Updated – Reader’s Rides: Liberty Bikes Builds an Amazing Sub 4kg, 8.8 LB Di2 Road Bike – with Pedals!


There’s light, and then there’s are you kidding me? That thing is actually rideable? Liberty Bike’s newest creation certainly falls into that latter category with a complete road bike with pedals that tips the scales just South of 9 pounds! Not quite as light as the 6lb road bike we featured a few years ago, but taking the wow factor up a notch is that this bike is built with an 11 speed Dura Ace Di2 drivetrain. Well, at least part of a Di2 drivetrain, meaning the shifters (modified) and the derailleurs. Mael from Liberty Bikes says that he worked with a friend and customer to build what they think is the first Sub-4 Di2 bike in the world (sub 4 kg). While they wanted it to be sub 4, they also wanted it to be safe meaning it could be ridden like a regular bike.

Is it possible to build a bike under 9 pounds that can be ridden like normal? Check out the details after the break! Updated with full specs and details on those shifters!

Liberty Bikes crazy  8 9 pound road bike super light di2 (1)

At the heart of this anti gravity machine is an AX Lightness Alpha frame, which from the looks of it is not a small frame either. The fork is a THM Scapula F with a built in front brake, while an AX Lightness Fibula brake is on the rear.

Liberty Bikes crazy  8 9 pound road bike super light di2 (4) Liberty Bikes crazy  8 9 pound road bike super light di2 (3)

Liberty Bikes crazy  8 9 pound road bike super light di2 (5)

Using Extralite Ultra Hubs laced to AX Lightness rims, the wheelset for this beautiful machine weighs a staggering 698g for the pair. Carbon chainrings on an AX Lightness crank mate with an extremely light 11-28 cassette for useable gearing for such a light bike.

Liberty Bikes crazy  8 9 pound road bike super light di2 (2)

We’ll have to get more detail from Mael as to what’s going on with the lever, but it looks like the stock rubber hoods have been ditched in favor of a carbon wrap. The Schmolke Carbon bar is wrapped very sparingly with bar tape, extending just past the hoods in either direction.

Update – Just heard from Maël on the shifters, and there’s a lot more going on than we thought. First, the mounting screw on the collar was changed to aluminum. Maël says he didn’t want to go with a carbon collar for safety reasons. The stock hoods are gone and have been replaced with vinyl that has been glued on though it is still able to be removed. Total weight saved? 3g between the two levers. Finally, what Maël rightly calls the hardest job was he somehow managed to remove the stock electronics from the shifters and replaced them with the guts from the TT shifters! He says the system is bigger, but lighter. Wow.

Liberty Bikes crazy  8 9 pound road bike super light di2 (6)

Finally, a very light one piece seat/seatpost provide a place to sit.


There it is – sort of a strange way to weigh a bike, but it works. 3985g, or 8.78542 lbs impressive in metric or imperial. We’re told that it may even get lighter soon as they are working with Cola Wheat and FastDad on a new derailleur!




Will - 02/13/14 - 9:08am

I love this. I would not ride it (that saddle!), but I absolutely love it.

I remember reading about the weight differences between Graphene and Carbon fiber, and doing some mental math came to the conclusion that a bike could be built around 5lbs in theory. Its amazing to think it is getting there, even without the graphene!

Brilliant build, kudos guys.

Alain - 02/13/14 - 9:20am

I have a AX Lightness Leaf saddle, weighs 71gr and has more comfort than a SLR.

Jimbo - 02/13/14 - 10:00am

Too bad they used so much of the Ax stuff which has a high failure rate. Would have been better to see them choose something a bit more reliable and less predictable for this “regular” bike. I also wouldn’t call the crazy light Tufo tires ride-worthy.

ilikeicedtea - 02/13/14 - 10:01am

What’s that BIG BLACK uh, tube do?

Evs - 02/13/14 - 10:22am

The ‘BIG BLACK uh, tube’ looks like it joins the seat tube to the head tube…

Mike - 02/13/14 - 10:25am

Poor guy spent all that money on an obsolete bike (no disc brakes). Just kidding – I’m not into discs on road bikes either.

Ultraclyde - 02/13/14 - 10:36am

ilikeicedtea – I think that’s the bar tape that hasn’t been applied yet. At least, in the enlarged shot the bar looks bare, and the “tube” looks kind of like something wrapped around a foam cylinder. If not, then I’m ( as usual) clueless.

Michael - 02/13/14 - 10:55am

Big black tube is the top tube, sitting on a gram scale on a table with the rest of the bike suspended underneath.

pmurf - 02/13/14 - 11:22am

He could have gone lighter with a Scapula SP and a set of AX 3000’s 😉 Seriously though, I can’t wait to see what FastDad and Cola Wheat come up with for the Di2 RD. BikeRumor, please stay on top of that story and post accordingly!

g-man - 02/13/14 - 11:23am

good for him.

mario - 02/13/14 - 11:45am

1+ ultraclyde that seems like the bar tape, strange way to store that though…

MeroMasta - 02/13/14 - 11:55am

I wonder how you take off those carbon wraps from the hoods.

Did they build the seat/seatpost specifically for this rider? I’m just wondering since the fore/aft of the seat changes once you lift/lower the seatpost.

Last but not least, the fork seems to be built to be aero, but it has the brake cable sticking out the side!

Other than that, wow that’s light.

Nate - 02/13/14 - 12:37pm

This bike was over a pound lighter 3 years ago and was supposedly ridden for a ton of miles attributing to it’s durability. Supposedly many of those parts went into production. And that isn’t carbon wrap around the levers, that’s how the lever covers look.


nunyab - 02/13/14 - 12:48pm

Not a bad build. Almost as light as this Di2 bike which was done 5 years ago: http://fairwheelbikes.com/geoff-mcfetridge-rue-sports-light-bike-ezp-33.html?chapter=1

Devin - 02/13/14 - 1:04pm

I spy several cable stops that have become unnecessary. Quickly, to the Dremel!

The Guy - 02/13/14 - 1:18pm

Good work y’all. #pantstent

cobrahawk - 02/13/14 - 1:34pm

Would love to take this beast on some pave… Paris-Roubaix anyone?

JoeNomad - 02/13/14 - 2:11pm

Wonder what’s the rider weight limit. If the owner is a 250lb doctor, lawyer, CEO then it’s a nice piece of wall art.

DrMabuse - 02/13/14 - 2:41pm

What pedals are these?

Dereksmalls - 02/13/14 - 3:05pm

@DrMabuse – custom built Speedplay Roubaix by the looks of things, not originals. I like the drillings in the bowties – will look into doing that to mine if possible!

Also the rear brake is not a THM Fibula, it’s another AX Lightness, looks like an Orion

Dereksmalls - 02/13/14 - 3:31pm


They look like custom built Speedplay Roubaix copies. Much the same as the pair I had built but with CNC machining done instead of using readily available off the shelf parts. I like the cnc work in the bowties!

Also the rear brake is not a THM Fibula, looks like an AX Lightness Orion

olimlili - 02/13/14 - 4:17pm

I am the owner of the bike , just read your comments and for futher questions Maël from liberty bike(www.libertybike.fr) will be delighted to answer… just wanted to say two things it was a challenge and I understand that fiability is at risk in some parts of the bike …
and no cobrahawk I won t do Paris-Roubaix with this bike :) and yes and no JoeNomad I am a CEO but ride about 12.000 km each year. Anyway tks for your comments and in puts.

Mike - 02/13/14 - 5:40pm

The seat/post combo looks like a Berk composites.

Tomi - 02/13/14 - 5:52pm

Call me a hater if you want but there are some big issues with this bike:

tufo elite 110 are track tires —–> high risk of flat even on the best roads.
recon cassette —-> theses aluminum cassettes are so fragile they are basically disposable one time use parts.
ti spokes are not known for making great wheels, those things must be noodles.

unknown to me : do carbon chainrings works as well as alu ones ? Shifting performance can make the difference between a great bike and a shitty one.

I’m pretty sure this bike would have been already very light with standard dura-ace cassette, a set of veloflex tires, DT swiss revolution spokes without compromising anything in term of performance and reliability. That bar tape job is also ridiculous considering the small weight gain. And don’t get me started on weight-weenies brakes.

Also, weight is not necessarily bad. Last week I rode in the swiss alps and the wind was so high it was a bit scary in the descents. I was glad I had taken my old +8kg aluminum bike instead of my current 6.x kg carbon one.

Bobby Frontbutt - 02/13/14 - 6:14pm

Meh. Art is one thing, but can be shaped like a bicycle. A bicycle is a different thing, but can be artistic. This sadly falls on the art side of that equation for me. I ride my bike hard and expect it to work without fail or issue every time I pull it off the wall.

Dereksmalls - 02/13/14 - 6:37pm

@Tomi aluminium cassettes are not one time use throw away parts. I’ve got over 2000km out of mine and it’s going fine

I’m impressed with the bike

tkeaton - 02/13/14 - 7:13pm

5g of tubular glue, huh?

1Pro - 02/13/14 - 7:36pm

i wouldn’t trust my life to anything AX makes.

Devin - 02/13/14 - 8:57pm

@olimlili- give me a call, I’d love to build you a custom version of that frame- we could drop some weight for sure.

Xris - 02/14/14 - 12:08am

Things like this make me feel happy inside.

Aaron - 02/14/14 - 2:21am

Yawn. Until they make the entire frame into a supercapacitor to power the di2 battery using layered graphene sheets with and inlaid conducting wire instead of dura ace wire, I’m not even remotely interested.


Champs - 02/14/14 - 4:57am

It would be lighter with 650B…

EM2 - 02/14/14 - 6:16am

I challenge you for a 7kilos bike that can really race (with pedals and computer) for no more than 3000$

eric - 02/14/14 - 6:31am

Still can’t figure out what that big black tube to the left of the handlebars does.

iperov - 02/14/14 - 7:41am

No thanks. Life more expensive than 4kg paper bike.

Tomi - 02/14/14 - 8:26am

@Dereksmalls : in my experience unless you soft pedal for 2 seconds at every gear change those alu recon cassettes get trashed in a very small number of ride. Unless you intend to start in small hillclimbs TT, they are totally useless.

Colin - 02/14/14 - 5:15pm


Take your favorite tubular glue, find a solvent that will dilute but not reduce the effectiveness of the adhesive. Reduce the viscosity to about that of maple syrup. Paint on in thin layers, letting it dry thoroughly between coats. Stick on tire.

I’ve done this on a few of my weight weenie wheel sets and my glue job holds better than the zipp or challenge base tape glue.

Paniagua - 02/15/14 - 2:13pm

Thinning tub glue? now I’m scared

Aaron - 02/15/14 - 7:42pm

Awesome build, but I’d rather have a 10lb bike with GP4000S clinchers, full bar tape, and a stronger (slightly heavier) stem.

Dereksmalls - 02/17/14 - 3:22pm

@Tomi I think maybe you’ve had a bad experience with them then.

I race mine all the time, and don’t soft pedal for 2 seconds whilst shifting, if I had to do that I wouldn’t be running one. My shifting with Campag Centaur shifters, a tuned Super Record RD and Aican Bungaras cables is damn crisp with no need to soft pedal at all either on up or down shifts.

FrankieB - 02/18/14 - 2:56pm

That has got to be a noodle. No thanks – I will just cut down on beer and pizza.

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