One Hundred Ninety-Six
I made up my mind to use TA Alize double cranks on the new Vanilla and Ira Ryan bikes. I was able to get two sets in 170mm, which is perfect for me. I already have a set of TA Alize tandem cranks in 170 (captain) and 165 (stoker). If the tandem cranks yield the same chainlines as the double cranks, then I might be able to buy four identical square taper bottom brackets. That's great in terms of stocking a spare and minimizing the number of tools I need.
On his website, Peter White says the Alize double cranks use a 103mm bottom bracket. I assume this would translate to a 41mm inner and 46mm outer chainline with 3/32" chainrings. So a 119mm symmetrical Phil Wood stainless steel bottom bracket would produce chainlines of about 47.4mm and 54.4mm when using 1/8" chainrings and 1.2mm chainring spacers between the inner ring and the arms of the spider.
A Phil Wood KISS-OFF 135mm single speed hub is 45.35mm from the center of the hub to the shoulder. A White Industries freewheel moves the chainline out 8.73mm from the shoulder or 45.35+8.73=54.08mm from the center. An 1/8" cog screwed on "backwards" produces a chainline of about 45.35+1.5=46.9mm. The 7mm difference in chainlines is perfect for an 1/8" chain.
In an email from Chris King, I was told that their single speed hubs allow for 45, 50, and 55mm chainlines using a combination of a cog and two of their spacers, all of which are 5.2mm thick. (The math to the right of the decimal point doesn't quite add up, but it's close enough.) Using two 2.4, 2.5, or 2.56mm spacers, I can position two King Kogs at approximately 47mm and 55mm from the center.
If I use 700c wheels on the tandem, I should be able to swap wheels between all three bikes and have the chainlines for both the inner and outer chainrings line up almost perfectly with the chainlines for 2 King Kogs, a White Industries freewheel, and a Phil Wood cog.
For RAAM, I'm thinking about this combination:
On the Vanilla, I'll use 40T outer and 42T inner chainrings.
On the Ira Ryan, I'll use 42T outer and 45T inner chainrings.
On the Chris King hub, I'll use 16T inner and 18T outer Kogs.
On the Phil Wood hub, I'll use a 15T inner cog and an 18T outer freewheel.
Using the inner ring for the bigger gear is sort of backwards, but it's the only way I can get the chainlines I want using the 1/8" cog and the White Industries freewheel on the Phil hub. Hopefully, the 45T inner ring on the Ira Ryan won't hit the chain stay.
So for RAAM I would have the following possible gear ratios:
Vanilla+Chris King
40x18 outer (58.6 gear inches, 58 total teeth)
42x16 inner (69.2 gear inches, 58 total teeth)
Ira Ryan + Phil Wood
42x18 outer (61.6 gear inches, 60 total teeth)
45x15 inner (79.1 gear inches, 60 total teeth) - fixed
Or these if I swapped wheels:
Vanilla+Phil Wood
40x18 outer (58.6 gear inches, 58 total teeth)
42x15 inner (73.9 gear inches, 57 total teeth) - fixed
Ira Ryan+Chris King
42x18 outer (61.6 gear inches, 60 total teeth)
45x16 inner (74.2 gear inches, 61 total teeth)
The beauty of this setup is the range of gears I can get (about 60, 70, and 80 gear inches) with only two chainlines on each bike and two sets of wheels.
On his website, Peter White says the Alize double cranks use a 103mm bottom bracket. I assume this would translate to a 41mm inner and 46mm outer chainline with 3/32" chainrings. So a 119mm symmetrical Phil Wood stainless steel bottom bracket would produce chainlines of about 47.4mm and 54.4mm when using 1/8" chainrings and 1.2mm chainring spacers between the inner ring and the arms of the spider.
A Phil Wood KISS-OFF 135mm single speed hub is 45.35mm from the center of the hub to the shoulder. A White Industries freewheel moves the chainline out 8.73mm from the shoulder or 45.35+8.73=54.08mm from the center. An 1/8" cog screwed on "backwards" produces a chainline of about 45.35+1.5=46.9mm. The 7mm difference in chainlines is perfect for an 1/8" chain.
In an email from Chris King, I was told that their single speed hubs allow for 45, 50, and 55mm chainlines using a combination of a cog and two of their spacers, all of which are 5.2mm thick. (The math to the right of the decimal point doesn't quite add up, but it's close enough.) Using two 2.4, 2.5, or 2.56mm spacers, I can position two King Kogs at approximately 47mm and 55mm from the center.
If I use 700c wheels on the tandem, I should be able to swap wheels between all three bikes and have the chainlines for both the inner and outer chainrings line up almost perfectly with the chainlines for 2 King Kogs, a White Industries freewheel, and a Phil Wood cog.
For RAAM, I'm thinking about this combination:
On the Vanilla, I'll use 40T outer and 42T inner chainrings.
On the Ira Ryan, I'll use 42T outer and 45T inner chainrings.
On the Chris King hub, I'll use 16T inner and 18T outer Kogs.
On the Phil Wood hub, I'll use a 15T inner cog and an 18T outer freewheel.
Using the inner ring for the bigger gear is sort of backwards, but it's the only way I can get the chainlines I want using the 1/8" cog and the White Industries freewheel on the Phil hub. Hopefully, the 45T inner ring on the Ira Ryan won't hit the chain stay.
So for RAAM I would have the following possible gear ratios:
Vanilla+Chris King
40x18 outer (58.6 gear inches, 58 total teeth)
42x16 inner (69.2 gear inches, 58 total teeth)
Ira Ryan + Phil Wood
42x18 outer (61.6 gear inches, 60 total teeth)
45x15 inner (79.1 gear inches, 60 total teeth) - fixed
Or these if I swapped wheels:
Vanilla+Phil Wood
40x18 outer (58.6 gear inches, 58 total teeth)
42x15 inner (73.9 gear inches, 57 total teeth) - fixed
Ira Ryan+Chris King
42x18 outer (61.6 gear inches, 60 total teeth)
45x16 inner (74.2 gear inches, 61 total teeth)
The beauty of this setup is the range of gears I can get (about 60, 70, and 80 gear inches) with only two chainlines on each bike and two sets of wheels.
posted by Sabertooth Salmon at 1:54 PM
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