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You might not like it, but faster electric bikes can be safer. Here's why (electrek.co)
submitted 11 months ago by to c/micromobility@lemmy.world
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[–] 2 points 11 months ago* (last edited 11 months ago) (7 children)

Counterpoint - here's what power (human or motor, doesn't matter) is required at a few speeds starting from 25 to 45 (28mph) with anecdotal hurt from personal and family experience. The power level is important because it shows you the relative energy you carry as you're moving with that speed, energy your body would have to absorb during an impact as it comes to a stop when you crash. The power grows exponentially with speed thanks to air drag. And so does the hurt.

Speed Power Hurt
25kph 150W Not too bad, maybe no road rash
30kph 230W Road rash likely, torn clothes, some impact bruising
35kph 350W Bad road rash, torn clothes, deep impact bruising
40kph 500W All of the above but worse, impact bruising so deep it takes weeks to months to heal, soft tissue damage likely
45kph 700W All of the above but worse, soft tissue damage likely, fractures possible

After crashing a few times at 35 or over, the last of which had my palm hurt for months, I no longer cross the 30kph threshold for any extended period of time.

Source: been riding in Toronto, Canada for a couple of decades, electric for a decade, used to have a 1500W (limited from 3kW) Tangent Ascent.

E: Clarified what I mean by power. Thx @litchralee@sh.itjust.works

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  • [–] 7 points 11 months ago (4 children)

    I'm struggling to see how power has anything to do with the amount of hurt that will result in a crash. Yes, higher speed means higher hurt, and everyone from motorists, motorcyclists, bicyclists, and e-bikers will agree to that. But power is the wrong quantity to focus on.

    Case in point: coming down a hill on an acoustic bike, I too can do 45 kph just like an ebike can. If both me and my ebike-riding compatriot both reach level ground at the bottom of the hill and are both doing 45 kph, and then we both crash separately, then it's equal hurt for us both. Motor power (with mine being 0 Watts) has nothing to do with hurt. Speed is kinetic energy, and that's the real worry when crashing: if that energy goes nowhere else, it goes into the fleshy human being.

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  • [–] 1 point 11 months ago (1 child)

    ↑Motor Power ∝ ↑Frequency of going at high speeds ∝ ↑% of time when a severe accident is possible.

    I understand the argument that any given rider doesn't have to use the power. It's the same argument as "guns don't kill people, people kill people". While technically true, it ignores all of the evidence that shows that having the thing accessible increases its use in aggregate. I'm okay with people choosing to put themselves at risk, but a user of a more powerful eBike increases the danger for those around them as well. That kinetic energy works both ways when you hit someone else, and it's way easier to get up to that energy on a powerful eBike.

    I hope we can agree that unlimited eBike power without a license is the incorrect policy. If my bike has as much power as a motorcycle (and electric motorcycles do exist), then I should need to be appropriately licensed. At some insane power, it should probably not be street legal. If you imagine a "smooth morph" between the most powerful electric motorcycle and the least powerful eBike on the market, there is some line where we need to transition categories. I'm willing to argue over where the various categorical lines around vehicle regulation and driver licensing should be, but I hope we can agree that they need to exist.

    That said, I'm not sure that the ~25km/h limit in NY is the right limit, I might choose something more like 30-35km/h (~18.5-22 mph). But that's without any data and I'm not an expert, so 🤷

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  • [–] 0 points 11 months ago*

    I build my own bikes and I definitely used to go faster on average when I had a more powerful motor and/or higher limits. I've done trips on the 1.5kW Tangent where I've averaged 45kph. These days I ride small 250W hubs, limited to 700W (overpowered) but with pedal assist that tops out at 2x human power. That way I can't go much more than 400W continuous. At the same time I get high torque when starting from a stop. Which is more or less what factory ebikes with torque pedal assist do. I now average 25-28kph.

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  • [–] -1 points 11 months ago

    Its an odd way to convey that they meant the kinetic energy once you impact something. But power is Energy over Time, so they are talking about energy at that speed and its irrelevant if it is manmade watts or ebike watts

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  • [–] 0 points 11 months ago* (last edited 11 months ago)

    I should have clarified. I didn't mean motor power. These are power levels needed for any average bike to maintain this speed on level ground. You and your friend would definitely be hurt the same if you both went 45kph and fell the same way.

    Speed is kinetic energy, and that’s the real worry when crashing: if that energy goes nowhere else, it goes into the fleshy human being.

    100% and you can estimate how much kinetic energy is stored by looking at how much energy is needed to maintain that speed. Can use bike sim to get the numbers. And as you said - that's the energy that the meatbag would have to dissipate. The real interesting part which isn't obvious to everyone is that the energy grows exponentially with speed due to air drag. So falling at 40 hurts much more than 2x than falling at 20.

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