years back for this purpose (they seem to have gotten very pricey as of late). This gives me 18 distinct, non-overlapping gears from 19 to 95. You do have to double shift (front and rear) sometimes to get the gear you want. When I was younger, I taped my gear ratios on top of the stem.
I use 7 speed freewheels for the rear hub for the same reason that Rivendell is looking into producing 7 speed cassette hubs - less wheel dish means a stronger wheel. So far I have acquired 3 Phil Wood rear hubs that were either 7 speed 135mm, or that I converted to 7 speed 135mm - a 36 hole, 40 hole and my latest - an NOS 48 hole. The 48 hole is going on the Bombadil to replace the 40 on it now.
One kind of odd thing about this is that the chainrings have ramps and pins, but the freewheel has none. I expect it to shift just fine. Rear derailleur is all silver Sun XCD and the front will be either the all silver IRD Alpina-d already on the bike or an all silver IRD Sub-C - whichever plays best with the chainring combination. The chain is a stainless steel Wippermann 8 speed that I have ultrasonically cleaned and Molten Speed Waxed.
Bar end shifters will be either Dura-Ace 8 speed or Rivendell Silver 2. If the indexing works with the Dura-Ace shifters - they will be used, otherwise friction will be the Silver 2.
Laing
Delray Beach FL
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