Author Topic: Internal Hub electric bike - DIY or buy?  (Read 1107 times)

Carless

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Internal Hub electric bike - DIY or buy?
« on: August 18, 2018, 08:01:43 PM »
Hello all, I'm looking to put together my 'dream bike'.  I want an electric bike that has an internal hub (I have a grudge against deraileurs) and a step through frame.  Combine this with a desire for disk brakes, and nothing I've seen pre-built seems to cut it.  But from there I go down a rabbit hole of frame materials and parts selection that seems to turn into a major project.  Any tips on good places to get started (i.e. starting frame or e-kit)? 

In general, I'm looking for something that will last and be reliable with a minimum of maintenance.  I need a frame that can take a load, a cargo trailer, and a pothole-pounding without any problem, year after year.  I also need something that works well as a regular bike: the idea is that I'll do at least half of the work.  Ideally, I'd be able to lift this thing onto the bus' bike carrier as well.

  • Range: Minimum 20 km
  • Speed: Minimum 25 km/h
  • Internal hub
  • Step through frame
  • Disk brakes
  • battery powered lights, front and rear

AccidentialMustache

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Re: Internal Hub electric bike - DIY or buy?
« Reply #1 on: August 18, 2018, 09:10:27 PM »
Heavy frame (even without being extended to be a true cargo bike) plus higher watt motor to move that weight and higher cap battery to feed the motor doesn't lend itself to going on a bus rack. I have a rad wagon and while I dig it, I wouldn't (probably couldn't, suspect it'd pass the weight limit on the bus bike rack) try to rack it on a bus. Carrying it up and down the stairs at work is right out (too narrow to maneuver an xlong bike, I don't want to be painted in dirt).

I feel like some of the recent folding bike reviews at electric bike review might have met all but the cargo bike / heavy cargo parts you have. You'll want to look for lower-watt mid-mount motors, likely geared. You'll have to trust your hub downshifting to let the electric motor help you up hills.

Carless

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Re: Internal Hub electric bike - DIY or buy?
« Reply #2 on: August 19, 2018, 06:41:50 PM »
The issue with folding bikes is that the small wheels cause problems and make the bike harder to use.  After spending a lot of time looking into it, I think the best way to go is a Bosch bottom-bracket mount bike frame, with custom selected additions to meet my preferences.  That'll give me a bike with lower weight as I don't need a huge motor or battery for assistance - I'm looking at ~50% pedal assist, mainly on hills.

There sure are some slick systems out there though.

Carless

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Re: Internal Hub electric bike - DIY or buy?
« Reply #3 on: August 23, 2018, 10:59:48 AM »
Changed my mind again due to more information about electric bikes.  I decided I'd start a list of required bike parts and underlying logic, which may prove useful to someone else going through the same process.
Goal: a lightweight but very robust e-bike for commuting with high reliability, good cargo capacity, and enough range to help me over those hills. 


Bike electrical

Hub Motor (vs Mid drive): you might get lower bang per the same motor power, but thereís a wider selection of hubs, it never needs a special bike frame,  hubs can be pretty subtle, and tend to be more robust.  If I need a replacement 10 years out, itíll be trivial to swap a hub motor.  With a mid-drive, it might be difficult to replace.

Front hub (instead of rear): improved weight balance, compatible with any gear choice, easy to switch out.  Downside: Limited traction for high power (>1500 watts) or loose gravel roads, neither of which are issues for me:

Geared instead of Direct drive: I want a freewheeling clutch to allow me to coast down hills.  Iím fine sacrificing regenerative braking for it.  Also geared motors are smaller in diameter (less chance people will notice it) and slightly lighter, for which I sacrifice some robustness (direct drive motors have fewer moving parts).

Possible models: Bafang G01 and G310 or eZee.

Motor sensors: Torque sensor to allow for more natural ride, eliminating issues with moving the pedal while dismounted.  Makes it less necessary to have motor cut-out from brake signal.

Battery: Needs to have enough excess capacity to be sufficient at 80% charge, and also allow for gradual capacity loss over time.  Expected life 4-5 years hopefully.  Should be a common connection type to allow for replacement later.

Battery charger: should be able to charge to 80%, which extends battery life dramatically

Motor controller

Motor readout: Speedometer, Odometer, Battery Level and assist level should all be included.

Bike lights: Front and rear, integrated with battery, well fixed to bike or easily removable.

Bike horn?

Bike
Frame: Prefer steel to aluminum.  More robust, can be lighter if a good alloy used.

Wheel covers: Side covering or only top?

Wheels/spokes/rim/tires:
Chain/guard:
Brakes
IGH: Sealed.
Carrier/basket
Kickstand: two legged
Security/locks
Drink holder
Pedals

Handlebar lock: collar or spring based.  Sick of the handlebars flopping around and grabbing onto me while trying to chain the thing up.

Handlebar grips: Not rubber.  Sick of having sticky disintegrating grips.  Maybe cork or leather?

CatamaranSailor

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Re: Internal Hub electric bike - DIY or buy?
« Reply #4 on: August 25, 2018, 09:24:46 AM »
So...I purchased basically the complete opposite of what you described in your earlier post.

Mine is an aluminum frame, mid drive mountain bike (hard tail) manufactured by Haibike. 500 watt motor, Yamaha drive system and battery. I've had it a year on trails (gravel and rocks...not hard core downhill MB stuff), roads, mix and match. I've commuted to work on it, ridden it all kinds of weather. I'm not a little guy and it moves me around just fine. I can get 50 miles in "Eco" mode. Probably 20-25 in "Boost" mode.

It's worked out great. I paid $1,300 for it, including shipping. It was formally part of a rental fleet from a bike shop across the state. I knew I was taking a chance when I bought it but I was thrilled when I got it and saw the battery had less than a hundred charge cycles on it.

It was probably the best purchase I've made in the last 5 years.

Carless

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Re: Internal Hub electric bike - DIY or buy?
« Reply #5 on: August 31, 2018, 10:20:21 PM »
Boy, is this looking like it's going to be a lot more money.  The combination of chrome alloy frame + step through+ internal gearing is three unpopular choices.  The only electric bike pre-set with these is the faraday, but I've decided I want more flexibility in terms of components (eg I want a battery that I can easily swap out, more choices for lights etc)  The base bike looks like it'll be 2k, and the electric parts another 2k. 

If I just wanted an e-bike it would be a lot simpler, but I want something that really handles like a normal bike and will be good for a long long time.  When you compare it to a car, it still looks cheap.  Compared to the bus...not so much.  I'm going to be paranoid about keeping it safe...

Carless

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Re: Internal Hub electric bike - DIY or buy?
« Reply #6 on: January 14, 2019, 08:45:42 PM »
So I've now purchased (almost) all of the parts, and thought I would report on the build process and what I've learned along the way.  At the end, I'll list all the prices.  Obviously I decided to DIY, one of the advantages being that at the end I should be intimately familiar with all the maintenance of the new bike, and in possession of all the required tools.

First is the bike itself: a Linus Dutchie 8.  This is a chromoly frame bike with a step through and an 8 speed Shimano internal gear hub.  I forwent the disk brakes, as they're not super necessary, hard to get, and not something I'm familiar with maintaining.  I love the new bike all on it's own, the ride is very smooth.  However, one issue was the low clearance between the rear wheel and the fender.  Even with the stock tire, you have to deflate the rear tube in order to remove the wheel, which is poor design.  When I swapped out the tire for a Marathon plus (removed from my old ride) there was contact.  I had to shift the front-most mounting point (I swapped it to the far side of the attaching bracket) and replace the rear fender wire with one that was slightly longer - I was lucky enough to have this on hand.

In general I'm quite pleased with the bike.  I love the feel of the ride, the glide, and the gears.  I've mounted a large basket on the back (see attached image), but that's not where the battery's going to go- it's for daily work luggage.
« Last Edit: January 14, 2019, 08:59:00 PM by Carless »

Carless

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Re: Internal Hub electric bike - DIY or buy?
« Reply #7 on: January 14, 2019, 09:26:25 PM »
Installing the electric motor:
I purchased a front motor (G311 as part of the advanced pedal-assist kit more on that later).  I elected for the front motor as it has the advantages of ease of installation and better weight distribution.  Rear motors can be better if you're planning on doing a lot of gravel hills, but I'm not.  Mid-drive motors are harder to retrofit.  Also, in the unlikely case that something happens to the chain, I'll still be mobile.  I picked this particular motor because it's small and relatively inconspicuous.  It's at the lower end of the power range but I want assist and not a motorbike, so that's fine.  It's a geared hub which makes it a bit smaller than a direct drive motor.  Geared hubs don't allow for regenerative braking, but i'm not interested in that.  The Bafang motors are quiet and have a reputation for being very robust and are correspondingly popular.

I purchased the motor laced onto a wheel, and you can see it in the as-shipped state in the first picture.

Tools: 10 mm Hex key, small flat file, wrench, tube, tires, and pump.

Step 0: remove the existing front wheel, and make sure the caliper brake jaws are open.
Step 1: put the inner tube and tire on.  Watch direction of rotation-  the tire and the motor need to match.  I used a Schwalbe Marathon plus here.
Step 2: This motor needs a 10 mm dropout.  Use the hex key to verify the dropouts are ready - as in my case there were some paint bulges that needed to be filed down.
Step 3:  The motor is provided with a tabbed anti-rotation nut (see second picture, looking up from beneath).  This goes inside the fork, with the tab at the open end of the dropout (for rear wheels these are generally put in the closed end of the dropout).  This motor has the wire coming out such that it is fed through the open end of the dropout, and thus the wire exit downwards before bending back to travel along the outside of the fork (as far as I can tell -doesn't seem like it would work the other way up).
Step 4: On the outside of the fork are a lock and regular washer, and a nut, these need to be tightened.  The solid axle for this motor is 3/8", so identical to my rear axle.
Step 5: Close the brake jaws to the working position, and check that the wheel spins freely.

The final picture shows the motor in place on the bike.