Anyone know the answer here?

How difficult is a gear system to make? No, not cars, bicycles?

Just a very simple 3 gear system to place upon a rickshaw. One thing I noted and did not understand – and despite explanations I still don’t get my head around – is that all of them were one gear only, direct drive I suppose. And it’s hellishly high physical effort that way.

Import duties mean that sending them in wouldn’t work (they’re insane, 300% and the like duties at times) but it’s a pretty simple technology isn’t it? They do, after all, already make the current chain, two umm, whatchamacallits front and back. A gear system is only making the same pieces but in different sizes and a system to switch between them.

Seriously, how tough is this? Labour’s damn near free, there’s a thriving set of workshops making the things in the first place. It’s almost doing the design work and then giving it out if not setting up a small shop to make them at local prices.

The thing that makes me think though is it’s such an obvious technological step. Thus the question isn’t whether it should be done but why hasn’t it already happened? Isn’t it worthwhile? Is it actually too expensive?

There’s a significant part of me thinking that some rich bloke with $50 k really should throw it at the problem. No, not to study it, to go and do it as an experiment. Design some, make some, start selling them (at those local prices, £5 tops for the system installed, £2 better). If it doesn’t work then it doesn’t work, we’ve learned something. If it does then great. There’re a lot more places where it would be of benefit too.

So, what is it that I am missing here? It must be something because I was only in country 48 hours and it puzzled me, better and more informed minds than mine must have pondered this before.

37 comments on “Anyone know the answer here?

  1. The hard part is making a gear system that will stand up to the torque involved in starting off when pedalling a work-bike with a heavy load. It’s non-trivial and considerably harder than making a regular gear system – it’s hard enough just to get a single-speed freewheel that can stand up the forces involved, and the way a normal geared system works requires the chainrings to be narrower than for single-speed.

  2. The question is not only is a gear system possible for that price, but also is it robust? Its no good having a gear system that can take the usual bike type of wear, but not the 24/7 no maintenance type hammering it would get in Bangladesh. A fixed ratio bike chain drive is pretty foolproof, the chain can break and eventually the cogs get worn away, but thats it, there’s no complex parts to wear or break, which would be a crucial importance one thinks.

  3. The “two umm, whatchamacallits front and back” are called sprockets.

    The switching mechanism is called a Derailleur.

    And I suspect Dave and Jim are right. Take a Derailleur from a bike shop in the UK, subject it to the loads that a Bangladeshi ricksaw generates, and it probably won’t work for long.

    So the design exists- it’s probably a matter of altering the design to be beefier, and then maufacturing it.

  4. What is wrong with epicyclic gear sets (planetary gearsets) like the old Sturmey Archer in-hub ?

    They can be very robust and with 3 pinions in a gear set self aligning so tolerant of wear and less demanding of manufacturing accuracy ?

    Gotta be better than all that messy derailer stuff .

  5. I’d be very surprised if a rickshaw operator puts more force/power through the system than Chris Froome climbing a mountain. Admittedly Chris rides with a team of mechanics and he won’t be using a standard derailleur from the local bike shop, but it’s not fundamentally different.

    A derailleur system for a trike has additional complexity because there’s no convenient part of the frame to fix it to – but they exist.

  6. If it’s flat, there is no need for gears. The Dutch showed us this years ago. And whatever gains you’d make from having a geared drive with a freewheeling hub you’d likely lose by having to pay for and install a brake system. The advantage of a fixed-wheel bike is you don’t need brakes. Again, the Dutch showed us this.

  7. Come on Tim, the market has spoken and it says single gear is adequate.

    Gears help when accelerating quickly and help to keep you pedaling up steep hills, other than that they add complexity and waste energy (you have to carry the unused gears around with you).

    I spent more than 15 years traveling everywhere by pushbike, I had a very good third hand 10 speed racer, it never left 9th gear.
    If a hill was so steep I couldn’t physically force the pedals round I got off and pushed.
    It never fails to amuse me when I see MiL pedaling furiously up hills in stupidly low gears and at slower speeds than I can walk and they could never match the speeds I used to go downhill or on the flat.

    Electric power assist will be the differentiator for the rickshaw drivers (rewind a washing machine motor for 12volts and use a car battery), the driver will get a greater return on their investment.

  8. Couldn’t you use a simple lever with a second geared cog on it the engages when lifted and disengages when lowered? i.e. gear the original cog for getting going and then gear the second one for once moving – being a simple cog / lever should mean it can be made of sturdy metals so make it robust / low cost?

  9. @ Steve
    That link sounds like the first thing that went through my mind – for the simplest possible mechanism, just double up the chain drive (so two sprockets at front, two at back, and have a dog lifter to disengage the drive from the higher speed sprocket to the rear axle.
    @ abacab
    Got an example of a simple, cheap, reliable, and EFFICIENT variable drive ? The v-belt and variable cone drives are very inefficient compares to a chain drive – and I can’t see something that saps a big chunk of the rider’s power being very popular.
    I vaguely recall having seen several ideas over the years. One I recall had a number of small cogs mounted on a wheel in place of the solid front cog. Under heavy load, these smaller cogs would move (sliding in slots against a spring) such that their PCD would reduce, and give the effect of a smaller front cog – once the load reduces, the springs push them back out again for a larger effective cog size. But it was complicated, with multiple sliding components exposed to all the crap (like wear inducing dust and grit) that’s around at road level.
    @ Striebs
    Sturmy Archer boxes aren’t that robust or strong – and no-one could have called me a “powerful” cyclist back in the days before I decided it was a mugs game.
    From experience, I can tell you that when you are setting off, stood on the pedals, and the box ‘lets go’ – the impact between soft fleshy bits and the crossbar is “uncomfortable”
    In that case, I’d broken the centre gear of the gear set, the collar where it’s pinned to the shaft just split and allowed the cog to turn. Also, the racket dogs are prone to wear – and again, it’s not conducive to remaining in control when you’ve just got into top gear and the dog lets go. And there’s also a dead spot between two of the gears (IIRC it’s between middle and top) where you get no drive.
    Like a Derailleur setup, it needs careful adjustment.
    A much simplified version, with just two speeds, no dead spot, and just a dog lifter to disable the higher speed would do the job – but it needs designing, testing, and getting into production.

  10. Guessing completely here, but flooding in Bangladesh used to be a staple of news reports on telly back when I were a lad, and I vaguely remember realising that I hadn’t seen a report of such for some time at some point, but yeah, Tim N is probably right, the place is flat and they don’t really need them.

    That said, turns out that technology adoption can have some weird kinks, so there might be some cultural factor or path dependency that will only get overridden by some form of exogenous shock, or when they get rich enough at 5% PA to jump straight to two strokes or something.

  11. “Thus the question isn’t whether it should be done but why hasn’t it already happened?”
    Good question.
    TimN’s points noted & agreed with. But the cloggies use bikes, not rickshaws with heavy loads.

    Sat & thought about this for a minute. Working with what materials & tools I have here – & that amounts to a basic DIY kit & what I could swipe from stuff in the garage – I could knock you up a basic pedal power two speed gear change by the end of the afternoon. Bit longer if I forgo the electric angle grinder & have to make the second sprocket from scratch. It’s just basic, backwoods engineering. Necessary if you don’t always have a major parts department on your doorstep.
    So the answer’s fuck-all innovative talent.
    Not that uncommon. Spanish don’t seem to have much. I seem to have spent much of the past few years getting dago cludges to do what they’re supposed to.
    The why?
    My suspicion’s religion. The sort of religion says pray & god/gods will provide. So they sit on their arses praying.
    Some god comes interfering in my life, it’ll get exorcised so fast it’s aura’ll get red shifted..

  12. No need to travel to Bangladesh to investigate. There are rickshaw hacks in London. How do they work?

  13. I’d assume you’d need some sort of precision engineering to make the gears. As far as I’m aware Bangladesh is incredibly corrupt, even more so than China. China can’t even make a ball for a ball point pen because of the precision required. Because at every point on the supply chain quality assurance is bought off so the final product is an absolute disaster.

  14. Striebs>

    Hub gears are standard on work bikes in richer countries. Largely because of the lower maintenance, though, I think. They make special heavyweight ones to take the loads, and they are decidedly not cheap. The cheap ones simply aren’t strong enough – usually it’s the nuts and bolts on the outside that fail, but I’ve seen shells with the flanges ripped off.

    Chris Miller>

    It’s not power, it’s torque. The most apt comparison from the world of cycle racing is the start of a track race, where there is immense torque at low speeds, just like trying to accelerate a heavily-laden workbike. Track bikes don’t have gears either (arguably for a different combination of reasons, though).

    Bobrocket>

    High cadence, low torque is the best way for humans on bikes to produce power. You were presumably fitter than the MiL. With proper use of the gears you’d sail past them (and go faster than walking) on the bits that were previously too steep.

    And I say that as someone who’s ridden a singlespeed a lot. It has a lot of upsides, but if you’re looking for peak power output it’s not the way to go.

  15. @TimN If it’s flat, there is no need for gears.

    True, and flat certainly describes Bangladesh, but I remember the same system in Jogja years ago – and that’s not flat. I always feel a bit of a fat capitalist oppressor using rickshaws, but the drivers need the business. The one in Jogja had a tiny, wiry old guy (he looked about 100, but was probably in his 30s) on the pedals, who must have weighed less than 1/3 of the two of us in the back. To watch him toiling up the hills in the pouring rain upped the guilt quotient. I gave him £5 tip, which I hope made his month!

  16. Magnus>

    Cheap rickshaws/tricycles don’t bother with a diff, they just drive one wheel and have the other freewheel both ways.

  17. Bicycle couriers in London and most other cities use “fixies” – a single gear and no freewheel. They’re low maintenance, and you don’t need a back brake (nor a front brake if you don’t mind dying).

  18. Pro Bono>

    I can tell you from experience that they don’t, at least in London. The bike-courier subculture is only about 10% (guesstimate) of cycle couriers. The subculture loves messenger bags, fixies, etc because they’ve imported NY culture, but the majority of cycle couriers are too busy making money for that shit.

    Mostly what cycle couriers ride in London are old supermarket bikes, usually with a decently set-up drivetrain but no new parts. You’re going to have your bike nicked at least every two or three months at a bare minimum, so no-one in their right mind uses a bike that costs much.

  19. With a fixie you can stand on the pedals and stay still, I prefered a silent freewheeler (no clicking) as I like to freewheel as much as possible. 28 inch wheels and thin tyres pumped up hard (no road noise)
    I had brakes but I didn’t like to use them because it is a waste, I would judge speeds and distances so I didn’t have to, plan routes that avoided traffic lights every 30 yards etc.

  20. Tim W

    Can you clarify two things?

    1) How much gradient do they have to cope with?

    2) How much load do they have to carry? Based on what I saw in Indonesia and Vietnam, I’m assuming they’d ideally like to be able to carry a couple of hundredweight of rice- or is this just for limited passenger use?

  21. Very flat, but that’s the landscape. There’s still bridges rising over rivers and all that.

    And carrying weight, yes. Two or three people not uncommon, the freight ones would indeed take three or four bags of rice etc.

  22. “I’m assuming they’d ideally like to be able to carry a couple of hundredweight of rice”

    Yeah, ideally. Instead of the 500kg+ they’re currently carrying (when heavily loaded).

    I used to ride a workbike in London, summer job. We were mainly doing deliveries round Kensington etc for posh ‘organic’ shops and similar. More than once I had the bike+trailer loaded up with a few hundred two-litre bottles of water, and while getting a load like that started was hard*, it was surprisingly easy to manage once it was moving.

    *Had to push off first, then jump on once it was moving – the hub gears would fail every time if you tried to pedal.

    I’d be surprised if some/many of the rickshaws aren’t carrying twice what I managed.

  23. Dave, I’ll take your word for it. But I suppose there was an economic reason for fixies to have become fashionable in the first place.

  24. It never fails to amuse me when I see MiL pedaling furiously up hills in stupidly low gears and at slower speeds than I can walk and they could never match the speeds I used to go downhill or on the flat.

    Faster cadence in a lower gear produces more power with less stress on the leg muscles, especially on longer climbs. On a long climb if you strain in too high a gear the lactic acid build up is rapid and you simply stop. A more rapid cadence switches some of the effort to the CV system and gets lactic acid from the legs faster.

  25. Rob,

    I don’t disagree with you but in my case I find I use my arm muscles as well as my legs when going uphill, pushing down on the pedal whilst pulling up on the handlebars, I can only do this pedaling slowly or when accelerating.
    If I pedal crazily in a low gear my legs just cramp up, same going up stairs which is why I take them 2 at a time or run up them.

  26. As someone who’s built bikes and ridden in all sorts of weather, most of the reasons why you’d use a fixed gear have been mentioned. To sum:
    _
    Why not use external gearing?
    – Shifting gears under heavy load causes troublesome ‘jumping’ and ‘hammering’ on the gears and chain
    – Differential gearing bends the chain side-to-side in operation, which is bad for it over time
    – Generally, lighter/narrower chains are necessary, which is worse for heavy rickshaws
    – A tension pulley is required, which is another thing that breaks and bends easily
    – The chain is much more likely to jump off the gears
    _
    Why not use internal gearing?
    – Internal hubs are expensive, often over $150 USD for something that can tolerate a heavy (400+ lbs) load
    – They’re quite difficult to repair; once they break they’re usually write-offs
    – Since the components are just physically smaller, they wear out more quickly, especially when under high load
    – They are generally fairly poor at shifting under significant load

    In contrast to these, a fixed gear is low-maintenance, accommodates quite heavy chain (I’ve even seen a motorcycle-chain fixie-tricycle!), is very cheap, easy to fix, and will handle heavy loads gracefully.

    Given that south Bangladesh is about as flat as a pancake under an anvil, I think our rickshawyers have made a very sensible choice.

  27. Tim

    “but it’s a pretty simple technology isn’t it?”

    Yes and no. Simple, but surprisingly difficult to get perfected and also not idiot proof enough to keep running smoothly without a bit of skill maintaining it.

  28. If the economic consequences of unreliability are high (and I imagine they are very much so for a Bangladeshi rickshaw operator) then reliability will be highly valued. Comfort, less so.

  29. That was a fascinating read.

    I conclude that the market found the optimal solution. Obviously we can’t have such neoliberalism xploiting the poor so now a load of SJWs need to go over there and tell them they’re doing to wrong(ly).

  30. “If the economic consequences of unreliability are high (and I imagine they are very much so for a Bangladeshi rickshaw operator) then reliability will be highly valued. Comfort, less so.”

    Exactly my thought. Broken bike gear = no income = no food in stomach. Hard work but functioning bike = income = food in stomach.

  31. A deraillieur gear would surely be immune to the forces the chain is subjected to. A hub gear would be a different matter for sure.

    Both (unless extremely well made and thus extremely expensive) need regular maintenance, especially on a bike that’s in use all day. An experienced hobbyist can realign a deraillieur, but for a hub gear that’s skilled labour. I’d guess the purchase price alone would put you off if you make a living from riding rickshaws in Bangladesh.

  32. I have no idea of it’s ergonomically feasible, but if you could find a way to mount a whole secondary chain/pedal set without breaking your toes you’d avoid the parts/maintenance/durability issues.

  33. “I have no idea of it’s ergonomically feasible, but if you could find a way to mount a whole secondary chain/pedal set without breaking your toes you’d avoid the parts/maintenance/durability issues.”

    If you just install two chains attached to the same set of pedals, with different gearing ratios, and then connected either one or the other to the axle using a simple clutch (which is potentially a much simpler and more robust mechanism), you also avoid most of the problems.

    If you search for rickshaws with gears, you’ll see there are quite a few about – including an inspiring story of a rickshaw driver who spent 15 years perfecting his design. I gather it’s perfectly feasible, but a little more expensive.

    I don’t know why they’re not used – my guess would be they’re a little too expensive, and more a luxury than a necessity. Someone with a design for a very cheap one could probably sell it, although it’d get copied so fast that they probably wouldn’t make much. Dunno.

Leave a Reply

Name and email are required. Your email address will not be published.