Development of an electric folding bike
 

Hi,
I'm studying product design / industrial design and I am currently working on my master thesis. The topic is the development of an electric folding bike, using the bosh system with an intube battery.

To get to know the target group (I'm not sure if I find the target group here because of the "electric") and possible painpoints, I created an online survey which I am not allowed to post here yet, until I got 10 points.

I expect you "core" folding bike fans to be a little against the use of electric engines but maybe I am absolutely wrong.

If you want to help me, maybe you guys have an idea where I can post my survey to get as much information as possible.

I planned to post the survey in a couple of facebook groups with camping and glamping topics but to be honest I don't know where I can find the commuting people.

Thank you very much!

Folding bikes are one of the better bikes for adding electric assist since they tend to be used for transportation and not for sport.

That said, I wouldn't want a Bosch mid drive on my folding bike unless it's way lighter than any Bosch system I've seen on the market. Folding bikes are also meant to be picked up (it's why they fold) and most systems on the market are too heavy to make that comfortable.

I want something like an Ebikemotion X35 in a Birdy. I assume there's enough space in the oversized frame/seat tubes to fit the controller and batteries and a 13.7 kg / 30 lb folder is still a good weight for mixed mode transportation. Plus Birdys are conspicuously the only non-electric in R&M's lineup specifically because Muller thinks they'd be too heavy with the electric system.

Perhaps the e-bike forum would be a better place to post for demographic? The only folding bike I've seen (Lectric eBike) is heavy (75 lbs) and bulky. Kinda takes away the purpose of purchasing a folding bike. On the other hand, the max speed is 35 mph!

Thank you both for your replies. Getting insights in your thoughts is very important to me!

I wished I could post the survey to get your opinions counting as well. I would open a new post in the e-bike forum if I could put in the survey.

There is no way to post a link before I wrote 10 entrys without, right?

Maybe you know a Facebook group where I can get into contact with commuting people?

I already posted the survey in a camping group which seemed to be a good idea and I expect those to mainly be the target group of a heavy mid-motor folder.

Or you could do what everyone else does. Engage in conversations which interest you and thereby become a member of the community. In no time, you'll have ten posts and be able to include links in your comments.

Having just put an electric wheel (Geoorbital) on a folding bike (Montague Swissbike X50), I'll agree that weight is a serious consideration.

While I'm looking forward to riding to work, and am feeling confident enough that I'm not going to bother with a test ride, carrying the bike up to the second floor is going to be a bit more of an effort than before, exacerbated by the bike now being markedly front heavy.

Your design with the motor at the bottom bracket (if I'm thinking of the correct Bosch system) would help with that, as would the in-tube battery.

As a counter-point, I'd suggest looking at other folding ebikes such as the Montague with the Superpedestrian Wheel: https://www.montaguebikes.com/produc...lectric-bikes/ or with the Zehus Hub motor: Montague Electric Bikes - Boston ZE

https://cimg2.ibsrv.net/gimg/bikefor...734482126a.jpg

Montague Swissbike X50 with Geoorbital Wheel.

The Vektron is a Bosch mid-drive folder under 50 lbs, I believe. Just barely under 50 though. Taking into account the fairly large rack, I think you could get that even lighter. The battery integration into the tube seems like a real reach however, given the folding consideration.

hey Grayrest-

you've made some really interesting points there!

good luck with this Kiwi; as every year goes past; the opportunity for improvement on such a project increases bit by bit...

I have a folding bike and also ride an e-bike with the Bosch mid mounted motor.

You definitely don´t want to be using the Bosch MMM for a folding bike application, it´s just too bloody heavy.

Go with a hub motor and a sleek integrated battery. Have a look at the way Cube integrates the latest e bike batteries on the downtube of their E-MTB range.

If you use a smaller battery (200wH?) you could maybe fit it into the shorter downtube of a folder.

Best of luck.

If you've got a light weight folding bike, it doesn't make sense to me to make it heavy with an electric motor. You should check out the stuff on endless sphere for light home made drive systems. If you're aren't electrically handy (like me) you could consider something like the onemotor.co. I have one coming in a couple weeks for my very light bike friday pakiT. Even with the motor/controller/battery, my bike will still be only 24 lbs. I wouldn't recommend this system for someone who wants to use the motor all the time, or who wants a moped-type, but if you're looking for help on hills, help in headwinds, something you can fly with, and something you can quickly remove when you lock your bike, it is suitable. Even has a custom mount for bromptons!

about flying...its not possible to fly in any south american airline with eletrical assisted bike.

Can you fly with a laptop battery? The onemotor system fully detaches in seconds from the bike, so you fly with a normal bike. Then you have 130W/h batteries (one or more
depending on what range you need) with a handheld controller/motor under 5 lbs. With one battery, it is no more electrical power than a laptop and not even as big as a laptop.
Can you fly with turned off electrical tools? Because that's what it would look like.

its not about wheight, but for risk of fires, explosions or even terrorist plots.

the general rules here are:
for acid phumbum base bateries(wet batteryes), its not allowed in any case.
for li ion or ly po bateryes: only allowed up to 10.000 mah, cannot be dispatched.

wheelchair batteryes: not allowed with user, but company changes to a regular wheelchair and dispatch the motorized and a check in luggage

10,000mah is a lot more than 130W/h, nearly 4 times as big. The batteries on onemotor are lipo. So can they be flown? If not, you couldn't fly with a laptop either, yikes.

that conversion voltages wattages seems strange to me.
10.000mah is a wallet size power bank.
my cellphone have 5.000mah battey.
doesnt seems possible that any aletric assistrd bike have any battery smaller the a cellphone.
batteryes for bikes here have 30.000mah at least, with many going up 50.000mah.

That's because you are thinking of hub motor or mid drive systems. Onemotor is a friction drive - with battery the whole thing only weighs 4.5 pounds so a 130 W/h 42v battery will give about 10 miles full speed, up to 25 miles range using pedal assist mode and low assist. Carry extra small batteries isn't a big deal at about 2 pounds each, so extending range is easy. But this is NOT a system for someone who wants to not pedal or who wants a "motorcycle" type experience. It's for light weight bikes to help conquer hills and headwinds. It creates a bike with assist, not an electric motorcycle/moped you can pedal. Depends on what you want and need. Imo, why buy a super lightweight bike at extra cost if you are going to weigh it down with a heavy motor system? And picking up a folding e-bike, even to put in the trunk, with total weight of 40-60 lbs is certainly not an option for everyone. Depends on what you're looking for. But - if you want to fly - you have to keep the batteries (at least in USA airlines) under 160 W/h (~3800 mah).

oh, i didnt knew this tech.
:thumb:

This is one of the smaller motors one can buy for a DIY ebike and would add about 5 pounds. I put these in our folders. They weigh about 35 and 40 pounds.

https://cimg8.ibsrv.net/gimg/bikefor...61455c336b.jpg

Folders are now available with the battery in the seat tube.
https://cimg0.ibsrv.net/gimg/bikefor...ca998f1f2e.jpg


While the above bike is probably too heavy, there are other nodels that are lighter, so I think the OP could be a bit late to market, even if it is only a study.

I could buy 100 Watt-hour 36V2.8AH packs from Grin technologies. Basically ten 2800ma lithium cells in series. but quite modular. Two in parallel would be 200 watt-hours. My wife and I use between 6-8 wh/mile on a summer day going about 12 mph. One of these sticks could give us a 10 mile range. We don't use them though.

HyrdoFoilBike
 

Seeking an engineer and equity partner to create HydroFoil Electric Bike.

Brompton electric? We also have a company in the UK who do conversions for Moultons and Bromptons using those 18v powertool batteries.

And, of course, there's the Hummingbird electric. 10 kg in the electric version, something like 6.2 kilos in the standard version.
I saw one in the wild; gorgeous, and light. It's what U$S 6000.- will buy.

I keep reading of problems with Bosch e-bike motors which are exasperated by limiting spares availability to repair agents only and many of the parts are relatively short life including plastic/nylon gears. A small geared hub motor would seem a far better solution for a folding bike, some of those are tiny and the torque output of around 40Nm approx would be fine for the small wheels of a folding bike even for a heavier rider. One of the great things about using a hub motor on a small wheeled folding bike is it can work quite well with single gear folding bikes so you can reduce the complexity of the bike and save a fair bit of weight that helps compensate for the weight of the e-bike components. Also if the folding bike doesn't need a long range a smaller capacity battery is acceptable and you can even fully enclose the chain or use a belt for the drive. To be honest being the cheapskate I am any bike with a Bosch motor will instantly scare me away.

1) See Bike Friday

I commute 26miles daily on a Stromer (coming up on 15K miles); rain, snow ... so I've got some ideas about what works for me ;> A couple of days ago, we scored a pretty new Tern Vektron D8 for my son (it's a folder with the Bafang M400 .. pretty similar to the Bosch mid-drive). The battery isn't integrated into the frame; but like many Bosch powerpacks is somewhat integrated (as opposed to my Stromer, which is completely encased by the frame.

I don't particularly care that the battery is or isn't visible. Time will tell if being external is problematic in rain, but based on the tightness of it, and connections being well protected I'm cautiously optimistic that will not be a problem.

The Bafang battery is a bit harder to remove than the Stromer (although that could be a lack of attention by the previous owner); normally I remove batteries when transporting a bike by car; I had no trouble lifting the Vektron into my wife's car without removing the battery (it is heavy for a folder, but a lot less heavy than my Stromer).

Hard to judge based on my first 10mile ride; but I fear the original owner may have damaged the battery. We will have to see. My wife's Haibike has a similar Bosch system, and that comfortably does more than 30miles with assist at reasonable levels.

The Bafang is rated at 80nm of max assist.

The Tern rides nicely without assist; it's a bit more stable/easier to mount panniers to than my aged Dahon Speed P8. The headset is a bit more adjustable which is a nice touch. Unrelated to design issues, the factory warranty for frame and such is only good for the first purchaser which doesn't suggest a large amount of confidence from the factory ... but I can imagine that protects them from user abuse (previous owner(s) ;>).

If you want to PM me the link to your questionaire, I can provide my perspectives for your project Requirements.