Kuvalda Grimlock complete, angle shot

In 2013, Russia’s Алексей Кочубеев read an article about an ambitious rider building a custom bike from plumbing pipes, alloy sheets and inexpensive materials. He found the story rather interesting, but it didn’t launch him into action right away.  Almost two years later the desire struck Кочубеев to own a custom bike with plenty of integrated adjustment, so he decided to put his own ideas into motion.

Кочубеев  found a small company called Kuvalda Bikes who were producing prototype frames. He contacted them in January 2015 and started designing what would eventually be called the Kuvalda Grimlock. Кочубеев’s creation boasts a huge amount of adjustability with four different travel settings, three chainstay lengths and compatibility with 26″ or 27.5″ wheels.

With such a wide range of set up options this frame is sure to spark engineering debates over its built-in versatility and how it’s ride characteristics might be affected as the rear shock position is altered. Read past the break to see how it works…

Kuvalda Grimlock prototype phase 1 Kuvalda Grimlock prototype phase 3

Кочубеев and Kuvalda set out to build his custom frame for a cost of about €800 ($895 USD). The design went back and forth between the manufacturer and Кочубеев, and after revisions around the bottom bracket area, some additional gusseting and a redesign of the suspension linkage, the third phase prototype (pictured on the right) began to resemble the final version of the Grimlock.

Kuvalda Grimlock frame

The Grimlock is made of aluminum, and the frame weighs in at 9.04lbs (with the 27.5” dropouts). Its head tube angle is 66°, and the seat tube sits at 74°. The 1x specific frame has no front derailleur mount and features ISCG 05 chain guide tabs, a 1.5” head tube and a 73mm BSA bottom bracket. It also features internal routing for a stealth dropper post, and a passage through the chainstay for the rear derailleur cable.

Kuvalda Grimlock, interchangable dropouts

Now here’s where the adjustability comes in: The Grimlock’s interchangeable rear dropouts will accommodate either 26” or 27.5” wheels, and adjust the length of the chainstays with three settings at 420, 427.5, and 435mm. Кочубеев lists the bike’s wheelbase at 1150mm, but did not note which configuration was measured.

Kuvalda Grimlock rear end

The Grimlock employs a single-pivot suspension design with four mount options for the inverted rear shock, allowing for several different travel settings at 155, 162.7, 170 and 185mm. The frame is designed to maintain its BB height and geometry regardless of your travel choice. While it aims to retain a familiar feel in all configurations, the compatibility with different wheel sizes and multiple travel options are intended to make the Grimlock a highly adaptable bike for tackling different types of trails.

Kuvalda Grimlock left side Kuvalda Grimlock side view

Kuvalda Grimlock front end

Кочубеев says he intends to continue upgrading the complete bike with better components, but funds got a little low so this is the best build he can afford for now! He plans to replace the tires, seatpost, cranks, pedals, brakes and rear shock seen in the photos. Кочубеев is apparently very happy with the current iteration of the Grimlock frame, and anxious to get it out on the trails.

19 COMMENTS

  1. Love seeing people make their dreams come true. Seems like the leverage ration would increase as the shock goes up through the different mounting holes. Great way to try a bunch of different leverage ratios, but I don’t see how the bike would ride the same in all travel positions. Maybe I’m missing something here though.

  2. Love it. Would love to see more iterations of the same concept but more refined and lighter, maybe carbon fibre. Pity there’s not much in the way of head angle adjustment.

  3. OK. As an ME who has dabbled in suspension design. I will commend the guy for building something to test. But I would have not gone forward with such an outdated design. This is a BSME senior project level build at best.
    Now go out and test it and figure out why that single pivot design has been replaced by several designs that ride much better uphill which is 80%+ of the time it will see on the trails.

  4. There are still many single pivot designs out there that climb just fine, especially with a well dialed shock.
    There are also many multilink designs that are pigs.
    It’s all in the execution.
    Scott’s ‘spark’ climb good enough to win world cups.
    Single front rings are a godsend to suspension designers.

    Now do we design around a 30T or a 26T?

  5. JP/Darryl-OK. Then we can discuss brake jack and torque squat. The bottom line is this thing is not market ready at 9lbs frame weight. Probably not doing him a favor with publicity at this stage.

  6. That single pivot bikes are more affected by brake jack is a myth.

    That single pivot bikes also can’t climb is another myth.

    These myths are often believed by people that have been convinced otherwise by marketing people. Marketing people are very good at convincing other people about things that are not true.

    Single pivot bikes are just as capable as any other design out there.

    I’m not GT fan but their bikes have won a few DH races have they not?
    I’m not a Scott fan but their bikes have won a few XC races have they not?

    All props to this guy, yes the frame needs some more work but it’s 10 times further along than what most arm chair experts have ever done…

  7. Chasejj if your finding brake jack ect while riding your single pivot you might find learning basic mtb trail riding skills again will help… I love my single pivots and if the shocks tunes and adjusted right their awesome, hence why my genius LT sits in the garage a lot haha..

    All suspension designs have faults and I agree with other poster that they are gaining popularity again even when being slammed by media nah Sayers…

  8. Single pivot ALL the way thank you. I have two here and would not trade them. With, *ahem*, modern suspension, they ride every bit as good as most other bikes. Sure they have their nuances but so do most other suspension/frame designs.

  9. ‘I have a single pivot bike and I like it’ is your basis for scientific argument? Single pivots are becoming more popular is the clincher argument? In the same sentence as multi pivots are marketing hype?

    I have no problem with someone living with the compromises of a single pivot system for the perceived advantages to them, but claiming that there’s no squat/brake jack etc issues is just uninformed. It’s not an opinion, its measurable and quantifiable, all vectors and formula and compromises. If you place a pivot here this force will cause this result :1+1=2.

  10. @The Boss I don’t mean to be that guy, but the bikes you mentions are not true single pivots like the bike posted here. They are linkage actuated single pivots, and the GT has a floating BB to manage chain growth and pedal feedback etc.

    Disclaimer: I am not an engineer.

  11. This is an awesome rig! I would throw a leg over this monster any day. If someone showed up to a group ride on this I can promise that everyone else on their carbon $10k wonder bikes would be gawking over this death metal machine. One thing though: it needs more black!

    Best thing about this bike is the answer the owner can give when the bike snobs ask what brand it is “oh, it’s mine”

  12. @Loki, +1.

    Stoked to see someone position the shock intelligently on a single pivot swingarm, though. No reason that Hecklers shouldn’t have a progressive leverage ratio and this is a good example.

    A single pivot with a more rearward main pivot plus a cleanly integrated floating brake arm could perform really well with the ease of maintenance and durability of a single pivot. Some day I’ll do that if no one else does.

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