Shifting TF hub with Suntour 7 speed barcon

[Patrick Moore]

I’ve rigged up a Suntour 7 speed bar con to shift my NOS 1937 SA TF hub — High/Direct and Low/75% Underdrive, 76” and 57” gears. I do have the top tube-mount OEM quadrant shifter and roller but these are a pain to install and then remove when I want to go back to the “main” Phil + 17/19 Dingle wheel.

I can shift the hub both in indexed and in friction mode, but “friction” is better since, tho’ it retains “ghost” detents, it more easily allows a bit of slop adjustment in both H and L positions. That is to say: the ST 7 sp barcon has just enough travel to shift this hub. In High/Direct the cable is too slack and risks banging the bulky pinch-bolt cable adjuster barrel against the frame; while in Low/0.75 the shift cable/rod is entirely tight instead of leaving just a wee bit of slack as SA recommends.

In friction/ghost detent mode it’s easier to pull up a bit of slack — 1/4”? — in High to keep the cable trim but not tight (not yet initiating any shifting action), and in Low it’s easier to back the shift lever off a wee bit as SA instructs.

The “ghost” detents serve the purpose of telling me when I’ve pulled enough cable to be securely in Low — this is in the bar con’s bottom/#7 gear position; important because in the lever’s  #6 position the clutch just barely engages, but tenously enough that you risk skipping and therefore stripping under high torque.

I will try this bar con with my refurbished (overhauled, rechromed shell) 1937 TC 2 speed fixed hub, direct and 0.8654, 76” and 66”.

Hope to try it out on an extended ride tomorrow.

Patrick Moore

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

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When thou didst not, savage, know thine own meaning,

But wouldst gabble like a thing most brutish,

I endowed thy purposes with words that made them known.

[Patrick Moore]

Forgot to add that the purpose of this exercise is to have a quick and easy on/off shifting system, given the Phil + Dingle “main” wheel.

The housing runs from bar con along the right side of the tt, held in place by 2 plastic “spring loaded” and easy on/off housing guides to a clamp-on Campy derailler shifter housing stop meant to be installed on the right chainstay. I installed it 6-8 inches down at the 14 mm portion of the right seatstay; the sole non-QR part of the system. Must decide if can bear to leave it in place permanently.

Far more easy to install and remove than the OEM tt quadrant shifter and roller.

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