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

[jabberwocky]

I've never seen any bike with a single chainring/cog using a 1:1 ratio. Something around/slightly above 2:1 is normal.

 

[Ken M]

I did some calculations and I believe the typical ebike (50lbs) + rider (150-200lbs) will break loose the rear tire (ie go from static to much lower dynamic friction) from 300-360nM of torque. So in my humble opinion that should be the minimum design torque the IGHs should be able to reliably be subjected to...and that's will no margin of safety/error. Can you imagine a car with transmission or rear end differential not strong enough to reliably take the full power of the motor it's integrated to (obviously muscle cars can do burnouts without damaging anything in the drive train). I'm just puzzled by the difficulty of finding information like apples to apples comparisons of the IGH torque ratings (almost like they cross their fingers they will last a year till out of warranty).

 

[scrambler]

Up until now IGH were use with human power and that was not an issue.
eBikes are now pushing the power envelope, and manufacturers are slow to adapt, in part because most of their IGH are not quite up to the task.

So at this point what matters is real world testing

And if you want a bike with a lot of power and an IGH, get one with a dual power train, like LMX, SEM, Boxxbike... so that the IGH only sees the pedaling power and none of the motor power.

 

[jabberwocky]

And the nicer IGHs are totally fine with most ebikes, for that matter. The people looking for something that can handle a super high torque motor on a heavy bike with a bunch of weight loaded on it are a niche market within a niche market within a niche market. Hard to imagine the R&D to cater to them would ever be remotely recouped. If you want someone to spend effort to design for that use case you need to be a market with more than a few hundred people worldwide.

 

[scrambler]

And the reality is that electric motors do not need gears, only the pedaling side need them.
So ultimately for high power bikes, dual drivetrains are the best solution

 

[Ken M]

I did a quick search for the Riese & Mueller models that have been reviewed on EBR to see what the belt ratio was on the models with IGHs. All but one was pretty much 1:1 which tells me alot. They do not need to reduce the torque to IGH with the 250W EU motors but the torque much be reduced when putting an IGH on the Bafang Ultra ebikes that are almost all at 2:1 (front the rear) which cuts to torque for the motor to the IGH by 50%. While some will say they did this to provide lower cadence at higher speeds that simply is not accurate as there are some 28mph S-pedelecs in the R&M line-up with IGHs that do not have that ratio.

 

[Ken M]

And the nicer IGHs are totally fine with most ebikes, for that matter. The people looking for something that can handle a super high torque motor on a heavy bike with a bunch of weight loaded on it are a niche market within a niche market within a niche market. Hard to imagine the R&D to cater to them would ever be remotely recouped. If you want someone to spend effort to design for that use case you need to be a market with more than a few hundred people worldwide.

Obviously the only legit market for the Bafang M620 is the US market because there is regulatory allowance for a 750W motor rating (some still insist it's a peak allowance but it's not below 20mph). But I believe that as more riders get some urban riding time on ebikes like the new Sonders models that power will become addicting simply because anyone can ride up say a 6% grade maintaining 20mph which is very challenging on the toy 250W EU limit. Riders will find that if they truly plan to get out of their car more frequently to commute on an ebike they will learn that the extra power is a big benefit. It's not so much about top speeds but making higher average speeds much more feasible for most riders. When commuting time is money so we are talking something entirely different than the leisure / recreation riding that many do.

It's clear that Bafang target the US market with the M620 and I'm guessing it will capture 5-10% of the US ebike market within the next 2 years and that motor really does need a robust IGH that has a long life cycle as well. With project US ebike sales expected to exceed 1 million units that means 50,000 powerful ebikes could benefit from a better IGH.

 

[jabberwocky]

I did a quick search for the Riese & Mueller models that have been reviewed on EBR to see what the belt ratio was on the models with IGHs. All but one was pretty much 1:1 which tells me alot. They do not need to reduce the torque to IGH with the 250W EU motors but the torque much be reduced when putting an IGH on the Bafang Ultra ebikes that are almost all at 2:1 (front the rear) which cuts to torque for the motor to the IGH by 50%. While some will say they did this to provide lower cadence at higher speeds that simply is not accurate as there are some 28mph S-pedelecs in the R&M line-up with IGHs that do not have that ratio.

You sure about that? A quick check of their US website says the Superdelite Rohloff comes with a 60t gates ring and 19t gates cog (more than 3:1), The Homage Rohloff is the same, the Multicharger Rohloff is 60/20 (exactly 3:1) and the Load is 55/19 (a little less than 3:1). For non Rohloff, the Roadster Vario (which comes with the Enviolo 380) is still 55/24 which is still more than 2:1, and the Tinker (same hub) is 55/22. Which one comes with a 1:1 gearing ratio?

Don't get me wrong, you can go 1:1 if you want, its just going to cut your speed for a given cadence/gear down a lot and reduce potential top speed. That might make sense on a heavily loaded cargo bike you don't want to ride quickly anyway, but with the gear spread on a Rohloff I suspect you're just putting some of your gear range at a speed thats so slow its almost unusable.

 

[kmccune]

I did some calculations and I believe the typical ebike (50lbs) + rider (150-200lbs) will break loose the rear tire (ie go from static to much lower dynamic friction) from 300-360nM of torque. So in my humble opinion that should be the minimum design torque the IGHs should be able to reliably be subjected to...and that's will no margin of safety/error. Can you imagine a car with transmission or rear end differential not strong enough to reliably take the full power of the motor it's integrated to (obviously muscle cars can do burnouts without damaging anything in the drive train). I'm just puzzled by the difficulty of finding information like apples to apples comparisons of the IGH torque ratings (almost like they cross their fingers they will last a year till out of warranty).

Muscle cars are frequently busting cogs, you can tear anything up if you try hard enough,I twisted the crankset out of an old middleweight bike doubling uphill one time,I guess I could generate more force in those days,I braced on the handlebars and was heaving pretty hard.
I like the idea of the cargo trailer with motor assist and brakes, you could haul a fair amount and still have an agile bike when separated. I believe some of these tech savvy Guys and Gals hereabouts could probably build an affordable "boosted" cargo trailer, some of those Asian people amaze me with what they can haul on a bicycle.

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.

Hats off to your Friend, He was a "beast"! RIP (Man Mule)

 

[m@Robertson]

I did some calculations and I believe the typical ebike (50lbs) + rider (150-200lbs) will break loose the rear tire (ie go from static to much lower dynamic friction) from 300-360nM of torque.

You are doing too much math on paper with zero time in the saddle. There is no way, no how, that any cargo bike is going to break traction from pedal power + motor power. Not even for a fraction of a second. Again as noted earlier your theoretical torque limit is correct but in the real world it doesn't happen. The Kindernays have no trouble reports with high powered systems. Rohloffs have only a few. Rohloffs have a LOT of time out in the market so 'only a few' is still very good. Kindernays were developed specifically with the torque of mid drives in mind ... but they are relatively new to the market.

 

[m@Robertson]

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).

Thats a Bluto on it in that picture. Since then I sold the Bluto and replaced it with a beefier Wren Inverted. The Bluto was referenced by Surly as acceptable to use, and the Wren is stronger still. Interestingly the Wren completely eliminates the slight death wobble the BFD has from the factory even with its factory fork.

The Surly Big Fat Dummy Project

Prologue (you are here)Episode 1: 138L (each) Panniers… Seriously?!Episode 2: Big Fat Dumb WideloadersEpisode 3: Kickstand KaosEpisode 4: Add a Flight Deck. And a HangarEpisode 5: LeftoversEp…

talesontwowheels.com

The brakes are Magura MT5 with 4-pc MT7 (8.P) pads and Tektro 203mm downhill rotors (2.3mm thick) front and rear.

In the 500+ lb range the brakes aren't really all that stressed because at best you can work up the courage to go about 8 mph and if you do go that high you are really conscious of the fact that its a runaway freight train. Braking isn't the fear, its steering. You can't zig even a little to avoid anything. If you do, you fall over. Such is the reality of a 500 lb bike. Running at 3-5 mph you use the granny gears big time. I have an 11 spd drivetrain (steel parts) and I'm running right up in one of the biggest three cogs even on smooth, flat pavement.

Nowadays I have a 36T chainring up front and use the bike for gathering firewood in the mountains while camping. The wideloaders + straps make for some effective shelves.

 

[m@Robertson]

And the reality is that electric motors do not need gears, only the pedaling side need them.
So ultimately for high power bikes, dual drivetrains are the best solution

No thats not true. A mid drive taking advantage of the gears is the reason why mid drives exist. Here again thats a theoretical argument that is correct in the textbook only. Ride up some steep hills in a 2000w hub that is singlespeed and powers thru the axle. Then try a 1750w mid that you gear down and you immediately appreciate the difference. This is the reason all *quality* emtb's are mid drives. The motor needs the gears. If we someday invent an ebike motor that has a 3-6kw of power and can be lugged down to 60 rpms long term without damage or inordinate power waste, THEN your electric motor doesn't need any gears.

 

[scrambler]

I should have qualified; it does depend on the motor of course.
But if you have a good enough motor, there is no need for gears.
Examples with the high-power eBikes using a dual drivetrain like LMX, SEM or BoxxBike. And of course, electric motorcycles and cars.

Another issue with current single drivetrain mid drive, is that because of the pedaling gear ratio needed to provide proper pedaling cadence range, the gearing for the motor is not ideal, hence the need to use the gears for the motor too.
If you were to give these eBike a separate drivetrain with a ratio suited to the motor, I suspect the motor could handle the power without gears. It would just spins at higher rpms at the top of the range.

 

[mschwett]

I should have qualified; it does depend on the motor of course.
But if you have a good enough motor, there is no need for gears.
...

but "good enough" depends on your criteria. as i understand it, if you'd like the motor to be light and small, it's going to spin faster to achieve the needed power, and have reduction gears to achieve the needed torque. isn't this why the VAST majority of mid drive and hub drives are not direct drive anymore?

if weight and size are not a criteria, then i agree, you'd simply size the magnets and windings and power system to provide exactly the torque and speed needed directly at the axle.

 

[mschwett]

I did a quick search for the Riese & Mueller models that have been reviewed on EBR to see what the belt ratio was on the models with IGHs. All but one was pretty much 1:1 which tells me alot. They do not need to reduce the torque to IGH with the 250W EU motors but the torque much be reduced when putting an IGH on the Bafang Ultra ebikes that are almost all at 2:1 (front the rear) which cuts to torque for the motor to the IGH by 50%. While some will say they did this to provide lower cadence at higher speeds that simply is not accurate as there are some 28mph S-pedelecs in the R&M line-up with IGHs that do not have that ratio.

uh, no? as in, not even close, and easily found directly on the r+m site. they offer a couple different IGH, but here's the first two bikes with belt & IGH that i looked at, representing a wide range.

2.89:1 and 2.29:1

there is no conspiracy here by a cabal of bike and IGH makers to rob you of efficiency, it's just good engineering.

 

[Ken M]

You sure about that? A quick check of their US website says the Superdelite Rohloff comes with a 60t gates ring and 19t gates cog (more than 3:1), The Homage Rohloff is the same, the Multicharger Rohloff is 60/20 (exactly 3:1) and the Load is 55/19 (a little less than 3:1). For non Rohloff, the Roadster Vario (which comes with the Enviolo 380) is still 55/24 which is still more than 2:1, and the Tinker (same hub) is 55/22. Which one comes with a 1:1 gearing ratio?

Don't get me wrong, you can go 1:1 if you want, its just going to cut your speed for a given cadence/gear down a lot and reduce potential top speed. That might make sense on a heavily loaded cargo bike you don't want to ride quickly anyway, but with the gear spread on a Rohloff I suspect you're just putting some of your gear range at a speed thats so slow its almost unusable.

Strange here's the delite with a Nuvinci with a 26T front and 28T rear. All I did was do a quick search on EBR for all the R&M reviews and then looked at the cogs when they had an IGH installed

Here's the super charger with Rolhoff with a 22T front and 20T rear. Obviously there is some strange ratio thing going on and it's not all about climbing or speed biasing.

 

[Ken M]

You are doing too much math on paper with zero time in the saddle. There is no way, no how, that any cargo bike is going to break traction from pedal power + motor power. Not even for a fraction of a second. Again as noted earlier your theoretical torque limit is correct but in the real world it doesn't happen. The Kindernays have no trouble reports with high powered systems. Rohloffs have only a few. Rohloffs have a LOT of time out in the market so 'only a few' is still very good. Kindernays were developed specifically with the torque of mid drives in mind ... but they are relatively new to the market.

The torque that would break loose a rear tire isn't that complex of a calculation but it's only an estimate. I was just suggesting that an IGH that could reliably handle that much torque is at the limit that would ever be needed on any ebike regardless of the motor power. I asked Kindernay if they would guarantee their IGH with a Bafang G620 (assuming 1:1 belt/chain ratio) and they said that was torque that they would not consider a normal bike. I assume that meant no.

Keep in mind I am not considering if the IGH from any of the brands are proven reliable with the 250W EU mid drives. I want to know if they will have the same success when they are integrated on an ebike with a 750W (or higher peak) Bafang M620 including the possibility of say a 200lb rider standing on the cranks. Oh, and not geared down to reduce the torque from the mid drive axle to the rear IGH. I think there is clear concern in the industry that the Bafang M620 is a bit much for the current IGHs (and not just with typical cargo bike loads).

 

[Ken M]

No thats not true. A mid drive taking advantage of the gears is the reason why mid drives exist. Here again thats a theoretical argument that is correct in the textbook only. Ride up some steep hills in a 2000w hub that is singlespeed and powers thru the axle. Then try a 1750w mid that you gear down and you immediately appreciate the difference. This is the reason all *quality* emtb's are mid drives. The motor needs the gears. If we someday invent an ebike motor that has a 3-6kw of power and can be lugged down to 60 rpms long term without damage or inordinate power waste, THEN your electric motor doesn't need any gears.

You are not correct on this. Motors like to spin fast so the best way to provide the motor power to the rear wheel would be a small front cog and a larger rear cog. Check out the configuration of Luna's Sur-Ron electric cycle (very small front and large rear and single speed but does have even reduction via belt inside the motor ... but still a single speed drive system that allows the motor to spin pretty fast even at slow speeds). This is pretty much how every electric motorcycle is configured. Sure mid-drives when in the lower gears (ie getting a mechanical boost from the gearing can climb well but there is a compromise taking place when you combine human and motor thru one drive system). Think about a rider putting their power thru that gearing you mention and they get a good boost at a desirable cadence but if the motor is separated a small front to a very large rear will significantly boost the motor torque more than sharing what is best for us weak pedaling humans. If you are riding a say 20mph with a 44T front chainring and an 11T rear chain ring on a mid-drive the combined human and motor torque is dropped 75% just to provide reasonable cadence for the rider. If the motor was on a separate drive the torque would still be magnified (there are other factors such as motor Kv and Kt that play into this but just given that motors are more efficient spinning fast I don't think there is much chance that integrating a motor and rider via a mid-drive is optimized. I don't think there is any technical merit to saying a combine drive system is best. Simple not true based on everything I know but I'm wanting to know if there is any chance this is wrong.

 

[Ken M]

I should have qualified; it does depend on the motor of course.
But if you have a good enough motor, there is no need for gears.
Examples with the high-power eBikes using a dual drivetrain like LMX, SEM or BoxxBike. And of course, electric motorcycles and cars.

Another issue with current single drivetrain mid drive, is that because of the pedaling gear ratio needed to provide proper pedaling cadence range, the gearing for the motor is not ideal, hence the need to use the gears for the motor too.
If you were to give these eBike a separate drivetrain with a ratio suited to the motor, I suspect the motor could handle the power without gears. It would just spins at higher rpms at the top of the range.

You are absolute right about this. You just will not hear anyone in the ebike industry admit that mid-drives simply are not optimized for motors. They fool people by saying they dramatically help climbing but over the gearing range that is as you say all about human cadence the motor capability is not optimized. Must be a separate drive system to be optimize for motor and human. Lots of koolaid out their to drink so be careful when marketing people speak.

I really wonder how good an ebike would be that had say a 750W (higher peak) inrunner motor driving the rear wheel via a belt ratio optimized for the motor on opposite side of the rider gearing. The only production ebike to ever explore this design was the Izip express but it was plagued by a bad slipping rear differential rear hub that was even needed in my opinion and a funky cadence based throttle such that the assistance provided was only based on the rotation speed of the cranks (why can't programmers just realize a throttle allows the rider to get the assist they want at all times and stop trying to think you can out-program that fact even with every potential sensor there is ... torque, speed, cadence, heart rate, gear, slope, etc. .... I'd rather just control the assist myself).

 

[Ken M]

uh, no? as in, not even close, and easily found directly on the r+m site. they offer a couple different IGH, but here's the first two bikes with belt & IGH that i looked at, representing a wide range.

2.89:1 and 2.29:1

there is no conspiracy here by a cabal of bike and IGH makers to rob you of efficiency, it's just good engineering.

View attachment 114243View attachment 114244

Any belt / chain ratio of a larger front and smaller rear reduces the torque from the crank axle to the rear wheel axle. That is just a simple T = F x D calculation. There absolutely could be other reasons for this like having the right cadence at the speed range the ebike is intended for which is impacted by if the IGH has under-drive gears or starts closer to 1:1 direct drive. Most planet gear IGH designs have some under-drive ratios (I think the Rohloff 14 speed has 6 and the CVT's have 50% of the range as under-drive).

I am merely try to understand if the current IGHs on the market are really OK and optimized for use with the Bafang M620 if the full torque is transmitted to the rear via a 1:1 drive ratio of the belt/chain rings. I think that is problematic for all the current IGHs.

My thoughts are that when you gear the Bafang at 2:1 via belt it pretty much makes it perform like a 250W mid-drive. I think if/when urban riders actually experience the real world performance of the Bafang M620 on an ebike (like easily going up a 6% grade at 20mph) they will will no longer think of the EU spec mids favorably. I remember as I went for a 50cc motorcycle as a kid to a 100cc then to a 250cc then to a 440cc then to a 750cc and finally buying a Honda V65 (1100cc) the power really becomes compelling. Ask anyone riding a 750W ebike if they would want to go back to riding a 250w ebike. Probably not.