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Rivian's TM-B electric bike

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188 points hasheddan | 1 comments | 22 Oct 25 18:00 UTC | HN request time: 0.222s | source
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soco ◴[22 Oct 25 18:48 UTC] No.45673474[source]▶
Bear with me I don't know much about bikes but I have this honest question: why does it need a chain, and won't place the engine (or whatever gear box it has) directly on the wheel?
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1. bullfightonmars ◴[22 Oct 25 19:08 UTC] No.45673709[source]▶
Putting the motor into the wheel makes for an excellent riding experience, I have a Bionx rear wheel (out of business) that is connected to the chain ring and pedals in the traditional way. The wheel detects torque from pedaling and applies it's own torque to drive the wheel. It can be used with and without power and feels almost seamless and is silent.

Unfortunately it seems to be difficult to engineer and build these wheel motors for reliability and longevity. They significanly increase the unsprung mass of the wheel which leads to increased wear on the hub components.