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Rivian's TM-B electric bike

(www.theverge.com)
190 points hasheddan | 1 comments | 22 Oct 25 18:00 UTC | HN request time: 0s | source
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dreamcompiler ◴[22 Oct 25 19:10 UTC] No.45673731[source]▶
808Wh battery and 100 miles of range. These two numbers track with each other and are roughly believable.

OTOH, with a battery this big, a generator powered by the pedals, and regen braking this thing has to be heavy. I'd expect it to weigh at least 80 lbs. More likely 100. The fact that their "specs" say nothing about weight suggests they're embarrassed about the weight.

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jeffbee ◴[22 Oct 25 21:22 UTC] No.45675314[source]▶
Regen braking is how you can tell this was designed by a moron. The energy balance simply does not favor regenerative braking on a bicycle, especially a bicycle that flippantly ignores aerodynamics like this one does. A bicyclist loses roughly all of their energy to air resistance. It's not a truck. There is not substantial potential energy to be recaptured going down hills.
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edaemon ◴[22 Oct 25 21:29 UTC] No.45675413[source]▶
What do you mean? The regenerative braking only kicks in when you engage the brake lever. It's not going to add much range but it's free, I don't see any downside to including regenerative braking.
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1. amluto ◴[23 Oct 25 01:40 UTC] No.45677263{3}[source]▶
As other commenters noted, rear wheel regenerative braking doesn’t work very well. But there are more problems: most mid-drive e-bikes fundamentally can’t regeneratively brake at all: the rear hub freewheels and cannot drive the motor. Even ignoring that, the chain/belt frequently also can’t drive the motor because that would cause the pedals to drive the motor, and a lot of e-bikes are designed to be pleasant to ride with the motor off, and the rotor has rotational inertia and often has drag as well.