If you’ve spent any time on two wheels, you’ve certainly experienced the woes of poor bicycle shifting. You hit the button or twist the knob expecting a smooth transition into the next gear, only to be met with angry metallic clanking that you try to push though but ultimately can’t. Bicycle manufacturers collectively spent millions attempting to remedy this issue with the likes of gearboxes, electronic shifting, and even belt-driven bikes. But Praxis believes to have a better solution in their prototype HiT system.
Rather then moving a chain between gears, their novel solution works by folding gears into or away from a chain. These gears are made up of four separate segments that individually pivot around an axle near the cog’s center. These segments are carefully timed to ensure there is no interference with the chain making shifting look like a complex mechanical ballet.
While the shift initialization is handled electronically, the gear folding synchronization is mechanical. The combination of electronic and mechanical systems brings near-instant shifting under load at rotational rates of 100 RPM. Make sure to scroll through the product page and watch the videos showcasing the mechanism!
The HiT gearbox is a strange hybrid between a derailleur and a gearbox. It doesn’t contain a clutch based gear change system or even a CVT as seen in the famous Honda bike of old. It’s fully sealed with more robust chains and no moving chainline as in a derailleur system. The prototype is configurable between four or sixteen speeds, with the four speed consisting of two folding gear pairs connected with a chain and the sixteen speed featuring a separate pair of folding gears. The output is either concentric to the input, or above the input for certain types of mountain bikes.
Despite the high level of polish, this remains a prototype and we eagerly await what Praxis does next with the system. In the meantime, make sure to check out this chainless e-drive bicycle.
I imagine it’s going to cost a lot too. Bicycling being the affordable hobby it is.
You seen the price of bikes recently?..
Bottoms dropped out.
Also KISS applies too. All the propietry kit is being frowned upon.
Thing is this is a mostly solved problem with things like hyperglide and clutched derailures.
Must be nice whatever you are, no such thing is happening here, partly because prices went up so far the drop in customers killed every dedicated bike shop, leaving only places that charge a significant premium or only carry garbage.
Cycling is a means of transport for way more people than a hobby. Like people who have driving as a part of their work and spend considerably more on a comfortable vehicle everyday cyclists want to have a comfortable way of cycling, too. Gears are one part of it.
Very true, but with the loss of dedicated shops in my area and the prevalence of mass produced junk that can’t upgraded like the old bikes it’s very much a premium thing. Adding to that, winter riding cannot be done with a conventional layout here, so those enthusiasts really are spending as much as car owners in some ways, at least until they are fully kitted out.
Personally I’m only set up for summer as a result.
“Cycling is a means of transport for way more people than a hobby.”
I am on the second group. I went to a debate about cycling in cities where i was the only one raising the ‘hobby’ part of cycling, riding enduro and biikng for fun in the forest.
I have a Pinion gearbox on one of my box. They are indeed expensive but as a heart attack survivor who learned his lesson: I see it as a luxury investment in myself. If I’m gonna torture myself to stay healthy, may as well make it a posh torture experience.
A low performance bike that is inefficient will give you a greater work out in less distance. Hit the trails on a beach cruiser with ape hangers. Probably swap out the coaster brakes though so you don’t wreck yourself in the dirt.
True! But since the heart attack two of my clinders have worn rings and bad compression. I need to make it easier not harder. Bought an ebike for that reason recently. Getting up there and age and gotta keep the maximum heartrate low. Don’t use nicotine kids, it ain’t worth it.
” But since the heart attack two of my clinders have worn rings and bad compression” LOL, good one! Hey, who cares the pace. At least your getting out and not staying on the couch.
Nice to hear you’re maintaining the activity with, most don’t.
Where are our really accessible body mods? Oh right, liability claims and DIY don’t play well together. Oh well, maybe we’ll be able to grow new valve tissue while you still need it. Too bad extra cylinders really aren’t on the table for now.
I invested in a bike with Pinion gearbox and gates belt a few years ago as well. Best thing i ever had on a bike. I commute to work all year on the bike, in a wet and cold (snow, roadsalt) climate.
Minimal maintenance compared to chain/derailleur systems, shifting the full gear range under load and at stand still and no chain oil messing up my pants and the bike is really nice. Maybe it’s not as good in transmission efficiency as a chain system, but the benefits for me are worth it, even if i have to pedal a bit harder and i had to pay more to buy the bike.
Yeah, you can spend $25K on a bike these days; but the few people who buy those are ones who know how to shift and would not be attracted by this kind of product.
Judging from the off center shaft rotation I think this design is just a cam lobe mechanically actuating the gear in and out. This would actually be pretty easy to machine mechanically if done in bulk. Though for a hobby job shop it would be super cost prohibitive.
>twist the knobWhat is this, 2001?
>metallic clanking that you try to push though but ultimately can’tBack in 2001 knowledge on how to properly adjust derailleur (and maybe diagnose faults like bent hanger or even something as basic as a worn chain) was a closely guarded secret. In my provincial town of some 30k residents there was only one dude dealing in that. He literally built a large house, bought two brand new BMWs and sent his kids to the college by importing, selling and then fixing cheap chinese MTBs. But this is not 2001 anymore. You can find dozens of high-quality video tutorials on YouTube. Basic (but not made of tofu) tools required for derailleur adjustment are like $30 delivered. There’s no excuse for riding a badly maintained bike nowdays. Even the BBB-4 book can be easily found at Anna’s if you can’t afford to spend $29.
I’ll still take mine to the bike shop as he does adjustments every day. Comes back all ready to go.
Neat tech above. Someone is always thinking!
switching to a larger (more teeth) gear while under maximum load is effectively impossible, regardless of how well-adjusted it is or what fancy derailleur you bought. if you don’t agree with me then your legs are weak haha
Impossible for the rider you mean? It looks like the transmission might be able to handle it as it folds in the gear segment when the chain is/would not be in contact with that segment of the gear.
“switching… while under load…”
Sooo…
Operator error makes things work bad… What a revelation.
In other news, keeping your engine at redline and trying to shift without your clutch is going to ’cause extra wear’…
I have never understood people who use a thing wrong, then complain about the bad experience.
Everything has flaws.
Learning how to work with those flaws is a requirement.
A literal requirement, not a suggestion.
I’m sure the gearbox highlighted in this article has flaws too, including being MUCH more expensive, mechanically AND electrically complex, and having more/different failure modes, among other things.
Even if it solves a “problem”, the operator still needs to use it properly, which is antithetical to it’s marketed purpose.
haha man yeah let me tell you a story…i’ve got 300lb of roofing supplies on a trailer on the back of my bike. okay, because i’m a moron. but at least this trailer, i actually engineered it for 300lbs before loading it up (unlike the previous trailer)
anyways, i think to downshift before i hit the one small hill in my journey, but i don’t downshift enough and as it slowly steepens i realize that what i’ve come to think of as ‘soft pedaling’ over the past 2 miles of dragging this thing around is in fact awfully close to what would normally be called ‘maximum load’ and in fact i don’t have any headroom to take the load off enough to shift. so i strain and strain and bend the shift lever, to no avail. and i can’t make it, so i stop. and now even though i shifted it manually while it was stopped, i have to get it going again from a dead stop on a hill. i barely pulled that one off.
so tldr: can confirmr. ‘requirement’.
I had that kind of experience last year without a trailer, on my road bike, but it was a nearly-20% grade and I thought I could power up it in the 42T middle ring (and the biggest (26T) cog. I was wrong, and I couldn’t keep it up for the duration, and had to go to the granny ring. That was my fault though. My eyes were bigger than my stomach, figuratively speaking, for this climb. I was forced to stop, shift, and go back downhill a bit to get clipped back in, and then try to turn around and head back up. That’s extremely rare though. The key us just anticipate the need for the lower gear early enough that you can soft-pedal for a turn or two before you get into trouble!
/me laughs from the 1970s. Derailleurs always were easy, and we only had books to learn from.
You had a book? We just had SWAG
And even before indexing, when we had down-tube friction shifters and only five cogs on the freewheel, we’d operate both levers at once with the right hand while braking with the left, and do it perfectly.
Sheldon Brown
There was and is a website. Just wasn’t easy to find without the right keywords.
Or you could just buy a 7-speed internal hub and not have to mess with a derailleur at all.
Or more – I am commuting on an 11sp internally geared Shimano Alfine hub, it works great, they’re cheaper than a regular drivetrain, and I get to tell people I changed my oil… on my bicycle!
“no moving chainline as in a derailleur system”
Maybe the primary chainline does not move but there is clearly a moving chainline in the video, So now instead of ONE chain that you can easily access and correct in a failure, you have 3 chains, two of which are locked away when they fail.
i don’t think that’s true. i don’t understand how it works but they’re explicit that the internal chains do not move laterally either. i am extrapolating from one photo, but it seems like the larger gear is itself made of four components, each quadrant hinging in and out of the chain line.
not saying it’s good but it does not seem to move the chainline, period.
There is no moving chainline, as the chains do not move from side-to-side. That’s nice.
However, I don’t really see the point in this system. I don’t see how it could support more than 4 gears without a lot of hassle and duplicated components. They are extremele vague about this, so my understanding is that they could just add another cluster with 4 gears, but that means extra chains, idlers, probably another freewheel or some clutch to decouple the different clusters, extra actuators, etc. — that’s hardly cost effective nor weight efficient. Of course they’d like to target the electric bike market: motors can overcome low efficiencies easily, and looking at the solutions on the market, neither designers nor riders know how to ride a bike properly, so shifting under full (motor) load is quite common. This is a system that can provide a wide range of gears (albeit few gears overall) with a robust transmission that can be shifted under heavy load.
It’s nice because it’s innovative, but I really don’t see the point. They don’t even want to publish their measured efficiency, excusing themselves that they are a small team and measuring the efficiency is just too much work, etc. etc. etc. — that’s a load of rubbish. Of course they know the efficiency (it’s not that hard to get some ballpark measurements of drivetrain efficiency, even hobbyists have been collecting measurements of various systems), and if they don’t publish it, it’ll be quite bad.
Would it be possible to combine two motor/generater units and a planetary to make a prius-like electric cvt?
the idea of a gearing system with non-interference meshing is attractive. just plain neat. the idea of a gear that folds in the middle is preposterous, but maybe outrageous is just a synonym for “bold” or “innovative.”
the idea of having all of this sophistication inside of a sealed box so that the grease doesn’t turn black and abrasive with road grime is definitely attractive too.
but this is an absolute non-starter, because it seems to require a new bicycle frame. one of the biggest things hindering adoption of belt-drive (which i would like to use) is that it isn’t just a drop-in replacement. this gear box has that problem on steroids. literally precisely zero people will drop this in as a replacement on an existing bike, because it isn’t possible. it will only be available on bikes that are purpose-built to sell this component, and that will be a very rough road to travel, even if they work out all of the weaknesses and make a very functional product. i could imagine it being included in some specialty bike, e-bike or cargo bike sort of thing. hard to imagine it standing out from the competition enough to catch on.
it reminds me of the constant battle with maintenance…when i started as a teenager, i never wanted to do any maintenance. and as i became aware of the importance of maintenance, i started looking into products that minimize maintenance…and it took me a long time to accept the reality that it doesn’t really work that way. there’s nothing that you ‘just works’ forever. at best, your window between maintenances might be twice as large. a better chain lube might go 2 months instead of 1 month. but i had already been in the habit of oiling it every 3 months (and all of the downsides) before i even read about the magical 2 month lube!
so i have always hated derailleurs because they become very frustrating as they express their need for maintenance. but i recently learned, on my 1990s mtb, the derailleur that i had kept frozen in one position for a literal decade of winter biking…all it needed was wd40 and elbow grease. that’s a level of maintainability that will be very hard to match, even on a product that is sealed so it doesn’t pick up road grime.
these days i delight in the ease of maintenance rather than the dream of foregoing it. for example, i lube every week now with a one-step clean&lube product. those sealed internal gears will last better than exposed gears, but they will still need to be replaced. so i like the gears i have that i know how to replace.
there is nothing “non starter” about something like this because it doesn’t work on an existing bike. there are like dozens of successful e-bikes on the market that are designed around specific drive units not made by the frame manufacturer.
yeah like i said it could easily be integrated into an e-bike because they’re already building custom frames. ‘successful’ is an interesting description for e-bikes so far. certainly there are sales volume successes but in my limited exposure they still all seem like one-off prototypes to me. i don’t think any company or design has won the market or shown any staying power yet.
the question for this company is whether the one ‘me too’ e-bike manufacturer that gambles on this gear system somehow outcompetes in a market with so many flops and niche dead ends.
one of the real problems of something like this is that if it is extremely awesome and extremely rare, then when it breaks you throw it away and it disappears entirely. without mass adoption, there’s no way to maintain it or even to justify development of a version 2.0.
Why would you expect one ebike manufacturer to ‘win’?
But yeah, this tranny ain’t going anywhere.
For this much effort, cost and weight, you could install a bicycle sized Muncie style 4 speed with gears and shafts.
Have a bike with a H shift pattern, would be cool.
Shell heads are a pretentious, weird bunch though.
No telling what they’ll buy, except it will be obviously expensive, useless to them and impractical.
i wouldn’t expect one ebike manufacturer to win, but i do expect one ebike design to eventually win, more or less. after a fashion, the parts will standardize through a process of attrition and value-engineering.
just like they have with normal bikes. i’m not clear entirely on the timeline but these days, in the middle of the US, most bikes i run into (keeping in mind that i never do anything top-of-the-line) have basically compatible sets of components….whereas i have stumbled on lots of evidence that there used to be an enormous useless diversity and incompatibility.
though i did just meet a “20 inch wheel” with a 12mm ID bearing…wanted a 1/2″ one. so there must be some parallel worlds out there
Unfortunately Greg there is still a log of incompatibility today in bikes. Frames and forks made for rim brakes can’t take disc brakes, and vice-versa. Most newer high-end bikes take thru-axles, not the regular quick-release type. There are lots of bottom-bracket bearing types (but I’m glad that it sounds like at least they’re getting away from the press-in types that drove people nuts with their creaking!). Many frames require seat posts that don’t fit other frames. Then there are lots of mutually incompatible freehub body types. (Why can’t they just standardize on HG?!) And there’s more. Wayne has a Rumble video channel Waynosfotos where he shows various problems with the industry’s new stuff which it uses to try to grow in a flat market by convincing us that what we have is not adequate and we need to buy the latest thing, and it runs the prices out of sight, and then it laments that it has warehouses full of bikes that don’t sell!
Get a Rohloff. That is as close to no maintenance as you will get on a standard bike frame. I’ve never ridden on a Pinion but I assume they are as “no maintenance” as a rohloff, but you have to have a special frame for them.
Every 6 months you drop the oil and put a syringe of new oil in. Nothing ever needs adjusting. Nothing ever misses a beat.
With regular derailleurs, the only maintenance issue I’ve had is that a couple of times the front derailleur has kind of frozen up and needed a little lube and working it back and forth to free it up. My rear derailleurs have never needed any maintenance after I went to ball-bearing pulleys some 60,000 miles ago. (The Shimano pulleys that claimed to have ceramic sleeve bearings were terrible.) Same goes for those of my family whose bikes I maintain. As for our chains, see my graphite-and-paraffin chain-lube method that gives me at least 20,000 miles on a chain and cassette and they keep themselves (and the rest of the drivetrain) clean, at http://wilsonminesco.com/bikes/chainwax/
it’s certainly neat tech. but the thing is already the size of an e-bike drive unit. partnering with a drive unit manufacturer to package it into something practical seems unrealistic. it will be relegated to bike trade show vaporware.
Very cool looking, but I’m skeptical about the wisdom of passing my motive power through an expensive gear that splits into 4 separate hinged arcs of metal each time I shift. Not to mention the electrical aspect.
When I break a chain I can just pull the spare from my saddle bag. When this thing breaks I feel like I’ll need to cancel my plans for the week.
Maybe there’s a cheaper way to compensate for the cables stretching.. like if there was maybe some kind of adjustments we as consumers could make to the cable to make it shift proper again.
That would be cool, but Elon musk would prolly have to solve it.
Has no one here had the pleasure of riding a bike with a proper set of derailleurs? Yes, the cheap stuff on WalMart bikes is horrible, but Shimano or Campagnolo’s higher end stuff that goes on competition level road and mountain bikes? It has none of those issues, even with two wildly different sized chainrings up front. Yes, it requires minor adjustment once every year or so to keep it shifting like a clock, but it’s much more maintainable than this ever will be.
It’s cool that they invented this, but it’s a solution in search of a problem. It’s also got to be so heavy it’ll only go on e-bikes, at which point why not just stick a belt-based CVT on it? Still less complex than this.
At first sight this looks interesting, but this moving of those 4 segments looks quite complicated, and thus heavy and expensive. (But apparently it’s still in the prototype stage, so it might see improvements) As an alternative, bicycle gears are are usually made of quite thin metal, If you cut a gear wheel open on one side, you can easily bend it into a slight spiral. Such a spiral can be moved into the gear path tooth by tooth. (And of course the other gear moved out of the way). This would look more like the classic gear stack for a derailleur, but with the gears moving.
Another option would even look more like the classic derailleur. The simplest would be to simply move the gears themselves over a spline (so keeping the chain in place), Shifting can be improved by canti levering the gear stack into the chain path, and then half a turn later, put the gear stack straight again but shifted into the new gear.
Yet another system I would find interesting (but have never seen in the wild) is to integrate a shifting method into the front sprocket. Some thirty years ago I had a Shimano Biopace (one of the first “not round” sprockets) and thought it was kinda neat, but was not really convinced of it’s effectiveness. Only when the sprocket was worn out and I replaced it again with a round sprocket, it became obvious to me how much I liked the biopace sprocket. But still, it was quite expensive, and also went off the market. In the last 10+ years other brands of “not round” sprockets have become more common. It should be possible to move segments of such a sprocket radially to change the sprocket diameter. Skipping a few teeth is not a big problem, with bigger gear ratio, extra segments could be put in between the other segments.
I disagree. Contemporary derailleur bicycle gears are fabulous! They’ve even worked-out the ratios, so you get super efficient acceleration. It will take some effort to improve on what we already now have.🚴=-
No one is going to call out how this is a copy of Veer?
This looks like gratuitous use of bicycle chain, to build a gearbox. It’s pretty and it’ll meat expectations, very “bicycle”, but would you buy that for your car? Motorcycle?
Looks like whenever not all of the segments are engaged, the rotations will be uneven?
I’m not bike expert, but this seems kludge compared to a planetary gear hub. Are there any advantages to that thing over geared hub? It’s bigger, more complicated, requires electronics, and has to be heavier.
Why would you need transmission on an e-bike? Aren’t e-bike electric motors constant torque?
This gave me an idea (that likely wouldn’t work).
A small gear made of individual slices that expand out as you shift.
My dad purchased one that worked like that in the late 1980s, it wasn’t great. Maybe it was just the way that they implemented it that was the main problem.