Brompton 4-Speed Stock Specs Before My Lightweight Tuning Project

Daily · Published 10/14/2022 ·

Before I start tuning soon, I’m recording the stock specs.

Whether it’s an M-bag or an S-bag, they’re generally advertised as being under 10kg, but depending on the model, some do come in right at 10kg.

• Frame: steel main frame, titanium rear frame.

• Fork: titanium.

• Weight: 9.89kg as listed.

• Gearing: 4-speed.

• Rear derailleur: external 4-speed.

• Crank: 50T forged aluminum crank.

• Shifter: Brompton 4-speed trigger shifter.

• Cassette: Brompton 4-speed, 11-13-15-18.

• Brakes: rim brakes.

• Tires: Schwalbe One Black 16×1 1/3in.

• Wheels: Brompton 16-inch.

• Seatpost: steel.

I’m planning to tune it for lighter weight, and I’ll be holding on to the stock parts.

Here’s what I’ve been thinking about so far.

Remove the mudguards -> dropping both front and rear saves about 200–250g.

Swap the cassette from 18T -> 21T - better climbing performance.

Saddle swap -> the Fizik saddle is rough on the sit bones, but I’m pushing this one down the priority list. Hopefully I’ll get used to it in the meantime.

Lighter water bottle -> the bottle that came with it pulls from a pocket and it’s a bit heavy, so I’m planning to switch to a lighter one.

That’s about it for now. I want to go as light as I can without compromising safety.

If anyone has good tips, I’d really appreciate a comment.

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