Cut yourself some slack if you haven’t heard of Spreng Reng 2.0. When the original rolled out in 2016, it was easy to write off this unique chainring design as BioPace’s progeny. But according to Hunter Allen, Founder and CEO of Peaks Coaching Group, the Spreng Reng’s odd shape increases your wattage up climbs.

“The Spreng Reng has incredible promise to help anyone increase their wattage on a climb,” says Allen. “This is a secret weapon that eclipses all other chainrings.”

So what the heck is it, exactly? And how is Spreng Reng 2.0 different from the original?

Spreng Reng 2.0 on scale

The Spreng Reng 2.0’s weight, according to Spreng Reng.

Hexagonal concept

The Spreng Reng may look like very other ovalized chainring you’ve seen, and it certainly conjures images of Chris Froome’s unique setup. But the Spreng Reng is actually hexagonal, which means there are “six quadrants that contain multiple gear torque increases along with gear rollout increase,” according to Spreng Reng’s press release.


That basically means the amount of torque being applied to the drivetrain will change depending on how you have the chainring positioned on your crank. Spreng Reng says that you’ll experience increased cadence and noticeably faster speeds, thereby allowing you to climb faster with less — or the same — effort.

But doesn’t everyone say that?

Fortunately for us, Bikerumor’s very own Zach Overholt ran the original Spreng Reng through its paces when it launched a couple years ago. He found that an early prototype of the Spreng Reng may actually deliver on its promises, at least in Overholt’s self-admitted un-scientific testing.

That hexagonal concept is different than the original. The first version of the Spreng Reng was asymmetrical. That means the shape, while irregular, wasn’t specifically defined. The Spreng Reng 2.0 has a distinct hexagonal shape. That apparently refines the ring’s ability to increase your wattage.

The original Spreng Reng also featured ‘banana holes.’ These allowed the user to position the chainring in just about any position on the crank. The Spreng Reng 2.0 features traditional bolt holes, though there are numerous holes for just as much adjustability and less potential for bolt slippage.

Spreng Reng on the bike

Hunter Allen has the Spreng Reng 2.0 mounted to his bike. It is, “installed in a reverse mounting position to illustrate hexagonal profile in relation to crank arm position.”

But where do Spreng Reng watts come from?

Doug Brown, Jr. is the brain behind the Spreng Reng. He’s tight-lipped about how his product is able to increase torque and changing rollout without increasing the amount of teeth on the ring itself. The patent has been filed, but Brown appears to be protecting his concept anyway — which is wise in a highly-competitive market.

For now, Brown simply says the Spreng Reng makes pedaling easier, and it will have enough adaptability to handle your drivetrain needs. “In addition to the inner chainring, the patent pending design also has applications for outer and 1x chainrings and multiple cassette cogs for added performance,” according to Spreng Reng.

Standing out from the competition

We’ve seen oddly-shaped chainrings before. Chris Froome notably rides Osymetric chainrings, which have a unique design based on the rider’s pedaling motion. Rotor has its own elliptical chainring system. And of course, all of those odd rings get compared to Shimano’s seminal pedaling oddball, BioPace.

Spreng Reng 2.0 stands out from those others based on its shape. But until we get a bit more clarity from Spreng Reng as to where that extra torque and speed comes from, it’s difficult to gauge whether it’s the real deal or not.



    • Dan Cavallari on

      It’s so good it has two extra quadrants!

      That was their language in the press release, but yeah, I believe the gist is that there are six general positions. Will seek clarification…

  1. Shafty on

    Uhhh…what? We’re 3 weeks away, this is a little early.

    You can’t increase effective rollout without increasing the effective circumference. It’s impossible. This is a snake oil product that makes dubious claims. The creator needs to take a course on geometry.

    • Doug Brown Jr. on

      Shafty, you are exactly right on your rollout conclusion and of course the exact opposite would obviously be true for increasing the gear torque. But yes, we’ve found a way to do both within the same gear teeth count. I know it sounds too good to be true but it is true. The combination of both, occurring multiple times within rotation, is where the increase in performance (i.e. cadence & speed) is coming from. Don’t forget, within the power equation for watts is the cadence element which means if you increase cadence with the same gear tooth, you have increased power.
      Hope this is helpful!

    • TheKaiser on

      Shafty, have you ever come across those niche BMX rings that will say they’re 42 1/2 teeth, or some other half tooth value? They claim to achieve greater rollout by subtly increasing the radius of the valleys between the teeth, while keeping all other dimensions the same. In other words, they view the ring as a pulley that just happens to have teeth, and the chain as a belt that just happens to be capable of interfacing with teeth, and when you increase the circumference of the pully at the point where the belt rides you pull more belt with each rotation. In that scenario, the teeth are incidental. I’ve never seen one in person but it seems like it would increase wear to me.

      If this Spreng ring truly does have greater rollout, I’d wondered if it uses a subtle and multiphase version of that 1/2 tooth design.

        • Runnen on

          Don’t bother. It doesn’t work, AT. ALL. I tested it. The chain cannot accommodate the ‘off-pitch’ teeth, and rides up high on the teeth, in exactly the same pitch diameter it would on a normal chainring. All you get is friction, wear, and that P.T. Barnum placebo effect.

          Think about it this way: if it claims to be a 44.1T, then in 10 revolutions, the rear cog will have to be 1 full tooth ahead, compared to normal. When did it skip that tooth? It didn’t. It can’t.

            • TheKaiser on

              Hi Doug,

              Those rings are made by Rennen Design, and they call it “decimal” gearing.There is a lot of skeptical discussion of them in forums, if you google them, and you can also find some youtube vids from Rennen explaining their claims and attempting to prove them via some basic chain tension measurements.

              Regarding your Spreng ring, if you’re looking for any beta testers then let me know. I’ve ridden a variety of round and non-round rings and and am always up for trying something new.

      • 2pacfan187 on

        Those BMX rings always seemed suspect, in terms of rollout claim.
        Let’s say it was 36t. If you moved the crank from top dead center to bottom dead center, the ring would pull the chain forward 18t. Every time. The chain doesn’t incrementally inch forward every pedal stroke — it’s still clocked by the teeth.

        • Matthias on

          Precisely. If this wasn’t equine manure, timing belts (or formerly, timing chains) wouldn’t work because small imprecisions in cog sizes would still add up to a shifted position after a few million rotations.

  2. Shafty on

    This is more marketing. You’ve used different terms than I defined to distract from my central argument. If the *effective* circumference doesn’t change, the rollout can’t. It doesn’t matter if it’s variable or not, rollout is based on a single rotation, not periods within a rotation. Chains have a fixed pitch, so the running diameter is constant per tooth count. If you make the teeth bigger, it will run poorly because they’re not matched. There’s no way around it.

    If your cadence goes up, of course rollout increases– you’re pedaling faster. Duh!

    Periodic changes in leverage can affect power output, as it can help to utilize the rotation more effectively, but it can’t change the nature of rollout or power transmission itself.

    • Doug Brown Jr. on

      Shafty, respectfully you, me, or anyone else should not be so critical of a design for which you do not know all the intricate details of. I have been working with some very talented mechanical engineers from Paul Hammerstrom Design for over four years now. I never indicated the circumference did not change. I understand “immediate disbelief” for this or any other new design. In fact, I am indeed the biggest critic of all since I am paying for all the engineering, prototypes, patent application, etc. but I assure you we are not claiming to have broken any laws of physics here, we’ve just taken what we’ve learned through a tremendous amount of “trial & error” and incorporated what worked into this chainring design. But I sincerely do enjoy an intelligent debate.

  3. Lee on

    Extraordinary claims require extraordinary proof. I was out after, “…He’s tight-lipped about how his product is able to increase torque and changing rollout without increasing the amount of teeth on the ring itself.”

  4. Skeen on

    Another vote for “rollout can’t change”. That makes no sense to me. I’m open to a sound explanation of this new phenomenon but not expecting to see one.


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