What brand?
'lightest.bike' 1.7kg 1000w mid drive
- Thread starter Grantmac
- Start date
nervagon
1 kW
- Joined
- Nov 18, 2020
- Messages
- 361
The bike? Mongoose Envoy.
Okay i just read about IGHs for a couple days solid, and i'm disappointed.
It seems the only IGH i could use is a 3 speed, i found some specs on the Shimano Alfine 8 that showed it can only take 60nm. Shimano says the 5 speed is 50% stronger, that means it's rated ~90nm if true. I can't find any rating on the 3 speeds but a wild guess would be 120nm.
But we have 120nm of motor power already before i start pedaling. Then maybe we add 80nm peak. We may hit 200nm on this IGH's input and it probably wouldn't have a long life.
So basically if you want a reliable experience with an IGH then you are looking at a Rohloff or '3x3 nine' for >$1000 and adding another 3lbs to the bike and also getting some % lower drivetrain efficiency for the privilege.
It doesn't make any sense. I could buy ~10 years of 11t sprockets and other drivetrain parts for that price.
How can we just put a honker of a chainring on here instead?
I have two sets of mid mount plates. I could use the second set as a replacement for the inframe mount bracket and gain 60mm of extra length at most. But we are going to dock ourselves 12mm because this midframe mount adds about that much and we gotta account for that.
Let's call this + 48mm unit a mid-long mount.
If we put a 60T on the bike ( let's just imagine ) and use a mid-long mount, we just barely miss clearing a 60T sprocket and having a strong 60T to 12T. Going from a 11T to 12T/13T motor sprocket wouldn't give us enough added clearance to make this work.
If i were to retain the inframe mount plates then i could cascade these 3 plates and have a total ~60mm of rise. and make the 60T -> 12T thing actually work. This configuration may lack lateral stability so i think it'd be wise to also create a solid front mount like Nervagon has.
52T is easy street and considering we probably need to upgrade from a 11T motor sprocket to 12T or 13T, then the mid-long mount should be able to clear at least a 56T. The frame should be able to clear it too with the narrower BB than stock.
With a 11T lowest cassette gear and some aggressive pedaling i should be able to hit the top speed of 35mph i desire.
In the gear with 14T, i should hit the maximum legal ebike speed, which is the speed i prefer to cruise at >90% of the time. perfect!
Can we actually go 35mph with high intensity pedaling and stock power?
This motor's burst wattage is 25A x 48v = 1200W.
By using a 52v battery we should have a burst power of 1300W.
Let's use the Shengyi SX2 ( highest efficiency geared motor RN ) as a model of the lightest considering the lightest is supposedly ~90% efficient. This should at least give us an idea of the watt requirements of that speed.
Yup.. just below 1300w burst power limit at 35.5mph, and we can pedal harder if the lightest is is -2% efficient as this.
On a 29er with a 10T lower gear you could just fit a 46T to a mid mount to hit this same speed.
But you may get tired of disposable 10T chainrings and eventually want to move up to my mid-long mount and 56T chainring + 12T lowest cassette sprocket.
I'm glad i can at least get the kind of gearing that would max out the drive without resorting to anything exotic!
It seems the only IGH i could use is a 3 speed, i found some specs on the Shimano Alfine 8 that showed it can only take 60nm. Shimano says the 5 speed is 50% stronger, that means it's rated ~90nm if true. I can't find any rating on the 3 speeds but a wild guess would be 120nm.
But we have 120nm of motor power already before i start pedaling. Then maybe we add 80nm peak. We may hit 200nm on this IGH's input and it probably wouldn't have a long life.
So basically if you want a reliable experience with an IGH then you are looking at a Rohloff or '3x3 nine' for >$1000 and adding another 3lbs to the bike and also getting some % lower drivetrain efficiency for the privilege.
It doesn't make any sense. I could buy ~10 years of 11t sprockets and other drivetrain parts for that price.
How can we just put a honker of a chainring on here instead?
I have two sets of mid mount plates. I could use the second set as a replacement for the inframe mount bracket and gain 60mm of extra length at most. But we are going to dock ourselves 12mm because this midframe mount adds about that much and we gotta account for that.
Let's call this + 48mm unit a mid-long mount.
If we put a 60T on the bike ( let's just imagine ) and use a mid-long mount, we just barely miss clearing a 60T sprocket and having a strong 60T to 12T. Going from a 11T to 12T/13T motor sprocket wouldn't give us enough added clearance to make this work.
If i were to retain the inframe mount plates then i could cascade these 3 plates and have a total ~60mm of rise. and make the 60T -> 12T thing actually work. This configuration may lack lateral stability so i think it'd be wise to also create a solid front mount like Nervagon has.
52T is easy street and considering we probably need to upgrade from a 11T motor sprocket to 12T or 13T, then the mid-long mount should be able to clear at least a 56T. The frame should be able to clear it too with the narrower BB than stock.
With a 11T lowest cassette gear and some aggressive pedaling i should be able to hit the top speed of 35mph i desire.
In the gear with 14T, i should hit the maximum legal ebike speed, which is the speed i prefer to cruise at >90% of the time. perfect!
Can we actually go 35mph with high intensity pedaling and stock power?
This motor's burst wattage is 25A x 48v = 1200W.
By using a 52v battery we should have a burst power of 1300W.
Let's use the Shengyi SX2 ( highest efficiency geared motor RN ) as a model of the lightest considering the lightest is supposedly ~90% efficient. This should at least give us an idea of the watt requirements of that speed.
Yup.. just below 1300w burst power limit at 35.5mph, and we can pedal harder if the lightest is is -2% efficient as this.
On a 29er with a 10T lower gear you could just fit a 46T to a mid mount to hit this same speed.
But you may get tired of disposable 10T chainrings and eventually want to move up to my mid-long mount and 56T chainring + 12T lowest cassette sprocket.
I'm glad i can at least get the kind of gearing that would max out the drive without resorting to anything exotic!
Vbruun
100 W
- Joined
- Sep 26, 2019
- Messages
- 294
The 5 speed is probably strong enough. It is used with the big Shimano motor which pulls 5-700w peak and then geared for a top speed of about 18 mph.Okay i just read about IGHs for a couple days solid, and i'm disappointed.
It seems the only IGH i could use is a 3 speed, i found some specs on the Shimano Alfine 8 that showed it can only take 60nm. Shimano says the 5 speed is 50% stronger, that means it's rated ~90nm if true. I can't find any rating on the 3 speeds but a wild guess would be 120nm.
But we have 120nm of motor power already before i start pedaling. Then maybe we add 80nm peak. We may hit 200nm on this IGH's input and it probably wouldn't have a long life.
So basically if you want a reliable experience with an IGH then you are looking at a Rohloff or '3x3 nine' for >$1000 and adding another 3lbs to the bike and also getting some % lower drivetrain efficiency for the privilege.
It doesn't make any sense. I could buy ~10 years of 11t sprockets and other drivetrain parts for that price.
How can we just put a honker of a chainring on here instead?
View attachment 350299
I have two sets of mid mount plates. I could use the second set as a replacement for the inframe mount bracket and gain 60mm of extra length at most. But we are going to dock ourselves 12mm because this midframe mount adds about that much and we gotta account for that.
Let's call this + 48mm unit a mid-long mount.
View attachment 350300
If we put a 60T on the bike ( let's just imagine ) and use a mid-long mount, we just barely miss clearing a 60T sprocket and having a strong 60T to 12T. Going from a 11T to 12T/13T motor sprocket wouldn't give us enough added clearance to make this work.
If i were to retain the inframe mount plates then i could cascade these 3 plates and have a total ~60mm of rise. and make the 60T -> 12T thing actually work. This configuration may lack lateral stability so i think it'd be wise to also create a solid front mount like Nervagon has.
View attachment 350301
52T is easy street and considering we probably need to upgrade from a 11T motor sprocket to 12T or 13T, then the mid-long mount should be able to clear at least a 56T. The frame should be able to clear it too with the narrower BB than stock.
With a 11T lowest cassette gear and some aggressive pedaling i should be able to hit the top speed of 35mph i desire.
In the gear with 14T, i should hit the maximum legal ebike speed, which is the speed i prefer to cruise at >90% of the time. perfect!
View attachment 350309
Can we actually go 35mph with high intensity pedaling and stock power?
This motor's burst wattage is 25A x 48v = 1200W.
By using a 52v battery we should have a burst power of 1300W.
Let's use the Shengyi SX2 ( highest efficiency geared motor RN ) as a model of the lightest considering the lightest is supposedly ~90% efficient. This should at least give us an idea of the watt requirements of that speed.
View attachment 350311
Yup.. just below 1300w burst power limit at 35.5mph, and we can pedal harder if the lightest is is -2% efficient as this.
On a 29er with a 10T lower gear you could just fit a 46T to a mid mount to hit this same speed.
View attachment 350312
But you may get tired of disposable 10T chainrings and eventually want to move up to my mid-long mount and 56T chainring + 12T lowest cassette sprocket.
I'm glad i can at least get the kind of gearing that would max out the drive without resorting to anything exotic!
If you want to gear twice as steep for that sweet 36 mph top speed, you can use twice the motor power with the rear hub seeing the same torque.
nervagon
1 kW
- Joined
- Nov 18, 2020
- Messages
- 361
@neptronix two words: dual chainring.
Fun fact about the 3X3 IGH. It has no freewheel. So it requires a crank freewheel, which you already have.
Fun fact about the 3X3 IGH. It has no freewheel. So it requires a crank freewheel, which you already have.
nervagon
1 kW
- Joined
- Nov 18, 2020
- Messages
- 361
@neptronix what you are trying to do (35mph) requires your 26" rear wheel to spin at 393rpm. That is faster than the pinion gear spins under load, and the pinion gear directly pulls the rear cog. See the problem? The chainring is only for you in the single chain config. It does nothing to the motor RPMs.
You have no choice but to use the power of a compound gear (dual-chainring) to get you there. See below:
You must use a compound gear to "overdrive" the RPM of the pinion gear to get your small wheel to high speed.
Pinion goes to the 38T, 46T goes to the 11T at the cassette. 396rpms and barely a reduction in torque. Magic.
So you are looking at installing a 46/38 chainring and shipping your motor back to Italy for the new firmware supporting dual-chainring. There is no way around, bro.
You have no choice but to use the power of a compound gear (dual-chainring) to get you there. See below:
You must use a compound gear to "overdrive" the RPM of the pinion gear to get your small wheel to high speed.
Pinion goes to the 38T, 46T goes to the 11T at the cassette. 396rpms and barely a reduction in torque. Magic.
So you are looking at installing a 46/38 chainring and shipping your motor back to Italy for the new firmware supporting dual-chainring. There is no way around, bro.
raylo32
100 kW
rhauff
100 mW
Did you find a different source for a larger motor pinion? Obviously Bikee won't provide as they just dashed me down when I asked.
I'm not able to measure the output shaft or spline count as I don't have one in hand, appears to be about a 30 fine spline by the few photos.
nervagon
1 kW
- Joined
- Nov 18, 2020
- Messages
- 361
@neptronix I was wrong my calculation for your rear wheel RPM. I entered the dimensions of your wheel incorrectly. You actually need a whopping 455rpm. Wow.
So here's a new compound chainring to achieve that:
And if you can have a machine shop make you an new pinion gear at 13T and stay at single chainring:
You can get there at 13T pinion, 10T rear cog. It would lower your torque, but so would the compound gear/double chainring you'd need to get the RPM overdrive. You will get a cadence of 90 with a massive 52T chainring and a 13T pinion. I can see why Bikee would never bother making a larger pinion. It handicaps the motor. And here's another problem: the rear cog must be larger than the pinion in single chain mode according to Bikee.
What I don't understand is why you didn't go with a direct drive rear hub. You have a small enough wheel for a hub, and you are trying to build a high speed electric vehicle. Your design criteria are high speed and narrow q-factor. You can get that with a powerful hub. A mid drive seems like a poor choice here. But if you insist, look again at my compound gearing above. It will get you to 455rpm way more practically than having a machine shop CNC you a new pinion gear.
So here's a new compound chainring to achieve that:
And if you can have a machine shop make you an new pinion gear at 13T and stay at single chainring:
You can get there at 13T pinion, 10T rear cog. It would lower your torque, but so would the compound gear/double chainring you'd need to get the RPM overdrive. You will get a cadence of 90 with a massive 52T chainring and a 13T pinion. I can see why Bikee would never bother making a larger pinion. It handicaps the motor. And here's another problem: the rear cog must be larger than the pinion in single chain mode according to Bikee.
What I don't understand is why you didn't go with a direct drive rear hub. You have a small enough wheel for a hub, and you are trying to build a high speed electric vehicle. Your design criteria are high speed and narrow q-factor. You can get that with a powerful hub. A mid drive seems like a poor choice here. But if you insist, look again at my compound gearing above. It will get you to 455rpm way more practically than having a machine shop CNC you a new pinion gear.
rhauff
100 mW
It was in this forum just last week:
'lightest.bike' 1.7kg 1000w mid drive
Te oimos... A partir de las solicitudes de @nervagon y viendo la imposible instalación de @neptronix en los reclinados, finalmente desarrollamos la configuración de cadena dual. Esta configuración tiene varias ventajas: 1) MÁS FLEXIBILIDAD CON LA INSTALACIÓN: ya no es necesario que el...
endless-sphere.com
I guess Matteo didn't Explicitly say its not available, but he didn't reply to my followup a couple days later either. Hope you get a better answer
nervagon
1 kW
- Joined
- Nov 18, 2020
- Messages
- 361
I also double checked my own wheel measurements and my loaded and unloaded real-world RPM estimates for my bike were slightly off.
At 52V:
My revised unloaded RPM is 450rpm. Same as Bikee's 48V numbers
My revised loaded RPM with heavy rider and top speed is 337rpm (also worst case RPM)
At 52V:
My revised unloaded RPM is 450rpm. Same as Bikee's 48V numbers
My revised loaded RPM with heavy rider and top speed is 337rpm (also worst case RPM)
Thanks for doing these calculations for me.
- 10T rear cassette cog: i have to switch to a 9-10 speed drivetrain just to do this and i incur additional drivetrain weakness in both the chain and sprocket now versus my existing 7 speed setup
- Dual chainring can work but i don't prefer it because of the lower efficiency ( can't hit 35mph without adding +1-2 amps to the controller ) and probably $200 cost when we consider shipping + programming cost + additional hardware + shipping.
- Lowest rear sprocket size for an IGH i can find is 14T so this discludes the 3 speed and 5 speed ( bad gear ratios ) Shimano IGH. Only the 8 speed would work but it has half the NM rating of the motor, so..
A DD hub that can handle my hills without melting and at an acceptable efficiency ( always a problem when climbing ) would be 16lbs.
I'm not trying to build a high power bike. My average speed will be 28mph but bike lanes in my area appear and disappear randomly which will force me into the car lane with traffic doing 35mph. I find that going slower than traffic in the car lane is extremely unsafe because drivers here usually aren't paying any attention to the road.
30mph would be fine but would limit the bike to not being a car substitute and instead a plaything because there are so many places i can't access. now the bike needs to get loaded into the gas powered car and unloaded at the mountain biking destination because it can't go 5mph faster. I don't like it
- 10T rear cassette cog: i have to switch to a 9-10 speed drivetrain just to do this and i incur additional drivetrain weakness in both the chain and sprocket now versus my existing 7 speed setup
- Dual chainring can work but i don't prefer it because of the lower efficiency ( can't hit 35mph without adding +1-2 amps to the controller ) and probably $200 cost when we consider shipping + programming cost + additional hardware + shipping.
- Lowest rear sprocket size for an IGH i can find is 14T so this discludes the 3 speed and 5 speed ( bad gear ratios ) Shimano IGH. Only the 8 speed would work but it has half the NM rating of the motor, so..
A DD hub that can handle my hills without melting and at an acceptable efficiency ( always a problem when climbing ) would be 16lbs.
I'm not trying to build a high power bike. My average speed will be 28mph but bike lanes in my area appear and disappear randomly which will force me into the car lane with traffic doing 35mph. I find that going slower than traffic in the car lane is extremely unsafe because drivers here usually aren't paying any attention to the road.
30mph would be fine but would limit the bike to not being a car substitute and instead a plaything because there are so many places i can't access. now the bike needs to get loaded into the gas powered car and unloaded at the mountain biking destination because it can't go 5mph faster. I don't like it
A 25% difference in loaded vs not loaded is expected but the RPM not going up with a higher voltage battery isn't.
These are cheap and accurate:
https://www.ebay.com/itm/265802912021?itmmeta=01HTDKM2J751YFEQM8KRR0MZAF&hash=item3de3169115:g:OlEAAOSw~YNjX-2d&itmprp=enc:AQAJAAAA4NtOL9A/k72lJ2YQsXhzEigI7t+cXPpcl9X/Q9zUw4WZgXMyrqDw4ADzORns1RklzkDtd0gPvnLq9EFZ19F6u9vPfkeTCfC19mZzM1VBv1+ZgOKI2O5Av3lb6NGEDT5POJt4M+M5q1bk6z2dMZSGhBuh9T1mwZBK+ShJ36gNHsSQOL4fnbBt5cXrH5FN0Vno9YT05vQSSfTZs1M6IU2Rpm4CFXR6hPnYug2PmSZx+cFAQiGwVw/o+ljuOsPQgynwQUE3ExVlEPgNgNxkNkMAocTkVQPh78WHjbk5FuM6UnJs|tkp:Bk9SR7Cp0LPTYw
rivers
100 mW
I have not removed the noisy Bikee kit from my carbon road bike as yet but getting close to doing so.
However, some recent testing has given a ray of hope. The horrible squealing/scraping sounds are worse when the bike is ridden at normal cadence with light to moderate loading. Those obnoxious sounds largely go away when the bike is under high pedaling pressure going uphill or when riding on level ground in a gear too hard for the terrain.
This made me think the problem could be coming not from the gearing, but rather, from one of the two freewheels in the drive train. Any thoughts would be appreciated.
However, some recent testing has given a ray of hope. The horrible squealing/scraping sounds are worse when the bike is ridden at normal cadence with light to moderate loading. Those obnoxious sounds largely go away when the bike is under high pedaling pressure going uphill or when riding on level ground in a gear too hard for the terrain.
This made me think the problem could be coming not from the gearing, but rather, from one of the two freewheels in the drive train. Any thoughts would be appreciated.
Vbruun
100 W
- Joined
- Sep 26, 2019
- Messages
- 294
Thanks for doing these calculations for me.
- 10T rear cassette cog: i have to switch to a 9-10 speed drivetrain just to do this and i incur additional drivetrain weakness in both the chain and sprocket now versus my existing 7 speed setup
- Dual chainring can work but i don't prefer it because of the lower efficiency ( can't hit 35mph without adding +1-2 amps to the controller ) and probably $200 cost when we consider shipping + programming cost + additional hardware + shipping.
- Lowest rear sprocket size for an IGH i can find is 14T so this discludes the 3 speed and 5 speed ( bad gear ratios ) Shimano IGH. Only the 8 speed would work but it has half the NM rating of the motor, so..
A DD hub that can handle my hills without melting and at an acceptable efficiency ( always a problem when climbing ) would be 16lbs.
I'm not trying to build a high power bike. My average speed will be 28mph but bike lanes in my area appear and disappear randomly which will force me into the car lane with traffic doing 35mph. I find that going slower than traffic in the car lane is extremely unsafe because drivers here usually aren't paying any attention to the road.
30mph would be fine but would limit the bike to not being a car substitute and instead a plaything because there are so many places i can't access. now the bike needs to get loaded into the gas powered car and unloaded at the mountain biking destination because it can't go 5mph faster. I don't like it
The nexus 5 only has overdrive ratios. 1:2,6 in 5th gear.
Really? I thought when the gear ratio went up in number.. in some listings for other IGH, it indicated the opposite.
Pardon me, i'm more of an power electronics/programming guy than a mechanical guy, lol..
Okay, that's quite the drive then. You can run some insanely oversized gearing ( 20T to 48T ) that achieves ~15mph/24kph and still hit ~40mph/65kmh.
Do you know if:
- The 1st gear is a direct drive.. so that we have some super strong gear for takeoffs..
- It has a maximum input torque spec listed anywhere
- Anyone has experience with running this.. most experience online seems to be with the 8 speed.. and blowing it frequently.
I browsed around and see you can buy an internals pack for this IGH if you blow it... that's a good sign.
These prices for Shimano IGHs are really cheap in Europe compared to the USA. Maybe it's worth sacrificing one to the ebike gods..
Pardon me, i'm more of an power electronics/programming guy than a mechanical guy, lol..
Okay, that's quite the drive then. You can run some insanely oversized gearing ( 20T to 48T ) that achieves ~15mph/24kph and still hit ~40mph/65kmh.
Do you know if:
- The 1st gear is a direct drive.. so that we have some super strong gear for takeoffs..
- It has a maximum input torque spec listed anywhere
- Anyone has experience with running this.. most experience online seems to be with the 8 speed.. and blowing it frequently.
I browsed around and see you can buy an internals pack for this IGH if you blow it... that's a good sign.
These prices for Shimano IGHs are really cheap in Europe compared to the USA. Maybe it's worth sacrificing one to the ebike gods..
nervagon
1 kW
- Joined
- Nov 18, 2020
- Messages
- 361
On the nexus: 1st gear is direct drive. Whatever gearing you have will be your low gear. The nexus 5 has high drag, cast gears, and thick grease instead of milled gears and oil bath like rohloff. The gear jumps are 21%. You will feel the drag. It is a low-end product that was often paired with 25kmh pedelecs, so it often ended up being only 3 usable gears because customers of those bikes found it too difficult to pedal gear 4 and 5 without motor assistance. It might work in your use case, but you should be aware of the extreme drag because you are very keen on efficiency.
nervagon
1 kW
- Joined
- Nov 18, 2020
- Messages
- 361
If their max unloaded rpm is disconnected from the drive train that would account for the lack of RPM boost I saw at 52V unloaded while connected to the wheel through a chain and derailleur.
nervagon
1 kW
- Joined
- Nov 18, 2020
- Messages
- 361
Which Bicycle Gearbox Has The Highest Drive Efficiency? Rohloff, Pinion, Shimano - CYCLINGABOUT
How do gearbox systems compare in terms of drivetrain efficiency? And what is the difference in cycling speed between gearbox options?
www.cyclingabout.com
Be prepared to dock another 10% from your calculations unless you go rohloff, but rohloff won't give you the overdrive you need.
Oh it has that thick grease huh..
I would be very unhappy about that drag and would want to convert it to an ATF bath immediately.
Because it has removable internals, there's a very small area on the hub where you could have ATF hanging out. Tilt the bike a few degrees and that ATF is coming out of the side seals so now you need to figure out how to make that not happen and make ATF spillage only happen out the axles which should be minor.
ATF would improve the efficiency and durability of the drive. We don't know by how much.
It's another science experiment to throw money into and i'm starting to get exhausted with this effort already.
My semi recumbent will do 37mph on 1200W and has two gearing stages so i have more than enough room to regear.
I'm trading gearing problems for mounting problems but i think those would be easier to cure with the lowest amount of compromises. I think that's the better route to go.
I've sent an email asking bikee if there are any other possible options. I'm not crossing my fingers.
I would be very unhappy about that drag and would want to convert it to an ATF bath immediately.
Because it has removable internals, there's a very small area on the hub where you could have ATF hanging out. Tilt the bike a few degrees and that ATF is coming out of the side seals so now you need to figure out how to make that not happen and make ATF spillage only happen out the axles which should be minor.
ATF would improve the efficiency and durability of the drive. We don't know by how much.
It's another science experiment to throw money into and i'm starting to get exhausted with this effort already.
My semi recumbent will do 37mph on 1200W and has two gearing stages so i have more than enough room to regear.
I'm trading gearing problems for mounting problems but i think those would be easier to cure with the lowest amount of compromises. I think that's the better route to go.
I've sent an email asking bikee if there are any other possible options. I'm not crossing my fingers.
Similar threads
