Kepler Super Commuter Mk2

Kepler

10 MW
Joined
Nov 8, 2009
Messages
3,922
Location
Eastern suburbs Melbourne Australia
Since completing the build on the Super Commuter, I have had quite a few requests from people to build a similar bike but at a more affordable price point. Although it is a kind "For Sale" thread, it is also a build log to share what I have done to build the bike in the first place and what is required so that anyone can use the information to build a similar platform if they wanted to.

The Super Commuter design has proven to be a fantastic high speed commuter that doesn't raise raise a second look out on the bike paths and gets to your destination in great comfort and without fuss.

So here is the build criteria.

> Build the bike on a strong 29er Mountain Bike platform
> Stick with an aluminium frame to keep costs down.
> Bike must have Hydro Disc Brakes.
> Bike must have reasonable front suspension fork.
> Bike must use a reasonably wide tires for comfort and small bump compliance.
> Bike must be fast (50kph sustainable) but user adjustable.
> Gear set needs to have a range wide enough to allow efficient cadence input all the way to the bikes maximum speed
> Bike needs to be light enough to pedal for long distance without assist.
> Bike needs to look like a bike and to blend in as much as possible.
> Bike electrical system needs to be water proof enough to withstand occasionally being caught out in a shower and still getting you home.
> Turn key bike needs to be affordable (Under $2K)
> Bike electrical system needs to be compatible with a wide range of voltages. (48V to 84V)
> Must be fitted with large screen Cycle Analyst to allow user definable limits to changed as required (Set to Aust legal limits)
> Pedal Assist option
> Prefered battery chemistry (but not limited too) will be LiPo due to its cost, weight, and performance. (Batteries not supplied with the bike)


So here is a little teaser picture of what the finish product will look like. (obviously missing the hub motor and wiring in this picture) Build pictures to come.

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Although this may look like to some that this is just fitting an ebike conversion kit to an existing bike, I can assure you it it is much more than this. Parts have been selected that I have personally tested over 1000's of km of riding with much of it being custom modified to my specifications. My aim is to build quality custom ebikes that still look and ride like bikes but outperform just about anything else out there.

The super Commuter opened up my eyes to what ebiking was really about. Keep it quiet, stealth and under the radar. Ride it like a push bike and enjoy the freedom to be able to mix it with the fastest bikes out their. I am surprised by the level of respect I get out there on this type of bike even mixing it with the fast lycras. Just yesterday was a perfect example with me latching onto a fast Lycra on the way to work. He was sitting 35kph to 40kph consistently. I stayed behind him for a while and he knew I there. Got an opportunity to pass him safely and took it up a notch (40kph to 45kph) Stuck with with this pace for the 5km. I had a feeling he would stay with me and as we came to slow selection, he pulled up beside me with a big smile on his face.

He says, "couldnt believe you passed me back there. No one ever passes me on these tracks" . I commented on his amazing pace and although I was puffing hard, i needed to put him out of his misery and point out that I had some assist. He was blown away. No comments about cheating, just totally impressed with the tech. Got going again and enjoyed the next 10kph flat out all the way to the city. His leaving comments were that it was the best ride to work he had ever had and thanked me for the draft.

This is obviously a geared hub motor based build however in a few weeks time, using the same frame, I will be building a 750W Bafang mid drive. Should be a very interesting comparison opportunity.
 
So with a suitable donar bike selected, time to gather components.

In this case, the customer wanted a bike that had a similar presents to my Super Commuter but will a bit more power on tap. He also was not interested in pedal assist and simply wanted a twist throttle for speed control.

A Bafang BPM Code 12 was selected for the bike and fitted up with a 9 speed cluster and mandatory torque arms.

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Next job was the speed controller. A trusty 6 FET Infineon board populated with 100V capable componentry was assembled complete with a custom loom to suit the bike lay out.

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This little controller will handle 3000W no problems and a voltage range of 40V to 85V in its current configuration. Current will be limited to 2000W via the controller software and further dialed down via the Cycle Analyst to keep overall consumption down and range up with the relatively small battery pack setup.

Customer has supplied 3 x Zippy compact 5800 mah 6S pack for a total of around 350Whrs usable. Should be good for 15km to 25km depending on speed and riding style.

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3 packs fit easily into a small handlebar bag with room to spare for tools and puncture repair kit or what ever.

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A custom series loom was then made using XT90 connectors.

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These are really nice plugs and a better option than bullet type plugs for connecting packs in series. Saves you suffering an embarrassing case of KFF (Kentucky Fried Fingers) that can happen with connecting packs with bullet plugs. :oops: ( The second picture is me. A trip to ER and 4 weeks of constant treatment)

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damn... Sorry to hear!
 
Kepler,

What position are you able to maintain on a 29er compared to the drop bar road bike the other biker likely had? At those speeds wind resistance is a factor.
 
This bike has been completed for a month now with the customer very pleased with his new toy.

A few shots of the completed bike. :mrgreen:
 

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Looks great! Could the controller have been placed in the bag also (assuming that there is room)? I assume it is the box right above the BB...

My controller always feels cool to the touch (and is mounted on the front of a rear rack). But I'd love to build a bike with the controller tucked away in a bag.
 
Thanks for that.

Yes, there probably would be room the controller in the bag if you wanted to mount it there. On a low power setup, temp would be fine but on 2000W setup like this one, I would prefer to keep the heatsink out in the open.
 
Hi Kepler,
Inspired by your earlier build I have attempted to go down as similar root. Picked up an old model brand new Kona dew hybrid (with hydraulic brakes and flat bar) for NZD 350 and mounted a small befang in the rear. The large topeak dry bag is perfect for 18650s. Went for 12s3p of LGD1 (48v 9ah) and there is still plenty of room for the controller. Power is only around 650w but enough for 35 -40kmph with minimal or no pedalling.
cheers matt
 

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good concept. But why a fork with so much travel? You don't need more than 60-80mm, and it won't soak up as much of your pedal energy if you stand.

I'm building my road ebike with a steel KHS 700c cyclocross frame with a tiny softail rear suspension. 60x11 top gear, 6t Mac in a 26" wheel, and 14s 5ah lipo to start. I will be approaching 45mph when hammering, with my roadie kit on. Bike weight should be 30lbs.
 
The fork is what comes with the donor bike so no real choice there on travel. I quite like having the travel though for a bit of xc riding as well as commuting.

Sounds like an intersting build you are doing. Look forward to the build log if you decide to do one.
 
Kepler said:
Thanks for that.

Yes, there probably would be room the controller in the bag if you wanted to mount it there. On a low power setup, temp would be fine but on 2000W setup like this one, I would prefer to keep the heatsink out in the open.

+1, I tried on my first outing with a new kit taking it easy this week, throttle only bursts in low power mode with usage 7Wh/km over 25km, while cool running on the outside, inside the bag with a zip open facing forward it still warms up after 25km.

I think the low rear black case bottle mount pickup controller on the example here is discrete, and fitting bottles would make it more-so, a cage coupler to raise it with shorter white bottle for instance.

Kepler do you have any video of ride-by's or out-of-wind rear mic pickup for a sense of motor noise with this motor and the assist engagement to max speed?
The new front Mac 8T I've started using this week is more noticable out front. I guess you can't have your cake and eat it too, freewheeling pedal efficiency and silence under max power like a direct drive.
 
Kepler do you have any video of ride-by's or out-of-wind rear mic pickup for a sense of motor noise with this motor and the assist engagement to max speed?

Sorry, no I don't. The Bafang BPM does have some whine especially under load and high speed. You hear it on the bike but riders around you don't notice unless you are over taking them under power.

The new front Mac 8T I've started using this week is more noticable out front. I guess you can't have your cake and eat it too, freewheeling pedal efficiency and silence under max power like a direct drive.

Actually there is. The new Bafang mid drive is as quiet as DD hub, maybe even quieter. About the same efficiency as geared hub so you can have your cake and eat too :) .
 
Keeping up with you is dangerous on fiscal health. I thought I glanced at you burning one out... R&D I am sure but will keep my head in the sand a bit before another kit, I haven't even completed last ride for this first week on new EM3EV kit. :lol:
 
No, I didn't burn one out, just stripped one down for a friend that had a stator failure. Looks like it was a manufacturing fault. Bafang replaced the stator under warranty. All good again.

Does get expensive trying new stuff all the time but I am not happy unless I have a build project going. Need to keep turning over stuff to finance the next project :)
 
Hi Kepler,

I was curious as to your choice of using the Bafang Motor for this build as opposed to say a MAC 10T or 12T?

I am looking to build a similar Stealth ebike for use in California, mostly for coastal bike path rides (50 - 60 kilometers round trip), but with a few fairly steep hills.
The motor would be primarily to assist me on the steeper hills and a bit help if tired at the end of the ride .

I like to pedal myself to a great extent for the exercise, and was thinking of using a Thun Torques sensor as opposed to a throttle. I suppose that I could use both.

I currently have a 350watt BH Emotion Bike and it does a nice job, but is somewhat underpowered and only moderately stealthy.

Any help or direction that you could provide would be greatly appreciated.

Thanks.

Best...Norb
 
Kepler, was testing an e-bike today with Bafang motor (labeled 8FUN)I think it was same as yours. It was geared and surprisingly, very quiet.
I was thinking of buying a MAC motor. My question is, you think that Mac have more noise?
 
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