Any IGHs with over 350% range, >20,000km service life & 300nM torque rating???

[Ken M]

Was helping a friend configure a cargo ebike with a Bafang M620 mid-drive. He is about 200lb so it's frequently expected that upwards of 300nM of torque will be subjected to the IGH when the bike is fully loaded which is expected to be upwards of 800lbs. He wants a 20,000km minimum service life as well.

Does anyone know of an Internal Geared hub that can just be ridden (ie not looking for the recommendation that with great caution this IGH may be OK) and provide this level of rubust performance. I honestly consider this a fairly typical cargo ebike looking forward so hopefully some one has a recommendation. If this is just a crazy expectation please let me know.

Note: I know the Bafang M620 can put out 160nM at the crank axle and a 200lb rider standing on the cranks will generate an additional ~150nM so I would think IGHs on cargo bikes would have to deal with this much torque on a frequent basis.

Note: I think i did overstate the total system load of the cargo bike - the 800lbs was considering a trailer and max of 500lbs total on the bike which is still pretty nuts.

By service life I meant I would like to know that the IGH will last that long...not that it will be maintenance free for 20,000km. I read that Shimano says the Alfine IGH is designed to last 15,000km which seems a bit low to me. That could mean buying a new Alfine every 2 years for some riders.

 

[Ken M]

Receiving some feedback from ebike brands using the Bafang M620 mid drives that indicate that non of the current IGHs are designed for the peak performance of this mid drive.

It's kind of known that these powerful mid-drives if ridden hard cause dramatically increased cassette wear (especially on the higher gear cogs) but apparently they can damage the current IGH offerings if not gently ridden and that just seems short of an actual integrated solution.

 

[m@Robertson]

I build and ride cargo bikes daily, and have never been able to load one past about 565 lbs. Thats with custom panniers that are able to hold about 138L each, plus a 46" top deck. I can tell you with certainty no human is going to be able to balance an 800 lb system load on the smoothest, flattest ground. Even if they can, they won't survive past the first stop light when they have to come to a safe stop, start again (you can't pedal and maintain balance at that weight from a standing start so you have to rely on throttle for the first few mph) and not crash over thanks to an unexpected pedestrian or *anything* in their path - a bike even in the 550 lb range cannot make any sort of course correction.

By the way, bikes in the 500+ lb range - which is beyond all but one factory spec for any manufactured production bike - are only going to be able to safely reach about 8 mph. They will have to have fat tires with tall sidewalls pumped up to nearly their full inflation level. The wheels will need to be the very best hand build - I use Nextie triangular carbon fiber 90mm rims that are rated to the max-available 250kg (which should tell you something about an 800 lb load right there) and DT 350 Hybrid hubs with steel cassette bodies and 24-point ratchet engagement to survive the torque from the 160 Nm motor. Also 1-piece, pinned steel cog clusters.

So first and foremost, an 800 lb system load cannot happen. It has to be done with a trailer. Google Carla Cargo trailers. They are stable 3-wheel trailers that have a front wheel direct drive hub motor that also has an overrun brake built in. $4500 before you get into the motor and brake version.

I use the BBSHD which is also 160 Nm. Furthermore, on some bikes I do a front hub accompanying it and this front hub works miracles to take the initial load of the from-zero stop off the drivetrain which now does not have to torque up a stationary bike. On a non-cargo bike it means an 11T cog can be used from startup and that 11T cog will last for about 1100 miles (versus around 50-100 if no front hub to help the process).

The 300Nm measure is wrong. I can't say by how much as theoretically its correct. But via actual experience I can say you will never apply torque like that. When starting up for instance you are typically focusing on balancing the load and you are letting the motor deal with acceleration. By the time you have the bike balanced from a stop and you start pedaling, the bike is likely going over 5 mph and this is well down off the peak torque point of 0 mph.

And even if you are not, the rider has to realize a heavy bike like that is not a bicycle, and is not to be ridden like one. When riding cargo bikes you learn to ride smart, and smart is typically throttle off the line followed by pedaling once you are up to a minimum level of speed. For me that means about halfway thru an intersection so... 30 feet? In steep hills its the same as flat land, btw.

The strongest IGH is the Kindernay. In second place is the Rohloff. I know of only a few Rohloffs that have died in cargo duty under the BBSHD lash, and zero Kindernays. However Kindernay is a newer player whereas Rohloff has been around forever.

Some cargo bikers who do an IGH have gone to half-link chains and badass singlespeed rear cogs. The Gates belt is oh so sexy, but a half-link chain will still work with bicycle cogs and is immensely strong. Myself personally, I use derailleurs. If I go IGH on a build (I think I am doing a Bullitt X later this year) it'll be a Kindernay with a Gates belt.

Mids do not cause dramatically increased chain wear. Thats all a function of the thought that went into the build, the components used, and the rider's technique. Start here:

How To Ride a Mid Drive Ebike Without Breaking It

If you can ride a bicycle you already know how to ride a hub drive ebike. Not so a mid drive. Particularly a powerful one that can tear your chain apart. Fear not. The rules are simple.

talesontwowheels.com

 

[m@Robertson]

oh and also you can forget about a 20,000 km service life . Kindernays are 5000km and then they need an oil change. Rohloff is the same.

 

[jabberwocky]

Rohloff makes probably the most robust IGHs on the market. The carry a high pricetag, but do have a wide range (14 gears with >500% spread) and are very low maintenance. Grip shift only though, if thats a dealbreaker.

No idea what torque they can handle. You could email them and ask, but it sounds like your use case is pretty extreme.

Speedhub - Rohloff AG

www.rohloff.de

 

[jabberwocky]

I build and ride cargo bikes daily, and have never been able to load one past about 565 lbs. Thats with custom panniers that are able to hold about 138L each, plus a 46" top deck. I can tell you with certainty no human is going to be able to balance an 800 lb system load on the smoothest, flattest ground. Even if they can, they won't survive past the first stop light when they have to come to a safe stop, start again (you can't pedal and maintain balance at that weight from a standing start so you have to rely on throttle for the first few mph) and not crash over thanks to an unexpected pedestrian or *anything* in their path - a bike even in the 550 lb range cannot make any sort of course correction.[/URL]

Man, that reminds of my friend riding out to mid Loudoun on his cargo bike (affectionately named "Battleship Stupid"). He signed up for a 150 mile charity ride, and since he was insane he decided to load everything he needed (including his road bike) on his Surly Big Dummy and ride the 70 miles there. I rode a leg of it with him and snapped a few pics. Definitely nowhere near 565 pounds, but probably 200 on that thing. I remember watching the entire frame flex back and forth over these gravel roads. Good times. He passed away last year on his bike, which is appropriate for him.

 

[m@Robertson]

Man, that reminds of my friend riding out to mid Loudoun on his cargo bike (affectionately named "Battleship Stupid"). He signed up for a 150 mile charity ride, and since he was insane he decided to load everything he needed (including his road bike) on his Surly Big Dummy and ride the 70 miles there. I rode a leg of it with him and snapped a few pics. Definitely nowhere near 565 pounds, but probably 200 on that thing. I remember watching the entire frame flex back and forth over these gravel roads. Good times. He passed away last year on his bike, which is appropriate for him.

My 565 lb record was on my Big Fat Dummy (this pic was not that time, but same filled bags). Since then I changed the wheels out to be much stronger.

I've had this one up to about 500 lbs... and that load convinced me I need to upsize to the BFD above.

The Rohloff G510 has a rated limit of 130 Nm. Thats under the limit the BBSHD and Ultra dish out, but still there are only a few reports of failures. Thats part of why I think the 300Nm measure is not real-world.

Whenever I am giving load weights I am doing 'total system load' which a) is what cargo bike manufacturers use when giving specs and b) includes me, the rider. If the OP was not, then we're talking a 1000 lb bike

 

[jabberwocky]

To be fair, my friend was not on an electric bike (this was 2010, so 12 years ago). Getting things moving took some work, but he was a strong mofo. 70 miles loaded to the site on Friday, 100 miles on the road bike on Saturday, 50 miles Sunday morning then pack up and ride the 70 home (so 290 miles in 3 days, half on a 200lb cargo bike). Pretty sure he rode to work on Monday too.

Thats a serious bike! Amazed you run a suspension fork (or that any suspension fork can handle that much weight). I see 4 pot brakes (XTs?). You're definitely pushing the limits on bike parts there. Thanks for mentioning Kindernay, never seen them before but looks like a solid competitor to the Rohloff. Trigger shifters too (I hate grip shifters).

 

[Ken M]

I think I did overstate the load a bit as I was thinking of a trailer. It makes sense to rationally think the "total system load" on even a robust cargo bike should be kept under 500lbs just do you have some rational control of the bike. Having a trailer with supplemental breaking makes sense if you want to really haul heavy loads with an ebike but probably only commercial use will drive the need for something like that.

If the Bafang Ultra does generate up to 160nM of torque (probably either the static start torque and/or just the low end torque), I know a 200lb rider standing on the cranks generates about the same so a total of 300nM at the crank axle is real-world possible. I think what most of the bike companies are doing is ensuring that this torque is reduced via the drive ratio to the rear IGH (in many cases reducing it by up to 50%). This to me seems like adding a layer of mechanical inefficiency to reduce the force / stress on the IGH understanding that it increases the speed relative to cadence a lot as well which may be desirable depending on the range of the IGH gearing.

I started this tread because it seems like all the IGHs were designed prior to ebikes and certainly didn't anticipate mid-drive motors like the Bafang Ultra yet I expect this level of performance will become popular in the US when rider realize this will enable higher average speeds for commuting because you will ride up hills as if just a flat lever surface (honestly 250W EU specd mid drives really can't do that).

 

[mschwett]

... I think what most of the bike companies are doing is ensuring that this torque is reduced via the drive ratio to the rear IGH (in many cases reducing it by up to 50%). This to me seems like adding a layer of mechanical inefficiency to reduce the force / stress on the IGH understanding that it increases the speed relative to cadence a lot as well which may be desirable depending on the range of the IGH gearing.

isn't that what the ratios are designed for though? the kindernay vii, for example, goes from .5:1.0 to 2.0:1. with a 44t up front and a 22t in the rear (just for convenience of the example) that gives a ratio of 1.0:1 to 4.0:1, which is pretty comparable to standard bike drivetrain ratios, say a 44t up front and a 11t to 44t in the rear.

that IGH is rated for 160nM, but i'm not sure if they are referring to the torque at the crank or at the input of the IGH itself. you'd hope the latter, since they have no control over the former which would actually give you your 300nM at the crank.

with 170mm cranks, that 140nM represents pretty much an entire 200lb rider's weight on the pedal at just the right time, without tipping the bike over . i tend to agree with m@robinson that it's possible but unlikely in practice for any sustained length of time. i guess the question is whether it's enough to break the IGH in that instant.

a more sustained amount of torque would be a strong rider putting out 400w for a few minutes at 90rpm. more like 40-50nM or something, without doing the math.

 

[Ken M]

isn't that what the ratios are designed for though? the kindernay vii, for example, goes from .5:1.0 to 2.0:1. with a 44t up front and a 22t in the rear (just for convenience of the example) that gives a ratio of 1.0:1 to 4.0:1, which is pretty comparable to standard bike drivetrain ratios, say a 44t up front and a 11t to 44t in the rear.

that IGH is rated for 160nM, but i'm not sure if they are referring to the torque at the crank or at the input of the IGH itself. you'd hope the latter, since they have no control over the former which would actually give you your 300nM at the crank.

with 170mm cranks, that 140nM represents pretty much an entire 200lb rider's weight on the pedal at just the right time, without tipping the bike over . i tend to agree with m@robinson that it's possible but unlikely in practice for any sustained length of time. i guess the question is whether it's enough to break the IGH in that instant.

a more sustained amount of torque would be a strong rider putting out 400w for a few minutes at 90rpm. more like 40-50nM or something, without doing the math.

This is what confuses me about the torque ratings of the IGHs. I would expect that they would be rated for the max static torque that they guarantee will not cause damage. That said if that is the case it just seems most/all are not adequate for the full power of the Bafang G620 + rider power with a 1:1 belt drive from the crank to the IGH.

 

[mschwett]

This is what confuses me about the torque ratings of the IGHs. I would expect that they would be rated for the max static torque that they guarantee will not cause damage. That said if that is the case it just seems most/all are not adequate for the full power of the Bafang G620 + rider power with a 1:1 belt drive from the crank to the IGH.

that isn’t surprising at all though, they were designed for bicycles with human riders or maybe human + mid drive motors in the 250-750w range, which don’t usually have that kind of torque (45-85 Nm is the common range), nor are they geared 1:1 from the chainring to the rear hub. if they were the gear ratios would also be way different - the range would be 1.0 - 4.0 and not .5 - 2.0

i would not be surprised if the “standard” city eBike in 5 years is mid motor belt drive plus IGH. i have a cheapie sturmey archer IGH on my city bike, and it’s just so much “easier” to ride when you don’t have to shift before and after stops.

 

[scrambler]

This is what confuses me about the torque ratings of the IGHs. I would expect that they would be rated for the max static torque that they guarantee will not cause damage. That said if that is the case it just seems most/all are not adequate for the full power of the Bafang G620 + rider power with a 1:1 belt drive from the crank to the IGH.

The Kindernay and the Rohloff have been tested (and are sold) with a Bafang Ultra boosted at 2300W with the Innotrace/Archon X1 bay WattWagon without issues

 

[mschwett]

The Kindernay and the Rohloff have been tested (and are sold) with a Bafang Ultra boosted at 2300W with the Innotrace/Archon X1 bay WattWagon without issues

isn‘t is sold with a fairly standard size chainring and rear cog though? approx 2 to 1, not 1 to 1 as Ken is talking about. Again, I have no idea why you’d do that…

and, of course, it’s also sold with a conventional 11 speed derailleur drivetrain that skips in the higher gears

 

[scrambler]

1 to 1 on a Kindernay XIV would indeed be very weird.
At a pedaling cadence of 80rpm, you would be going 10 mile per hour at the most in the highest gear

 

[Ken M]

isn‘t is sold with a fairly standard size chainring and rear cog though? approx 2 to 1, not 1 to 1 as Ken is talking about. Again, I have no idea why you’d do that…

and, of course, it’s also sold with a conventional 11 speed derailleur drivetrain that skips in the higher gears

The 2 to 1 reduction without question cuts the transmitted torque 50% while shifting the cadence/speeds to be more speed biased which is OK given that the Rohloff has like 6 underdrive low gears.

I just think the IGHs are being protected by this ratio as they really can not handle the potential max torque of the Bafang Ultra + rider at starts and low speeds. I would think all IGHs would have a torque rating at their axle so an apples to apples comparison can be made.

 

[Ken M]

1 to 1 on a Kindernay XIV would indeed be very weird.
At a pedaling cadence of 80rpm, you would be going 10 mile per hour at the most in the highest gear

In my opinion when the ratio is not 1:1 via the belt cogs this is the equivalent of a mechanical inefficiency. I'm just trying to figure out why it's not easy to find the max torque the IGHs can take at their axles.

 

[scrambler]

In my opinion when the ratio is not 1:1 via the belt cogs this is the equivalent of a mechanical inefficiency. I'm just trying to figure out why it's not easy to find the max torque the IGHs can take at their axles.

I am not sure what your reasoning is here, but how useful is a bike that can't go above 10mph??
And I would assume the torque value given by the manufacturer ARE at the axle of the Hub, or else they would have no way to know what configuration. This is also why they have a recommended max ratio ahead of the hub.
In any case, you should certainly be able to confirm that with the manufacturer directly.

 

[mschwett]

it doesn’t seem hard to find at all.

Tables - Rohloff AG

www.rohloff.de

there is lots of data out there - and there is a reason why bikes have gearing, it’s not a conspiracy nor any kind of “mechanical inefficiency.” you might as well say that all motors should be direct drive for the same reason. there is an optimum balance of speed and torque to create a certain amount of power for a given use. bicycles add a human element, so scaling those inputs and outputs around the practical limits of the human body is just good engineering, not a conspiracy!

 

[scrambler]

And if anything a two to one ratio between the motor (front) sprocket, and the Hub (rear Sprocket), is a good thing in that it protects the hub by reducing the torque at the hub.