Folding 27.5+ wheel frame for 12s 1kw ebike

[Teslafly]

The time has come to build myself an Ebike.
With a monster hill on campus when I'm at school, a 4 mile commute to work during the summer (reasonably flat & bikeable, but leaves you fairly winded), and a slight amount of inspiration coming from the Moar kickstarter, the time has finally come to build myself an ebike where my current road bike is not cutting it anymore. (I should note, that I ride on campus year round, that means facing Wisconsin winters and all the fun that comes from icy hazards)
I have compiled a list of wants, and am currently looking at bits and pieces to get me there.
The two that are giving me the most trouble are the base bike, and to a lesser extent, the motor/controller.

Total budget: somewhere around $1200 max
Max speed: about 20-25mph, 1kw power level.
Rider weight: 180lb, probably 200lb with cargo.

Base bike frame:
Looking for a folding mountain bike with at least front suspension.
Budget: about $600, but flexible to reach a good frame. Less is better though.

Must:
- Brakes: ideally comes with disk brakes, but must have mounts for disk brakes, I am not opposed to installing later.
- Folding: Do not have to remove wheels to reach reasonable compactness.
Only has to fold so it can fit in my trunk/dorm room without hassle (my current bike needs both wheels
So a mid frame joint and releasable handlebars (so they flip 90 degrees to be parallel with the front wheel) would be optimal.

Want:
- Tires: would like to use 27.5+ sized tires (27.5 X 3.0) or (27.5 x 2.8), but recognize there may not be many good folding bikes that can support these wheels yet.
- Rear suspension: as someone who has never owned a bike with rear suspension, is this really necessary? How would a rear hub motor effect this? Especially with 27.5+ tires with more cushion?

Durability:
- Ride year round, in rain, snow, etc. (sidewalks/roads are cleared)
- Brakes / motor should handle a 1/4 mile long hill with [strike]30% grade[/strike]. Edit: I actually took a rough measurement, and it's more like a 10-15% grade at a bit over 5 degrees inclination.

Current options:
- Montague paratrooper: https://www.amazon.com/Montague-Paratrooper-Mountain-Safecastle-Stainless/dp/B01KYERXA6(wheels not + sized, expensive, handlebars don't release)
- http://usa.dahon.com/bikes/matrix/ (26" wheels, complex folding mechanism)
- https://www.amazon.com/Altruism-Bic...4396732&sr=8-8&keywords=folding+mountain+bike (good folding, small/weird wheels)
- https://www.aliexpress.com/item/20-26inch-folding-mountain-bike-21-speed-double-disc-brakes-bicycle-6-knife-wheel-and-3/32803888685.html?spm=2114.01010208.3.3.qYsvjT&ws_ab_test=searchweb0_0,searchweb201602_2...lgo_pvid=f6d7b619-375e-4f32-b599-57aa17d50ff2 (good folding, possibly low quality)
- Please suggest more

If a folding bike with 27.5+ wheels cannot be found, or even one with 26x3.0 wheels, that will be the requirement that is dropped.

Power system
- motor: ~1000w. Thinking rear hub motor.
○ Looking for suggestions on the motor / controller
○ Around $300 expected here
○ Have not put much effort into this so far as I don't have a selected frame.
○ Basically this: http://www.ebay.com/itm/48V1000W-26-Rear-Wheel-Electric-Bicycle-Motor-Kit-E-Bike-Cycling-Hub-Conversion-/231520160623?hash=item35e7ad4b6f:g:keUAAOSw4A5YrQJE
○ Not opposed to lacing on the rim myself if there are no motors that come ready for 27.5+ tires

- Battery: 12s/48v, ~16ah hobby battery. Thinking 2x 6s 16ah multistars if I can get them on sale. (around $90 each on sale)
○ Have similar battery on my power racing series cart.
○ Finally have a good test bed for my bms project. https://endless-sphere.com/forums/viewtopic.php?f=14&t=63863

- Monitoring:
○ Custom bms
○ Cycleanalyst / custom diy solution. - only really need battery level, current power, and speed

I have access to a makerspace with all the standards, mig/tig welding, 3d printer, laser cutter, etc. so I am capable of fabricating simple high cost/custom components.

So these are my design parameters. Are there bike frames or motor systems that would meet this?
Are any of my parameters a plainly bad idea or misguided?

 

[tln]

A mid drive will handle that hill better than a hub motor. If you can stretch that part of the budget for a bbs02, I think you'll be happier.

The multistars are a fine choice, I actually recently ordered an extra pair of 16ah 6s when it went on sale. Waiting for a sale is the worst part!

For bbs02 you could consider 10ah or 12ah multistars and save $ and lbs. Bbs02 pulls 26a, multistars should max at 2.5C

Looking for a folder that works without removing the wheels is a good idea for convenience.

I'm curious, why you are interested in the bigger wheels? What do you expect to be rolling over?

 

[Teslafly]

While I have investigated mid drives, and they definitely have a better torque option, there are a couple of things I don't like:

- loss of regen
- integrated controller (I eventually want to design / experiment with my own brushless controller)
- higher cost
- more complex and higher wear.

I can usually get up to at least 10mph at the bottom of the big hill, and can maintain speed most of the way up while
pedaling, so maintaining enough speed for a hub motor shouldn't be too much of an issue.

As for the large wheels, I do ride year round through wisconsin winters. and while I haven't taken a spill yet (on a road bike no less), I have tried out some bikes with wider wheels and quite like them. you can even ride on top of some snow /ice where it hasn't been cleared. off path mud is also less of an issue.
Measuring the forks of several mountain bikes and the installed wheel width of a 26.0x2.8 tire, it's about 2.5", and the clearance in the front forks (with suspension) is 3", and rear forks vary from 2.6 to 4" at the wheel, but the rear wheel mat be offset to make room for the cassette. so it may be possible to get a folding 26" bike and retrofit wider wheels onto it, but clearance would be small.

I would be happy with a 26"x2.8 wheel if there exist folding bikes with such. which is my main problem.

 

[tln]

Can't vouch for it, but it popped up during a search...

http://www.lightinthebox.com/21-spe...tJhspn1GsulemRPFsfutlv2LIK2_Un4b3VhoC7tHw_wcB

 

[ScooterMan101]

" motor should handle a 1/4 mile long hill with 30% grade. Edit: I actually took a rough measurement, and it's more like a 10-15% grade at a bit over 5 degrees inclination. "

With what he has stated , Teslafly does not need a mid drive with such a short 1/4 mile long hill that is 10-15 % grade.

My 2013 vintage Mac 6 T rear hub motor easily does that and more, and Note I have the 6 T ... a 10 or 12 T Mac will do all you want , and more, go up longer climbs .
The new Mac's ( 2016 year to present ) also have a way, when combined to the newest Cycle Analyst V 3 , to shut off the motor before it gets too hot .

Telsafly ,

You can do all you want with the Mens version of the bike I have and converted ( I have the Womans , DiamondBack called the Lux ) . to stay within your budget ( you will have to forget about a folding bike they are just too expensive at least any that you would want / be satisfied with . ) , just do not do all the upgrades to the Brakes/Shifters/Cranks/BB/Suspension Seatpost, etc that I did,
Meaning keep the bike stock, get the Mac Motor that accepts cassettes.

It is easy to take off the front wheel of a bike and turn the handle bars sideways.
You can also stand up the bike , on the back wheel with the front wheel to the wall of your room by using a hook , your bike will take up very little space that way, you can even make a platform on the floor with enough height for storage of shoes, etc. .

You can see my conversion here ...
viewtopic.php?f=3&t=71378&p=1077497&hilit=my+first+build+scooterman101#p1077497

 

[Chalo]

In almost every case, regenerative braking costs a bicycle more than it gives back. Regen is a better deal for very high powered bikes that are never pedaled than it is for light, efficient bikes with functional pedals. Real bicycles benefit much more from coasting than from regen.

Being able to use the bicycle's gears with motor power means less motor will climb steeper hills than an equivalent weight of hub motor, and it will do it with a smaller cheaper battery.

Also, large wheels such as 27.5+ put hub motors at a disadvantage by reducing thrust and decreasing efficiency. That's a faddish wheel size that is outperformed by 26" in some regards and by 29" in others. It has no advantages over both, unless you're the one selling it--because it costs more than the same thing in the other sizes. Hub motor bikes are better off with 26" or even 24" wheels, and mid drive bikes are better off with 700C/29" wheels if the rider is tall enough to fit them.

 

[ScooterMan101]

To add to what Chalo is saying,

Since most bikes being sold these days are in fact 27.5 wheel bikes, ( unless you get a small bike that will come with 26 inch wheels , or a large bike in which case it will come with 29 inch wheels ) , you should be building up your hub motor into a rim anyway. ( cheaper shipping costs and you can chose a better quality rim and spokes )

Just get a 26 inch rim , and lace your hub motor into it , it will hardly be noticeable in looks, but will give you that little extra torque for going up hills. ( no need for a 24 inch for the hill you describe, )
But really , unless you are going to be moving to a different location with hills/mountains a Mac 10 t in a 26 inch rim or Mac 12 t in a 27.5 rim will do just fine since they are higher torque motors .

You can save your stock wheel for when you sell your bike with or without the electronic's .
Also
Once you get a bike that is 27.5 with plus size wheels ( 27.5 + ) you will not need suspension there is suspension in the tire, a Thudbuster Seat Post will then be fine ... if needed at all .

 

[markz]

Find a used Montague, but those are 26" I have never seen a 27.5" folder. I havent seen many Montague's for sale in the used section. You can buy a new Montague frame for $800CAD from a dealer. Whole bikes are $1500CAD. So could only really assume a used one they'd want $500 or $600 for them.

I think what I am going to do myself, because I need a comfortable daily cruiser that folds because the situation with the buses is its very hit and miss if one bus out of 6 routes or 12-15 buses (during rush hour) for a 30 minute period, would have a bike rack. It quite pissed me off today, with the numbers I just stated. They can spend millions of stupid bike lanes in the downtown core, but bike racks on city buses no no. BC Transit has bike racks on every single bus in the entire province, even the small buses. It quite pisses me off.

I am thinking of just building one myself, you may consider it yourself. I know of a place I can rent a welder if my idea holds any fruit.

1st Method - I take two bicycles that I want to ride, all they need to be is same wheel size. Cut one bike in front of the seat tube so you have a back half of a bicycle. Then take the second bike and cut it in the back of the seat tube so then you have the front half of a bike. Then figure out a decent connection method. The bikes would need to be steel. The connection method I am thinking of is just welding on some flat bar and a simple bolt of action. This is the simplest solution from my ponderings, may not be the lightest weight solution, but how much extra weight can a couple 1.5"-2" flat bar of 1/4" thick weigh?

2nd Method (More complex) - Use one bicycle, cut it right in the middle, then slip in some metal tubes inside the bike tubes, and slip some metal tubes over the outside of the bike tubes to sandwich the bicycle tubes together. The problem that pops up is not so much the connection method, a simple bolt through all 3 layers of tubing, but more on how do you line those holes up, and how do you slide the tubes that go on the inside of the bicycle tube so the holes do line up. I got some funky idea's on how to easily move the tube, its the lining up of the holes thats a problem. Thats why I think #1 Method is the best solution.

I haven't quite decided the route I want to take, plus I have been very hesitant because I do not have a welder. But what I think I will be doing, is starting off with a battery welder which is simply connecting batteries up to make 30V or 36V and using batteries of such discharge capacity to get 100A or 125A or whatever you require for the rod you will be using.


But going electric with the folder/bolter weight of the flat bar wouldnt matter much. Its more of a matter of how compact can I get a 26" folder/bolter to be without being too big to take on the bus. Fuckit man, strollers can go on, old peoples walkers, grocery carts, but not regular bicycles that dont fold.

 

[melodious]

Before discovering electric assist, I extensively used public transport to get around. Bringing a bicycle (even a folding bike) inside a bus would be against most company's protocol; even more so, since media have reported random battery fires. You could be lucky and gamble for a nice driver who will bend the rules, but that's still not a guaranteed ride.

Sorry if I'm going off the original topic. Get a middrive if you ride off-road & steep hills. Go hub drive (on a dual suspension bike) if you want speeds above 30mph.

 

[motomech]

My 2 cents- If you are really going to ride in a Wis. winter, I would wager you will have to go w/ mittens at some point and that means hub motor. Even w/gloves, you do not want to be shifting gears.
As I really don't see your budget allowing for all the "one off" things you want to do, you might want to look at the lesser expensive BPM options @ BMS Battery. The only thing it doesn't have vs. the more expensive Large Geared motors, , like the MAC, BMC and the Ezee, is that it lacks dedicated axle seals, which would be nice for severe weather. None the less, if you dis-assemble and clean the BPM each Spring, it should last a while. A low-speed (201 rpm @ 36 V) in a 27.5 whl would yeild 22 MPH on 12S(46V). Fast enough to be fun.
Fatter tires are not necessarly better in snow and ice. Sometimes it's better to have a skinny tire that "knifes" thru to the frozen surface. Studded tires would be best, but there is the real danger of wet pavement.

Battery: 12s/48v, ~16ah hobby battery. Thinking 2x 6s 16ah multistars if I can get them on sale. (around $90 each on sale)....
...○ Custom bms
○ Cycleanalyst / custom diy solution. - only really need battery level, current power, and speed

While I understand your desire to add your "touches", a BMS is not needed. The beauty of the MultiStar and the large brick capacity they offer, is a low brick count system and the ease in which the pack can be bulk charged;



Above is a Mean Well HLG LED power supply w/ 2 Battery Medics. I charge my 2S/2P(46V/20Ah) pack within 2 hr.s and very rarely have to balance, just check;



The key to using LiPoly on an Ebike is having a good LVC and most 48V controllers have a 42V LVC. which works out to 3.65 V Cell/avg. w/ 12S, perfect.

I started out w/ a Cycle Analyst(years ago when they cost a lot more than they do today) and while it was a good learning tool, I perfer the minimalist approach these days. W/ the controller handling the LVC, all I need is a Voltmeter and a way to control speed-limiting w/ the PAS. LiPoly is very linear in the way it discharges and Volts alone make a good "fuel gauge". Besides, w/ a 16Ah pack, range should not be a concern(expect 1 1/2 to 2 miles per Ah). I only mention this because the little things in the build, like connectors, wire, balance extensions, a DNP free wheel, a bigger chain ring, torque arms, etc. add up quickly and you mightg have to trim some of your proposed items or increase your budget.
Gd. luck.