Which Is The Lightest Bike? | Real Weights And Rules

Here’s the short answer: a few production road bikes sit around six kilos, led by halo builds like the S-Works Aethos and the latest Cervélo R5. Size, groupset, wheel depth, and tires move the number on the shop scale. If you came here asking which is the lightest bike, you also want the rules, what counts as “production,” and how to keep ride quality high.

Which Is The Lightest Bike? By Type And Use

The phrase “which is the lightest bike?” often refers to drop-bar road machines. Track, TT, and gravel rigs play by different rules and usually weigh more. Within road, two buckets matter: ultra-light consumer bikes aimed at enthusiasts, and UCI-legal race bikes capped at 6.8 kg. A few boutique builds slip under six kilos, but most everyday sizes with pedals and cages land a bit above.

Lightest Production Road Bikes Right Now

Brands publish claimed weights for specific sizes and specs, usually without pedals. Those claims guide you, but real builds vary. The table lists current models with maker-stated weights to show how close they sit to the six-kilo line.

Model	Claimed Complete Weight*	Source
Specialized S-Works Aethos 2	5.9 kg (size 56)	Specialized Aethos 2
Cervélo R5 (2025)	5.97 kg (size 56)	Cervélo R5 page
Scott Addict RC Ultimate	5.9 kg (approx., size M)	Scott spec
Trek Émonda SLR 9	6.6–6.7 kg (size 56)	Trek weight
Canyon Ultimate CFR Di2	13.94 lb (≈6.33 kg, size M)	Canyon CFR Di2
Canyon Ultimate CFR AXS	6.78 kg (size M)	Canyon CFR AXS
Bianchi Specialissima RC	6.6 kg (size 55)	Bianchi Specialissima

*Weights are manufacturer claims for listed sizes/specs; actual builds vary with size, paint, and components.

Why A 6.8 Kg Race Limit Still Matters

For sanctioned road events, bikes must meet a 6.8 kg minimum set by cycling’s governing body. That rule keeps sub-six-kilo rockets off race day. You can read the current rule in the UCI technical regulations; see article 1.3.019 on minimum mass.

Crews can add ballast to reach 6.8 kg, so teams build for the course first.

Build Choices That Move The Scale

Two bikes with the same frame can differ by 500 grams or more after wheel, tire, cassette, crank, and cockpit swaps. The next table maps typical gram cuts without turning your bike into a garage queen.

Component Swap	Typical Weight Change	Notes
Alloy bar/stem → one-piece carbon	-120 to -200 g	Can also clean cable routing.
Mid-depth wheels → climbing set	-200 to -400 g	Lighter rims spin up faster; watch crosswind stability.
Tube-type tires → tubeless	-60 to -120 g	Fewer flats and lower rolling loss when set up well.
Heavy saddle → carbon shell	-80 to -150 g	Pick shape first; comfort beats grams.
12-speed cassette tiers	-40 to -80 g	Top cassettes drop weight with more alloy and titanium.
Rotors: thick steel → light steel	-30 to -70 g	Stay within maker limits for heat and wear.
Round post → ultralight post	-60 to -120 g	Mind rider weight and setback range.

How “Production” Differs From One-Off Builds

Ultra-light custom projects grab headlines with sub-5 kg numbers, but they mix rare parts, drilled hardware, or size-specific trade-offs. Production bikes ship with warranty-backed parts, safe torque ranges, and spares you can buy worldwide. If your goal is a reliable ride that stays light, start with a light frame and wheels, then trim grams where the trade-offs are small.

Close Variant Keyword H2 — Lightest Road Bike Now By Trim And Year

Model lines change often. The Aethos 2 top build claims 5.9 kg, mid-tier about 6.7 kg. Addict RC Ultimate sits near 5.9 kg. Ultimate CFR ranges roughly 6.3–6.8 kg by trim. Émonda SLR 9 hovers near 6.6–6.7 kg.

Reading Weight Claims The Smart Way

Weight charts can be apples to oranges. Some brands print exact sizes; others round. Some include tubeless sealant; others don’t. When you compare, match size, spec level, and wheel depth. If the site lists only frame weight, add a realistic parts stack to estimate your size and spec.

Real-World Picks For Different Riders

Climb-Hungry Rider

Aethos and Addict RC builds near six kilos feel alive uphill. Run 28 mm slicks and compact gearing for long grades.

All-Round Racer

Racing under UCI rules? Aim for 6.8 kg with parts that suit the course. R5 and Émonda builds make that target easy.

Everyday Speed Seeker

A mid-tier carbon frame with light alloy wheels and tubeless tires can sit near 7.2–7.6 kg and still feel quick.

UCI Rule And What It Means For You

The UCI’s 6.8 kg floor applies only to events it governs. For solo rides and most local fondos, ride any weight you like. But the rule shapes the market, so many brands target low-six-kilo builds that can be tuned to that number. You can check the rule text in the UCI regs here: UCI Technical Regulation 1.3.019.

Care And Durability On Super-Light Builds

Low mass parts need correct torque and regular checks. Keep fresh pads and true, clean rotors for steady stopping. Inspect carbon cockpit parts after travel or a tip-over. Use a torque wrench on clamps and heed maker limits for bars, posts, and rotors. With basic care, modern light parts hold up well for training and long rides.

Answering The Exact Search

So, which is the lightest bike? Among production road bikes you can buy, current claims point to the S-Works Aethos at 5.9 kg and the latest Cervélo R5 at 5.97 kg in quoted sizes. Both give you bikes that feel weightless yet still ride solid. If you meant “race-legal,” the lightest bike you’ll see on a UCI start line will still read 6.8 kg or just above. That’s the rule, and brands build to it.

Which Is The Lightest Bike? The Takeaway For Buyers

When someone types which is the lightest bike? they want a fast choice, not a rabbit hole. Start with a frame that posts clear, low claims. Add light wheels you can service. Spend the last grams where they help most: tires, wheels, cockpit. Keep an eye on UCI limits if you plan to race, and enjoy the free speed from a bike that weighs less and rolls better.