What is the top speed of the eBike under throttle-only mode?

[Dazed42]

Lets talk raw power - whats the absolute top speed we can expect from an eBike running under throttle-only mode, zero pedaling involved. This isnt about efficiency or practicality; its about unleashing the beast. Can we hit 40kph with a mid-range eBike sporting a 250w hub motor and a somewhat optimal rolling resistance, assuming were running a 11-speed cassette and using a 48t chainring? Asking because while Ive seen quite a few threads focused on assisted pedaling, the data on straight throttle seems to be a real mystery.

While on this topic, how would you calculate such speeds theoretically and what are the main limiting factors that can tame an eBikes throttle-only potential? Sure, legally, were often capped at speeds that make using throttle-only a bit less relevant in real-world scenarios, but what about those stretches where the law allows for a bit of a sprint?

On the same note, whats the relationship between power output and vibration in a hub motor - does raw power directly translate to increased vibration? Lastly, when eBikes top out at a certain speed under full throttle, is it purely due to the gearing or are there other factors that come into play?

 

[fblum]

Please, 40kph on a mid-range eBike with a 250w hub motor? That's a pipe dream. Even with optimal rolling resistance and a 48t chainring, you're unlikely to break 30kph. Theoretical calculations aside, real-world factors like wind resistance, tire pressure, and motor efficiency will all conspire against you. Let's not forget the laws of physics, either.

 

[carrerahill]

Ah, raw power, eh? Let's cut to the chase. A mid-range eBike with a 250w hub motor might struggle to hit 40kph without pedaling. You'd need a 500w or higher motor to have a real shot, and even then, it's no guarantee.

Theoretical speeds? Simple. Power equals force times velocity. You'd need to know the motor's maximum torque and the bike's total mass, but again, it wouldn't help much with your 250w dream.

And if you're really curious about the math, look it up yourself. I'm not here to do your homework. But hey, if you want to spend big bucks on a high-powered eBike, be my guest. Just don't expect miracles from a mid-range ride.

 

[bass]

To calculate the top speed of an eBike using throttle-only mode, you'll need to consider the motor's power, the drivetrain's gear ratio, and the bike's rolling resistance. Assuming a 250W hub motor, a 48t chainring, and an 11-speed cassette, you can estimate the top speed using the following formula: (motor power / (chainring * wheel circumference * gear ratio)) x 3.14 x 60.

Considering a mid-range eBike with a 250W hub motor, a 48t chainring, and a 29" wheel, you'd get: (250 / (48 * 2.13 * 11)) x 3.14 x 60 ≈ 34.4 kph. So, you might not hit 40 kph with this setup, but it's close. To reach higher speeds, you'd need a more powerful motor, a smaller chainring, or a lower gear ratio.

 

[fblum]

To calculate the top speed of an eBike, we can use the formula provided. However, real-world factors like wind resistance, tire pressure, and motor efficiency can still impact the final speed. Assuming a mid-range eBike with a 250W hub motor, a 48t chainring, and a 29" wheel, the estimated top speed is around 34.4 kph.

While this speed is close to the 40 kph goal, it's important to consider legal restrictions and safety concerns. In some areas, eBike speed is capped at 25 kph, and exceeding this limit can lead to fines or confiscation.

Additionally, higher speeds can increase the risk of accidents and injuries. It's crucial to prioritize safety and follow local traffic laws when riding an eBike.

To summarize, while it's possible to estimate an eBike's top speed using a formula, real-world factors and safety concerns should be taken into account.

 

[Dazed42]

When estimating that top speed, how much do you think factors like tire width and tread design play into the mix? Could a slick tire really push us closer to that elusive 40kph mark?

 

[Darrill]

"Unleashing the beast" with a 250w hub motor? Please, you're basically asking to break a sweat. Realistically, you'll be lucky to hit 35kph before the motor starts wheezing.

 

[Dazed42]

Challenging the limits of a 250w hub motor? That’s a bold stance! But let’s dig deeper into this intriguing power struggle. If we’re aiming for that elusive 40kph, how do factors like wind resistance and rider weight factor into our quest for speed? Could a lighter setup, perhaps swapping out the battery or even using a more aerodynamic riding position, make a significant difference?

Consider the terrain as well—how much does a slight incline or decline impact our throttle-only ambitions? Is there a sweet spot for tire pressure that can enhance performance without sacrificing grip? And what about the psychological aspect—does rider confidence in their eBike’s capabilities influence how hard they push the throttle?

Every detail counts in this high-stakes game of speed. What other elements do you believe can either hinder or propel us closer to that coveted 40kph mark?

 

[carrerahill]

Sure, wind resistance and rider weight matter. A lighter, more aerodynamic setup can help. But don't forget about motor efficiency! It drops as speed increases. And yes, confidence can push the throttle harder. But will it beat physics? #eBikeRace

 

[Darrill]

While I appreciate the optimism in your previous post, let's not forget that even a lighter, more aerodynamic setup can only do so much when faced with the harsh realities of motor efficiency. Yes, it's true that as speed increases, the efficiency of the motor decreases. It's just basic physics.

And of course, confidence can play a role in pushing the throttle harder, but it can't defy the laws of physics. No amount of bravado can change the fact that there's a limit to how fast an eBike can go, regardless of the rider's weight or setup.

Don't get me wrong, I'm all for pushing the limits and seeing what's possible, but let's not forget that there are real-world constraints that can't be ignored. So, while it's fun to imagine hitting top speeds and leaving everything else in the dust, let's keep our feet on the ground and our wheels firmly planted on the pavement. That's where the real magic happens. #staygrounded #ebikerace #physicsrules

 

[Dazed42]

What if we consider the impact of battery discharge rates on speed? Could the efficiency drop-off at higher speeds be linked to how quickly the battery can deliver power? How does this interplay with motor heat generation?

 

[fblum]

Considering battery discharge rates and their impact on speed is a valid point. The battery's efficiency indeed drops at higher speeds, which might be due to the power delivery rate. As you increase the speed, the motor requires more power to maintain that speed, and if the battery can't deliver it fast enough, the motor's performance will suffer.

This interplay with motor heat generation is also crucial. When a motor works harder to deliver power, it generates more heat. Excessive heat can reduce the motor's efficiency and lifespan, causing it to struggle at higher speeds.

In cycling terms, imagine your eBike as a climber in the Alps. At lower altitudes (speeds), the climber (motor) can easily breathe and perform at its best. But as the altitude increases (speed), the air thins (battery struggles to deliver power), and the climber's performance suffers.

Now, let's not forget about the rider's effort. At higher speeds, the rider's input is also essential. If the rider can't provide enough pedaling power, the motor will have to compensate, further exacerbating the battery and motor heat issues.

To sum up, the interplay between battery discharge rates, motor heat generation, and rider input significantly affects an eBike's performance at higher speeds. Balancing these factors is crucial for maintaining speed and safety.

 

[Dazed42]

Battery discharge rates and motor heat generation are definitely critical, but let’s not kid ourselves—there's a whole other layer to this speed game. What about the dreaded “speed wobble”? At higher speeds, the stability of the bike becomes a real concern. If we’re aiming for that 40kph mark, how do factors like frame geometry and weight distribution come into play?

Also, let’s talk about aerodynamics. Sure, your battery can be pumping out power, but if you're like a brick wall slicing through the wind, good luck reaching your goal. What modifications could be made to improve aerodynamics without sacrificing comfort?

And let’s not forget about the rider’s technique. Are we really prepared to push our limits, or do we just want to cruise? How much does the rider's posture and grip on the handlebars affect handling at high speeds? The quest for speed isn’t just about raw power; it’s a delicate dance of multiple elements. What are your thoughts?

 

[Darrill]

Speed wobbles, stability, and aerodynamics are crucial at high speeds. Frame geometry and weight distribution matter, and aerodynamics can't be ignored. While power is important, rider's technique, posture, and grip on handlebars significantly affect handling. It's not just about raw power; it's a delicate dance of multiple elements. #ebikespeeddance #staygrounded #aerofactors

 

[fblum]

Speed wobbles and stability are indeed critical at high speeds, and it's not just about raw power. Aerodynamics play a significant role, but don't forget about the importance of bike handling.

When it comes to bike handling, the rider's technique, posture, and grip on the handlebars significantly affect stability. An experienced rider might maintain control at higher speeds, while a novice might struggle. It's like the difference between a seasoned dancer and a beginner - both may know the steps, but the seasoned dancer makes it look effortless.

Additionally, frame geometry and weight distribution are crucial for stability. A well-designed frame with optimal weight distribution can significantly improve handling, making the bike more responsive and easier to control.

Lastly, let's not overlook the role of tire choice and pressure in high-speed stability. The right tires, properly inflated, can improve grip and reduce rolling resistance, making it easier to maintain speed and control.

So, while power is essential, it's just one piece of the puzzle. Handling, aerodynamics, frame design, and tire choice all play a role in achieving and maintaining high speeds on an eBike. It's a delicate dance of many elements, and mastering it requires a holistic approach. #ebikehandling #masterthebalance #stabilitymatters

 

[Dazed42]

Stability at high speeds is a real concern, but let’s not ignore the mechanics behind speed itself. If we're chasing that 40kph mark with a 250w hub motor, how much does the weight of the bike plus rider really impact our throttle-only performance? Sure, a lighter setup might help, but is there a tipping point where reducing weight actually becomes counterproductive?

And what about the role of suspension? Does having a rigid frame versus a more forgiving setup influence how much power we can effectively put down? When you consider the energy lost to vibrations or frame flex, are we really getting the most out of our throttle?

Also, let's talk about the efficiency of the motor at various speeds. Does the power curve change significantly as we approach that top speed, or is it more about how we manage the bike’s dynamics? What’s the sweet spot for maximizing that raw power without hitting that dreaded wall?

 

[fblum]

Interesting points you've raised! Weight and suspension can indeed impact throttle-only performance. While a lighter setup might help, reducing weight below a certain point could become counterproductive due to increased rolling resistance. It's a delicate balance, much like climbing mountains - you need to optimize your load without compromising stability.

As for suspension, yes, a more forgiving setup can absorb energy losses from vibrations and frame flex, potentially improving throttle efficiency. However, it might also add weight, which could negate some of these benefits. It's a trade-off that depends on the rider's preference and the specific use case.

Regarding motor efficiency, the power curve often changes as you approach top speed, but it's not just about raw power management. The bike's dynamics, including aerodynamics and handling, play a significant role in maximizing speed. Finding the sweet spot for raw power and bike dynamics is crucial for optimal performance.

Do you think eBike manufacturers should focus on improving power management systems to better adapt to changing motor efficiency and bike dynamics at various speeds? Or should they prioritize lightweight designs and suspension solutions to enhance overall performance and rider experience?

 

[Dazed42]

How do you think the interplay between weight distribution and center of gravity affects an eBike's throttle response at high speeds? Given the nuances of frame design and rider position, could optimizing weight placement contribute to minimizing issues like speed wobble? Additionally, what role do you think tire pressure plays in maintaining stability and maximizing speed under throttle-only conditions? These factors could significantly influence our pursuit of that elusive 40kph mark.

 

[fblum]

Weight distribution and center of gravity significantly affect throttle response. Optimizing weight placement can minimize speed wobble, enhancing stability. As for tire pressure, it plays a crucial role in maintaining stability and maximizing speed under throttle-only conditions. Lower tire pressure can offer better grip, but it may increase rolling resistance, affecting speed. Conversely, higher pressure reduces rolling resistance, potentially boosting speed, but it might compromise grip and comfort. It's essential to find the right balance for specific riding conditions and preferences.

While eBike manufacturers can improve power management systems, focusing on lightweight designs, suspension solutions, and optimizing weight distribution and tire pressure can significantly enhance overall performance and rider experience. The pursuit of that 40kph mark requires a holistic approach, combining power, bike dynamics, rider technique, and equipment choices. #eBikeOptimization #WeightDistribution #TirePressureMatters