Hypothetical bike build. (Electrifying a Surly Moonlander 2.0 with Pinion Gearbox for max range)

[Bvagu]

Hello,

I'm new to e-bikes, but have been "unfortunately"(or not) been pushed down the rabbit-hole of e-bikes by a friend of mine. He is trying to convince me (and he is almost there) to buy an e-bike, but I have been reluctant to do so because of range. I was of the opinion that if you want at least 100-150km range the bike will be very heavy and that will have a very bad consequences on parts made for bicycles (especially off-road).

He was of the opinion that technologies have moved on and now it's not that far off to get to that range, and that was the start of the rabbit-whole...
After some "rabbit-holing" I came to the conclusion that so far no one (and probably for a good reason) has tried to combine two mid-drive motors in one bike (granted one is technically a hub motor) to overcome some drawbacks of different systems.

So for a climbing mountains (which is what I like), I was thinking of combining "normal" mid-drive motor in a Qulbix Q140MD frame that will sit in the bottom bracket slot, and that motor to be connected to a direct drive motor in the place that the Q140MD frame has for that purpose, so this way the normal geared mid-drive motor will provide enough push for the direct-drive motor not to stall and be in optimal rpm, this way you can still have regen braking. Since air-drag is the biggest enemy to biking in terms of efficiency, I was thinking of staying at the 15-25km/h range for speed. I know that speed is really slow and probably not very fun, but we are after range.

So lets say a 72V battery with like 60Ah that can fit in the Q140MD and have Toseven DM01, that "spins up" a leaf hub dd motor that will act as the regen-brake and cruise mode and we keep the whole system throttle free and only use the torque sensing of the DM01 to manage the speed (so we are not tempted to abuse the power).

I know that there is no such thing as free energy, but the question here would be, can the first (DM01) work with less power needed, then the DD "wastes" in heat during acceleration.

I'm sure there is a plethora of things I'm missing in the whole picture, but it was fun exercise.

How would you guys go about and plan for a monster range? I know that it all depends on many other factors, but still a bit food for thought.

Thanks for the time.

P.S. I asked "The intellect" to try and predict a hypothetical range on a 150kg rider + bike, using the dual motor and pedaling with 100W and using a 65Ah battery at 72V. The split of the terrain for this "simulation" was 30% flat, 30% mild incline/rolling hills, 40% steep mountain terrain, and here is what it spat out:

This unique build is a high-torque, heavy-duty "dual-mid-drive" hybrid designed for mountain mastery and efficiency. It leverages the Qulbix Q140MD moto-style frame to carry a massive 4.7kWh battery, powering two distinct motor systems controlled via a Cycle Analyst V3 (CA3).

The Mechanical Drive Train

• Stage 1 (Primary): A Toseven DM01 mid-drive motor (with torque sensor) is mounted at the bottom bracket. It drives the Leaf motor using a 24T sprocket.
• Stage 2 (Intermediate): A Leafe 2000W Direct Drive motor acts as a secondary power stage. It receives power from the DM01 via a 12T sprocket and outputs power to the rear wheel via another 12T sprocket.
• Stage 3 (Final): The power reaches a 19-inch motorcycle rim (dual-sport tire) via a 42T rear sprocket.
• Chain: The entire system uses motorcycle-grade chain (#420 or #428) for maximum durability under high torque.

Electrical & Control Specs

• Power Source: 72V 65Ah (4,680Wh) battery with 21700 cells and a 200A Dynamic BMS.
• Primary Controller: Fardriver ND72450 (14kW capable) managing the Leaf motor.
• System Logic: Controlled via Cycle Analyst V3, which limits total battery draw to 60A (~4.3kW).
• User Input: No throttle. The system is entirely "pedal assist," triggered by the DM01’s torque sensor. You provide 100W of human power, which the CA3 scales up across both motors.

Performance Estimates (150kg Rider + Bike)

• Top Speed: Electronically capped at 30 km/h.
• Range: Approximately 90–103 km (based on 30% flat, 30% rolling, 40% steep mountain).
• Efficiency Features:
  • Regen Braking: The Leaf motor provides electromagnetic braking on descents, recovering ~10% energy and saving your mechanical brakes.
  • Dual-Motor Efficiency: The CA3 balances the load between the high-reduction DM01 and the high-torque Leaf 11T winding to keep them in their efficiency "sweet spots."

Key Build Constraints Verified

• DM01 Sprocket (24T): Diameter (~102mm) is well within the 240mm limit of your 120mm cranks.
• Rear Sprocket (42T): Diameter (~178mm) is well under your 230mm maximum limit.
• Middle Sprockets: Both are 12T, meeting your minimum requirement.

Are those numbers anywhere near reality?

P.S.S. I tried the same config with different motors on their own and non of them came close to getting that range. May be there is something to it, or more likely I missed something obvious.

 

[99t4]

A two motor ebike is going to be heavy...

How would you guys go about and plan for a monster range?

First let's see how often you need a monster range. If less than, let's say, 60% of your rides, how about a modular battery setup with two identical paralleled single port batteries where mostly you can ride with just one (saving weight) but use both when needed for longer distances?

Regen Braking: The Leaf motor provides electromagnetic braking on descents, recovering ~10% energy and saving your mechanical brakes.

While 10% regen recovery is possible, many here report less.

I asked "The intellect" to try and predict

What is "The intellect?"

 

[scianiac]

These types of systems I think rarely ever work, 1 larger motors is almost always more efficient than two smaller ones. The only times that is not true, as is the case with putting gears on an electric motors to increase efficiency, is when you are spending a lot of time in two dramatically different operating regimes. For instance doing both heavy towing and high speed cruising. But at 30km/h max on a bike you pretty much have one operating zone unless you intend to only go up steep hills at 1kph.

The differences in efficiency between the motors is going to be maybe 10% for very very brief periods of time like when accelerating and most of the time one will be slightly more efficient and the other will be dead weight and probably use more energy in drag than what you gained during those short times where maybe one motor is slightly more efficient.

Not to mention in reality using both motors all the time is probably going to be more efficient just because each one will be loaded less due to the weight of the bike and size of the motors. At which point one larger motors would be more efficient at doing that without all the drawbacks.

I do find it amusing though, how many people I've seen had the same thought or similar ones. All revolving about how they can make their already absurdly efficient electric motor very slightly more efficient by adding vast amounts of extra weight, drag, complexity, cost, unreliability, etc. That is instead of targeting the easy losses in the system or just spending the same weight on a few more batteries.

 

[neptronix]

If you are electronically capping to 30 kmh, you may get by with just a very high turn count hub motor, given you're using an effective 22" bike wheel. The slow speed will keep it from overheating. The small wheel is an efficiency advantage.

Here's a 45mm wide stator hub motor pulling up a 12% grade with medium to hard pedaling.



Adding statorade would cut the heat in half if needed.

If the grades aren't above 12% average, a single motor solution might work for you.
A 50mm wide motor like a QS would be a bit tougher, but they are heavy as sin.

This motor is weight optimized and comes in at 6.8kg whereas the leafbike 35mm wide motor is 7.2kg, so you are saving a bit of weight while also getting more power.

With this bigger motor you'll also have stronger regenerative braking than the leaf

 

[scianiac]

If the grades aren't above 12% average, a single motor solution might work for you.

I mean he wasn't clear on what he even means by climbing mountains, on a road 12% average is very rare, Mount Washington is 12% average and Pikes Peak is only 8% average. If we are talking off road then that changes a lot of factors, I don't want to be doing any extreme off road climbs with a heavy hub motor so then a larger single speed mid drive motor would be more suited. With that much battery an LR Big Block or XL would be more suited but at some point you are just building an emoto.

The thing about any build, but more important with off road builds, is you want the absolutely smallest battery you can without being too small. You add a larger battery for more range, not you need a larger motor and controller, so more weight, so need stronger parts, so more weight, now you need a larger battery to compensate for all the weight you added.

What is "The intellect?"

Presumably an AI, and not a very smart one considering how many basic misunderstandings are in there. Like I don't think I've seen an LLM output that bad in a long time. Why does it want to both switch to moto chain but then also use tiny sprockets for a toseven drive? Completely ignores that you have to do some pretty invasive hacking to the toseven to extract and then convert the torque sense to then feed it into the CA, etc, etc.

Now I'm wondering is there some consistency to battery mass per vehicle mass? OK I can't help myself here is an AI made table.

Vehicle class	Typical total mass​	Typical battery mass​	Battery as % of vehicle​
Lightweight e-bike	14–20 kg​	2–3 kg​	~12–18%​
Standard commuter e-bike	20–30 kg​	3–5 kg​	~15–22%​
Heavy / fat-tire / cargo e-bike	30–45+ kg​	5–8 kg​	~18–25%​
Light e-moto (e.g. Sur-Ron Light Bee)	~50–60 kg​	~11–16 kg​	~20–30%​
Mid/full-size electric dirt bike (e.g. Stark Varg)	~110–120 kg​	~30–35 kg​	~25–30%​
Large electric street motorcycles	200–300+ kg​	60–120 kg​	~25–40%​

That is sort of about what I expected, you can add a little more battery per vehicle as you go up since you can only make things so light on a bike for instance but you can't really push things too far. Interestingly my off road bike is around 14-15% and I would make it far less than that if I ever rebuild the battery with top of the line cells. There is a place on both ends of the range for short and slow ride smaller battery to range optimized high battery mass percentage. But the high end does start to cause some issues and there is a limit, you probably can't go over much over 50% even on a highly road optimized bike and probably 40% is pushing it for even light off road.

 

[offGridDownUnder]

Hi @Bvagu. As you are new here, perhaps you didn't know about the Grin simulator(s) - one of which was referenced by @neptronix above? I use these for what-if scenarios, and they include significant details about many real-world motors. I have entered characteristics of my reduction motor design using the facility for mid-drives this way:

Grin Web Tools

 

[Bvagu]

Hello all,

Thanks for your time to read and respond, my apologies for not being more specific in terms of what and where and how I like to ride and general info on how I wanted such a hypothetical bike to operate.

For myself, I'm young middle-aged boy that comes from potting along on small cc motorcycles 50-125 (Simson 50cc was my first ride) both two, and four strokes so my perception of riding is always been around 100-200kg for the bike. My only experience on e-bikes is from your "generic" SCOTT rental eMTB.

Now for the terrain. I live in a valley between Rila and Pirin mountains, the two highest on the Balkan peninsula. My starting point is roughly 1000m above sea level and within hiking distance I have peaks of over 2700m.

For the grin simulator and the Max45. I have been following Grin as a company for a long time and have used the simulator, the trouble with it is I'm sure I can simulate that particular scenario where a torque-sensing mid-drive is spinning up a hub direct drive that is also a mid-drive. I simulated using two hub motors as hub motors, like the Leaf in the back and the all-axle front one from Grin and split the "workload" 70% to the rear 30% to the front and it look really good, but people seem to shy off hub motors on off-road, and I kinda see why, hence the Q140MD frame where you can use hub motor as a mid-drive. As for the regen I really want it for the continues and varied braking on a decent, not so much for the power recovered, coming from the motorcycle world I love me some engine break, and from what I've read dd hub motors are relay good at that but not so good in continues climb.

Now for the dual motor set up. From what I've been reading most of the people are using a big motor and pumping all sorts of power to it, which in turn produces lots of heat and speed, but if I'm not mistaken the biggest killer of range is air drag, hence the low initial top speed set for this. Perhaps I can get away with just the Leaf motor in like 12T wind or 14T or 16T and see what rpm would that be, and how much power it will need to get it spinning in it's peak efficiency, and just use the pedals to help it get there and stay there. That way I won't have to "choke" the motor via the controller, but would rather have it's normal peak efficiency at that 30km/h.

The weight issue. Here again from what I've been reading, generally there are two camps - the less weight is god, and on the other hand if you add weight you add proportioned amount of Jeremy Clarksons to compensate. I'm yet to see a somewhat middle ground. For me coming from small cc motorcycles I don't have problem with navigating a slowly moving mass of 100kg, to me that's natural, so a 50-60kg (bike + battery) is actually an improvement.

I should have probably started with his, but I imagine this kind of "light electric vehicle" to be my exercise machine, hence the pedaling part. What I liked about the "generic" SCOTT eMTB, was pedaling the way up, not so much on the way down, to me going down with about 100kg worth of bike + rider on a bicycle breaks was not fun, and we were doing short trails. So for me the Ideal experience that I'm after with an ebike would be long climbs of sustained pedaling to get to a top of a peak and a long descend afterward for which I need the regen braking for the braking part itself so I don't waste brakepads on one descent. So bicycle feel on the way up, motorcycle feel on the way down.

Thank you very much for your time and responses I'll try and simulate just the Leaf at very high winding options and see where this goes.

Much Obliged.

 

[scianiac]

It seems you may be falling into a trap I've seen many times before, you are trying to make a bike that can do everything. You want motorcycle power, pedable, regen, highly efficient, long range, good off road, etc. You should optimize the bike for what it actually will be doing and not try to make it do everything or do things you like the idea of but don't actually add to it's performance in doing what you want.

There are a lot of aspects that are counter to each other here but there is one option that I think balances them all the best. That would be a powerful mid drive, how much power you should consider as I don't think you need as much as you think. That mid drive is a left hand drive with a low gearing. That way you get, power, efficiency, regen, good offroad performance, pedable (right hand drive is standard bike stuff), torque sensing, and a wide range of vehicle weight/battery size options. This would be something like a box bike, bomber, whatever type deal with something like a swingarm mounted LR motor is one config I've seen done before but there are other options.

To add, I still think even with that config you should consider some of the options carefully. A big bike with a big battery means the pedaling is basically pointless but that's up to you.

 

[hillslayer@]

I live in a rural area with lots of hills, my go to long distance bike runs a bafang bbso2 and a 1500 Watt direct drive hub. This will climb most hills at close to 30 mph with both motors and cruise at over 30 mph on just the hub. Way easier build than what you are considering.

 

[neptronix]

If you are running a DD through a gear reduction, you can expect even better efficiency and continuous power than i projected. It may do everything for you.

This ~15% reduction ( simulated using a stronger wheel ) can now climb 14% grades continually.
No need for gears



And even better is that the single motor configuration is a lot simpler.

 

[Bvagu]

I live in a rural area with lots of hills, my go to long distance bike runs a bafang bbso2 and a 1500 Watt direct drive hub. This will climb most hills at close to 30 mph with both motors and cruise at over 30 mph on just the hub. Way easier build than what you are considering.

The hub motor is in the back I assume and you still have the cassette and gears that are driven by the bbso2?

So kinda the same principal but I added complexity to move the hub from the rear to the mid in the Q140MD frame and I loose cassette gears + possible reliability bonus of having a hub motor in the wheel in case a chain fails.

Trades and compromises everywhere you look.

Out of curiosity what battery do you have and what is your total weight bike+rider, and range do you normally get out of that set up?

To add, I still think even with that config you should consider some of the options carefully. A big bike with a big battery means the pedaling is basically pointless but that's up to you.

Is that really the case?

What I mean by pedaling is the feeling I had with the eMTB I think it had the torque sensing mid-drive, and the feel was amazing. I don't see why this couldn't be replicated on a bit heavier bike. In my mind and I do admit that this might not work the same, the analogy goes, if you can pedal a normal 10-15kg bike unassisted and a 25-30kg eMBT with 750-1000W, why shouldn't you be able to get the same feel on a 55-60kg bike, you just need more power to the motor/s, but the feel with the torque sensing should be similar, but that is just in my head, and often there's not much in there.

You want motorcycle power

Not quite the power, but the feel of engine braking + bigger brakes on the way down and as I mentioned, I'm more used to the 100kg physics of a small cc motorcycle then an MTB. I do admit that's all dew to me not having any skills with MTB and especially single tracks, but then again a heavy 55-60kg "bike" has no place on such tracks, and if I get such a thing it will be used as the replacement for my normally used Aprilia Rx 50cc and would give me the option to get into the national park areas of the mountains, where normally all ICE vehicle are forbidden.

 

[Bvagu]

If you are running a DD through a gear reduction, you can expect even better efficiency and continuous power than i projected. It may do everything for you.

Isn't this done by default on the Q140MD frame where the DD motor is positioned as a mid-drive and then you can choose a "gear reduction" by the correlation of the sprocket set, like a small driving sprocket on the DD side to a bigger driven sprocket on the wheel?

Apologies if I didn't understand that correctly, but if I did, that was the point of the original post I just wanted to add an additional mechanical torque multiplication by using the bottom bracket of the Q140MD frame so the DD doesn't struggle on a sustained hill climb, and be heat saturated by the high phase amps needed for a single DD motor to handle that weight.

 

[E-HP]

If you essentially have a 14kW stokemonkey style mid-drive, why do you need the Toseven DM01 at all? The CA accepts a torque sensor input, so just use that.
With the gearing you mentioned, the regen rpm is going to be pretty high. Regen creates about the same amount of heat as climbing does, but maybe more with the gearing, so if you are descending big mountains, a temp sensor for the Leaf would be a necessity.

 

[Bvagu]

If you essentially have a 14kW stokemonkey style mid-drive, why do you need the Toseven DM01 at all? The CA accepts a torque sensor input, so just use that.
With the gearing you mentioned, the regen rpm is going to be pretty high. Regen creates about the same amount of heat as climbing does, but maybe more with the gearing, so if you are descending big mountains, a temp sensor for the Leaf would be a necessity.

From what I understand, and I admit that is not much, I though that the problem with the big powerful DD motors like the qs205, they get heat saturated by the phase amps needed on a sustain climb, I was thinking of using the Q140MD frame configuration to get more mechanical torque multiplication and split the load so you don't dump all that heat in one motor.

On the regen side I have no Idea how much heat that produces, but however it is, it's welcome relief for the brake rotors, as I mentioned the regen is mainly another way of stopping power that can be regulated in terms of severity, but any amount is more then welcome on the way down.

 

[E-HP]

From what I understand, and I admit that is not much, I though that the problem with the big powerful DD motors like the qs205, they get heat saturated by the phase amps needed on a sustain climb, I was thinking of using the Q140MD frame configuration to get more mechanical torque multiplication and split the load so you don't dump all that heat in one motor.

On the regen side I have no Idea how much heat that produces, but however it is, it's welcome relief for the brake rotors, as I mentioned the regen is mainly another way of stopping power that can be regulated in terms of severity, but any amount is more then welcome on the way down.

During my heat testing, I use my 20% test hill, which is just long enough to reach around 90C at the top, depending on the starting temp. On one of my test runs, I decided to just turn around and descend back down. About 2 blocks down the hill, I happened to glance at the temp and it was rising over 100C, so I stopped right away to wait for the motor to cool. After that, I always monitor the temps while descending, since the automatic high temp rollback doesn't help for regen.

 

[Bvagu]

After that, I always monitor the temps while descending, since the automatic high temp rollback doesn't help for regen.

Right, so now we need to incorporate a clutch on the driving side of the DD so we can let the tire itself to freewheel when the DD gets hot. I think we are succeeding in simplifying things.

Much appreciated for all of the replays.

 

[hillslayer@]

Trades and compromises everywhere you look.

Out of curiosity what battery do you have and what is your total weight bike+rider, and range do you normally get out of that set

Running 2 48 volt batteries about 35 ah for the hub a 52 volt 20 ah for the mid -drive. Will easily burn threw the hub batteries and only half the mid -drive battery. Whole setup with me and gear 350 lbs. Range doing hills at max speed is around 50 miles.

 

[Bvagu]

Whole setup with me and gear 350 lbs. Range doing hills at max speed is around 50 miles.

That is slightly higher in terms of weight to what I asked the AI to simulate, and like 10Ah less in terms of battery capacity, tho it was a 72V battery in the simulation and it was powering both motors, and it came out to roughly 110-120km (70mile give or take), so not that far of. Interesting. Thank you very much.

 

[E-HP]

If you are electronically capping to 30 kmh, you may get by with just a very high turn count hub motor, given you're using an effective 22" bike wheel. The slow speed will keep it from overheating. The small wheel is an efficiency advantage.

Here's a 45mm wide stator hub motor pulling up a 12% grade with medium to hard pedaling.

View attachment 388166

Adding statorade would cut the heat in half if needed.

If the grades aren't above 12% average, a single motor solution might work for you.
A 50mm wide motor like a QS would be a bit tougher, but they are heavy as sin.

This motor is weight optimized and comes in at 6.8kg whereas the leafbike 35mm wide motor is 7.2kg, so you are saving a bit of weight while also getting more power.

With this bigger motor you'll also have stronger regenerative braking than the leaf

I didn't know what "150kg rider + bike" meant, so I just put in 200kg (441lb) as the total weight, which is either too high or too low. Anyway, using the Grin Max45 in standard wind, in a stokemonkey setup, and 18:34 gearing seems like another good option. More complex than a straight DD, but runs cooler.



It can do 20% for a bit over 5km before overheating in that configuration. If the speed requirement only applied to flat ground, then dropping the front cog down to 15T would allow it to climb 20% forever without overheating, but at 25kph.

These are all modeled with no pedaling.

 

[Bvagu]

I didn't know what "150kg rider + bike" meant, so I just put in 200kg (441lb) as the total weight, which is either too high or too low. Anyway, using the Grin Max45 in standard wind, in a stokemonkey setup, and 18:34 gearing seems like another good option. More complex than a straight DD, but runs cooler.

View attachment 388199

It can do 20% for a bit over 5km before overheating in that configuration. If the speed requirement only applied to flat ground, then dropping the front cog down to 15T would allow it to climb 20% forever without overheating, but at 25kph.

These are all modeled with no pedaling.

Very interesting. The rider+bike in my post was the total weight, so you simulated it at 50kg more. I don't know why I framed it that way. My apologies. English in not a native language to me.

I completely missed the the small blue dot in the simulator, that allows you simulate a DD motor in mid-drive config. I see that in this simulation with that gearing you "only" get 103.4Nm to the wheel, would that be enough to push 150kg up 15-20% slopes? But then again you can just change the gearing, and "help" the motor a bit with pedaling. As to the speed I didn't have a good enough of a reason to think about drag below 40-50km/h until now, but apparently that is a huge factor in e-bikes, so in our case dropping down to 25km/h is better for range?

I was reading in another thread that some people have experienced some problems with the Max45 where the stator is connected to the trough-axle, but didn't bother to see the dates of those posts. Is that fixed?

 

[neptronix]

OP, i think you can get the thermal robustness you need ( beyond 14% constant hill climbing ) by adding ferrofluid to a hub motor.
I think it is unlikely you'll be pulling 14% grade on average unless the elevation climb on these mountains are super sharp
I live next to the rocky mountains in the USA ( VERY STEEP ) and generally any >15% sections are short / there's opportunities to take advantage of 'switchbacks', so ~14% grade capability would work here.

Please keep your first build simple

I was reading in another thread that some people have experienced some problems with the Max45 where the stator is connected to the trough-axle, but didn't bother to see the dates of those posts. Is that fixed?

Yes, one person had a problem with the first generation motor because the axle was too weak to be used at up to 7kw
To me this is not a shocker, but no follow up has been done on how the stronger version fares

I'd guess it could handle 4kw peaks if you keep to a low battery amp to phase amp ratio.
If you are limiting top speed, you'll be in the 2-2.5kw power draw range while climbing a 14% grade in my simulations.
So you don't need more than 3kw peak which should be quite safe.

 

[Bvagu]

OP, i think you can get the thermal robustness you need ( beyond 14% constant hill climbing ) by adding ferrofluid to a hub motor.
I think it is unlikely you'll be pulling 14% grade on average unless the elevation climb on these mountains are super sharp
I live next to the rocky mountains in the USA ( VERY STEEP ) and generally any >15% sections are short / there's opportunities to take advantage of 'switchbacks', so ~14% grade capability would work here.

Please keep your first build simple



Yes, one person had a problem with the first generation motor because the axle was too weak to be used at up to 7kw
To me this is not a shocker, but no follow up has been done on how the stronger version fares

I'd guess it could handle 4kw peaks if you keep to a low battery amp to phase amp ratio.
If you are limiting top speed, you'll be in the 2-2.5kw power draw range while climbing a 14% grade in my simulations.
So you don't need more than 3kw peak which should be quite safe.

Thank you.

I guess I need to play a bit in the sim with different DD motors around the 2500W continues, and the variety of combinations, of motor wingdings to sprocket ratios so I get to what I'm after.

Once again much obliged for all of the comments, very helpful!

 

[E-HP]

OP, i think you can get the thermal robustness you need ( beyond 14% constant hill climbing ) by adding ferrofluid to a hub motor.
I think it is unlikely you'll be pulling 14% grade on average unless the elevation climb on these mountains are super sharp
I live next to the rocky mountains in the USA ( VERY STEEP ) and generally any >15% sections are short / there's opportunities to take advantage of 'switchbacks', so ~14% grade capability would work here.

Please keep your first build simple



Yes, one person had a problem with the first generation motor because the axle was too weak to be used at up to 7kw
To me this is not a shocker, but no follow up has been done on how the stronger version fares

I'd guess it could handle 4kw peaks if you keep to a low battery amp to phase amp ratio.
If you are limiting top speed, you'll be in the 2-2.5kw power draw range while climbing a 14% grade in my simulations.
So you don't need more than 3kw peak which should be quite safe.

I agree, but if he nixes the mid drive pre motor, then it becomes a pretty straightforward pick your parts assembly because of the frame he's choosing, which is made for a hub motor stokemonkey kind of mid drive setup. It's really a matter of choosing the motor, battery, and gearing. The pedals are really just for show on that sort of frame anyway.
Personally I'd go with a normal bike that can be pedaled, and spec the battery for the task, instead of going for the mammoth 50 pounder. It's going to get really ugly if you ever need to push that thing.

Qulbix Q140MD | Modular Frame Kit for Custom E-Bikes & E-Motos

Discover the Qulbix Q140MD. Featuring 25kW peak power, the QRBS removable battery system, and a 5000Wh lockable compartment. Shop complete or as a DIY kit.

qulbix.com

 

[neptronix]

Same here, being that it's a euro-bicycle, it should be able to be pedaled and the electric bits should be very stealth if it is to be ridden in the city at all, that's 1 point for a single drivetrain, if we can make it work!

 

[Bvagu]

I think, I might have figured out something that is not that difficult to execute and checks all the boxes I need, I just need to ask Quilbix to make me a frame that can accept a pinion c.1 gearbox instead of normal BB.

Full Mechanical & Electrical Specifications

1. Frame & Cockpit Integration

• Chassis: Qulbix Q140MD Cr-Mo Steel Frame Kit, maximizing internal capacity and using front ram-air ducts for cooling.
• Human Transmission: Pinion C1.6 internal gearbox (6 gears, 0.950 underdrive to 0.320 overdrive)
• System Controller: Fardriver ND72450 Sine-Wave Controller (14kW peak capable) with Bluetooth and CANBUS, safely capped via software to a strict 50A battery current draw limit (3,600 Watts peak). Phase current is set to 120A–150A for torque multiplication.
• System Computer: Grin Cycle Analyst V3 (CA3) acting as the main processor, intercepting analog pedal inputs and outputting a translated voltage to the Fardriver throttle pin.

2. Power Plant: Leaf 2000W "2026 Black Lightning" Core

• Stator Material: 0.35 mm ultra-thin silicon steel laminations minimizing magnetic drag.
• Upgraded Phase Wires: Factory 4.0 mm² high-temperature silicone wires (11 AWG equivalent) handling up to 150A phase bursts up inclines without voltage drop.
• Thermal Safety: Integrated NTC temperature thermistor mapped to the CA3. Soft thermal throttling initiates at 90°C, with a hard emergency shutdown set at 130°C to eliminate risk to the magnets.
• Total Battery Capacity: 72V 65Ah pack (4,680 Wh total / 4,212 Wh usable at 90% Depth of Discharge) nested securely in the frame center.

3. Dual-Stage Chain Transmission Architecture

• Stage 1 (Speed Step-up Line): A 45T Pinion output sprocket drives a freewheel single-chain sprocket on the input side of the jackshaft axle (2.81x step-up).
• Human Torque Sensing: A BeamTS chain tension sensor clamps to the frame directly under the Stage 1 chain, outputting a clean 0–5V analog signal to the CA3 tracking real-time pedal pressure.
• Stage 2 (Torque Multiplier & Regen Path): A fixed 16T sprocket on the output side of the jackshaft drives a fixed 42T sprocket on the rear wheel hub via a secondary independent chain (2.625:1 reduction).

[ Pinion C1.6 Gearbox ] ───(45T)───> [ Stage 1 Chain Line ] ───> [ Freewheel Sprocket ]
│ │
[ BeamTS Tension Sensor ] [ Q140MD Jackshaft Axle ]
│ │
[ Rear Wheel Hub ] <──────(Fixed 42T) <── [ Stage 2 Chain ] <────── [ Fixed 16T Output ]

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Gear Performance Matrix (Based on 90 RPM Human Cadence)

Gear Selection	Internal Ratio	Rear Wheel RPM	Final Ground Speed	Practical Terrain Focus
Gear 1	0.950 (Underdrive)	100.8 RPM	12.5 km/h	Continuous 30% Ski Slope Climb. 87% peak motor efficiency, safe 54 Nm motor torque, zero thermal risk.
Gear 2	0.764	125.4 RPM	15.6 km/h	Technical trail riding or steep gravel access roads.
Gear 3	0.615	155.8 RPM	19.3 km/h	Mild singletrack or rolling off-road hills.
Gear 4	0.495	193.6 RPM	24.0 km/h	Standard low-speed urban city commuting.
Gear 5	0.398	240.7 RPM	29.9 km/h	Rapid paved road transit.
Gear 6	0.320 (Overdrive)	299.4 RPM	37.5 km/h	Flat-Ground Cruise. 100% natural voltage balance, zero electronic field-weakening tax, maximum mileage.