Eurobike 2013: World’s Lightest 29er Hardtail?

29er Cross Country Eurobike

Open co-founder Gerard Vroomen has no problem one-finger lifting a bike he claims is the lightest 29er hardtail in the world.

There is no UCI minimum when it comes to mountain bikes, but if there was it’s safe to say two new concept bikes from Open would be flagged illegal. As it is the pair of hardtail 29ers on display at Eurobike (one fully rigid, one with a 60mm leaf spring fork) are both under the UCI’s 6.8kg minimum for road bikes.

This fully rigid steed weighs just 14.1 pounds.

The fully rigid Open weighs in at 6.4kg (14.1 pounds), while the suspended version tips the scale at 6.7kg (14.8 pounds). Both bikes are spec’d with a litany of lightweight parts and wheels from German-weight-weenie parts maker AX Lightness, plus SRAM XX1 drivetrains. The suspension fork is the yet-to-be-released 990-gram Lauf TR29, which uses glass fiber leaf springs instead of more traditional suspension mechanisms. Tires are Schwalbe Furious Fred. The cranks are THM Clavicula.

“We did it because we could,” explained Open co-founder (and former Cervélo) boss Gerard Vroomen. “They are exceptionally lightweight but they are still bikes that are fully functional and can be raced. These are not spec’d with crazy drilled out stuff that breaks when you look at it.”

Frame weight of the O-1.0 is under 900 grams for a size large, added Vroomen, who figures these are the “lightest 29er hardtails in the world.”

Vroomen also gave a thumbs up to the yet unproven Lauf fork. “I think one really big advantage is that it solves the problem of stiction,” he said. “Normally there’s a slight delay in the initial action of a fork, but not here. So over small bumps this fork reacts much quicker. But we still need to do some fatigue testing before we commit to spec’ing it on our bikes.”

However, Vroomen said that sort of testing has already been done with these two super light bikes. “We brought them to the testing agency here in Germany,” he explained. “And they said there were the lightest mountain bikes that have ever passed even though when we first brought them in they were sure that they wouldn’t pass.”

This proof-of-concept steed weighs less than the UCI minimum for road bikes.

The rigid Open is available as a fuselage only, meaning drivetrain and wheels are not included, and retails for $6,700. The suspended bike is simply a proof of concept and is not yet available for sale.

About the author: Jason Sumner

An avid cyclist, Jason Sumner has been writing about two-wheeled pursuits of all kinds since 1999. He’s covered the Olympics, Tour de France, MTB world champs, and dozens of other international cycling events. He also likes to throw himself into the fray, penning first-person accounts of cycling adventures all over the globe. Sumner has also done extensive gear testing and is the author of the cycling guide book "75 Classic Rides: Colorado." When not writing or riding, the native Coloradoan can be found enjoying life with his wife Lisa and kids Cora and Tommy in and around their home in the MTB Mecca of Crested Butte.

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  • mort broker says:

    Put a real front suspension on it, then way it…then we will see.

    • Gerard Vroomen says:

      Why would you judge a fork just by lookin at it? Of course it is a fork with a trade off, you balance weight with travel. As for putting another fork on it to weigh it, I trust people can do the math and see that with another light fork, the weight will be 7.1-7.2kg depending on the exact fork chosen.

    • trevor riley says:

      it is a real fork on that bike ! i ride a lauf and they are amazing , never go back to a conventional fork !!!

  • Val Hemedes says:

    I applaud Open for their effort to advance MTB technology and design in the form of their new light weight frames and suspension. I don’t understand the haters who snap at first read. I hope Open is able to successfully design a durable and strong light weight bike and patent their design and technology. Hoards of copy cats that will follow.

  • Nigel says:

    With a fatigue life of 1-month off road… LOL

  • bryan says:

    Under the UCI legal limit for road bikes huh? Roadies will be fuming when they read that, this article is like flipping a mud covered middle finger at the roadie world. Why is it that technology is evolving to the point that mtb hardtails are approaching and in some cases weighing less than road bikes, with disc brakes fatter rims and tires at that, yet roadie hardware is exorbitantly more expensive with IMO decades long outdated components? I welcome these kind of projects even if they are just an engineering exercise.

  • Johan says:

    Awesome! I still struggle to find a 29er HT under $10K and 22 pounds at my LBS. This would be a Godsend! Even 18 pounds would be a huge win! Great job and stuff it to the haters. Hopefully the bike can hold up on the rough stuff.

  • rain says:

    No way that Motobecane FLY is under 22 lbs. Absolute marketing nonsense.

    • OneGuy says:

      Not knowing HOW it is possible, doesn’t make it impossible. It just takes time, research and industry knowledge with a few price pillferings. In size small with 26″ 300gr tires, foam grips, ultralight tubes, carbon cranks, bar, post and xx parts with SID fork and ultralight wheels with few spokes and no wasted metal around the wheels built for a 190lb rider. Just how it works. I worked at a LBS where my colleague custom built a TI 26er w/100mm fork under 20lbs with XO and SID fork in size 17 frame. A wisely built MTB can weigh less than a road bike, as the reverse is also true. It’s all in the build. As your mental conclusion is all in your own build. But sure, marketers can pilfer.

  • ginsu says:

    Think of how much lighter it would be with 26″ wheels!

  • Jim says:

    Perhaps the name “OPEN” is for people to be open to other ideas when it comes to a bike frame and suspension. Would I buy an Open? No way, I’m a poor mtber/road rider, but I can appreciate the bike.

  • whereisthepedals says:

    where is the pedals?
    this total stupid idea to weighting bicycles without pedals is out of mind.
    JUST FIRST RIDE THE BICYCLE 1 mile THEN WEIGHT IT without to use any tool first! simple!

  • jhon says:

    Just imagine my road bike with sora 2005 (full iron!) suspension fork at 7.9 kg! (cost 1500$ ready to ride it!)
    Now imagine the same bike with something like Dura Ace or something else! … 6 kg with suspension fork! Now imagine it without suspension fork, 5.6 kg. A bike for a rider, me, 92 kg.
    have a nice day

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