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Building a Safety Bicycle — Chain Drive, Equal Wheels, and Personal Freedom
Palpatine

作成者

Palpatine

25. 6月 2026US
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Building a Safety Bicycle — Chain Drive, Equal Wheels, and Personal Freedom

The bicycle that everyone rides today was settled in the 1880s and is still called, in the trade, the safety bicycle — to distinguish it from the terrifying high penny-farthing it replaced. Two equal wheels, a diamond frame, a chain driving the rear wheel, and soon air-filled tyres made cycling safe, fast, and available to ordinary people.

Each feature solves a problem. Equal wheels and a low frame mean you can put a foot down and cannot be pitched over the handlebars. The chain and gearing let a small wheel travel fast without the giant front wheel of the penny-farthing. The diamond frame, built of brazed steel tubes, is astonishingly light and strong for its weight. And Dunlop's pneumatic rubber tyres turned a bone-shaking ride into a smooth one.

The safety bicycle was more than transport. Cheap, simple, and needing no horse or fuel, it gave working people and especially women a freedom of movement they had never had — which is why it is often credited with as much social change as mechanical.

中級者
Several days for a full build

手順

1

Understand the safety design

The safety bicycle has two equal-sized wheels, a low diamond frame, and a chain driving the rear wheel. Together these let the rider reach the ground with a foot and avoid being thrown over the front — the dangers that made the tall penny-farthing so risky.
2

Braze the diamond frame

Cut steel tubes to length and braze them into the classic diamond: head tube, top tube, down tube, seat tube, and the rear triangle of seat-stays and chain-stays. Brazed thin-wall steel tube is light yet stiff, which is why the diamond frame has never been bettered for simple bicycles.

このステップの材料:

構造用鋼管構造用鋼管4 メートル

必要な工具:

ろう付けバーナーろう付けバーナー
3

Build the wheels

Lace steel spokes between a central hub and a steel rim, then tension them evenly so the wheel runs true. A tensioned wire-spoked wheel is extraordinarily light for the load it carries — the spokes work in tension, hanging the hub from the rim.

このステップの材料:

鋼製スポーク鋼製スポーク72 個
自転車のリム（アルミ）自転車のリム（アルミ）2 個

必要な工具:

ニップル回しニップル回し
4

Fit pneumatic tyres

Mount air-filled rubber tyres on the rims. Dunlop's pneumatic tyre, made possible by vulcanised rubber, cushions the ride over rough roads and grips far better than the solid tyres it replaced — the single biggest comfort improvement of the era.

このステップの材料:

ゴムタイヤゴムタイヤ2 個
5

Build the chain drive

Fit a large chainwheel at the pedals and a smaller sprocket at the rear hub, joined by a roller chain. The ratio between them gears the bicycle so that equal-sized wheels can still travel fast for each turn of the pedals.

このステップの材料:

ローラーチェーンローラーチェーン1 個
チェーンホイールチェーンホイール1 セット
スプロケットスプロケット1 セット
6

Fit the bottom bracket and cranks

Mount the pedal axle in the bottom bracket on smooth bearings, then fit the cranks and pedals. Good bearings here turn the rider's effort into motion with little loss, so the bicycle rolls easily.

このステップの材料:

ボールベアリングボールベアリング1 セット
7

Set up the steering

Fit the front fork through the head tube on headset bearings and clamp on the handlebars. The fork's slight forward rake gives the steering a self-centring trail that makes the bicycle want to balance itself once moving.

このステップの材料:

ハンドルバーハンドルバー1 個
8

Fit brakes

Add brakes that press pads against the wheel rims, operated by levers on the handlebars. Reliable braking matters far more on the fast, low safety bicycle than it did on slower machines, so set them to grip firmly and evenly.

このステップの材料:

ブレーキキャリパーブレーキキャリパー2 個
9

Fit the saddle

Mount a sprung leather saddle on a seatpost and set its height so the rider's leg is almost straight at the bottom of the pedal stroke. Correct saddle height is the difference between an efficient ride and a painful one.

このステップの材料:

革の鞍革の鞍1 個
10

Assemble and true

Bring it all together: wheels in the frame, chain on, brakes and steering connected. True the wheels by adjusting spoke tension until they spin without wobble, and adjust every bearing so it turns freely but without play.

必要な工具:

パイプレンチパイプレンチ
11

Test and tune

Ride gently at first, checking that the brakes bite, the steering is steady, and nothing rubs or rattles. Fine-tune the saddle, bars, and bearings. A well-set-up safety bicycle feels stable and almost steers itself at speed.

必要な工具:

パイプレンチパイプレンチ
12

Appreciate the freedom it gave

Pedal away on a machine that needs no horse, no fuel, and no rails. Cheap and simple, the safety bicycle gave ordinary people — and famously women — independent mobility for the first time, reshaping society as much as it reshaped travel.

材料

11

必要な工具

3

関連ブループリント

これらのブループリントは知識を共有しています — 技術、材料、原理

Vulcanizing Rubber with Sulfur — The Accidental Discovery That Put Tyres on the Road

Vulcanizing Rubber with Sulfur — The Accidental Discovery That Put Tyres on the Road

Charlie 作DE

産業用

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