Gears: 20T × 1/8"
• 20 teeth deliver a lower (easier) gear than 16/17/18T—great for smooth takeoffs, relaxed cadence, and gentle hills.
• 1/8" chain compatibility offers a wider, stronger tooth interface that resists skipping under load.
Model: SFW
• ALTA’s Standard FreeWheel line—straightforward, durable, and parts-bin friendly for shops and home mechanics.
Size / Thread: 1.37" × 24 TPI (BSA/English)
• The most common freewheel thread → screws directly onto the freewheel side of flip-flop hubs and other threaded single-speed hubs.
• Not interchangeable with metric M30 × 1 freewheel threads.
Type: Standard
• Classic threaded freewheel body with internal ratchet + pawls and ball-bearing races.
• Removal: uses a standard notched/splined freewheel remover (e.g., BMX/SS 4-notch style such as Park FR-6, or equivalent—match your tool to the SFW interface).
Color: Brown
• Protective brown oxide/phosphate-style finish for corrosion resistance and that classic “old-school” aesthetic—pairs nicely with chrome or black wheels.
Brand: ALTA
• Rider-trusted brand for dependable single-speed/BMX parts with broad compatibility and good value.
Body/Teeth: Heat-treated steel for wear resistance under single-speed torque.
Internals: Self-contained ratchet & pawls with cup-and-cone bearing races (service via removal tool; replacement is typically simpler than full overhaul).
Tooth Profile: 1/8" single-speed profile for solid chain seating and reduced skip.
Install: Clean & lightly grease hub threads → hand-start (avoid cross-threading) → pedaling torque self-tightens the freewheel.
Removal: Fully seat the appropriate freewheel remover for SFW → turn counter-clockwise with wrench/bench vise to break torque.
Chain care: Keep a 1/8" chain clean/lubed and replace at ~0.5% wear to extend cog life and keep things quiet.
Designed for easy pedaling and comfort builds; perfect for beach cruisers, utility bikes, and relaxed commuting.
Common pairings:
42 × 20 ≈ 2.10:1 – very easy starts, casual cruising
44 × 20 ≈ 2.20:1 – smooth city cadence
46 × 20 ≈ 2.30:1 – comfy on flats with a touch more pace
48 × 20 ≈ 2.40:1 – quicker cruising on flat routes
(Bigger front ring = faster; smaller = easier.)
Hubs: Any 1.37×24 TPI threaded hub, including flip-flop (install on the freewheel side).
Chains: 1/8" single-speed chains only (not 3/32").
Bike Types:
• Cruisers & choppers (beach cruisers, comfort bikes, utility SS)
• BMX (threaded freewheel models & older/entry builds)
• Commuter/Urban single-speeds seeking easy starts & hill-friendliness
• Track/fixie with flip-flop hubs when set up for 1/8" on the freewheel side
Brand/Model examples (model/year dependent—confirm hub thread & chain width):
Cruisers: Electra (SS), Firmstrong (Bruiser/Urban SS), Micargi (Rover/Tahiti SS), Schwinn Cruisers, Huffy Cruisers.
BMX (freewheel-type): Mongoose (older/entry Legion & freestyle singles), Haro (older Freestyler & entry lines), GT/Dyno (heritage/entry), Redline (older/entry), Diamondback (’90s–’00s), Eastern (budget), Huffy/Kent/Magna (dept-store BMX).
SS Road / Flip-Flop (1/8" setups): State Bicycle Co., Pure Cycles, 6KU, Retrospec, Windsor/Mercier (when built for 1/8" chain; freewheel side of flip-flop).
1 × ALTA SFW 20T × 1/8" threaded freewheel – Brown (no chain/tools/spacers included)
✔ Fits 1.37×24 TPI threaded hubs (incl. flip-flop, freewheel side).
✔ Use 1/8" single-speed chain.
❌ Not compatible with cassette/freehub systems or metric M30×1 hubs.
❗ Verify hub thread and chain width before purchasing.