Inefficiency and Unreliability of Chain Drive system

[numberonebikeslover]

Subject: Un-efficiency and Unreliability of Chain Drive system

It has been always been observed time and again that chain drive systems in electric bikes are unreliable and snap at odd hours.
Knowing the fact that a chain is as strong as its weakest link it is understood that there are as many possibilities of breaking of a chain as many links are there in it. Having a chain with 100 links would mean 100 possibilities of a chain to break or snap. So it concluded that:
1) Number of links of a chain = number of possibilities of chain breaking or snapping. Thus smaller the chain the reliable.

Having front and rear gear shifters/derailers at most of times (see the following figure) the chain goes through a number of zigzag twists and off alignment that it increase the chances of a chain to snap. There are only few gears where chain is aligned. So:
2) Front and rare derailers increase the chances of a chain to snap. Better solution for giving the rider the opportunity to change gearing ratio, probably a gearing box like a small bike e.g. Yamaha 50cc.

Note that the distance between both front and rare chain gears play a major role in this regard. Greater the distance between both gears greater will be tolerance of chain against zigzag un-alignment, as every chain link has very little room to bear zigzag twist/un-aligned situation. This tolerance increase with the number of chain links. (see the following figure)
3) During bumpy rides (off-road conditions) it again makes the chain with shifters / derailers more un-reliable.
4) Lubrication can’t stay on chains and makes it porn to catch dust and mud, which increase in its friction and power loss. Having energy crisis in the world the modern technology is after efficiency, thus chains seem to have very little room in modern technologies.
5) Chains if not lubricated in wet conditions, rust will deteriorate its life.

Keeping in mind the afore-cited facts I’ve the intentions of using gears instead of chains for gear-reduction. (see the following figure). I’m also working on a suitable solution for replacing gear-shifters.

You are all requested for comments and precious feedback.

Wish me luck guys.

 

[liveforphysics]

It's not the fault of chain drive, it's the fault of improperly sized chain, and system rigidity.

If you were to use a properly sized chain, like #219:

http://www.go-karting.com/mm5/merchant.mvc?Screen=PROD&Store_Code=GL&Product_Code=105&Category_Code=Chain

And proper #219 sprockets, and keep the center-to-center distances on the sprockets constant and well aligned, you would never see a chain failure for 10's of thousands of miles, and it would be able to easily handle 50times the amount of power you're putting through it.

The motorcycles you see in Pakistan might be frequently having chain problems, I don't know. Here in the US, a chain failure on a motorcycle is extremely rare, and all it takes for preventative chain-failure avoidance is replacement of chain and sprocket every 10-15 thousand miles or so.

They are only unreliable if you're using the wrong sized chain and sprockets for the application.

It would be like fishing for 15lbs fish using 2lbs strength fishing line. You're going to be plagued with failures. It doesn't mean the concept of fishing on a line is flawed, it simply means you need to size the components appropriately for the stress they will be under.

 

[gestalt]

My porn never catches dust and mud : p

but seriosly, why not use belts for reduction?

 

[AussieJester]

Subject: Un-efficiency and Unreliability of Chain Drive system

It has been always been observed time and again that chain drive systems in electric bikes are unreliable and snap at odd hours.

Chain is one of the (if not the) most efficient means of powr transfer somewhere close to 98% efficient. When setup correctly they are also extremely reliable.

Not to sound like a spelling Nazi but, its "inefficiency" not "un-efficiency" <--no such word.....

KiM

EDIT: Apologies i didnt realise it was you Naeem, your 50 chain and cog reduction setup is a sight to behold, i guess with that many chains and belts and cogs and sprockets something is bound to give from time to time haha PLEASE dont change it though thats what makes your bike so special!!...best of luck with it mate... :lol:

 

[cargo]

.

 

[amberwolf]

Keeping in mind the afore-cited facts I’ve the intentions of using gears instead of chains for gear-reduction. (see the following figure). I’m also working on a suitable solution for replacing gear-shifters.

You might consider a belt-driven CVT for the shifting. Depends on the amount of power you need to put thru it. If you use it where the speeds are higher, before the reduction, then it might not have as much slippage from torque. Have the motor run into the CVT, then the CVT out to the reduction (which can still be a chain, as long as like the CVT it is sealed in a box).

The link to the Phaser chain gearbox above is a lot like the belt-driven CVT I am still pondering--two opposing adjacent cones with a belt held in tension by a pulley in the middle, which is also used to shift it across the cones. Sealed in a box to keep it from getting wet or dirty, it'd probably be about the same size as that Phaser chain gearbox, maybe smaller.


Lubrication can stay on chains fine *if* you enclose the drivetrain. That will also keep the dirt out, and prevent FOD. But that's more weight and space taken up. I have considered doing it on my CrazyBike2, using plastic sheet, or possibly very thin aluminum or steel sheet from old signs. The problem on my bike is that I always end up experimenting with other things so I'd have to keep taking it off to get to the other components. In a "final" design that would not be the case.

You'd have to enclose any gear reductions you make, too, and they will be lower efficiency than a chain reduction would be. Might as well just enclose the chain reduction and keep it.

The regular pedal drivetrain is another matter. You could enclose that chain and it will help it a lot in the lubrication and cleaning, which may help with other problems. A chain that gets gummed up with stuff or that gets a rock stuck in it might not pivot freely at the pins, and when that happens it can get sucked into sprockets or stuck in the derailer and break things (or just cause wierd shifting problems or noises).

 

[liveforphysics]

Belt drive CVTs are like 85% efficient at low power levels... they are a maintenance hassle with a number of springs, weights, and wear parts.

The only thing more efficient than chain drive is direct drive, but in the case of a bicycle, this means too low of motor RPM to get decent performance.

 

[Ypedal]

I've switched to wax based lube for my chains vs oil/grease... much cleaner, works just fine and my pant legs look much better too !

 

[numberonebikeslover]

It's not the fault of chain drive, it's the fault of improperly sized chain, and system rigidity.

The chains for gearing reduction on my bike never snaps as it is correct sized and very well aligned. It is only the chain on wheel which has two derailers, as per diagame/figure attached. This region creates so much problem, and the chain always snaps while derailing or shifting gears.

The motorcycles you see in Pakistan might be frequently having chain problems, I don't know.

I've Piaggio 125cc never had such problem. Again the same you said earlier stands that correct sized chain and well aligned chain have almost no faults.

It would be like fishing for 15lbs fish using 2lbs strength fishing line. You're going to be plagued with failures.

I also have a Dirt bike which i have custom made my self and i own it from the last 17 years. It was XL honda 100cc, 1981 model when i bought it. Later on i increased the engine power to 125cc alongwith so many other modifications on the bike frame and suspension and now it is with a 200 cc engine which i fitted some 3 moths ago. Now with increased power the chain is not sufficient and recently with doing a wheeli it snaped.

you need to size the components appropriately for the stress they will be under.

No other size of chain is available here in the market than the sports mountain bike size chain which works with derailers and rare group of seven gears. Another larger chain for common bicycles without any gearing shifting etc. is also available which i used in the gear reduction part and it never snapped.

I'm so thankful for the precious time you took to respond me. Thanks for sharing your knowledge.

 

[numberonebikeslover]

The problem on my bike is that I always end up experimenting with other things so I'd have to keep taking it off to get to the other components. In a "final" design that would not be the case.

Thats amazing! I also end-up doing something every time i pay attention to my bike. My wife always complain about and say that nothing is enough for me. most of the time she says to me to cover it up and forget it. but thats not me. ha ha ha. In this regard we both are alike.

About CVTs! my God, this is something I always thought about doing it and never was able to sort out till the end. You know what, i most of the time make all the designs in my imagination, having my eyes closed, or sometimg open. My wife always say to me " don't stress you mid so much you will go mad" but hey i like it and enjoy it. Sometime a design in my imagination i put it on the paper to remember it.

thank you very much for your response.

Naeem

 

[numberonebikeslover]

My porn never catches dust and mud : p

but seriosly, why not use belts for reduction?

Dear brother

thank you for your response. The place i live in is a hell of dust and mud. I keep my face covered on the rode while I go to my office. It is so much dusty and some time it gets hard to breath. Chain can become so muddy and thick with chocholate like mud on it.

I've thought of using timing belts with teeth and toothed pulley but so limited resources i have here. Timing belts and toothed pulley is the most efficient way of gear reduction. one more plus point is that there is no noise.

thank you.

Naeem

 

[numberonebikeslover]

Not to sound like a spelling Nazi but, its "inefficiency" not "un-efficiency" <--no such word.....

Apologies i didnt realise it was you Naeem, your 50 chain and cog reduction setup is a sight to behold, i guess with that many chains and belts and cogs and sprockets something is bound to give from time to time haha PLEASE dont change it though thats what makes your bike so special!!...best of luck with it mate... :lol:

Thank you very much for the correction. My English is not much strong and really not good with spellings. Please accept my appologies for such blunders.

yes, that is what a kid said that day while i was going through a crowded place "So many chains and gears" ha ha ha.

thank you very much for appreciation.

Naeem

 

[TylerDurden]

Greetings, Naeem.

Perhaps dual-chains are the simple solution. You might only need dual-chain on the high-stress stage.

 

[number1cruncher]

Don't think you got the "porn" joke...

Seriously though, timing belts are the way to go. Although I've never had a chain break on me, as I'm a lazy pedaller, I hate the greasy leg it gives me. My newest bike came with a Gates belt drive and it is wonderful for e-biking. Quiet, smooth, greaseless, etc... However the product comments on the vendor's website showed it is not appropriate for regular bike use, as the belt tends to slip a lot under pressure. It was reduced from >$500 to <$300. Don't have that problem with the hub picking up most of the torque for me!

Take care and good luck!

Bryan

BTW - Keep that porn clean, I don't care if you live in a dirty area. Thats just disrespectful... :lol:

 

[amberwolf]

Belt drive CVTs are like 85% efficient at low power levels... they are a maintenance hassle with a number of springs, weights, and wear parts.

That's a part of why I have not yet made one; I'm still trying to figure out simple ways to do it without the weights and stuff, possibly while making it "automatic" (though that is probably beyond my abilities). If I knew of another way I could actually *build* a CVT than cones/belts with stuff I have around here or could find as scrap, I'd try it out.

The Nuvinci method does not seem to be good for high power levels, either, based on reports here on ES; it doesn't seem to be any more efficient than the belt version. I know there are other types of transmission *called* CVT but that are not actually continously-variable using stepped ratios of gears/etc, but I am not that interested in one of those.

I'd still use one like the Phaser box linked above if I could build one, and I'm now pondering doing something like it, just because it would at least be a sealed unit to keep maintenance low.

Thats amazing! I also end-up doing something every time i pay attention to my bike. My wife always complain about and say that nothing is enough for me. most of the time she says to me to cover it up and forget it. but thats not me. ha ha ha. In this regard we both are alike.

It is quite difficult to "leave well enough alone". That's how I destroyed the drivetrain on CrazyBike2 most recently, by "fixing" a problem that was only very minor, and ending up messing up the alignment and thus causing the chainrings to be destroyed (though the chain was fine).

About CVTs! my God, this is something I always thought about doing it and never was able to sort out till the end. You know what, i most of the time make all the designs in my imagination, having my eyes closed, or sometimg open. My wife always say to me " don't stress you mid so much you will go mad" but hey i like it and enjoy it. Sometime a design in my imagination i put it on the paper to remember it.

This is also how I usually do things, though I don't have anyone around to tell me such things. The real problem is that if I don't at least sketch it out roughly, I will forget it before I can do anything with it. So I think of things while I am at work or other places where I cannot just stop and write it down or draw it, and usually forget them by the time I'd be able to do so.

The place i live in is a hell of dust and mud. I keep my face covered on the rode while I go to my office. It is so much dusty and some time it gets hard to breath. Chain can become so muddy and thick with chocholate like mud on it.

That is why I would strongly recommend making at least a thin enclosure for the system. I have had something as small as a 1/4" pebble get tossed up from the road and stick in the chain cause it to derail, as it kept the tooth from going into the hole, and pushed the chain to the side instead. That has happened even on my pedal-only bikes over the years.

 

[dequinox]

I've switched to wax based lube for my chains vs oil/grease... much cleaner, works just fine and my pant legs look much better too !

I know I need to switch to wax-based lubes also...the stuff keeps the water out much better.

Not to mention I still need to finish my vacuum former so's I can gets my reduction covers finished! I get tired of the #25 chain eating my jeans :lol:

PS- What data does anyone have direct-drive vs our fellas with the high-efficiency chain drives? Is the ES garage the best place? It seems to me that typical wh/km values were in that spread sheet...

 

[AussieJester]

Thank you very much for the correction. My English is not much strong and really not good with spellings. Please accept my appologies for such blunders.

Naeem

Apologies not needed buddy your English is better than most people i know here in Australia ...

I have a bunch of belts here Naeem they were given to me few weeks ago, unfortunately they
aren't toothed belts like i use on my setup so i have no use for them, if they could be
of use to your project i would be happy to pop them in a post pak and send them your way (no cost too you)





Lemme know if they of use mate and ill get them off to you

KiM

 

[liveforphysics]

V-groove belts make continuous friction pinching on the way into the groove, and continuous friction pulling it out of the groove. They also require about 50% more bearing loading and bearing friction to maintain the needed friction to not slip.

In other words, if you're not liking the efficiency of a chain, you're really not going to like the efficiency of a V-belt.

A cogged belt drive overcomes most of these short comings, and is only slightly less efficient (losses from continuously bending and unbending the belt creates heat from internal rubber friction) than a chain.

If you don't mind the sound, a proper chain and sprocket setup is absolutely going to be the most efficient and reliable. But you're not going to have any luck with chains if you keep trying to reel-in the 10lbs fish on the 1lbs fishing line.

 

[dequinox]

A cogged belt drive overcomes most of these short comings, and is only slightly less efficient (losses from continuously bending and unbending the belt creates heat from internal rubber friction) than a chain.

If you don't mind the sound, a proper chain and sprocket setup is absolutely going to be the most efficient and reliable. But you're not going to have any luck with chains if you keep trying to reel-in the 10lbs fish on the 1lbs fishing line.

Are the cogged belts really less efficient than a chain? That's pretty amazing...I would have thought a good carbon belt would outdo any chain drive system to date. Lighter so a lower 2nd moment, and as far as the bending friction goes I guess testing would be the only way to really determine that. Do you have a link tucked away somewhere to a study on that stuff? Thanks!

 

[numberonebikeslover]

Lemme know if they of use mate and ill get them off to you

KiM

Dear Kim

I'm so greatful to your offer but i've decided and made a pact that i will only use the resources present in my city. This is what project is about "very low cost electric bike". To my knowledge timing belts are of great worth, in case of efficiency plus no noise. but a toothed pulley is something that will be very costly for me to custom make. And my project will no longer be a low cost.

I admire your help. It is once said by a great scholar of old times that "the hand giving something is better than the hand taking something" (Muhammad peace be upon him).


Yours truly,
Naeem

 

[liveforphysics]

A cogged belt drive overcomes most of these short comings, and is only slightly less efficient (losses from continuously bending and unbending the belt creates heat from internal rubber friction) than a chain.

If you don't mind the sound, a proper chain and sprocket setup is absolutely going to be the most efficient and reliable. But you're not going to have any luck with chains if you keep trying to reel-in the 10lbs fish on the 1lbs fishing line.

Are the cogged belts really less efficient than a chain? That's pretty amazing...I would have thought a good carbon belt would outdo any chain drive system to date. Lighter so a lower 2nd moment, and as far as the bending friction goes I guess testing would be the only way to really determine that. Do you have a link tucked away somewhere to a study on that stuff? Thanks!

Yep. There are studies. I've had to go through loads of them for various engineering projects at work. It boils down to gates quoting 99% in a test with enormous pulleys, and all practical application tests around ~95-97%, with the largest variable being the relative size of the smallest pulley compared to the pitch of the belt, as this is what has the big influence on the amount of sheer friction as the tooth on the belt settles into the groove in the pulley, and then gets pulled up out of it again. On a large diameter pulley, there is almost no losses from this, as pulleys get smaller, you quickly reach a point where it's not even a safe drive for higher speed operation because it will melt/chafe teeth right off the belt.

The friction from a steel roller over a steel/aluminum pulley is always lower than rubber over steel, and a chain also doesn't deform to always be mushing the last load bearing tooth to be distorted/compressed in the groove.


Belts have some advantages and disadvantages, chains have some advantages and disadvantages. As used for a bicycle with a large reduction between motor and wheel, the limitations of pulley diameter on a belt drive system could mean requiring 2-3 stages of drive reduction, where a chain could be done in a single stage. Each stage's losses multiply together, so a 3 stage belt setup at 97% for each stage makes a 91% reduction system efficiency. Using a chain getting it done in a single stage (like my bike for example), means 1 x 98%, or 98% system efficiency.

 

[numberonebikeslover]

Dear All!

After a tiresome search for gears i went to almost every corner of my city, from junkyard to junkyard I've collected some of the gears as i mentioned earlier (pictues as follows). How about their efficiency? if i were to use the lagrer one with 57 teeth while the motor has a 5 toothed gear. so it is a ratio of 1:11.4 to be accurate and thats what i need.

i've also attached a pic of timing belt, which are different then the ones kim has shown.

Sincerely
Naeem

 

[numberonebikeslover]

Dear All!

I've attached some of the pics of my bike for the users who have not seen my bike yet. These pics explain the area of multiple chain reduction (two of them) and third pic shows the chain that drives the wheel having derailers that is breaking its chain while shifting gears.

Warm regards

Naeem

 

[number1cruncher]

Naeem,

The third picture of that timing belt looks about the size of mine. However I'm kind of confused, which is nothing out of the ordinary. I thought the drivetrain was giving you issues, not the reduction. If this is the case, are you going to use those cogs and belt instead of the chainring, derailers, etc? Those cogs look HEAVY. Mine are plastic for comparison.

I hope not to overstep any boundaries and am totally entranced by your ingenuity, but it would seem to me that a person of such talent as yourself could take on at LEAST two e-bike projects. That being said it would seem to me that by placing parts in your hands, it would definatley add enormous value to both you and the community as a whole. I am only suggesting that you contemplate a second project that would allow us to collaborate with you. Of course, you know what is right for you. And you definately do not need help. On the contrary, I think you would be helping us!

Take care,

Bryan

BTW - If you are going to mess with the reduction drive, make sure to keep that Pheonix cog on your e-bike somewhere. That thing is too symbolic to lose. :wink:

 

[amberwolf]

Regarding the reduction gearing, the only thing I can say is that if you do use them, make sure you enclose them to keep the dirt out--if you don't, they're going to either break, wear out quickly, or be less efficient than your existing setup.

Regarding the breakage, it occured to me that perhaps you're shifting while the motor is running. If you are, try always cutting throttle before you shift; just pedal thru the gear changes to get shifting to happen, and after it has shifted *then* reapply throttle.

I have had to do this on CrazyBike2, especially with the bike-destroying 4-pole motor on there; if I am accelerating or otherwise running the drivetrain under load then shifting is not smooth.

Other than that, the only thing is to find a way to keep at least that part of the drivetrain clean by enclosing it. I *know* dirt, sand, and gravel all cause horrible problems to a shifting chain, from experience.

So also make sure your chain is not "stretched" (worn, actually) from having the pins/holes ground out from grit. It's common, and in an environment like yours, it won't take long either. Here in Phoenix, Arizona, we have dirt that is more sand than anything else, and the grit in it is highly abrasive. I'm pretty sure I could use the stuff in my backyard for sandblasting.