I like to maintain and repair my bikes myself. Including my Brompton P3L.
While relatively simple mechanical devices, bicycles require a bit more than a knife and a roll of duct tape to repair properly.
WHICH BIKE TOOLS TO MAINTAIN AND REPAIR THE BROMPTON?
It depends.
Although the majority of bicycles share the same standard kinds of fasteners, some models require more specific tool kits. In the case of the folding Brompton, their philosophy of customizing the bike’s components to achieve a compact fold leads to some less common bike tool requirements.
So, in order to assemble my take-along tool kit for the Brompton and compliment my workshop tools, I first had to measure almost every part of the bike and record their fastening methods.
BROMPTON P3L PARTS MEASUREMENTS
- May 2008 data for a January 2008 Brompton P3L
- measured with a digital caliper
- “width” indicated for parts thinner than normal, like wheel cones, to choose tools of appropriate thickness
- please report errors and inaccuracies: comment below or contact me directly
// Front wheel
| |
Fastener |
Size |
Width |
| Spoke nipples (nuts) |
4-side nut |
3,2 mm |
5,0 mm |
| Primary axle lock nuts (exterior of the fork) |
hex nut |
15,0 mm |
7,0 mm |
| Secondary axle lock nuts (interior of the fork) |
hex nut |
15,0 mm |
4,0 mm |
| Front wheel hub cone nut |
2-side semi-circular nut |
13,0 mm |
2,5 mm |
| Speed magnet screw |
hex (Allen) socket bolt |
2,0 mm |
|
// Front dual pivot caliper brake
| |
Fastener |
Size |
Width |
| Brake pad bolt |
hex (Allen) socket bolt |
5,0 mm |
|
| Dual pivot minor adjustment screw |
hex (Allen) socket bolt |
2,5 mm |
|
| Caliper arm bolt head |
hex (Allen) socket bolt |
5,0 mm |
|
| Caliper arm nut |
hex nut |
10,0 mm |
|
| Caliper arm brake cable fixer bolt |
hex bolt |
10,0 mm |
|
| Brake axle bolt |
hex (Allen) socket bolt |
4,0 mm |
|
| Brake axle (brake spring-locking) nut |
2-side semi-circular nut |
|
|
| Brake axle nut (main fastener) |
hex nut |
10,0 mm |
|
// Front mud-guard
| |
Fastener |
Size |
Width |
| Side fixture of the mud-guard bolt |
slotted bolt |
9,0 mm |
1,3 mm |
| Side fixture of the mud-guard nut |
hex nut |
8,0 mm |
|
| On-the mud-guard fixing bolts x2 |
hex (Allen) socket bolt |
2,5 mm |
|
// Headset
| |
Fastener |
Size |
Width |
| Headset locknut 1 |
hex nut |
36,0 mm |
4,0 mm |
| Headset locknut 2 |
hex nut |
36,0 mm |
7,0 mm |
// Handlebars
| |
Fastener |
Size |
Width |
| Handlebar catch’s bolt |
hex (Allen) socket bolt |
6,0 mm |
|
| Handlebars clip bolt |
hex (Allen) socket bolt |
5,0 mm |
|
| Brake lever clip bolt |
hex (Allen) socket bolt |
3,0 mm |
|
| Brake lever cable adjustment bolt |
hex (Allen) socket bolt |
2,5 mm |
|
| Gear selector clip bolt |
hex (Allen) socket bolt |
3,0 mm |
|
| Gear selector switch bolt |
hex (Allen) socket bolt |
2,0 mm |
|
// S-Sun 3-LED battery headlight
| |
Fastener |
Size |
Width |
| Light mounting station screw |
Philips screw |
1 Ph |
|
// Seat tube
| |
Fastener |
Size |
Width |
| Seat tube clamp nut |
hex nut |
10,0 mm |
|
| Rear frame hinge retention hook |
pozidriv bolt |
1 Pz |
|
| Rear frame rubber suspension block locking nut |
hex nut |
10,0 mm |
|
// Saddle
| |
Fastener |
Size |
Width |
| Saddle fore-aft and up-down adjustment bolt |
hex (Allen) socket bolt |
5,0 mm |
|
// Cranks and pedals
| |
Fastener |
Size |
Width |
| Crank bolt |
hex nut (socket for access) |
14,0 mm |
|
| Pedal bolt |
2-side semi-circular nut |
15,0 mm |
3,6 mm |
| Toe clips bolts |
hex (Allen) socket bolt |
3,0 mm |
|
| Toe clips nuts |
hex nut |
7,8 mm |
|
// Rear wheel
| |
Fastener |
Size |
Width |
| Spoke nipples (nuts) |
4-side nut |
3,2 mm |
5,0 mm |
| Primary axle lock nuts (exterior of the rear fork) |
hex nut |
15,0 mm |
7,0 mm |
| Secondary axle lock nuts (interior of the rear fork) |
hex nut |
15,0 mm |
4,0 mm |
| Rear wheel hub cone nut |
4-side nut |
16,0 mm |
2,5 mm |
// Rear gears
| |
Fastener |
Size |
Width |
| Chain tensionner main locking bolt |
slotted bolt |
9,0 mm |
1,4 mm |
| Chain tensionner secondary sprocket locking bolt |
slotted bolt |
9,0 mm |
1,4 mm |
| Chain tensionner tertiary sprocket locking bolt |
slotted bolt |
9,0 mm |
1,4 mm |
| Gear change cable locking nut |
hex nut |
8,0 mm |
|
// Rear dual pivot caliper brake
| |
Fastener |
Size |
Width |
| Brake pad bolt |
hex (Allen) socket bolt |
5,0 mm |
|
| Dual pivot minor adjustment screw |
hex (Allen) socket bolt |
2,5 mm |
|
| Caliper arm bolt head |
hex (Allen) socket bolt |
5,0 mm |
|
| Caliper arm nut |
hex nut |
10,0 mm |
|
| Caliper arm brake cable fixer bolt |
hex bolt |
10,0 mm |
|
| Brake axle bolt |
hex (Allen) socket bolt |
4,0 mm |
|
| Brake axle (brake spring-locking) nut |
2-side semi-circular nut |
|
|
| Brake axle nut (main fastener) |
hex nut assembly |
10,0 mm |
|
// Seat post stop disk assembly
| |
Fastener |
Size |
Width |
| Stop disk nut 1 |
hex nut |
15,0 mm |
|
| Stop disk nut 2 |
hex nut assembly |
19,0 mm |
|
// Rear mud-guard
| |
Fastener |
Size |
Width |
| Side fixture of the mud-guard bolt |
hex bolt |
8,0 mm |
|
| Side fixture of the mud-guard nut |
hex nut |
8,0 mm |
|
| On-the mud-guard fixing bolts x2 |
hex (Allen) socket bolt |
2,5 mm |
|
| On-mud-guard wheel bolt x2 |
hex (Allen) socket bolt |
2,5 mm |
|
| On-mud-guard wheel nut x2 |
hex nut |
7,0 mm |
|
| Mud-guard flap bolt |
hex (Allen) socket bolt |
2,5 mm |
|
| Mud-guard flap nut |
hex nut |
7,0 mm |
|
// Rear light
| |
Fastener |
Size |
Width |
| Rear light fixture bolt x2 |
hex nut |
8,0 mm |
|
| Battery change bolt x2 |
Philips screw |
1 Ph |
|
Henry Byrd / 2015-09-14 23:21
An excellent piece of work. Unfortunately it doesn’t give the answer that I was specifically looking for – the thread size of the front wheel retaining nuts. To simply show the spanner size (15mm) as you have done doesn’t help as this can cover several thread sizes. Because of the need to retain the folding hook of the mudguard stay, it is difficult to fit a flanged nut, so the usual bicycle track nuts are unsuitable. The standard nuts are dull steel and prone to rust. and I would prefer to fit stainless steel replacements but cannot find the thread size whilst retaining the 15mm spanner size. I don’t know if this is even possible, Perhaps these are made specially for Brompton?
My apologies for replying so late… I have since replaced both wheels / hubs / rims / spokes. My front wheel is a Phil Wood and I had no access to my older wheels.
I have gotten them out of storage for you today. What measurement do you need? Thread size sounds a bit weird to me as a query. Do you mean metric vs imperial? Thread count? Or inside diameter?
ARJUN ramasamy / 2019-02-19 14:07
Please give dimensions for Brompton hinge such as length, breadth,thickness and thread size, etc
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