Bicycle Adds Reliability With Second Chain – Hackaday

Ignoring the International Cycling Union‘s mostly arbitrary rules for what a bicycle is “supposed” to look like (at least if you want to race), there are actually reasons that the bicycling world has standardized around a few common parts and designs. Especially regarding the drivetrain, almost all bikes use a chain, a freewheel, and a derailleur if there are gears to shift because these parts are cheap, reliable, and easy to repair. But if you’re off grid in a place like Africa, even the most reliable bikes won’t quite cut it. That’s why a group called World Bicycle Relief designed and built the Buffalo bicycle, and the latest adds a second gear with a unique freewheel.Bicycling YouTuber [Berm Peak] takes us through the design of this bike in his latest video which is also linked below. The original Buffalo bicycle was extremely rugged and durable, with a rear rack designed to carry up to 200 pounds and everything on the bike able to be repaired with little more than an adjustable wrench. The new freewheel adds a second gear to the bike which makes it easier to use it in hilly terrain, but rather than add a complicated and hard-to-repair derailleur the freewheel adds a second chain instead, and the rider can shift between the two gears by pedaling backwards slightly and then re-engaging the pedals.Of course a few compromises had to be made here. While the new freewheel is nearly as rugged as the old one, it’s slightly more complex. However, they can be changed quite easily with simple tools and are small, affordable, and easy to ship as well. The bike also had to abandon the original coaster brake, but the new rim brakes are a style that are also easy to repair and also meant that the bike got a wheel upgrade as well. Bicycles like these are incredibly important in places where cars are rare or unaffordable, or where large infrastructure needed to support them is unreliable or nonexistent. We’ve seen other examples of bicycles like these being put to work in places like India as well.Thanks to [Keith] for the tip!Interesting idea. I really wonder how well two chains will work: You need two exact lengths, they’ll stretch and wear differently, and sooner or later a chain will be thrown.And that plastic chain guard? How long will that last? Fortunately non-critical to function, and cheap and easy to replace.Didn’t watch the video I see 😉
Check it out around the 4-minute mark.I carefully watched the whole thing prior to my post, which prompted my question. If you missed the issue, that’s on you.The whole rear wheel slides to adjust chain tension. The chain guard is metal.Yes, the rear one might be metal, but I’m taking about the obvious one in the video thumbnail: The chain guard over the chainring/chainwheel at the crank, very much looks like injection-molded plastic.it’s not plastic. it’s metal with a matte coating.Sure about that? Got a reference?
The manufacturer says a very similar-looking one is plastic.
https://wheeltop.com/products/wheeltop-city-6That doesn’t seem to me to solve the 2 chains that need to stay tensioned though – a sliding wheel can tension 1 chain easily, but when both chains are it seems sharing axles at both ends and the frame seems to be simple and rigid with no extra trickery then once chain 1 has got tensioned if chain 2 is still loose there is nothing you can do about it. Going to have to look at this thing in more detail to really figure out how its supposed to work maybe there is some trickery to deal with a more worn chain/sprocket that means the two won’t get proper tension.Go to 6:40. They just fiddled with the ratios and found a compromise. The chains don’t carry the same tension.Yeah got a good look at it now, and that really doesn’t fill me with confidence in its longevity, chain and sprocket wear, and in those sort of conditions probably quite badly and that looser chain to me looks not that far from skipping on its own at the start. I can see a simple chain tensioning addon being made relatively soon as if you use your bike lots for a few years in harsh conditions… Probably to keep it simple and rugged just a smooth block the chain can rub over on a screw adjustment to provide that adjustable tension.But maybe the two chain and sprockets all wear close enough to each other that it is really reliable enough, and even if its kinda terrible the parts are actually pretty simple and cheap. So easy to maintain really.I was surprised they didn’t include some sort of chain tensioner on the slack chain. Even a crude one without a spring would have been easily field serviceable. You really have to hope for equal wear, or more wear on the tighter chain.Indeed, though as the parts are simple and cheap I guess as long as it lasts long enough to be worth having the second chain that isn’t a bad thing – on such rugged terrarin its certianly far more simple, durable and repariable than any other gearing system I’m aware of. Plus any trouble pull off the bad chain and adjust the rear wheel to tension the one you need – back to be single gear, but at least that gets you home without as much hassle walking the bike (I did that once, though in this case it really was carrying on the shoulder didn’t want to risk pushing it after a vandal got to my bike at the train station as it really wasn’t fun, can’t recall if that was the bike with suspension or not but either way a steel frame as I’ve always gone in for durable and cheap).I assume you start out less than one link different?I wrenched in a bike shop for many years, and competed semi-pro for at least a decade.
I’m pretty comfortable with bike failures.Most of these feel like they were designed by people who don’t actually ride bikes. That chain is going to break WAY before the other components.They spent how much effort getting rid of the derailleur to make the bike repairable with an adjustable wrench? Id love to see them change a chain with just an adjustable wrench. No cheating with universal links. Those are the weakest part of a chain so you would be asking for it to break again.Derailleurs do break. I’ve seen it happen…maybe 15 times over the (literal) many hundreds of bikes I have worked on.Compare that to the…40+ chains I have personally broken?
universal links.
I thought all chains were adjustable? You know when you punch through the centre of one of the links and the pin comes out?Most modern chains either use a master link that has some sort of clip/retention mechanism, or they use single-use pins that are pressed in and then crushed to make them essentially non-removable. You can remove a pin by pressing it out, but can’t add links back in and expect them to work well.
Which is dumb and frustrating and a consequence of people wanting to have a huge number of gears on the cassette.i did this thing where id use progressively larger flat edge screw drivers, a hammer, and a block of wood. you would locate an outer link, place it on the wood block (this is mostly to protect the floor, outside id just do it on the asphalt) jam the small screwdriver between the plates and thwack it with a hammer, move up to the next biggest driver and repeat, by the time you finished with the third the plate would be free. to reverse the process, push it on with pliers until it clicks, then mushroom the end to hold it all together. you can just use a small ball peen hammer for that, but i made a custom tool by cutting off a surplus screw driver and putting a dimple in the flat at the end. this would both push the link on and deform the end of the pin to keep it on. master links are for noobs.If you don’t have a master link, you need a chain-breaker tool, which is a specialized tool that isn’t useful for anything else, which goes against the supposed point of design goals of these bikes.As a bike mechanic you should know that single-speed chains are thicker and more durable than multi-speed chains. You should also know that it’s trivial to change the chain without breaking it on a single-speed, especially ones with reversed “horizontal dropouts” like this one. You slide the wheel forward, take the chain off, put the new one on, and slide the wheel back into the mounting position.These are not fred bikes for triathletes. They’re tanks and they’re sold in department stores all over Africa and the manufacturer knows exactly what they’re doing. I rode the previous model all the way around Lake Naivasha a couple years ago, and it was great.Are you some kind of 5th-dimensional being so Euclidian geometry doesn’t matter? Chains go /through/ the rear triangle on a bike that doesn’t have a motorcycle style swingarm. You have to break the chain to get it fully off of the bike. The dropouts have no bearing on the situation.loosen dropouts, push hub forward. derail the chain from the front sprokets, this gives enough slack to be pulled around the axle. I dunno man. seems easy enough. if you gotta break chains to get a wheel off, you’re doing it wrong.Might add for some of the other comments here. I rode street bmx for a long time, not all chains are created equal. I bought a specialized (not the brand) chain where there are no inner vs outer links, they all start outer and go inner, never broke that chain… busted every other chain every few rides or so. And this is with doing sprocket stalls. If you want to find out what breaks all the time, find a heavy street bmx rider. We break everything.There is also something to be said for properly torquing your bolts. Without proper tension, everything will bend and shear. Conversely too much torque and your bearings will smash and bolts will shear. Quality hardware makes a huge difference when you’re beating the living tar out of a machine. Specialty shops like dees fat nutz make special hardware just for the people that use and abuse their bikes.OP was specifically talking about getting a chain off without breaking it. Know any tricks?The whole question is a red herring, since you can just literally break the old chain on removal. Get it loose and bash it with a rock or something. I’m sure you can wedge your adjustable wrench in there somehow and twist it until the pins come loose.Did you even watch the video? I bet you haven’t, you’d rather be busy typing a rant for 10m than watching a 10m video :facepalm:But how many of the bikes you work on are used in such unforgiving terrain carrying so much weight and can’t be serviced and washed after each use??? There is a reason why bikes that are expected to get a lot of abuse do not use a derailleur.I guess that depends.We had bikes that were loaded with panniers and used to ride cross continent. Lisbon to Beijing if I remember right.But about half of our bikes were owned by 15 year olds who fix everything with a hammer and a vice-grip, and the salt air around here eats everything. Mostly 20″ BMX, flatland, and various half-pipe or dirt jumping bikes.We started sourcing stainless parts and packing our bearings in marine grease because the kids kept building ramps at the end of the piers and jumping their bikes into the ocean.I’ve seen one-piece cranks snapped in the middle because the kid jumped into the ocean in the fall, hit it with a hose, and then put the bike in the garage for the winter with a bottom bracket full of salt water.But I’ve also been deployed to the desert since working in that shop, and I’ve seen what dust and dry can do to equipment too.
I know there are plenty of other awful environments than I have experienced servicing.I wasn’t suggesting that they use multiple years or derailleurs.
I think their gearing system is interesting.I just think that the chain is going to be the biggest problem their bikes have, and they haven’t solved that problem at all.I don’t know what ‘Africa’ is supposed to mean in the author’s mind as it encompasses more than 50 wildly different countries that are very much not off grid but being born and having spent a significant amount of time on that continent I can assure you that you will have an easier time finding a place to repair your bike over there than almost anywhere in Europe or the US.And by repair I don’t mean just ordering a new part to swap and call it a day, I mean actually welding parts back together or patching air chambers and tires.Every major city in Africa has a marketplace where you can find and have repaired almost anything mechanical/electronic.Meanwhile in Europe people will throw microwaves, laptops, and washing machines the second they hear a weird noise“Meanwhile……….the second they hear a weird noise”Amen brother. It’s a ridiculous shame. Repair is good for the environment and the people. With notable exceptions of course.While there seems to be disagreement on this bike, it is fair to say that even considering serviceability is a positive thing, especially with so many other entities trying their hardest to discourage it repair and longevity.I saw Buffalo bikes (the previous model, not this one) in Eldoret, if that helps.I’m pretty sure the company producing those bikes knows exactly what Africa is like, and what the repair infrastructure is over there.
Meanwhile in Europe people will throw microwaves…
Last time I heard a weird noise out of a microwave, the magnetron burned out. It would have been illegal for me to fix it, since I’m not a qualified appliance repair technician. Not to mention I had no spare magnetrons for that model. Maybe you could pull a magnetron out of another microwave and cross your fingers that it works, but the results would have been somewhat unpredictable and hazardous.There are good reasons why people shouldn’t go poking inside mains powered electronics.And for the price of hiring a technician instead of some random guy off the street at the marketplace that is no more qualified than I am, I could buy two new microwave ovens.I prefer not being obligated to spend all my money paying people to do things only for them to often cause more problems than I would have, so it’s a shame you have to deal with that. But often microwaves with a rotating tray might have the tray slip a bit and squeal, and that’s really not something to toss the entire thing over. Plus, ought to salvage stuff from something that’s not itself fixable sometimes. And while people cause themselves a lot of trouble with microwaves, they’re still not particularly unpredictable, people just poke around without taking the time to figure out everything about what they’re doing.My mom’s bike from the late 60’s/early 70’s has a two-speed rear hub that changes gears by pedaling slightly backwards. Uses a single chain and from what I recall it’s very rarely required any maintenance. Why would two chains be better, exactly?My dad’s bike from the 70’s is the same. Very reliable as it is still in almost daily use. Brakes works by pedaling backwards to. I’ve had a few bikes like this too. I’d say it’s a really good design for a robust and simple bike.Here in Finland they still sell bikes that have 2-gear hubs with normal foot brake. Maybe there is licensing / patent issue that prohibits using similar design or too expensive to license. Those hubs can handle anything, but are more complex to fix, may not work at all and when broken. In my exprerience riding bikes that had those when I was kid, they were called ‘Grandma bikes’Called granny bikes here, with the three-speed Sturmey-Archer hub. We have one more than 50 years old, bought for a teenager, and now she’s the granny 🙂 Still works fine (the bike and the granny).the two chains are an awful design. the key to bike repairability is common parts. adding components unique to your bike makes it less repairable, no matter how great an idea each individual component is. besides, no one wants to maintain two chains. chains wear out. yeah single speed chains are slightly thicker but they wear out too.yes, it requires some tools, even specialized ones, to work on a ‘regular’ bike. but they’re not large or expensive or numerous. regular bikes are very maintainable and giving the markets what they need to maintain the bikes they have would be a much better investment.people want to use western ingenuity to solve the problems with africa but that’s backwards. the problems africa faces are created by western ingenuinity, not solved by them.I understand your complaints, but in this case it’s an organisation specialized in the problem. When I look at the solution myself I expect two chains to wear less quickly than a single chain. Furthermore, if the chain breaks, you can still bike to a shop to fix it. Instead of walking there, or giving up on the mobility dream.The two chain system seems to me about the simplest solution, and is therefore a good one. If you want to help, I’m sure they will listen. The challenge is yours to build a bike with a gear change mechanism which is more reliable than this one.
in this case it’s an organisation specialized in the problem
Kinda like the organization responsible for the OLPC?OLPC wouldn’t really have been saved by perfect laptops. But simple pedal power can be a great advantage over pulling a cart by hand, and I suppose there’s situations where two wheels can get somewhere but three or more could not, and carefully balancing an overloaded two-wheeled contraption isn’t the end of the world.I’d also prefer to have a waterproof solar watch (so that it could feasibly last a very long time with no service, despite being too complex to service) instead of a sundial. If and only if it was built well enough to last decades, I’d also think some kind of solar led light would be good – if someone’s been busy all day, there’s a way to read at night without flame, or do whatever else they might find useful. Of course, there’s lots of different situations, these are just things that would have been great to have historically – it’s not the same, nowadays.
seems to me about the simplest solution
The simplest solution to that problem is a spare chain cut to the correct length and the tool to install it. You store it in a little satchel under the seat.I saw this type of conversion when youtube was still smelling new-out-of-the-box, bit still amazing.So summary, you need a bike shop to service it.TL;DR: You didn’t watch the video, did you?is there a bicycle dealer/shop in the USA that sells them? email me the info if they are available in the USA kennard0321 at the G dot comthanksWithout regard to the above discussion, for those who just want to know how the AK2 freewheel 2-speed shift mechanism works, here’s the patent:
https://patents.google.com/patent/US11655004B2/The story reminds me of a bicycle type I encountered in childhood. Many people here may not be familiar with two-speed coaster bikes. IIRC the hubs were made by Sturmey Archer, though I could be wrong.the looked like regular coaster bikes, and pedaling backward applied the brakes as expected. But it also changed gears, and it was common for riders to do a quick “re-brake” motion when they wanted the ‘other’ gear ratio after having slowed down or stopped.I don’t think the idea ever really caught on, but I saw at least a few of them when I was a kid.Hmm, I wonder why some folks don’t believe the video when it was mentioned that other well-known solutions were tested and deemed not reliable enough for the target market? I suppose there’s an obvious answer for that.SPOILER: You’ve all fallen for the cleverly camouflaged YouTube ragebait.It’s Africa. It has to be kept simple since many of the people do not have exposure to complex mechanical ideas. Look at videos on youtube of Africans trying to build airplanes and helicopters. A dual chain system is something they can comprehend easily. Not putting them down at all. Someone in tune with the culture and education level of many of these people understands why a dual chain unit would be understood and why it lends itself to easy repairs to them. I mean eventually, they will break a chain and put the big chain on the smaller sprocket while using a crudely fashioned tensioner. When they want to go fast, they’ll stop and move the chain over by hand, and continue on. That in-your-face simplify is what will stand the test of time in parts of Africa.Boy, saying it that way makes it sound like you are white and have never been anywhere in Africa.You know, I was skeptical, but apparently these are in heavy use and we’ll regarded in many parts of Africa, and that proves my skepticism wrong. I wanted to say “bah, just have a simple cassette and derailer and pack them with a chain breaker and repair tool, that’ll do all the same things and with an established manufacturing base.” I do thing such a method would still be a little cheaper, but the proof is in the pudding, and they’re doing the real work. Bravo!Derailleurs are not reliable. All it takes is a twig caught in the spokes and derailleur, and the derailleur will end up twisted like a pretzel. I’ll never buy anything but a gear hub.you know, i have this mentality too, but the experience that gave it to me is probably actually evidence in the opposite direction :)i had an old bike with the wrong derailleur poorly-mounted to it (bike and derailleur pulled out of separate discard piles), and i was doing a 26 mile route, the morning after a snow storm. about 6 miles in, i got caught in a tire rut and fell over. it bent the derailleur into the spokes. so i just grabbed the derailleur with my hand and bent it back, and was able to complete the ride. going forward, i accepted the limitation that i was thenceforth unable to change gears. after about a year of that, i gave up on the bike because its frame was too severely bent (unrelated / cumulative damage). but i decided to stick with single speed and since then i buy single speeds. no derailleur to break, and i’m happy with that.so the moral of that story is that the derailleur is a frustration i can do without. but a different perspective on the same story is that even with all of the challenges that derailleur faced, the fact of the matter is, it reliably performed the minimum function of tensioning the chain.but for my ‘winter bike’, which sees a lot of abuse, i’ve lucked into a couple of free 1990s mountain bikes. and each of them, the derailleur was basically unusable. they could just tension the chain, and i rode them as single speeds…sometimes manually shifting it with my fingers on the mechanism if i needed to tow a trailer or something. and i built a better trailer that i use more often so i had the thought…i simply flooded the mechanism with WD40. and what do you know, it works perfectly now! even after a decade of being effectively rusted in place and coated in salt, all it took was 5 minutes of working wd40 into it. fwiw i didn’t add any other lubricant to it and it’s been solid for a year.so i think the moral of the story is that actually derailleurs are super durable and easy to maintain shrugstill probably gonna stick with single speeds for my much-beloved summer bike but kind of an eye opener for meNo gear case. Bad design.Please be kind and respectful to help make the comments section excellent. (Comment Policy)This site uses Akismet to reduce spam. Learn how your comment data is processed.
By using our website and services, you expressly agree to the placement of our performance, functionality and advertising cookies. Learn more

Source: https://hackaday.com/2025/02/03/bicycle-adds-reliability-with-second-chain/