Regen on EBikes

[MikeFitz]

I would like to see a discussion about EBike Regen features. I like to ride my mountain bike in mountainous terrain and I can't imagine that any EBike battery could last for 3 or 4 hours out there. Since I spend a lot of time going downhill it seems like having an EBike with regen is a must have requirement.
Regen works great in my Prius, but from some of the forum posts here it seems like regen on EBikes is not well developed and not really worth the unsprung weight and other disadvantages.
What do you think?
Is regen a feature worth having?
Is regen a feature that has room for improvement on EBikes?

 

[Ravi Kempaiah]

I would like to see a discussion about EBike Regen features. I like to ride my mountain bike in mountainous terrain and I can't imagine that any EBike battery could last for 3 or 4 hours out there. Since I spend a lot of time going downhill it seems like having an EBike with regen is a must have requirement.
Regen works great in my Prius, but from some of the forum posts here it seems like regen on EBikes is not well developed and not really worth the unsprung weight and other disadvantages.
What do you think?
Is regen a feature worth having?
Is regen a feature that has room for improvement on EBikes?

For cargo bikes, it can be very handy. When fully loaded, a good cargo bike can handle 450 lbs including the rider. Such a bike going downhill can make the rotors red hot and sometimes even warp it.
Also, if you live in a place where there are long hills, it could be useful.

If you are on road, you really don't notice the unsprung weight. It is more pronounced when you're riding over very technical terrain but otherwise, it really doesn't matter.
Currently, BionX , Stromer and Specialized bikes are equipped with regen. On my Stromer, a set of brake pads lasted me over 5000 miles.

 

[harryS]

"There is also endless debate about how much you actually get back with regen, some poopooing it at just 1-2%, and other regen proponents touting the 10-20% claims. The fact is both these extremes and everything in between are true. It depends entirely on your riding environment; how hilly is your terrain and how much stop and go you have to endure."

Written by Justin Le eight years ago.
https://endless-sphere.com/forums/viewtopic.php?f=2&t=7891

You do need a direct drive motor.

 

[Ravi Kempaiah]

"There is also endless debate about how much you actually get back with regen, some poopooing it at just 1-2%, and other regen proponents touting the 10-20% claims. The fact is both these extremes and everything in between are true. It depends entirely on your riding environment; how hilly is your terrain and how much stop and go you have to endure."

Written by Justin Le eight years ago.
https://endless-sphere.com/forums/viewtopic.php?f=2&t=7891

You do need a direct drive motor.

Great info and test results from Justin!

 

[Nirmala]

It seems that carrying a second battery or getting a very large first battery makes more sense than regen to accomplish that long a ride on hilly terrain....or both regen and a second battery. I don't think regen by itself is going to increase range enough

 

[Nirmala]

Of course another option is to get an ebike with two or three chainrings in the front, and let your legs give you the added range. Then you can save your battery for the really big hills.

 

[MikeFitz]

Currently, BionX , Stromer and Specialized bikes are equipped with regen.

I contacted Specialized when their new Turbo bikes came out and they are not regen.
From what I see about Stromer is they don't have a suspension fork and that is crucial when riding in Annadel in Sonoma County. The BionX system looks good since it is a retrofit to my existing bike. I looked at the EBR review and they said good things about BionX regen.

 

[JohnT]

I don't think regen is worth it. With direct drive hub motors, it isn't just the unsprung weight, but the rotational inertia. It's not a huge difference, but you can definitely feel it when you pedal without power. If you only pedal with power, maybe it doesn't matter, but to me, it's not worth the 10% or so extra range that you get under ideal conditions.

I hear it makes a big difference on brake pad life, though. With regen, you don't have to hit your brakes as much. Again, not worth it to me, but something to consider in hilly areas.

 

[Ravi Kempaiah]

what I see about Stromer is they don't have a suspension fork

http://overvolted.com/stromer-st2-finally-gets-optional-front-suspension-fork/

Suspension fork for ST1 and ST2 are available.

It's not a huge difference, but you can definitely feel it when you pedal without power

Haibikes or BULLS with Sprocket equalizing system is probably more tougher to pedal without power than ST2 DD hub.

That's why e-MTB companies are getting rid of that SES system.

 

[Bicyclista]

I'm on my second ebike. Neither my first nor my second ebikes had regen. I don't miss it. I'm the kind of recreational rider that never rides far enough to exhaust my battery, and I suspect I'm in the majority of riders, even when counting hard-core commuters (my hat off to you guys!). So getting 5-20% battery power back is... not sufficient!

The negatives of regen, such as cogging and a direct-drive axle motor are negatives to me. The one positive (at this time), increased brake pad longevity, is easily trumped by the need to replace brake pads because they are dirty (and, therefore, squeal). I clean my disk rotors with denatured alcohol frequently, but I don't clean my brake pads. It's just too hard! So I am resigned to replacing my brake pads before they are worn out.

Perhaps I'm misinformed. If anybody would like to enlighten me, I would be grateful.

 

[Ravi Kempaiah]

such as cogging and a direct-drive axle motor are negatives to me.

I do think you're mis-informed.
DD hubs have their place. Cogging is over-rated (S*%@, I sound like Trump talking about Meryl).
Specialized, BionX, Stromer, GoSwiss and many other companies use DD hubs and some of these motors will last 30,000 miles or more.

A classic example of the limitation of mid-drive's limitation was demonstrated by my friend, Adam. He owns a Focus Aventura and has had 3 motor failures. Simply because he was pedaling hard. Then, he switched to Stromer ST2 and hasn't had a motor replacement in over 8K miles.
If you try to maintain 25mph+ for long stretches of time, most mid-drives lifespan would be greatly reduced. I am really curious to know the breaking point of Bosch/ Yamaha system. In fact, Yamaha isn't bringing speed pedelecs to the US. Even though Giant is using the Yamaha system, they have modified the original Yamaha system.

Here are some of his videos:

Even some of the overbuilt BBS-HD's would fail if you push it to 28mph for 1000 of miles. Simply because, the weak point in most of these mid-drives is the plastic nylon gear. At low speeds, it works ok but at running at high rpm for extended time increases the temperature inside enough to change the mechanical yielding of that gear material. The point is, most people would never push their bikes to the limit and for 95% of the demography, Bosch/Yamaha/Brose works just fine.
The biggest + of DD hub is its longevity. Regen is a side benefit of a good DD hub.

 

[Trail Cruiser]

It looks like Bafang has beefed up the nylon gear strong enough to outlast the metal pinion gear on heavy loads.

 

[tomjasz]

Talking with Cali eBikes, and Biktrix, the plastic gear failure rate is GROSSLY exaggerated. Fat Bike blog has done more to continue the rumor than relate the facts, IME. Bruno will report the same thing.

BTW I have all the versions of nylon gears for comparison. Attached are the two BBS01-02 versions

 

[tomjasz]

Simply because, the weak point in most of these mid-drives is the plastic nylon gear.

Where are all these failures? Every reseller I've talked to reports very few failures. I have 4 and two are over two years old. The biggest frustration is Bafang's changing the design of the pinion, pinion plate and the gear. Please don't continue the overplay of this rumor. The biggest reseller hasn't seen failures. Where are they documented?

BTW, we'll be visiting my nephew in the spring, we're looking forward to the visit.

 

[tomjasz]

I like the regen on my 1000W MXUS front drive. The additional braking is extremely helpful to me. The regen is of little value in itself.

 

[Ravi Kempaiah]

Where are all these failures? Every reseller I've talked to reports very few failures. I have 4 and two are over two years old. The biggest frustration is Bafang's changing the design of the pinion, pinion plate and the gear. Please don't continue the overplay of this rumor. The biggest reseller hasn't seen failures. Where are they documented?

BTW, we'll be visiting my nephew in the spring, we're looking forward to the visit.

Hi Tom,
Thanks for your input. Well, when it comes to mid-drives, I don't think it has reached its best design/performance yet. Just like batteries, it is a constantly evolving space.
I have had discussions with Rakesh of Falco (who is a big proponent of DD hubs) and I have gotten to see both sides. While, Bosch system works well, I do wish it had little more oomph to it. Bafang MAX is still not as refined but it serves the purpose as poor man's Bosch.
Adam (who made those videos) shared this pic with me. It's a stripped nylon gear from his 2nd motor on the Focus Impulse motor.
Very recently, I suggested him to try a Bosch speed pedelec but based on his experiences, he was very wary of it.

I have been riding few Haibikes and I know the system well and I do think it's pretty reliable 99% of the time but they are not suited for speed cruising. In fact, having sold 300+ Bosch powered bikes in the last 12 months, the store has seen less than 1% failures but that comes at a price. Slightly conservative power delivery. As I said, mid-drives are still work in progress and I do think there is significant room for improvement in these mid-drive systems.. In 2019, we would have much better systems for sure.

Please do visit Madison in March and we will ride around the lakes on E-bikes.

 

[tomjasz]

Bafang MAX doesn't interest me. Frankly I'm tired of Bafang and their antics. Sorting out changes and parts is a pain. BUT at least when sorted a mechanically inclined person can effect a repair.

 

[Prof_Stack]

The Bionx regen, with the newer 48V 555wh battery, works very well. The 555wh battery really soaks in the regen juice compared to the older 36V versions. I do miss it when I take the other e-bike out.