The drivetrain of most modern bicycles has remained relatively unchanged for nearly a century. There have been marginal upgrades here and there like electronic shifting but you’ll still mostly see a chain with a derailleur or two. [Matthew] is taking a swing at a major upgrade to this system by replacing the front derailleur with a torque converter, essentially adding an automatic transmission to his bicycle.
Most of us will come across a torque converter in passenger vehicles with automatic transmissions, but these use fluid coupling. [Matthew] has come up with a clever design that uses mechanical coupling instead using a ratchet and pawl mechanism. There are two gear ratios here, a 1:1 ratio like a normal bicycle crank and a 1.5:1 ratio that is automatically engaged if enough torque is applied to the pedals. This means that if a cyclist encounters a hill, the gear automatically shifts down to an easier gear and then will shift back once the strenuous section is finished.
[Matthew] machined all the parts for this build from scratch, and the heavy-duty solid metal parts are both impressive but also show why drivetrains like this haven’t caught on in the larger bicycling world since they’re so heavy. There have been some upgrades in internally geared hubs lately though, which do have a number advantages over traditional chain and derailleur-based bikes with the notable downside of high cost, and there have been some other interesting developments as well like this folding mechanical drivetrain and this all-electric one.
Thanks to [Keith] for the tip!
NO.
Slushboxes were a bad idea for cars.
Wow there’s a term I haven’t heard in a while. I generally agree, and students should still be required to learn on manual, it’s better for overall mindfulness
It says right in the summary here that it’s NOT a fluid coupling (aka slushbox); it’s a mechanical ratchet. Other than the tiny fraction of a second while the pawl flips, one gear or the other is 100% engaged all the time with nothing slipping.
What witchcraft is this that you know the contents of the summary?
Looking at the design, the gear teeth are aligned in such a way that slippage at most would be equivalent to the backlash of the smaller gear.
What I am more concerned with is the sound in low.gear.
Automatic transmission ?
Is this for using your bike in North America ?
lol
huh, a bike tech “innovation” i don’t outright hate on sight, those are rare-ish.
it’s basically a two-chainring front gear arrangement with the front “derailer” automated based on crankarm torque, i guess? i’d like to have seen more details of how that switching/ratcheting system works.
i suppose it actually might have some use cases, for some riding styles at least. not all riding, but perhaps enough to find a niche. although i can foresee a separate little devil hiding behind every gear tooth and bearing ball, never mind all the other details, but i don’t think there’s necessarily any totally unsolvable issues with it. barring maybe that infernal ratchet-clicking noise in high gear, dunno how you’d shut that up.
wonder who else have tried this in the past, and how and why it failed for them? because bike design is an old enough field that this obvious of an idea just cannot have never been tried before.
The classic bicycle chain and derailleur is one of those fantastic examples of an “optimal design,” up there with the rifled barrel and the aeroshell and several others. Additions and tweaks can occasionally be made, usually for the purpose of spinning up a new patent to sell… But generally they will still be in use and look very similar in 300 years.
The laws of nature have created an emergent form which is by far the best one, doesn’t require extremely advanced technology to discover, and the threshold to exceed it is high enough that it won’t go out of style until we discover gravity manipulation or whatever ultra-futuristic technique. So we are stuck with it.
This creates a very unique temptation for the engineer. Everyone wants to usurp an optimal design, it brings eternal renown to the inventor. There are all sorts of new designs for transferring power from the crank to the rear sprocket… But it’s going to be incredibly difficult to defeat the economy, efficiency, simplicity, repairability, weight, compactness, and dozens of other qualities that the chain and derailleur absolutely nails, and nailed a long time ago.
You can apply lots of advanced tech to the problem and still lose to what people figured out in the nineteenth century. But it makes for a great education and entertainment to look into the long line of innovations and oddball mechanisms people have attempted over the years.
See also: shoelaces
It just blows my mind that nobody has invented something better. But I try alternatives pretty much every chance I get, and it’s true: nobody has invented something better. Side-zipper boots are pretty great, but mine still have laces to fine-tune the fit.
Elastics and Velcro are better but Velcro makes you look old.
Velcro and elastic both suck.
On closer inspection, these are loafers
+1
I paid 5$ for a pair of Shimano (gears) shoes a thrift store. I am not into high end biking just year round street use. When I pulled those 3 Velcro flaps down and pressed them tight I realized I’d never go back to that extreme dexterous litigation again. Velcro, good enough to keep you stuck to your spaceship during an EVA. Haven’t worn a tie in half a century. I have slip on shoes now as well. Seeing all those XXXXs on shoes is ugly too. Zipper on a shoe what a joke, it’d jam up for sure and is not adjustable.
Having to tell a young piano mover when the hip style of floppy strings was vogue and could be stepped on by any of us while coming down the ramp they had to go. Scissors or tuck ’em in. I used to have a few gear-string events till they got cut short. For safety’s sake cut ’em short and then you won’t to deal with them at all. Tying them more than once in a day, fail.
I’ll have to admit having become rather fond of the bunggie laces, but very specifically the ones you need to loosen and re-tighten them each time you put on or remove your shoes. The squeeze and slide a clamp style.
If you want a more progressive tension curve? Run a double set of laces in the shoe (assuming the eyelets will fit two laces) Lets you have a comfy fit but yet the steeper tension curve helps keep the shoes from being as prone to slipping off with a twisting step or some other maneuver.
I moved to a very flat city and did away with derailleurs all together. One speed, fixed hub. I do have a single front brake in there for… being annoying I guess? Haven’t touched it in 5 years.
My bike with a steel frame is bulletproof, I do zero maintainence and it is so light I can pick it up one handed and carry it up three flights of stairs to the office. I’ve had the frame set for almost 15 years, paid maybe $300 for it plus another $100 for wheels and the rest of the hardware I had laying around.
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If that isn’t perfected technology I don’t know what is.
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I am so fortunate to ride a coupe hundred yards to a nice bike path then near work the brief non-path part is through residential area with nice wide bike lanes.
I haven’t really paid attention to this stuff in years. But used to be (if long enough) the derailleurs travel limit screws could be run enough to push the derailleur chain guides in a bit.
Often you could get them shifted enough to set to align with a second sprocket in the stack.
This was a trick for if your ( under tension type ) shifting cable ever broke.
And yes, we ($ort of broke boomer) kids actually did this type stuff sometimes on the road.
Now days you can’t carry a pocket knife anywhere, that we kids used to turn (abuse) screws.
So you’ll need to have a tiny screwdriver twist wired under your seat or somewhere hidden. Use a bread tie wire or something that you can untie with your bare fingers and -not- a zip tie.
Might need to change to a bit longer derailleur stop screws, assuming this idea still is applicable for you.
Happy pedaling on your “classic” (cough, old ) iron, to all.
I just carry a pocket knife. Unless a law actually changes, I’m not going to let shame turn my tools into weapons.
I’ve been riding fixed for many many years. I love it. I live in the Netherlands and this country is as flat as a ruler. I pump up the tires and every few years, I replace the tires as they are worn out or dried out. Oh and once a year a tiny bit of lube on the chain. Have owned one of them for 20 years and that’s all the maintenance I’ve done. It lives outside.
The ovoid gear to even out the pedaling cadence is probably the most recent actual improvement on the bicycle. Simple to understand and implement, and assuming you already have a derailleur or other chain slack gathering mechanism it does not introduce any more points of failure.
It could be produced by a hobbyist using a machine cut blank and some hand tools or a lathe. But I’m not sure if the patent still prevents copy-cat products.
The simplicity of a wireless pinion is definitely my choice in complicated bike transmission. This is intriguing, but just.
The only way an automatic would work on a bike would be to have to accurate GPS so the bike would know to downshift before the hill not part way up. I found a discarded bike I wondered why, it had a flyweight shifter built in the rear wheel. It was almost unrideable. Always changing unless you kept steady speed in between the shift points. No thanks I scrapped it. The shifts were unexpected and dangerous at times. Automatics in cars sense throttle position or engine vacuum so they know something is about to change.
yeah that’s exactly what was in my mind as i tried to imagine what it would be like to use this thing. but i’m a single speed guy so wanting to pair any amount of torque with any RPM is pretty ingrained in me. i can only guess that people must be able to learn how to use an automatic transmission (though perhaps not the one in this article)
As soon as I saw the grinding wheel being used on a lathe, with nothing to keep grit off the ways, I stopped watching. I don’t much care for gore videos.
This was already commercially available from Sachs 50 Yeats ago. Since SRAM has aquired Sachs it is sold under the name SRAM automatix. It is mostly used in bikes for little childreen, since they do not yet comprehend how to manually shift gears.
What about when you wantto increase speed on the flatterrain? Will it downshift and stay, preventing achievement?
Kudos for the effort and result, and I wish I had the patience to learn how to do all that machining.
This thing looks every bit as heavy as my bike’s Pinion 12 speed gear box.
I don’t think a torque converter is involved in this product. It is just an automatic gearbox.
I like the ones that use a governor to shift a standard derailleur. Like the LandRider AutoShift.
Or the AutoBike SmartShift 2000 https://www.disraeligears.co.uk/site/autobike_smartshift_2000_derailleur.html
IMHO, IF I am to design such a thing (entire drivetrain) for a bike, I’d probably look into a small flywheel inside the pedal hub that also doubles as a magneto that drives electric motor in one of the the wheel hubs. Wait, no, I’d probably have two wheel hubs, again, with a reverse magneto inside (and not permanent magnet brushless thingie, which seem to be the cheapest thing I can procure for under $300 total).
Reason being, throttling electricity is not only simpler, it is also lightweight and doesn’t require mechanical solutions (with their own predictable limits, btw). I’ll also have spare electricity for things like lights/blinkers/controller aplenty. Oh, and adding a supercapacitor bank for helping out up a hill (while generating extra whilst rolling downhill). I suspect ordinary/ubiquitous op amps can do the “computing” and I also highly suspect that this has been done before by people smarter (and more capable) than me, just supercapacitors (and lipos) weren’t invented just yet, so their solutions languished in relative obscurity.
Not because I have some electrical engineering background (not a lot, but enough), but because my whole life I’ve been riding both kinds of bikes, single-speed and advanced speeds mentioned aplenty, and I hated both for their idiosyncrazies (pun intended). Neither one is robust enough to my liking (low-maintenance, ideally, maintenance-once-upon-a-blue-moon), and the local economies of scale what makes one more affordable than the other (sadly, the mentioned nightmare with the derailleur), but this is one place where there is way too much noise and the best solution is steamroll everything (ie, ignore) and start from scratch.
Now about robustness, yes, anything electrical tends to burn out and quit at the moments least expected. Yes, a proper safety shutdown kind of Plan B has to be built in, which brings another point – maybe even op amps are not ideal, and it can be just ordinary coils and few solid-state stuffs like diodes and relays. Back to magneto, it only needs a “starting voltage” to make it work, while AA battery may not have enough juice to kick-start a 12v magento (not enough power to power the internal coil), supercapacitor sure will.
Thinking “I am not the first one down this rabbit hole” and “just HOW complicated THIS can be?”