Interest Bromptnot mid-drive ebike
 

Although I have no interest in ebikes, that's pretty slick.

This ebike is smokin!!!:love:


https://cimg2.ibsrv.net/gimg/bikefor...2bea72f6f.webp

Its a very good idea, it demonstrate that its possible to integrate a mid drive motor in a tri-fold with a small folded size.

When the new eBirdy was announced, it was with a mid drive motor too, a Bosch Performance Line SX which with the TQ HPR60 and Fazua Ride 60 fits very well for a folding bike due to their small size and low weight (with an advantage for the Bosch which is much more powerful than the TQ and Fazua, i.e. 600W peak and exists in 28mph under the name Performance Line Sprint).
But, unfortunately, when the eBirdy called Birdy H was eventually presented at the Taipei Cycle Show 2026, it was with a Mahle X30 rear hub motor.

The potential issue with this Upland is the type of mid motor mounted and the weight of this motor.

Its obviously not a Bosch nor a TQ and also not a Fazua Ride 60 and I do not know any other mid drive motor weighting 2kg or less ?

Perhaps, and I share concern with getting an off-brand motor with difficult replacement prospects. However, regarding motor weight... with those tiny 349 wheels AND mid drive to use the multispeed gearing, that allows a small, low-torque but fast-spinning motor. Motors like low gearing.

The fat seatpost battery... they stole that idea off the Dahon E20.

I like that this Brompnot is external gearing only (lighter), but only if it has the gearing range I desire, which is 400%, easily obtained with a 2X crank (cheap) or Schlumpf drive ($$$)... DOH! No Schlumpf with mid-drive! I wonder if a front derailleur mount is possible? I wonder if you can mount a 2X crank? If square taper spindle on the mid-drive, probably. Alas, no 2-piece hollow spindle crank, I'm sure that wouldn't work with the mid-drive.

There are several brands that put the battery in a big diameter seatpost. The drawback is of course that this battery is proprietary.

For the fast spinning motor due to small wheels, its only valid for a hub motor, not for a mid drive motor because the mid drive motor output turns at the pedaling cadence which is independent of the wheel size.

Almost all mid drive motor are made of a fast spinning motor and a gearbox or internal belt that reduce the spinning speed to the pedaling cadence (the Pendix mid drive is an exception, its a direct drive mid motor but due to its low spinning its pretty heavy)..

Aren't all e-bike batteries proprietary?

I would have liked the placement of the battery better if it were in the frame, like Igogomi Alps. Theirs is a 6.8 amp-hour, too.

A bunch of new e-bikes are hitting the market, it seems. I like the new Birdy, but I doubt if it will be US spec. at 20 mph because of the small battery. Of the recent e-bikes, I think my preference would be the Dahon K Feather. I like its minimalistic approach. Their battery, though, is only 24 volts. Onyl Dahon knows why. They could have had a third more capacity if they had gone with the typical 36-volt.

According to Bike Radar, the Mahle hub motor are able to assist till 25mph (why 25mph and not 20mph or 28mph?).

But these are hub motor, their rotation speed is limited like for all hub motor, not sure they can reach these 25mph in a small diameter wheel?

Yes the mid-drive motor turns at pedaling cadence, but can take advantage of the derailleur (or IGH hub) gearing to maintain low torque and higher cadence at the pedals. If a mid-drive e-bike is set up to torque up hills in highest gear without much pedal assist, that motor is stronger than need be.

Regarding smaller wheels, whether it's a mid drive or hub motor, smaller wheels help, because you need less motor drive torque for the same ground thrust, assuming the same transmission gearing. On this particular 16"/349 wheel bike, usually the problem is not a low enough gear (although it bugs me that Bromptons typically came with a low 30s inch low gear and near-racer high, when low 20s would be better). It's the high gear requirements that usually necessitate an IGH rear hub for overdrive, or smaller than 11 high cog, or way larger than 52 chainring. These days, cogs smaller than 11 are more common, to avoid the IGH, which this bike appears to have done, or just like Brompton, biased the gears to the higher end, and rely on the E-drive to climb the hills with an inadequate low manual gearing. Me, if I got an e-bike, I'd still want gearing that I can make it home with, or go without electric drive on a good day.

About the proprietary battery, I was meaning bike brand proprietary battery and in this case proprietary for one bike model vs. mid drive motor brand proprietary batteries like Shimano, Bosch, Mahle... batteries that are used by many bike brands and available outside of the bike brand resellers network, are produced in much bigger quantities and spare batteries availability is guaranteed for a long time.

With a battery proprietary to one bike model of one bike brand, this battery will most probably only be produced for the bikes produced with very little spare batteries available.

You are right about the gear inch range of current Brompton Electric, the lowest gear inch is not short enough meaning that for steep hill climbing the bike is unusable without e-assist.

The good news is that there are now third parties components to easily to upgrade the Brompton 4s gear system to a 7s gear system with a 11-32t cassette that gives about 23 gear inch with a 44t chainring (but its a pity hat Brompton doesn't propose it on their bikes).

(above) Batteries: Yeah before this thread I had commented on the seatpost batteries on the Dahon E20; If replacements not available, I think one could package a more cubey battery behind the seat tube, sitting on the chainstays. Assembling an aftermarket battery array is not hard, but I don't know what other components are part of the battery pack in terms of power management, fault detection on individual cells, etc. With lithium batteries and dangers, that stuff is not trivial. 20+ years ago, the danger was enough that the professional, safety-critical project I was a part of, chose nickel-metal-hydride as an upgrade from the previous lead-acid-gell-cell, not making the leap to lithium though that was already available.

If de battery connection to the motor is only power, without any control bus (CAN or anything else), the the easiest replacement for a battery not available as spare part is to use batteries for professional portable electric tools from a known, reliable brand like Makita, Bosch, Milwaukee... there are several voltages available, 12v, 18v, 36v.

These batteries made to be used outdoor are waterproof, rugged and very reliable. Since they are made for professional use, there are fast charging systems for them.

To have a higher capacity, a simple solution that can fly is to use two 12v batteries for a 24v e-assist and 2x18v < 100Wh batteries for a 36v e-assist. Its easy to find on Aliexpress a tool side connector for these batteries.

+1. That's a really good idea. In quality, availability, and probably even price. And flight capable, breaking down to less than 100Wh segments. Bike Friday should have thought of that. Are you going to make such a pack for your electric Friday? Or just rent a Bosch battery?

Its not possible for Bosch e-assist because there is a connection bus between all parts of the e-assist, its not a CAN bus, its an high speed encrypted bus that provide several features including brake ABS, bike tracking, e-assist locking (of both the mid-motor and battery that makes a stolen motor or battery unusable), online SW update...

I read the article; they are claiming 185 km range. That seems crazy.

Oh wow, that's pretty great stuff, especially since the motor and battery are big money. There were small-wheel e-rentals here, they had pedals but nobody used them, just used like scooters, and they had a BIG battery in a large rectangular-section tube under the seat; I think thieves broke the lock at first, and that was improved, and then they just showed up with Sawzalls and cut through the aluminum below the seat, to steal the battery. I saw 4 bikes lined up, all 4 cut. Since then, those bikes have disappeared. There's still e-rentals, but the batteries are different, I haven't seen cuttings, and I would bet they have the same countermeasures as you mentioned. Lots of little-wheel e-scooters now too.

I think it may have been CAN bus that allowed a brand of asian car here, for thieves to yank a cable at the headlights and tie into the bus to unlock and start the car.

Yes, CAN is not safe enough and can be hacked.

Therefore, Bosch used another interconnect bus for the Smart System that provides several theft protections.

Now, if thieves put the bike in some enclosure that cut the tracking, they can still make the bike disappear but the ebike components will be unusable.

First gen rental bikes in Seattle, among them, Uber Jump (very heavily built, fork more like a motorcycle) were seen with rear wheel lock cut, I'm sure GPS disabled, and rattle-can painted, used by homeless folks. I saw an unpainted one halfway down a ravine, called them, it never got picked up, as shortly after they went electric, and the non-electric ones evidently meant nothing to them. Bigger issue in recent years has been bike theft in general. But the e-rental bike and scooter program seems to be very successful. They have frequent servicing for battery and relocation, so I would bet that if GPS suddenly went offline, if they are smart, the system immediately alerts and their field folks are dispatched to the location pronto. I know they are geo-fenced because I'll see a group of them at the "border".

Just an FYI: Dahon got the idea of the seatpost battery from the Qualisports folding bike... I had one, and it was FANTASTIC!!!

Thanks. Never heard of'em, just looked. Nice. However I think your E20 is superior, it has a full rear triangle instead of rear monostays, I think especially important in aluminum, and mid-drive instead of hub motors. That was a deal and a half. Lithium batteries are pretty durable these days, but if you ever need to replace them, I'm sure you can find something suitable. It would be great if Qualisports uses the same diameter seatpost, and battery voltage, and sells that as a replacement part.

The Qualisports ebike was more solidly built, had a 48v battery (Dahon is a 36v), more range (higher capacity), and could easily hit around 28 MPH while pedaling (throttle was up to 20 MPH) after I replaced the rear cassette. The Dahon is mid drive (it's good, but not all it's cracked up to be), lighter, and definitely folds smaller. I could also swap parts and use an IGH if I decided to go that route. Battery wise, they have a replacement seatpost battery available now, but the damn thing is currently "on sale" for $609. And it's not easy to just open up the seatpost (afaik) and just swap out the batteries. I've, honestly, moved back to riding solely human-powered bikes at this stage. I'd just rather get the work in, than have to deal with the constant need of worrying about electrical/electronic componants.

Yeah that's a lot for that battery, considering what you paid for the whole bike! For what Dahon is currently asking on it, you should be able to get your money back if you sell it, at least if there is demand on the Dahon; There's a lot of competition, including the (name escapes me) electric with the Pinion mid transmission.

A mid drive will typically have a smaller motor than hub motor, because it can use the bike transmission, so I would not doubt if the E20 is a bit weak accel in the higher gears.

IGH on a mid-drive electric, you'd want to check the torque limit rating of the hub before doing that, this was a discussion on another thread. Unfortunately, some manuals just say, "Don't run a small chainring", rather than give an actual torque value. However, most ratings are with large wheels; Smaller wheels means less torque for the same ground thrust, so that would be in your favor.