OutbackHack's Cannondale Hardtail 29er build

[outbackhack]

First ebike build, just throwing some pictures up here to document my progress.

Specs so far for version 1.0
Bike: Cannondale hardtail 29er with Thudbuster seatpost to take the edge off.
Tires: Michelin Pilot Sport 700x35 front & 26x2.3 rear
Motor: HS3540 in a 26" rim
Controller: Infineon 100V 40A
Battery: Ping 48V x 20AH
Throttle: Half-twist w/ regen button
Brakes: Avid hydraulic 160mm front, mech 140mm rear
Drivetrain: 1 x 7 gearing, 54t front x 11-32t rear

 

[outbackhack]

Had to up the gearing so I could pedal at 30+mph. Couldn't find a suitable 4 bolt chainring or 5 bolt crankset that was both compatible with my bottom bracket and/or would clear the wide mountain bike chainstays. So I went with this accident waiting to happen. It's held up for 200 miles so far with no visible signs of loosening or fatigue, plan to keep a close eye on it though.

 

[outbackhack]

Rolled over 700 miles today and started hearing a new sound coming from the rear wheel. Didn't see anything wrong at first, and just assumed it was the rear brake rotor making more noise that usual. 30 miles later I make it home and take a closer look to find 3 broken spokes. Each one spaced ~90 degrees apart.



I do have 20lbs of battery on the rear rack, but my commute is also almost entirely well paved streets & paths, which I guess is why the spokes made it this far. Guess I'll have to rebuild the wheel sooner than I hoped with a better rim and spokes. Plus I'll have to get serious about improving the weight distribution and move at least half of the battery to the front frame triangle.

 

[outbackhack]

Data from the first 33 cycles of my Ping battery. Pleased to see wh/mile averaging only 29.7 vs the ebike.ca simulator which put it over 40.

 

[GCinDC]

sorry to hear about your spokes. mine started w/ one and quickly multiplied. stop riding if you can, to save the rest. i replaced a bunch w/ JRH 13/14's which were fine, but i'm going to use washers at the end for now on. as in, from here:

 

[outbackhack]

Rebuilt the rear wheel with 13/14g spokes w/ washers and an Alex Supra-D welded downhill rim. Hopefully it proves to be stronger than the stock one.

Also made a frame mounted battery holder to move the 22lb battery from the rear rack to the front triangle. Riveted & epoxied together, hopefully it'll hold the 2-piece battery in place surrounded by 1/2 closed-cell foam padding. 3 quick-release straps hold it in place on the bike, then when I remove it to bring inside to charge, a shoulder strap clips in to 2 holes along the top.

Wasn't able to make the BMS fit along with the battery, so I'm planning to rely on the CA to handle low voltage cutoff while riding and then hook up the BMS along with the charger to balance the pack every evening. Hoping it won't be a problem since my average commute only burns up 12-15ah out of 20 available.

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[outbackhack]

Putting the wraps on version 2.0
Based on an older Kona Kikapu 26" FS frame that will hopefully handle the rough bike trails around here that were tough on my hardtail. Also reconfigured the Ping battery & mount so that the whole thing setup is only 4" at it's widest point, down from 6", so pedaling should be a bit more comfortable than the previous setup.

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