Compact Half-Step plus Granny gearing

[lconley]

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

[Keith Paugh]

This is really cool. Interesting ideas at play.

I want to see it in action.

k.

On Feb 26, 2023, at 9:49 AM, lconley <lco...@brph.com> wrote:

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.

<Half step s.jpg>

Laing

Delray Beach FL

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<Half step s.jpg>

[Patrick Moore]

Laing: Why the concern with ultra-durable wheels with 135m OL spacing? Just curious. And what chainings?

I recall that one of the smoothest wheelsets I ever rode was a 48-hole -- must have been built at one time for a tandem -- pair with old Campy Record freewheel hubset and fixed cog on a 1960s Paramount track bike that my brother lent me to ride with him in LA over 20 years ago; a very smooth and inevitable feeling of momentum. 

I commuted on a 44/47 5+2 halfstep (no granny; big cog was granny; see below), later switching to 45/48, with crusiing 17 t cog in the middle of the cassette shifted with wonderful Kelly Takeoffs and old Record shifters. Most of my riding was just back-and-forth on the left shifter, 65"/70" or 66"/71" gears. I half stepped the middle 5 cogs and used the outer with big for downhills and the inner with the small for steep uphills; ~100" to ~35", a very usable set of gears, of which I generally used only the middle band for our rolling terrain (I was a young late-40-something). In fact, most of my riding was in the 17, just flicking the left shift lever back and forth -- half-step indexing. All this was on my 1995 26" wheel (25" actual commuting wheel diameter with 32 mm Tioga City Slickers or somesuch) Riv Road custom that I'd demoted or promoted to commuting use.

	48	45			47	44
12	100			12	98
13	92	87		13	90	85
15	80	75		15	78	73
17	71	66		17	69	65
20	60	56		20	59	55
24	50	47		24	49	46
32		35		32		34

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Patrick Moore

Alburquerque, Nuevo Mexico, Etats Unis d'Amerique, Orbis Terrarum

[Garth]

Funny you should post this Laing as I'm considering going back to HS+G myself for at least one bike. Also considering drop bars for the Bombadil, the lower and more forward I get the better I feel. The bottom line for me is I really like 7-speed, even 6-speed freewheels, and the lack of hub and cassette choices only steers me to make another set of 135mm FW wheels with a set of solid axle Specialized hubs(Purchased as a 140mm tandem set). I already have two Phil rears, I have hubs for 3 more. (Damm shame PW doesn't offer the FW hubs anymore, one reason I'll never buy anything from them again... rant rant rant ...). I like FW hubs, having independent freewheels from the hub. I also have many freewheels, for this I may use the 13/15/17/20/24/28/32 NOS Sachs or possibly a new 14/16/18/21/24/28/34 Sunrace of SImplex, with 26/44/48 rings(I've done before), maybe changing the big ones to 42/46 or even 46/50.

I love riding the 44, easily my favorite ring in this gearing. On my road bike with a 36/46, it's the 46. I think many people who have either raced or simply ride bigger rings do it because big rings and big-ger cogs(24 to 32) feel really efficient, just plain nice.

I also dig 36 holes. Call me old fashioned, I've just always purchased 36 hole hubs and rims, save a few recent Shimano T610's. All my better hubs are 36 hole. I'd even consider getting a 174mm solid axle for my Campy SR hubs to use as 135mm OLD. They're just so nice and have been sitting around since the early 90's.

I know Riv is working on a 7 speed cassette hub, but I'm not holding my breath that it'll be quiet or there won't be some other gotchas. Not to mention cassette choices, what few there are, are all wrong for me. While I appreciate the general idea of manual shifting, steel frames and having some of their own branded parts, where the rubber meets the road I don't relate to the manner of which those are implemented by Riv. Kind of a bummer, but not actually, there's more out there.

[lconley]

I am down to 11 Rivendells and 10 of them have 135mm spacing (the Frank Jones, SR. is 120) and I weigh 275 lbs - thus the ultra durable 135mm wheels. I have a 40 spoke 132mm Sturmey Archer 3 speed on the Rosco Baby. Jobst Brandt worried about breaking frames, I worry about breaking wheels; not that I break spokes, but like Jobst, I am also a mechanical engineer.  I have too many bikes and way more hubs than bikes, I am afraid to count the hubs and wheels that I have. 

The 120mm wide Frank Jones SR. has my 2nd coolest hub set, a old, fairly rare Campagnolo Hi-Lo hub set with track axle conversion - only 36 holes.  

Laing

[JohnS]

Nice!

[Nick Payne]

I played around with half step + granny gearing when I first got seriously interested in cycling in the 1970s. In the days of five speed freewheels it made some sense. However, I found that I just couldn't be bothered making all these double shifts, and so I gave up on that setup.

These days I use this sort of gearing - this is my Appaloosa, with 36/26 chainrings and an 11-40 11-speed cassette:

Nick Payne

[Garth]

Well gee Nick, the group is full of pie plate cassette small ring setups. I myself would never use that. That you have to now shift 11 cogs on a cassette hub, well that's exactly the point of the gearing we're talking about here. Nay to the mega cassette hubs, yay to 7 speed freewheel hubs. Not only the fewer number of cogs and the greater spacing(shifting ease), but the wheel builds themselves, seven speed hubs allowing for less offset. Half step plus gearing doesn't require double shifting if you take any time to select a proper range for your riding, any more than any other kind of shifting. The half steps are available, but not necessary.  

[Berkeleyan]

I ran my LongLow with H/S + G for many of its so-far 25 years. I use a Sachs six-speed freewheel on a Phil hub, and learned to shift initially for the correct rear cog, then trim up or down with the front Der. It felt natural and fine, an easy way to ride.

- Andrew, Berkeley