How to Convert a Road Bike to Fixed Gear (Without Ruining It)
Fixed-gear conversions are one of the best things you can do with an old road bike. Simpler, lighter, more direct. Here's how to do it properly.
What You Need
- An old road bike with horizontal dropouts (essential — vertical dropouts won't work for chain tension)
- A flip-flop rear hub, or a dedicated fixed hub
- A chainring and single-speed chain
- Patience with your bottom bracket
Steel frames from the 70s–90s are ideal. Look for horizontal dropouts — the axle slot runs backwards, allowing you to tension the chain by moving the wheel. Without these, stop now.
Step 1: Strip the Drivetrain
Remove the rear derailleur, front derailleur, shifters, and cables. Keep the brake levers — you'll still want at least a front brake. Anyone telling you to run brakeless on UK roads hasn't ridden in Brighton traffic.
Step 2: Bottom Bracket and Chainring
Check your BB isn't on its way out — a loose or grinding BB is worse on a fixed drivetrain where there's no freewheel to mask it. Replace if in doubt.
Select a chainring in the 42–46t range for town riding. 46/16 gives you a gear of about 77 inches — comfortable for flatish terrain, survivable on the Downs.
Step 3: Rear Hub and Chain Tension
Thread the fixed sprocket onto the drive side. Use a lock ring — tighten it against the sprocket direction so pedalling back locks it tighter, not looser.
Flip-flop hubs give you a freewheel option on the other side. Useful while you're learning.
Thread the chain and set tension by sliding the wheel in the dropout. You want about 1cm of vertical play in the chain at its tightest point. Check around the full rotation — most chainrings aren't perfectly round.
The Two Common Mistakes
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Not checking chain line. Measure from the centreline of the frame to your chainring and sprocket. They should be within 2mm. A bad chain line wears fast and runs noisy.
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Forgetting to lock the sprocket. The lock ring is not optional. Without it, pedalling backwards (which you will do accidentally) loosens the sprocket. Ask anyone who has had this happen at speed.
Final Checks
- Front brake functional, cable fresh
- Wheel centred in the frame, axle nuts tight
- No lateral movement in the cranks
- Ride somewhere flat first. The learning curve on fixed is real but short.
Good luck. Come to the next ride and show it off.