AI 速览
- A fixed gear bike has no freewheel — the rear cog is threaded directly to the hub, so the pedals turn whenever the rear wheel turns. You cannot coast
- Track bikes (built for the velodrome) have steep geometry: 74–75° head and seat angles, 65–75 mm bottom bracket drop for pedal-clearance in banked corners, and zero tire clearance
- Track bikes have no brakes. Road-legal fixies almost always add a front brake — many jurisdictions require it, and stopping a fixie with leg pressure alone needs practice
- Fixie technique: leg-speed modulation for slow-downs, skid stops for emergencies (unweight rear, lock legs, slide), and constant awareness that you can't stop pedaling through corners or descents
/ 01
What makes it 'fixed'
On a fixed gear bike, the rear cog is threaded directly onto the hub with a reverse-threaded lockring holding it in place. There is no freewheel mechanism — no pawls, no ratchets, no click-click-click when you stop pedaling. The crank arms rotate whenever the rear wheel rotates, full stop. Pedal backward and you roll backward. Stop pedaling abruptly and your rear wheel can skid.
This is mechanically simpler than any other drivetrain: one gear, no shifters, no derailleur, no freehub body. The simplicity is the appeal — minimal maintenance, near-zero failure modes, a direct tactile connection between legs and road. Track sprinters can feel wheel slip through their feet milliseconds before it shows up anywhere else.
/ 02
Track geometry vs road geometry
Steep angles put the rider's weight forward over the bottom bracket — ideal for sustained high-cadence power on a velodrome, terrible for technical descents. The high bottom bracket (low BB drop) keeps pedals from striking the track banking in turns, but on the road it raises your center of gravity and feels twitchy.
Why a track bike feels twitchy on the road. Numbers are typical for a 54 cm track frame vs an endurance road frame.
| Dimension | Track bike | Road (endurance) |
|---|---|---|
| Head angle | 74–75° | 72–73° |
| Seat angle | 74–75° | 72–73° |
| BB drop | 65–75 mm | 68–72 mm |
| Wheelbase | 960–990 mm | 1,000–1,030 mm |
| Tire clearance | 23–25 mm (tubular) | 28–35 mm |
| Brakes | None | Dual-pivot disc or rim |
| Front-rear weight distribution | Steep, forward | Balanced, neutral |
/ 03
The brake question
Velodrome track bikes have zero brakes — and the rules forbid them. Riders slow by easing cadence and moving up the banking, where gravity does the work. None of that transfers to public roads. Road-legal fixed gear bikes (sometimes called 'fixies') almost always add at least a front brake; in many jurisdictions (UK, parts of the US, most of the EU) a front brake is legally required.
A front brake alone gives you roughly 70% of your stopping power — weight transfer under braking unloads the rear wheel, so rear braking is mostly ineffective. Riding brakeless fixie on public roads is legal in some cities but objectively more dangerous: skid-stop distance at 30 km/h is roughly double the distance of a front-braked stop, and wet-weather braking is dramatically worse.
/ 04
Riding technique
Three things catch new fixie riders. First, you cannot coast through corners — your inside pedal will hit the tarmac if you stop pedaling at the wrong phase, which on a banked velodrome is fine but on a road corner is a crash. Second, descending requires sustained high cadence; 60 km/h on a 48×15 gear is 130 rpm, which most riders can't sustain smoothly.
Third, stopping takes practice. Leg-pressure modulation (resisting the rotating cranks) works for gentle slow-downs. Skid stops — unweighting the saddle, locking your legs, and letting the rear wheel slide — work for emergencies but take weeks to learn and shred tires quickly. A front brake doesn't make you less of a fixie purist; it makes you a surviving one.
/ 05
Track vs road fixie: use cases
Track bikes belong on the track. Their geometry, tire clearance, and complete lack of braking make them objectively wrong for road use, regardless of local legality. If you want to try track cycling, find your nearest velodrome and rent — most run beginner sessions with loaner bikes.
Road fixies (purpose-built with road geometry, tire clearance for 25–32 mm, and a front brake) are a niche but rewarding category: ideal for messengers, urban commuters who value simplicity, and cyclists who want to refine their pedal stroke. A single-speed bike with a freewheel gives you most of the simplicity with none of the technique demands — that's the right choice for most riders drawn to the look.
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