How to Boost Low-End Torque in Your E-Bike

To boost your e-bike’s low-end torque, focus on gear ratio and power delivery. If you have a mid-drive, shifting to a lower gear (or using a smaller front chainring and bigger rear sprocket) increases mechanical leverage for more grunt.

Additionally, raising the controller’s current limit, and using a battery that can handle it, will directly bump up motor torque.

In short, lower the gearing and increase the amps (safely) to get stronger acceleration and hill-climbing power.

This blog is a complete guide to understanding what affects e-bike torque and how to improve it through smart riding, tuning, and DIY upgrades.

What Is Low-End Torque in an E-Bike?

Torque is the twisting force your e-bike motor applies to the wheel. Measured in Newton-meters (Nm), it represents the motor's "pulling power" or "push-off strength."

High torque means quicker acceleration from a stop and easier hill climbing. Low-end torque specifically refers to this power at low speeds or from a standstill—it's what gets you moving fast and up steep inclines. Think of it like a bicycle's low gear: more leverage for starting or climbing.

Why Low-End Torque Matters: If you often start at lights, carry heavy loads, or face hills, strong low-end torque makes the bike feel powerful and responsive. An e-bike with 70–90 Nm will feel "zesty" and strong, while one with ~40 Nm might struggle on inclines. For daily riders, more low-end torque means less pedaling strain, easier take-offs, and more confident hill climbs.

Why Your E-Bike Might Lack Torque

Several factors can cause an e-bike to have unimpressive low-end torque. Understanding these will help you target the right solutions. Below are the key contributors:

Motor Type and Gear Ratio

Hub Motor vs. Mid-Drive: The type of motor greatly affects available torque. Hub motors (mounted in the wheel) drive the wheel directly. This means if you have a hub-drive e-bike, the motor’s torque is fixed and not amplified by your bike’s gears.

As one rider pointed out, a hub motor bike can even run with the chain removed – changing pedal gears won’t change the motor’s torque to the wheel. So, if you have a hub motor that feels weak on hills, it’s because the motor itself isn’t getting any mechanical advantage from gears.

In contrast, mid-drive motors (mounted at the crank) leverage the bike’s gear system. The motor drives the chain, so if you shift into a lower gear, you effectively multiply the torque going to the rear wheel. Mid-drives are known for climbing ability because of this gearing effect – they can “crawl” up steep terrain by spinning fast in a low gear.

Geared Hub vs. Direct-Drive: If you do have a hub motor, there are two kinds. Geared hub motors have internal planetary gears that increase torque at the wheel (at the cost of top speed).

Direct-drive hub motors have no gears; they are simpler and often faster on flat ground, but tend to have less torque at low RPM. If low-end torque is your goal and you’re choosing a hub motor, a geared hub (or a hub motor wound for torque) will perform better for acceleration and hills.

For example, enthusiasts often seek out slower wind hub motors (like a MAC 12T gear hub) for more torque, trading off some speed.

Gear Ratio & Wheel Size: Even on a mid-drive, the stock gear ratio might not be low enough for very steep hills. Many off-the-shelf e-bikes come geared for a balance of speed and climbing, but not extreme torque.

If your rear sprocket is relatively small, the bike will feel “taller geared” and the motor has to work harder at low speeds. One experienced rider noted that mid-drives only truly shine in torque when you use a big rear sprocket relative to the front.

For instance, a bike with a 1:1 gear ratio (say 32-tooth front, 32-tooth rear) can climb impressively – one rider could pedal up a 15% grade with no motor using that setup, and their 1000W motor easily hauled heavy cargo up the same hill.

However, such low gearing (like a 48T rear cog) is rare on stock e-bikes. If your bike isn’t geared low enough, the motor might struggle at very low speeds and you’ll feel it lacking torque.

Wheel size also plays a role: Smaller wheels effectively provide more torque to move the bike (because the lever arm is shorter). That’s why some cargo or folding e-bikes with 20-inch wheels can start and climb better than if the same motor was in a 29-inch wheel.

One forum expert straight-up advised a rider to go to a smaller wheel to get more climbing torque. This isn’t always practical to change, but it’s good to know: a motor driving a 26" wheel will feel torquier than the same motor in a 29" wheel. If you can’t change wheel size, focus on gearing and current.

Controller Current and Battery Limits

Current = Torque: Electric motors produce torque roughly proportional to the current (amperage) fed into them. This means the e-bike’s controller, which limits the current for the motor, is a huge factor in how much torque you actually get. If your controller only allows, say, 15 or 20 amps peak, that caps the motor’s twisting force.

On many budget e-bikes, the controllers are set to ~15–18A to protect the battery and motor. Simply put, if the controller doesn’t let enough amps through, you won’t get strong low-end torque.

An experienced user on an e-bike forum explained it well: “Torque is directly related to amperage... increase amperage by 10%, you increase torque by 10%”. However, there are safety and component limits behind that.

The restrictions include: how much current the battery can supply, how much heat the motor can take, and what the controller’s own components can handle. If any of those are maxed out, they will bottleneck your torque.

For example, a small battery might only safely deliver 20A before its Battery Management System (BMS) says “enough” and cuts out. Likewise, a controller might be programmed or built to allow only a certain current; pushing beyond could cause it to overheat or even fail. And motors can overheat if you feed them more current than they can dissipate as heat.

Battery Voltage and BMS: Voltage itself doesn’t increase torque at low speed (torque mostly comes from current), but voltage does affect how long you can sustain that torque as speed rises (due to back-EMF).

That said, one way voltage plays into “feel” is via voltage sag and BMS limiting. If your battery is weak or nearly empty, its voltage drops more under load, and the BMS may interpret that as “undervoltage” or “overcurrent” and momentarily cut power.

Riders often experience this as the bike losing power on hills or under heavy throttle, even if the battery shows 50% charged. This is often a BMS protection kicking in to prevent damage.

In short, the battery BMS (Battery Management System) is a protection circuit that can limit current (for safety) and shut the bike off if it thinks the current draw is too high (“discharge overcurrent”) or the voltage has sagged too low.

If your e-bike consistently feels like it has no torque and cuts out on big hills, an overly sensitive BMS might be to blame – it’s essentially tripping a breaker to protect the battery, but robbing you of power in the process.

Example: Suppose you have a 48V 10Ah battery with a BMS limited to 20A. No matter how powerful your motor is, the maximum input to the controller from that battery is 20A × 48V = 960 watts, and at low speeds the current is capped at 20A, which caps your torque.

If you try to draw more (say by upgrading the controller), the BMS might shut down (“BMS trip”) to protect itself. This is a common scenario when people upgrade controllers or motors but not the battery: the bike gains a bit of torque until the BMS senses overcurrent and kills the fun. We’ll discuss how to address this in the solutions.

Mechanical Drag and Other Factors

Not all torque issues are electronic. Sometimes your e-bike feels low on torque because of simple mechanical factors:

• Excess Weight: If you’re carrying a lot of cargo or the bike itself is heavy, it will of course feel like it has less torque (it’s working against more load). This is just physics – the motor has to work harder to move more mass. In such cases, even a high-torque motor will only accelerate so fast. Removing unnecessary weight or distributing it evenly won’t increase torque, but it can reduce the demand on the motor.

• Tire Pressure & Rolling Resistance: Under-inflated fat tires or sticky off-road tires can make the bike feel sluggish. Make sure your tires are properly inflated for the terrain – low pressure can improve traction off-road but will increase rolling resistance, making more torque necessary just to move. On pavement, higher pressure will roll easier.

• Brakes Rub or Stiction: Ensure your brake calipers aren’t rubbing on the rotors and your wheels spin freely. Any constant drag will make the motor’s job harder and effectively “use up” torque overcoming that friction.

• Motor Condition: If you have a geared hub motor, a worn-out clutch or damaged planetary gears can lead to slippage – the motor spins but the wheel doesn’t get all the torque. For example, a rider with a Mac geared hub noted the clutch had worn out, which reduced its drive effectiveness. In a mid-drive, a worn chain or sprocket could slip under high load. Make sure your drivetrain is in good shape so all the torque the motor produces actually gets to the wheel.

By considering these factors, you can identify why your particular e-bike might not have the low-end oomph you desire. Next, we’ll dive into ways to actually increase that torque, from easy tricks to more involved upgrades.

Recommended: Common Torque Sensor Problems in Electric Bikes

Quick Tips to Get More Low-End Torque (No Major Mods)

Before you break out the toolbox or spend money on upgrades, try these simple tips. They can give you a noticeable boost in low-end performance or at least ensure you’re getting the most out of your current setup. These are beginner-friendly and mostly free adjustments:

1. Use Lower Gears (If Applicable)

If your e-bike has multiple gears (especially mid-drives or hub drives with a pedal drivetrain), take advantage of them. Shift into a low gear when starting out or climbing hills. This lets the motor spin faster while the bike goes slower, multiplying torque at the wheel. It sounds obvious, but many riders forget to downshift before a stop or hill.

As one forum member emphasized, appropriate gearing is crucial for conditions – many e-bikers need to “garner an understanding of appropriate gearing for conditions”. In practical terms, that means if you’re approaching a steep hill, drop to a smaller chainring or bigger rear cog (just like you would on a normal bicycle) before you hit the climb.

For hub motor bikes, remember the gears only help if you’re also pedaling. Since the hub motor isn’t affected by your bike’s gear, you might think “gearing doesn’t matter for me.” But it does if you combine motor + pedaling.

Pedal-assist riders can add a significant amount of torque with their legs. Even an average cyclist can put out 100+ watts for short bursts, which translates to extra Newton-meters of torque when in a low gear.

So if your bike is slowing on a hill, help it out: shift down and pedal along with the motor. It reduces strain on the motor and battery, and you’ll climb faster. Essentially, cadence is king – keep your pedaling RPM in a comfortable range (around 60–80 rpm if possible).

Grinding super slowly (low cadence, high force) is hard on your knees and not very effective for the motor either. If you find you can’t spin any faster because the bike is barely moving, that’s a sign you need a lower gear ratio or more motor torque.

2. Maximize Your Assist Level and Throttle Usage

Many e-bikes have different assist levels (Eco, Tour, Sport, Turbo, etc.). When you need max torque (say a steep incline or starting with a heavy load), use the highest assist mode or full throttle if your bike has one.

Higher assist modes typically allow the controller to give more current, which means more torque. It sounds simple, but some riders forget they might be in an eco mode and wonder why the bike feels weak. Double-check that you’re in the mode that delivers the most power.

If you have a throttle, you can also use it to give an extra kick when starting on an incline – even if you’re mostly a pedal-assist rider, a bit of throttle from a stop can spool the motor up quicker.

However, be mindful of traction. At maximum torque (especially on a torquey mid-drive in a low gear), you might spin the rear wheel on loose terrain. Lean forward on steep climbs to keep weight on the front if it’s a front hub, or back if it’s a rear hub, to maintain grip. Smoothly applying power (or pedaling) can prevent wheelspin while still using full power.

3. Keep Your Battery Warm and Charged

Believe it or not, a simple thing like battery temperature and charge level affects performance. Cold batteries deliver less current. If you ride in cold weather and notice weaker torque, it’s partly due to the chemistry slowing down. Keep the battery indoors before a ride in winter, and consider an insulated case for it in freezing temps.

Also, a battery at 50% charge will have more voltage sag under load than one at 90% charge. So if you know you need all the torque you can get (maybe a long steep hill on your route), start that climb with as much charge as possible. It can make the difference between the BMS cutting out or not.

Some riders even top off their battery right before a tough hill to prevent voltage sag from triggering a shutdown. And if your battery is nearing the end of its life (several years old, lots of cycles), it might have higher internal resistance, meaning it sags more and can’t sustain high current. In that case, you’ll feel a drop in torque.

The only remedy is a new battery or rebuilding it, but recognizing this issue prevents you from chasing motor/controller upgrades when the culprit is actually a tired battery.

4. Reduce Unnecessary Load

This is more about making the most of your existing torque. Remove any unnecessary heavy accessories or cargo when you don’t need them. If you have a huge rear rack with bags that you only sometimes use, leave them at home for a spirited ride. The lighter the bike (and rider/cargo), the less torque is required to accelerate. It’s the same concept as why a lighter car feels peppier with the same engine than a heavy truck.

You can also crouch a bit or lean forward when climbing to help the bike if it’s a mid-drive – this is more about balance and traction, but every little bit helps in tough climbs.

5. Climb at a Steady, Moderate Pace

Interestingly, climbing slower can help if you’re on the verge of overpowering your system. One veteran rider suggested not trying to “pull the grade as fast” – in other words, don’t attack a steep hill at high speed if your bike is struggling. If you slow down a bit, you reduce the power demand (wind resistance is lower at slower speed, and you can stay in an efficient RPM range).

However, you don’t want to go so slow that the motor bogs down to a crawl, because most e-bikes are not geared for ultra-slow speeds. There’s a sweet spot: a steady pace where the motor can spin comfortably and not overheat, but you’re not trying to rocket up the hill drawing max amps the whole time.

Think of it like downshifting a car and steadily climbing rather than flooring it in a high gear. If you find your bike losing torque as you slow down, you’ve hit its limit and may need the upgrades discussed next.

But if it’s just a technique issue, maintaining a consistent cadence and speed can prevent the BMS from tripping due to sudden spikes and can keep the motor in a happier state.

These quick tips can help you squeeze more performance out of your e-bike without any modifications. Next, we’ll look at the more impactful changes – upgrading components and altering settings – to significantly boost low-end torque.

Upgrades and Modifications to Boost Torque

When simple tricks aren’t enough, it’s time to consider hardware changes. The following upgrades require some technical know-how (or help from a bike shop/experienced friend), but they can dramatically increase your e-bike’s low-speed power. Just remember that any upgrade should be done within reason – overpowering your bike can lead to broken parts or safety issues, so proceed carefully and understand the trade-offs.

Upgrade 1: Higher Current Controller (More Amps = More Torque)

What it is: The controller is the “brain” and power manager of your e-bike. Upgrading to a controller that allows higher current (more amperage) will directly increase the torque your motor can produce. For example, moving from a 20A controller to a 30A controller means the motor can receive up to 50% more current (if the battery can supply it), roughly giving you 50% more torque at the low end.

How to do it: Some e-bikes have programmable controllers where you can simply change settings (often via a display or USB connection) to increase the current limit. Check if your bike’s controller is programmable.

If it is not, you might replace the controller unit entirely with an aftermarket one that has higher amp limits. This usually also means replacing the display and possibly the throttle, as these systems need to be compatible (many e-bikes use integrated controller+display combos).

A forum user succinctly put it: “I don't think you can adjust settings [for more torque]. To get more power for hill climb, you would upgrade to a larger controller, like 25A... You also need a battery that's happy supplying the extra current.”. In other words, a controller swap is a common path to more torque.

Considerations: Upgrading the controller will likely void warranties, and it puts more stress on the motor and battery. Make sure your motor can handle the extra current without overheating (some motors can take 2-3× their rated power for short bursts, but will overheat on long climbs at that power – monitor how hot it gets).

Also ensure your battery can deliver the amps. If not, the BMS might shut down (we’ll talk about fixing that shortly). As a rule of thumb, a quality battery can safely output continuous current equal to 2C (two times its Ah capacity) and higher in short bursts. E.g., a 48V 10Ah (480 Wh) pack might do ~20A continuous. Pushing it to 30A might trigger BMS unless it’s designed for it.

Pro tip: Instead of blindly cranking up amps, find out what motor you have and research what others have successfully run it at. Some controllers also have separate phase current vs battery current settings – phase current is the current in the motor windings, which is often higher than the battery current and is what really dictates torque at very low speeds.

Ideally, use a controller or programming that lets you increase phase amps for that initial kick. But even just a bigger generic controller (with higher amp rating) will usually have higher phase amps proportionally.

Shunt Mods: A DIY trick some have used is the “shunt mod,” where you modify the controller’s current-sensing shunt resistor by soldering it or adding wire, effectively tricking it into allowing more current.

While this can work, it’s not recommended unless you really know what you’re doing – it can disable safety limits and you might blow the controller or battery BMS. It’s usually better to buy a controller designed for the higher current.

Upgrade 2: Improve Battery Output (BMS and Cells)

There are two sides to the battery equation: the physical cell capability and the Battery Management System (BMS) limits. Upgrading one or both can give you access to higher current (and thus torque):

Higher-Discharge Battery or Cells: If your battery is the weak link (for example, it sags a lot or cuts out on hills), consider a battery with higher discharge rating. This could mean a pack made of cells with higher amp output (like using automotive-grade 21700 cells or quality 18650 cells known for high discharge).

It could also mean increasing the parallel count of cells. For instance, a 13s3p battery (3 cells in parallel per series group) might be swapped for a 13s5p battery – more cells in parallel means more current capacity. Of course, this is a major change (essentially a new battery or rebuilding the current one).

Upgrading or Bypassing the BMS: Many off-the-shelf batteries have BMS rated for a certain continuous current (e.g., 20A, 30A). If you upgrade your controller, you might also replace the BMS with a higher amp one (if you’re technically inclined and comfortable opening up the battery case and resoldering).

A temporary hack some people do is bypass the BMS for discharge – this means the BMS still handles charging balance and protections, but the discharge leads are taken directly from the cells, so the BMS no longer limits current.

Warning: Bypassing BMS is risky because you lose the overcurrent and sometimes low-voltage protections, which can lead to battery abuse or damage if not careful. A better approach is using a BMS that has adjustable or higher limits.

If you suspect the BMS is tripping, an easy first step is to perform a BMS reset. Often, simply disconnecting the battery for a few minutes can reset an internal “trip” state. This can clear any false fault codes. However, if it keeps tripping under load, that’s a sign you need a BMS or battery upgrade to handle the current you’re demanding.

Battery Voltage Upgrade: Another angle is increasing voltage (like going from a 36V to 48V system, or 48V to 52V). Higher voltage won’t give more torque at zero speed, but it raises the speed at which the motor can continue to produce torque (because of the back EMF effect).

 In practice, if you go from 36V to 48V, you will have a higher power output and the motor will feel stronger across the range, including moderately low speeds. Just ensure your controller and motor can handle the higher voltage.

Many 48V controllers can run on 52V (which is 14s lithium) as well – this gives a bit more punch. Do note that if your controller was limiting current, it may still do so, and torque at stall is still current-limited. But since power = volts × amps, a bit more voltage helps maintain torque as the bike accelerates.

Diagnose First: If your e-bike frequently cuts out on hills or under hard acceleration (like it dies for a moment then comes back), that is a classic sign of the BMS overcurrent or low-voltage cutoff kicking in. In that case, prioritize the battery/BMS upgrade. No motor or controller upgrade will help if the battery is hitting a self-protect shutdown.

You might also notice your display flicker or cut off when this happens – another clue it’s a BMS event and not a controller fault. A user-friendly way to monitor this is to watch your voltage readout (if you have one) when climbing: if it drops dramatically and the bike cuts off, you’ve got voltage sag triggering BMS. A healthier or higher-capacity battery will sag less and maintain power.

Recommended: How to Test and Balance E-Bike Battery Cells

Upgrade 3: Switch to a Torque-Optimized Motor or Gear Reduction

If you currently have a speed-oriented setup, swapping to a more torque-oriented one can make a world of difference. Here are some options:

Mid-Drive Motor Conversion: If you have a hub motor e-bike and it’s just not cutting it on hills, one sure-fire (though involved) solution is to switch to a mid-drive kit. There are kits like the Bafang BBS02/BBSHD or Tongsheng TSDZ2 that replace your crankset with a motor. Mid-drives let you use the bike’s gears, meaning even a 750W mid-drive can often out-climb a 1000W hub drive because it can stay in its optimal RPM range.

The original poster on a forum who wanted to “climb a tree” with their bike was advised plainly that “with a hub motor... if you want a stump-puller, it’s a mid drive. Hubs are great for other jobs but not that one.”.

That advice holds: if low-end torque is your absolute priority (e.g., for off-roading or cargo hauling on steep hills), a mid-drive setup is generally superior. Of course, switching means significant investment or DIY effort, so consider it if you’re really unsatisfied with the current bike.

Geared Hub or Different Winding: If you have a direct-drive hub, you might consider a geared hub motor replacement. Geared hubs have internal reduction (typically 4:1), which multiplies torque to the wheel (and they also freewheel when not powered).

They provide much better low-speed torque and efficiency for most riding (at the cost of some potential top speed and a bit more maintenance, since they have moving parts). If you already have a geared hub, you could look at different windings.

For example, hub motors often come in different turn counts (like 8-turn, 10-turn, etc. – higher turns = more torque, lower top speed). On forums, riders discuss using e.g. a “MAC 12T” motor for cargo bikes to get that strong pull, whereas a “MAC 8T” might be for speed.

These specifics aside, the point is: a motor optimized for torque (often marketed with higher torque or lower KV rating) can give you more grunt without increasing power – it just trades speed for force.

Smaller Front Chainring / Larger Rear Cog: For mid-drives (or if you’re adding one), don’t underestimate the impact of gearing changes. Something as simple as dropping from a 44T chainring to, say, a 36T can significantly increase wheel torque in each gear (at the expense of some top speed in that gear). If you rarely hit top speed or don’t care about it, this is a great trade-off.

Similarly, if your bike’s rear freewheel or cassette can be swapped, choose one with a mega range low gear (there are 34T, 36T, even 40T sprockets that fit some freewheels or cassettes, if your derailleur can handle it). A “big dinner plate” sprocket on the rear will let even a moderate motor shine on hills.

On a forum, a user recommended going as far as possible: “a bit bigger rear sprocket (or a smaller front one) to get more RPMs on the motor, make it easier for the motor to get up hills.”. This is sound advice – more RPM for the motor means it can stay in its power band, delivering torque more efficiently rather than lugging at low RPM.

Consider Wheel Swap (Diameter): If you have the means, and especially if you’re building a custom e-bike, using a smaller wheel size can boost effective torque.

For instance, putting a hub motor from a 700c wheel into a 26" wheel will give roughly a ~15% increase in torque at the wheel (in exchange for ~15% reduction in speed). It’s like permanently being in a lower gear.

Some riders who needed insane climbing ability for off-road have even laced hub motors in 20” rims for their builds. It’s an extreme step, but worth mentioning. 

More commonly, if you’re choosing between wheel sizes (say, a 27.5 vs 29 e-MTB), the smaller will climb a tad better due to this effect.

Upgrade 4: Tuning Software Settings (If Available)

Certain e-bike systems (like Bafang mid-drives, or open-source controllers) allow you to tweak settings that influence torque:

• Current ramp and throttle curves: Making the throttle or pedal assist deliver current more aggressively at low RPM can give a torquier feel. For example, setting a higher phase current proportion or a more aggressive PID controller tuning (on advanced controllers) can improve initial torque.

• Torque Sensor Assist Level: If your bike has a torque sensor and the assist is feeling weak, some systems let you increase the assist multiplier. This isn’t increasing motor torque per se, but it tells the motor to provide more support for a given pedal input. Effectively, it can make the bike feel torquier because it’s responding more strongly.

• Field Weakening (for high speed): This is the opposite of low-end torque, but if your controller has field-weakening turned on to reach higher top speeds, note that it can cause extra heat and maybe slightly less efficiency at low end. If you only care about torque and not top speed, you could disable field weakening so all the system’s focus is on the normal operating range.

These software tweaks are highly dependent on your controller and motor system. Check online for programming guides specific to your model. A word of caution: always note the original settings before changing anything, and increase limits gradually. Test each change to ensure the motor isn’t overheating or the BMS isn’t tripping.

Don’t Forget the Drivetrain and Frame

If you significantly boost your e-bike’s torque, remember that the bike’s physical components must handle it. High torque can chew up cheap bike chains, cogs, and even bend dropouts if it’s a powerful hub motor. Here are a couple of precautions:

• Use a Torque Arm: If you have a hub motor and you increase power, install a torque arm (or two). This is a steel arm that helps the axle secure into the frame without spinning out. It’s a cheap piece of insurance that prevents the motor axle from damaging your dropouts under high torque.

• Stronger Chain / More Frequent Maintenance: More torque = more stress on the chain and gears. If you convert a mid-drive to high power, consider using an e-bike specific chain or even a single-speed chain if you’ve converted to single speed for simplicity. Lubricate and check the chain often, and replace it more frequently to avoid breakage. One rider noted that extremely large rear cogs (48T) often come in high-end 11-speed setups which wear faster; he got ~5000 miles on an 8-speed but higher torque setups wore out chains quicker. So expect a bit more maintenance.

• Brakes: With more torque and speed, ensure your brakes are up to par. This isn’t directly about torque, but if you suddenly have a bike that can climb like a mountain goat and accelerate hard, you want to be sure you can slow it down just as confidently!

At this point, you should have a good idea of hardware changes to boost torque. Implement the ones that suit your needs and budget. For some, a simple controller and gear change might suffice; others might go for a full motor swap. Now, let’s address some advanced troubleshooting in case you’ve made mods but still aren’t getting the desired results.

Advanced Troubleshooting: When Torque Still Feels Weak

So you’ve tried the basic tips and even implemented some upgrades, yet something’s still not right? This section covers a few advanced issues that could be holding your e-bike back from delivering that satisfying low-end punch, and how to diagnose/fix them.

BMS Trip and Battery Voltage Sag Issues

One of the most sneaky torque killers is the BMS cutting power right when you need torque the most. As discussed, an overly sensitive or inadequate BMS will shut off if it senses overcurrent or undervoltage. The telltale sign is the bike suddenly losing power on a hill or under full throttle, then coming back if you reset it or ease off.

How to diagnose: Use a voltmeter or your bike’s display (if it shows voltage) and observe the voltage while replicating the problem (e.g., full throttle from standstill or a steep climb). If you see the voltage plummet and then the system cuts out, you’ve got a battery sag/BMS issue.

Another sign is error codes or blinking lights that correspond to battery faults. Additionally, if the cutoff happens very predictably at a certain current every time, it’s likely the BMS’s overcurrent protection.

Fixes:

Reset and Calibrate: First, try a BMS reset as mentioned earlier – disconnect the battery for 10-30 minutes to let the BMS reset. On some batteries there’s a small reset button – use it if available. This is the easiest step and sometimes the BMS was just latched in a protective state from a past event.

Upgrade or Bypass BMS: If it’s clear your BMS is just not allowing the current you need, consider upgrading it to a higher amperage model (same cell configuration, just higher current rating). BMS units are relatively inexpensive, but installation requires opening the pack and careful soldering.

Alternatively, bypass for discharge as a temporary workaround (with great caution). If you bypass, you should at least have a fuse inline for safety since the BMS won’t be there to trip off.

Mitigate Voltage Sag: Voltage sag can trigger low-voltage cutoff even if current isn’t above limit. To reduce sag: make sure the battery is fully charged (as mentioned), avoid running it to near-empty when you need high torque, and keep the cells warm.

If a particular cell group is weak (causing early sag), the long-term fix is repairing the battery (replacing bad cells). In the short term, you can baby the battery by not drawing max power for long – use lower assist for a moment, then burst high assist, etc., to give cells a breather.

Some riders also parallel a second battery to share the load; if you happen to have a second pack, running them together (with proper wiring or diode isolators) effectively halves the stress on each and doubles available current.

Remember, a BMS trip is a safety feature, not a flaw. It’s telling you that something in your setup is beyond what the battery can handle safely. The ultimate cure is aligning your battery specs with your power demands.

Controller Thermal Throttling or Limits

Some controllers have in-built thermal protection or current limiting that might not be obvious. For example, a controller might allow 30A for a few seconds but then scale back to 20A if it starts to heat up. If you notice that you have strong torque at first, but on a long hill it gradually diminishes, this could be the controller (or motor) overheating and throttling down to protect itself.

How to diagnose: Carefully feel (cautiously, with the back of your hand) the controller case after a climb – is it very hot? Some advanced displays or external devices (like the Cycle Analyst) can show you real-time current and temperature if sensors are present.

If the controller is indeed overheating, you might notice it reducing power output autonomously. Another check is to see if it’s limiting current electronically: if you have a way to log or view current, does it drop after a few seconds of heavy load?

Fixes:

• Improve Cooling: Make sure the controller is getting airflow. If it’s enclosed in a bag or frame compartment, consider relocating it or adding ventilation. Controllers are often potted (sealed), but mounting it to a metal frame can act as a heat sink.

• Upgrade Controller (again): You might need a controller that can handle more continuous current without overheating (bigger MOSFETs, better heatsinking). Sometimes simply a higher quality controller of the same specs can perform better under sustained load.

• Firmware Settings: If the controller’s software has a very conservative thermal rollback, you might be able to tweak that (not all allow this). Alternatively, some controllers let you increase the duration of peak current before rollback.

One more thing: check wiring and connectors. A partially melted or corroded connector (battery or phase wires) can mimic a “lack of torque” because it resists current flow. If your wires or connectors get hot, that’s a red flag.

Upgrade thin phase wires if you increased current significantly, and use high-quality connectors (like XT90 or Anderson/Sermos connectors) that are rated for the amperage. This ensures full power actually reaches the motor.

Motor Overheating or Saturation

If you push any motor too hard, it can overhead or even reach magnetic saturation (where more current no longer equals more torque).

Usually, overheating will occur first. A too-hot motor might temporarily lose some performance (due to increased resistance or thermal protection if it has a sensor). Or worse, it could damage itself leading to permanently reduced torque (demagnetization).

How to diagnose: After a hard ride or hill, carefully check motor temperature. Some hub motors have a thermal sensor that could display on advanced screens. Otherwise, feel the hub or mid-drive casing – it can be very warm, but it shouldn’t be so hot that water sizzles on it or it burns you to touch (be careful testing this!).

Also watch for any burning smell from the motor – that’s a clear sign of overheating insulation. If the motor shuts down completely until cooling (and the battery is fine), that’s likely an internal thermal cutoff in the motor or controller.

Fixes:

Cooling: For hub motors, some enthusiasts add ferrofluid or Statorade inside the hub to improve heat transfer to the shell, and add ventilations or aluminum heat sinks on the cover.

This is advanced tinkering but can significantly boost continuous torque handling by shedding heat. For mid-drives, it’s harder to actively cool, but ensuring it’s clean (no mud insulating it) and maybe even adding small heat sinks to the casing could help a bit.

Ride in a Lower Power Mode intermittently: If you need to climb a long hill, it might be better to go a bit slower or give the motor a break rather than full-throttle the whole way. It’s like not flooring your car up a mountain – sometimes easing off to prevent overheating gets you there faster overall (since you won’t have to stop from an overheated system).

Bigger Motor: Ultimately, if you find you are routinely overheating the motor even after trying these things, you might need a motor with a higher power or torque rating. This circles back to the earlier suggestion of a more robust or lower-KV motor that can handle the current.

Expectation Check

Lastly, do a reality check on what you’re expecting from your e-bike. If you have a typical $1,500 retail e-bike, understand that it’s designed as an assist, not a motorcycle. As one experienced rider put it, “a $1500 electric assist eBike is not a motorcycle... what you bought is not a motorcycle.”.

That perspective is important: e-bikes (especially street-legal ones) are usually limited in power for a reason – they’re meant to augment human power, not completely replace a dirt bike (unless you specifically bought an off-road high-power e-bike). 

If you find yourself wanting to tow cars or blast up 30% grades without pedaling, you might actually be in the territory of needing an electric dirt bike or a significantly more powerful custom build.

That said, with the tips and upgrades in this guide, you can greatly improve the torque and get your e-bike feeling snappier and better at hill climbs, all while staying within reasonable limits of the platform.

Recommended: How to Solve Common E-bike Motor Errors

FAQs

How can I get more torque from my e-bike?

You can boost torque by lowering your gearing (smaller chainring, larger rear cog) and increasing the controller’s current limit—just make sure your battery and BMS can handle it. This gives stronger starts and better hill-climbing.

Does battery size or type affect torque output?

Yes. A battery with higher amp output (like 30A vs. 15A) can push more power into the motor, improving torque. If the battery is too weak, it can trigger a BMS trip fix or shut down under load.

Can I tune my e-bike for better hill climbing?

Absolutely. Mid-drive e-bikes benefit most from gear changes. You can also tweak controller settings and check your motor’s firmware for torque optimization. Just ensure your setup has proper ebike battery protection.

What type of e-bike motor gives the best low-end torque?

Mid-drive motors offer the strongest low-speed torque because they use your bike’s gearing. Hub motors are simpler but don’t climb as well unless paired with the right gearing and power settings.

Will increasing torque reduce my e-bike’s range?

Yes, more torque usually means more current draw. If you ride aggressively or up steep hills often, your battery will drain faster. Using a larger battery or riding in eco mode when not climbing helps offset that.