I am looking for an electric bike for my wife. The problem is that she has a large hill to go down on the way home from work and she does not want to spend 5-10mins constantly on the brakes. I have tried a couple of bikes like one from Stromer that has regenerative braking the problem is that it does not brake enough, when it is set to max braking (-2) the braking force is almost imperceptable.
I do not care about charging the battery (though that would be nice) what I need is decent braking force from the engine so she can cruise downhill without braking and at a reasonable speed. As I understand it the battery cannot take the whole current that can be generated by the motor but I would think there would be some way to divert that power to a capacitor or resistor (with heatsink) or something.
I would consider building my own bike if needed.

Anyone know of such a bike/conversion kit?
Seams that bionx has a system, does anyone know how well it works? Can it slow my sufficiently on a long steep hill?

BionX is the ticket for what you want... When I put the re-gen to level 4 I almost always have to pedal to keep up the speed to as fast as I want to go on 99% of any hills I have went down... As for going up the hills you also always have to pedal as it is an assist type of system, not a throttle type...

+1 with 350; I rode a BionX down a really steep hill and the regen stopping power was fantastic.

I ride a BionX. I thought the regen/braking was pretty good. However, on a steep hill I still didn't have problem hitting 20mph on regen level 4. I'm 240 lbs and I was carrying a good 30 lbs of gear... add the weight of the bike, and we're talking about a 320 lbs load. I can't remember what the BionX user manual said about the max speed you should not exceed while in regen mode. I'm not sure what happens if you exceed that speed. Anyway, I converted my cantilever brakes to mechanical disc brakes... and the conversion did not play well with the regen braking, so I have completely disabled it. I use the disc brakes to stop... they do a much better job than the regen braking. I don't believe BionX, or any other manufacturer, intends the regen braking to be the main brake... especially on a steep hill. If you have concerns, I'd recommend hydraulic disc brakes. I'm not sure why anybody would have difficulty pulling a brake lever if they want to slow down or stop - I use the brakes in my car, I don't just downshift.

Thing I noticed was the regen with a 500D seemed to be less than with (I think) a 350 kit. Didn't even need to use any brakes on an extremely steep hill with the 350 bike (actually slowed me down too much). FOR ME, if it were my bike I wouldn't use this feature at all because I don't like the stress on the axle/dropout even though I know it can be minimized with torque arms.

With the BionX system you can "adjust" how much re-gen braking happens, menu code 2002. I set mine to the highest "40" and like I said, I have to pedal to keep up the speed going down most hills. If I don't feel like pedaling and want to go faster I just use a lower re-gen level from 4 down to 1...

Agree with 350; really was a restraint when set up correctly; like towing an anchor.

On level ground on my set up if I put it in level 1 re-gen, I would have to pedal hard to ride "normal", in level 2 re-gen I would need to pedal like up a 5-6% hill, On level 3 re-gen I would have to pedal like going up a 12-13% hill, On level 4 re-gen I would have to stand up and pedal to go anywhere... That's how much resistance re-gen can make in rolling resistance on level roads...

Many thanks for all the great replies. Now I just need to figure out how to get a 350 system in Switzerland.
The dealers list on the bionx web page only shows one dealer in Switzerland and they only have 250 systems. Anyone else know a good place to get it?
I can only see 250 and 500 online. is this 350 an old system or something?

AFAIK, the BionX is very dealer dependent since they install the system. I don't think the warranty is valid (at least not in the US) otherwise. You can procure a complete bike from some companies in the US, but shipping/tariffs could be steep. Also, some OEM companies (like Ohm) sell bikes with BionX.

eBike Systems - e-bike, electric bicycle systems | ridebionx.come-bike, electric bicycle systems | ridebionx.com You may have to order the 350 from somewhere else, outside the country if it's not legal there... https://ridebionx.com/products/oem/where-to-buy/