6 ms·

That blog post is pretty misguided, IMO. I'll assume the math is right, and the potential gain from regen braking is small. But it's free! > The way regenerati

That blog post is pretty misguided, IMO. I'll assume the math is right, and the potential gain from regen braking is small. But it's free! > The way regenerative braking is implemented is to have the motor continuously engaged. This is wrong. Regen braking only requires the motor be engaged _when braking_. There's no reason you can't coast when you want to coast.

Tostino 4y ago
You are absolutely right about it being small, but free. Do keep in mind, a direct drive is always "engaged" to some extent by the cogging force. An advanced controller can make a direct drives "freewheel", but it actually takes power to do that. Totally worth budgeting for a slightly larger battery to allow a simpler overall design. Now if you say, had a mid-drive bike, or an internally geared hub, there are some complicated mechanical systems you can put in place to lock the freewheeling mechanisms in the gearing when you want to apply the brakes, but I haven't seen anyone design that yet.
- HPsquared 4y ago
  Does cogging actually absorb energy though? (When averaged out)
KennyBlanken 4y ago
Regeneration on a bicycle is only possible on hub motors, which usually have a planetary gearset to have acceptable low-end torque, and that gearset has significant drag. Mid-drive bicycles are able to leverage the freewheel, and thus have very high coasting efficiency. You don't really seem to know much about this. It's odd that you seem to have formed strong opinions on said subject. There is fierce competition in the industry for efficiency/range/price...not really sure why you think you can just casually stroll in and go "well DUH, folks, just do..."
samatman 4y ago
It's certainly opinionated, I don't view 50-100 stops in ~30 miles as at all unreasonable. Something which is rarely done but easily could be for a bike is regenerating first into a couple supercapacitors, which are 99% efficient and fill and discharge as fast as you can push current. They don't have the capacity to be as useful in cars, for a bike they can also provide a nice kick to overcome starting torque. The downside is it's another two drink can's worth of volume to add somewhere on the bike.

Tostino 4y ago

You are absolutely right about it being small, but free. Do keep in mind, a direct drive is always "engaged" to some extent by the cogging force. An advanced controller can make a direct drives "freewheel", but it actually takes power to do that. Totally worth budgeting for a slightly larger battery to allow a simpler overall design. Now if you say, had a mid-drive bike, or an internally geared hub, there are some complicated mechanical systems you can put in place to lock the freewheeling mechanisms in the gearing when you want to apply the brakes, but I haven't seen anyone design that yet.

HPsquared 4y ago
Does cogging actually absorb energy though? (When averaged out)

KennyBlanken 4y ago

Regeneration on a bicycle is only possible on hub motors, which usually have a planetary gearset to have acceptable low-end torque, and that gearset has significant drag. Mid-drive bicycles are able to leverage the freewheel, and thus have very high coasting efficiency. You don't really seem to know much about this. It's odd that you seem to have formed strong opinions on said subject. There is fierce competition in the industry for efficiency/range/price...not really sure why you think you can just casually stroll in and go "well DUH, folks, just do..."

samatman 4y ago

It's certainly opinionated, I don't view 50-100 stops in ~30 miles as at all unreasonable. Something which is rarely done but easily could be for a bike is regenerating first into a couple supercapacitors, which are 99% efficient and fill and discharge as fast as you can push current. They don't have the capacity to be as useful in cars, for a bike they can also provide a nice kick to overcome starting torque. The downside is it's another two drink can's worth of volume to add somewhere on the bike.