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“What’s the most interesting thing you’ve seen at the show?” That’s a question we get a lot while we’re hustling through the rows of booths at a trade show like Interbike. More often than not, my answer consists of a sort of glazed look over my eyes as I can barely remember the last booth, much less the entire show. But every so often, something catches my eye that really sticks out.

IB17: Wild Mandaric Standard 21.5 concept runs the cassette outside the frame

IB17: Wild Mandaric Standard 21.5 concept runs the cassette outside the frame

This time, that something was ‘Standard 21.5’ – a wild new drivetrain concept from the brilliant mind of Veso Mandaric. Named after the diameter of the rear axle, Standard 21.5 has a lot going on – it’s far more than just putting the cassette outside the frame. Still in the very early concept stages, Veso said that he was literally still hand making parts to get it together the Tuesday before the show. But the proof of concept was enough to garner the attention of much bigger drivetrain players like Shimano and SRAM, so it seems like it could end up as more than just a wild concept.

IB17: Wild Mandaric Standard 21.5 concept runs the cassette outside the frame IB17: Wild Mandaric Standard 21.5 concept runs the cassette outside the frame IB17: Wild Mandaric Standard 21.5 concept runs the cassette outside the frame

The design starts with two crazy stout box section chain stays, which are positioned to be narrower than your average 142 x 12mm spaced road frame. Much of the concept centers around drastically increased drivetrain efficiency so Veso says this part of the design is important for power transfer. While the half prototype is mocked up in aluminum, he expects the final design to be made in carbon – including the axle. That’s one of the reasons the axle is so big, as it can be made from carbon and still be lighter than a comparable 12mm axle.

This is even more important than usual, because one of the most peculiar design elements of Standard 21.5 is that the axle actually spins along with the cassette. To make that work, the cassette is essentially fixed to an XD free hub body that is captured in the right dropout of the frame. The free hub is mounded inside of a bearing, and a hand made C-clip holds it in place at the moment.

IB17: Wild Mandaric Standard 21.5 concept runs the cassette outside the frame

The axle has a keyway that locks into the driveside frame bearing, but also into the prototype free hub mechanism inside the hub. Currently a unit from REAL Components, the free hub engages the hub shell as normal, but this time the axle spins along with the cassette and the cranks.  IB17: Wild Mandaric Standard 21.5 concept runs the cassette outside the frame IB17: Wild Mandaric Standard 21.5 concept runs the cassette outside the frame

For the sake of the prototype, Veso used a standard 142 x 12mm hub that he removed the free hub body from and modified it to fit the 21.5mm axle. In his mind, the finished axle may actually be triangluar with rounded lobes since he says three points of contact on the inside of the bearing are adequate. That would also allow the free hub to float on the axle rather than rely on the key. The finished version would also allow for new hub designs which could potentially result in stronger wheels.

IB17: Wild Mandaric Standard 21.5 concept runs the cassette outside the frame

One of the hidden benefits of the system is that the bearing spacing is wider than your typical road wheel, especially given the fact that there is a bearing outside of the driveside frame member. Vero says that this has the potential to offer greater stiffness and power transfer over a traditional design, while also opening up the possibility to fitting more gears into the rear cluster.

IB17: Wild Mandaric Standard 21.5 concept runs the cassette outside the frame

Perhaps most importantly, the design seems to have impressed a few important people when it comes to the design of the rear derailleur itself. Calling it a mid mounted design, the current derailleur shown as a placeholder won’t actually work with the bike. But a derailleur that was specifically designed for it could offer better and more precise shifting since it offers better chain wrap, and would use more of a horizontal movement that wouldn’t be fighting against the spring tension of traditional derailleurs. This is the part of the design that makes it all seem like a production bike could be a ways out, but Veso says he is currently trying to figure out a way to make it work using pieces of existing derailleurs.

For those worried about crashing or the exposed cassette, the finished design may have a larger protective disc on the outside integrated into the spindle. Also, the non drive side will likely have a saftey pin that engages once the derailleur is in place as a guarantee that it won’t back out accidentally.

IB17: Wild Mandaric Standard 21.5 concept runs the cassette outside the frame

If that wasn’t enough, in order to offer huge tire clearance, Veso cut a BB30 spindle in half on a lathe, and then welded it back together in order to make a spindle that would work with a 105mm bottom bracket.

IB17: Wild Mandaric Standard 21.5 concept runs the cassette outside the frame

And Standard 21.5 wasn’t even the only wild concept at the Mandaric booth – they also had this clever take on the threadless headset and stem. Not much has changed in the design of threadless headsets and stems in years, but that might change if Veso has his way.

IB17: Wild Mandaric Standard 21.5 concept runs the cassette outside the frame IB17: Wild Mandaric Standard 21.5 concept runs the cassette outside the frame

Instead of just two bearings on the bottom and top of the head tube, Veso’s design uses three – with the third bearing above the stem. He says that this increases strength and stiffness of the system, and should eliminate the potential for carbon steerer tubes to shear  off underneath the stem which has happened to a few racers in the past.

IB17: Wild Mandaric Standard 21.5 concept runs the cassette outside the frame

More importantly, it would allow for a complete redesign of steerer tubes and stems as we know it. Vero envisions a D-shaped steerer tube, with a corresponding D-shaped stem. The shape would prevent the stem from ever going out of alignment, and since the upper headset design would clamp down on the system, he imagines a stem without any bolts on the steerer clamp. This would potentially allow for a much lighter stem design, though there’s the obvious addition of a third bearing in terms of weight.

IB17: Wild Mandaric Standard 21.5 concept runs the cassette outside the frame

More than anything, even if Veso’s creations don’t make it to production, they were a refreshing dose of outside-the-box thinking. I have no idea if we’ll see these ideas make their way to production any time soon, but we’ll be following Veso Mandaric’s work very closely from here on out.

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    • possibly, though a largish flange/saucer on the outside would likely prevent the chain from dropping out into space. Same concept on the inside.

    • I think the significant increase in chain wrap would likely nip that in the bud. Going from roughly 90deg to 180 gives more tooth engagement across the entire cassette, and the derailleur sitting forward of the cassette would isolate more vibrations from the cassette. That derailleur mount position is an interesting design standpoint all on its own. But if you did throw a chain, it’d be easy enough to slip it back on.

      • Dude, noone’s shoes or pant legs are that big. They simply do not go close enough to the cassette. And another baseless critique: the chain is no more exposed to the elements than on a conventional frame! SMH…

    • Its no easier to lose than a standard chain. It may hit the deck and get dirty, but the flip side is that its really easier to get back on. There is the little end nob there too, which should capture it on an overshift.

      Anyway, has anyone dropped a chain on the back? Sure it happens, but I think its really rare.

  1. The Windcheetah recumbent trike mounts the cassette outboard of its single chainstay. And ISTR a concept road bike in the 80s that used this setup. Cinelli’s Bivalent hubs put the freewheel between the stays, but the freewheel stayed connected to the frame when removing the rear wheel (the hubs also used an early version of through axles).

  2. Seems like it would be difficult to adjust the stem height vertically.

    Very interesting concepts. I doubt anything will come of them, but it’s great to see someone thinking creatively and then executing those ideas. Certainly refreshing compared to the photoshop concept bike.

      • Rustilicus, I suspect VP was referring to hanging a giant, draggy cassette out in the wind or the reduced triangulation this frame provides via its narrower stays and wider bottom bracket, which are closer to an inherently flexible parallelogram than they are to an inherently stiff triangle. As I mentioned in my other post, I see no reason to believe the manufacturer’s claim that this frame is inherently more efficient than others.

        That said, the cassette-in-the-wind theory may or may not hold water. I’m not convinced it matters aerodynamically whether the stays enclose the cassette or not. And it’s unlikely that this chainstay arrangement is inherently less efficient than a conventional one.

        VeganPotter, do you care to elaborate on why you think this will be less efficient than a conventional frame?

        • If anything I can see more turbulence with the current cassette inside the stays. With this set up you just have to put a fairing in front of the cassette to completely eliminate most drag …

    • Veganpotter, I’m not sure I’d join you in going full-snark, but the author repeatedly quotes Mandaric as claiming that this design increases stiffness, efficiency and “power transfer.” Stiffness? Maybe, maybe not. Narrowing the width of the rear dropouts makes the rear end more flexible, not less. But rear triangles are tetrahedral trusses and inherently quite stiff. But I see no improvement in efficiency here.

      Finally, this design’s power transfer is no better or worse than any other frame’s: there’s no such thing as power transfer. People who extol a frame’s “power transfer” usually mean “this frame feels stiff and fast when I pedal hard.” If that’s what you mean, just say so. Tarting up “stiff and fast-feeling” as “power transfer” doesn’t make you sound smarter. If Mandaric is a non-native English speaker, he probably deserves a pass on this.

      But I really wish Bikerumor wouldn’t just repeat manufacturers’ claims of increased efficiency (no matter what they call it). It would be nice if they’d at least ask things like “what makes your design more efficient?” and “how do you know it’s more efficient?” or “how have you tested it to validate this improved efficiency?” People love to complain about marketing spin, but just reporting the two-sentence answers to these questions would go a long way towards cutting through it.

      For what it’s worth, I worked Interbike three consecutive years as a reporter for a bike industry newspaper, so I know how crazy it is. The questions above are ones I’d like to see asked in general, but I know that there may not be time for them at trade shows.

      • Mechanical physics applied , it will be stiffer, it will be more efficent. How much, not easy to say but just from my rough estimate enough to start a trend for those who have advanced engineering backgrounds. It the first concept I have seen in six years that I look out for on a new bike. Granted there might have been others before, this is now ready to market.

        • Nah. It’s not stiffer; Veganpotter is right when he says it’s quite possibly more flexible. And even if it were stiffer, that doesn’t make it more efficient, counterintuitive though that may sound.

  3. That 105mm bottom bracket shell may offer huge tire clearance, but that’s not its primary purpose. This design puts the right stays between the cassette and the spokes. Since the hub flanges are spaced wider than on a conventional hub, this means the cassette is farther outboard than on a conventional hub. Thus, the chainline is pushed outboard by about 25-32mm (or so I expect).

    The main problem here is that the crank’s Q factor increases by a similar amount. Future revisions of the design might bring this down to a ~15mm increase, but that’s still substantial. The derailleur mounting concept is interesting, and although I’m concerned about how it will shift on the smaller cogs, I look forward to hearing more about it. The idea that “it wouldn’t be fighting against the spring tension of traditional derailleurs” doesn’t make any sense at all…perhaps the author left out some important information about how the cage takes up chain slack.

    • …..Since the hub flanges are spaced wider than on a conventional hub….
      It is unmodified SRAM 746 hub body.
      Chain line is 9mm to the right. It will be the same as on “standard” bike when we make our own hub. Keep in mind, there is no dish on the spokes! They are symmetrical. Keep in mind that this is also dealing with disc brake, where calipers are oversized and on the “wrong” side. Road design will offer much slimmer design, and ample space.
      ….The main problem here is that the crank’s Q factor increases by a similar amount….
      9mm in this case.
      …it wouldn’t be fighting against the spring tension of traditional derailleurs…
      Believe it or not, words from Shimano guy.

      • Thanks for replying, Veso. You say the Q factor increases by 9mm…what is the Q factor of your system? It’s a 9mm increase from what baseline?

        I look forward to seeing what you do for the road. Though I’m skeptical that you can keep a standard road Q-factor, you might surprise me.

        You seem to claim that your design is somehow more efficient than a standard rear triangle. Can you explain why you think so? As I’ve said above, I don’t see an obvious improvement in efficiency. I don’t see an obvious decrease in efficiency either.

        One thing I really like about this design is its capacity to add gears without widening the rear triangle. I’d love to have a 14-speed 11-30 or 11-36 cassette to ride 1X on the road.

        Thanks for explaining a bit about the “fighting spring tension” quote. Either the Shimano guy said something that doesn’t make any sense or we’re missing some context. If the Shimano guy was in marketing, I’d bet it’s the former. If he was an engineer, I’d put my money on the latter.

  4. The rear derailleur mounting location was done before by Suntour. Late 80’s or early 90’s I think.

    On the headset, how do I raise my stem? If there are no bolts how do you keep the D-shaped stem from having play and wobbling unless you press fit it? We all know how much bicycle people love press fit stuff.

    Also this is pretty close to the time trial and aero bikes that integrate the stem into the steerer of the bike in front of the headtube or welded the bars onto the fork blades. No alignment needed on those either and equally difficult to adjust position.

    I agree that the most fun thing about Interbike is seeing people come up with crazy new ideas. That side of the show has been lacking for the last few years. Just hard to justify most of the inventions when current stuff works so well and has so little problems compared to 20 years ago.

    • Actually SunTour was simply copying what was the norm for many years. Go back and look at bikes equipped with Cyclo and Nivex derailleurs. Those derailleurs worked surprisingly well and were also quite light.

  5. This appears to rearrange things so now the freehub bearings (mounted in the frame) also carry the rider’s weight in addition to the bearings in the hub. Freehub bearings currently last so long because when they are under the load of pedaling they are not moving and when they are moving they are not under load. This design has both sets of bearings loaded by the rider’s weight.

  6. Referring to the 21.5 as a “standard” is way to premature. These are concept models, not production machines. I’ll be very surprised if either the new hub design or that headset concept ever see mass use.

  7. Increased chain wrap with give you longer wear, but shifts would be slower. This was an original derailleur design from the 30s and 40s, called the Cyclo, a French invention. Increased Q factor not a good thing, tho.

    One would have to dish the wheel to the other side, to compensate for the brake disc.

    Regarding headset, would work for time trial bikes, where the position of the bullhorns aren’t so critical, as long as the extensions can be adjusted up or down with spacers.

  8. This design also reminds me of a Regina freewheel, from the 70s, which would stay on the bike when the wheel is removed.

    The keyed bearing in the hub means more fishing around when inserting the through axle. But I don’t want to nitpick, this guy is pretty clever. Unfortunately, there are always trade-offs.

  9. This is what I think would be really revolutionary: a lighter internal gear hub. They solve a lot of problems that a traditional derailleur bike has.

  10. If roadies are worried about a disc brake rotor slicing them up how are they going to feel about the cassette just hanging out in the breeze?

  11. The issue is that the rear wheel is weak for heavy people, the spoke tension on the non-drive is is too low and there are many hub designs and spoke patterns that try and eak out every mm/tension. I had hoped that when the industry moved to disks brakes they would use the extra/new space to help fix the issue and they did not.

  12. The minute I saw that, I was hit with a ‘well duh!’ moments. F’n brilliant, so obvious but as far as I know, no-one’s thought about it to this level. Well done and I’d have it in a heart beat.

  13. Clevis to cantilever in the back and vice versa in the front? Which one is more efficient again?

    Plus somebody said there’s no such thing as power transfer and then went on to extol the virtues of intelligent questions.

    Contradictions abound. It’s all good though, we’ll get there in the end.

  14. I’ve seen quite a few crash on their mtb (incl. myself) and as a result, the stem has turned out of alignment. Easy fix here. But a D-shaped stem is more prone to breaking the stem, steerer tube, fork legs og wheel (weakest link!). Either way, you walk from here.
    Easy alignment is great, but I’m not convinced.

    • Kudos for noticing the easier/quicker wheel swapping. Excellent benefit; makes life easier: rear wheel changes wld be the same as the front!
      -> ALSO: Chain slap and chain suck are eliminated.

  15. Is this another “just out of school” project by people who do not ride bikes?
    Don’t have to be an engineer or even a mechanic to understand the huge limitations of both cassette and stem.
    Stop trying to re-invent the wheel.

    • If you did even bothered a quick Google, you’d discover that Veso is a master frame builder ( A fact I have been aware of for over 2 decades)… I can certainly appreciate a builder who thinks outside the box and pushes design & engineering in a different direction. Any industry needs people to look at the norm and re investigate it…this can & will cultivate better products. At no point are you going to be forced to buy anything you read about on Bike Rumor, so relax your B@alls

      • Huh, thank you.
        For Pinko.
        I raced some 11 years in ’70. UCI Amateur Junior and then Senior A. 9 years fighting with monsters from CCCP, Poland, CZ and the rest of Europe. I say the rest as those from Eastern Block were on the level of Pro guys. I stopped racing in 1982. Unfortunately.
        I started making frames in 1977, out of the need for better frame. Got Reynolds 753 certified in 1981.
        And school, I got some basic knowledge, but I left Mechanical University, after passing more than 20 courses, when Mechanic of Fluids and Thermal Dynamics came. I thought they don’t have nothing to do with my trade, and would blow my mind.
        Would you mind listing “huge limitations”?
        It would be really beneficial for me. I might learn something?

    • Congrats Pinko on proving how little you know about bikes! Mandaric has been around for decades. Lot longer than Cervelo, Focus, Canyon, etc.

    • The thing about the disc is that the bearing can still be optimally placed with relation to the loads the wheel sees. it’s the freehub side which is difficult to properly support. Cheap shimano freehub bodies that carry the axle bearings are the best we’ve got as far as distribution of force, so far.

  16. Very cool engineering !!! I love the thinking outside-of-the-box mentality ! I wish Veso much success and I look forward to other creative designs in the future.

  17. Clever drivetrain and always good to see people thinking outside of the box. That said, the design really does seem to borrow heavily from the past, namely the Nivex and Cyclo derailleurs (along with more recent SunTour models) and also the Cinelli Bivalent.

  18. Wow. It really does seem like Veso is really pushing the design envelope here. It may not be pretty, but it will get people thinking outside of the box a little bit more.

    I really like that idea of the top mounted bearing in the frame. I’m one of those racers that had a fork crack right under the stem in a race. Lotsa weight on a 130mm stem and a railroad crossing. That flush stem and top tube would look incredible on a TT bike where you could pedestal the aerobars anyhow.

    • I agree. I actually think the cassette mod is pretty standard (if not conventional). The head tube fork interface could be really nice after a little more development work.

  19. The first thing I thought of with the mid-chainstay mounted rear derailleur is heel clearance. When the driveside crankarm is pointed back, horizontal, your heel extends quite a ways rear of that pedal spindle. The custom design of that alternative derailleur would need to seriously take this into consideration.

  20. THIS is the next level. Now put the disc outside the triangle as well. For pro road racers (mechanics really) who do long races (tours) one of the gripes about discs is that tolerances on disc plane do not always equate to a lack of rotor rub on the pads. Love to see thinking outside the box. Its what we need.

  21. I don’t think anything about this design is bad. But since there’s this prevailing attitude in the bike world that puts bicycles next to computers, cars, etc in terms of tangible technological advancements from year to year, we come up with things like this that pass for “innovation”.

  22. This solves the problem of how to use a belt drive without having an “openable” seat stay. Combine this with a Gates carbon belt and a Pinion bottom bracket internal gear drive and you’ve got a bike that doesn’t care about mud and water. Also, without the cassette and derailleur back there, un-sprung weight is really reduced.

    • This is only really necessary if you go to 12+ external gears because of the inherent, extreme spacing/wheel dish issues.
      That being said, and once we get there, yeah as mentioned, there are a slew of benefits:
      1. Rear wheel changes/flat fixes as easy as the front bec the drivetrain is independnt of the wheel! Awesome!
      2. Cassette change and freehub service without removing the wheel!
      3. No chain slap or chain suck or it’s nearly impossible.
      4. Totally symmetrical rear wheel. No more funky left/right spoke lengths and lace patterns or hub designs = Simpler, stronger and cost less to make and wld offset cost of the proprietary freehub.
      5. Belt drive compatible.
      6. As janisbalodis pointed out above: potentially, front and rear wheels could be exactly the same, thus interchangeable = super ez to rotate tires to prolong their life.
      7. Just thot of this but it shld be #1 or 2: since wheel independnt from cassette/freehub, replacing wheel would also be cheaper bec rear wheels wld not come with a freehub body.

      Come t think of it, this is beneficial even without goin to 12+speeds!

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