How Berk built this astonishing 3.9kg road bike

[Bunged Knee]

From Bikeradar

Slovenian carbon specialists build one of the world's lightest road bikes (and it can be ridden every day)

Rider limited to 85kg

Berk has built one of the world’s lightest road bikes that, unlike many featherweight bikes, gives up little in terms of usability. The Slovenian brand has exclusively shared details with BikeRadar on how it created this mind-blowing 3.9kg road bike.

No info of price but expect it might be over $10k -$15k+.

3.9kg Berk road bike full specs with weights
. Custom Berk frame (including seat mast and saddle): 631.1g
. Custom THM Scapula fork: 228.8g
. Expander plug: 3.9g
. Top cap screw: 4.8g
. Headset: 39.5g
. Custom 3D-printed spacer: 2.1g
. Modified SRAM
Red 11-speed shifters: 255.8g
. SeqLite cassette: 111.7g
. Cables: 46g
. Powercordz internal cables: 8.5g
. THM Clavicula crankset: 331.7g
. Unidentified carbon chainrings: 76.9g
. Bottom bracket: 71.4g
. Modified SRAM
Red 11-speed rear derailleur: 121.9g
. Modified Tiso
Altore front derailleur: 49g
. Front derailleur mount: 7.4g
. Rear derailleur hanger: 15.6g
. PYC SP1101 chain: 213.2g
. Speedplay Ultra Light Action Titanium pedals: 133.8g
. Ciamillo Gravitas brakes: 156.8g
. Custom one-piece Berk cockpit: 203.6g
. Handlebar tape: 5.2g
. Tune/Reynolds wheelset: 898.5g
. Tufo Elite Jet tyres: 317.5g
. Quick-release: 26.6g
. Air: 14g
. Screws: 8g
. Fabric cageless bottle stubs: 3g
Total weight: 3,986.3g

[P!N20]

What, they couldn’t put hydrogen in the tyres?

[g-boaf]

From Bikeradar

No info of price but expect it might be over $10k -$15k+.

3.9kg Berk road bike full specs with weights
. Custom Berk frame (including seat mast and saddle): 631.1g
. Custom THM Scapula fork: 228.8g
. Expander plug: 3.9g
. Top cap screw: 4.8g
. Headset: 39.5g
. Custom 3D-printed spacer: 2.1g
. Modified SRAM
Red 11-speed shifters: 255.8g
. SeqLite cassette: 111.7g
. Cables: 46g
. Powercordz internal cables: 8.5g
. THM Clavicula crankset: 331.7g
. Unidentified carbon chainrings: 76.9g
. Bottom bracket: 71.4g
. Modified SRAM
Red 11-speed rear derailleur: 121.9g
. Modified Tiso
Altore front derailleur: 49g
. Front derailleur mount: 7.4g
. Rear derailleur hanger: 15.6g
. PYC SP1101 chain: 213.2g
. Speedplay Ultra Light Action Titanium pedals: 133.8g
. Ciamillo Gravitas brakes: 156.8g
. Custom one-piece Berk cockpit: 203.6g
. Handlebar tape: 5.2g
. Tune/Reynolds wheelset: 898.5g
. Tufo Elite Jet tyres: 317.5g
. Quick-release: 26.6g
. Air: 14g
. Screws: 8g
. Fabric cageless bottle stubs: 3g
Total weight: 3,986.3g

From reviews and various people who've used the highlighted cassette, I think you'll find it isn't an everyday use proposition. They wear out quickly. I'd wear out that cassette in a week. Not good. Just get a SRAM XG-1190 cassette and have peace of mind that it will be durable. My bike also is supposed to be fitted with the THM crankset (and THM Fibula brakes too), but I won't use those, just don't trust them.

I can bring my bike down into this very extreme sub 5kg weight zone if I want to, but I'm happy that at 6kg to 6.4kg it is a very dependable and usable bike.

[find_bruce]

Yeah I’ll worry about an extremely light bike when I’m within 3kg of my ideal weight

[rkelsen]

What, they couldn’t put hydrogen in the tyres?

What about helium? That'd help surely...

[MichaelB]

Ridden every day by a 50kg rider on smooth roads only ...