K2 Retired

Over this winter I dismantled my K2, having travelled well over 3,000 miles on it in all sorts of conditions. Unfortunately the forces generated by the weight of the battery on the rear suspension main bushing (where it connects to the frame) caused it to become unsettlingly loose. I deemed the bike unsafe to ride further. If my route to work had been a bit more smooth with fewer potholes, I imagine I could have travelled many more miles on this setup. I am currently deciding what I would like to do with the parts for my next project, as everything from the battery to the motor and controller are still working great.

Still going strong with a new rack

The Ping duct tape battery is still performing well after 2526 miles and 221 cycles. I have found the bike is a little bit slower (voltage sag) if the battery is very cold (below freezing out), but I think this occurs with many types of battery. The rough roads that I take to work have destroyed two previous aluminum rear racks, which made me decide to go for home-brew tubular steel and all-thread. This homemade rack has worked out much better than either of the other commercial racks that failed previously. The battery is also much more stable with a lower center of gravity.

Since completing my ebike I have used it to travel 1364 miles to date, mostly from using it instead of my car for my work commute.  Here is the bike as it stands today.  A couple tweaks I made were to attach the battery permanently to the rack, as the quick release system I had before was too annoying with its rattling.  The battery is now bolted to a piece of aluminium, which is attached to the tubular frame of the rear rack with 8 insulated metal cable holders.  Zoom in on the pic above to see this.  In the dark I used a pair of high power LED flashlights with handlebar mounts, though I am now down to a single light as one fell off and no longer functions correctly.  I also added a convex mirror and Superflash rear light for safety.

My biggest issue for a long time was that of flat tires.  The torque on the rear tire seems to drive any pointy object it comes into contact with right into the tube.  What seems to work for the most part are the kevlar fabric liners from Panasport.  Since installing them I have had only one flat, which came from an a very thin piece of glass which worked its way through the fabric over time.  It looks like I will have to get a new rear time sometime soon though, as it is pretty worn down and full of penetrations (the front is still like new).

The main ebike components appear to be holding up pretty well, though I did experience the common stripping of the axle threads on the Crystalyte motor.  I used a 14mm die to clean up the axles (slightly smaller than original I believe) and added a new pair of big 14mm locking nuts to repair this issue.  I also found my Cycle Anyalyst screen filled up with water during heavy rain, making it hard to read.  Taking the unit apart and resealing the screen with silicone appears to have solved this issue.

My First Ebike Ride

I took my first ride on the electric K2 today, Memorial Day. I was able to ride to my work and back at top speed without charging (about 20 miles), and had significant life left in the battery. Overall I am pleased with how the bike turned out. My main gripe is that there is too much weight on the rear, and so the bike does not handle as well as is could if the weight was more evenly distributed.

The above photo of the bike charging in my garage was taken a few days later. The charger is on top of the battery. Note the Kill-a-Watt energy meter the charger is plugged into. I was interested to know how much (or little rather) it was costing me to commute to work now.

Installation: Making it all Fit

While waiting for the new charger I've installed the rest of the electric components on the K2. Most of this work was fairly straightforward and quick. I found velcro ties to be the best wire securing device, as they are easily moved and will not pinch the wire like a zip tie might. As expected, the axle of the motor was slightly too wide for the dropouts on my bike. I mostly just needed to sand down a little beyond the thickness of the paint inside the dropouts to arrive at a smooth but snug fit. The only issue I've found is that when shifted to the tallest gear, the derailleur hits the motor case side. I don't really plan to use this gear much, if at all, so for the time being I will leave it as-is. If I wish to fix it ebikes.ca said they will send me an additional spacer.
I had originally thought that I would place the controller inside a waterproof pannier as I plan to use the bike in all weather conditions, and the controller is not waterproof. On further thought this did not seem like a good idea as the controller needs to dissipate a significant amount of heat. I ended up mounting it to the side of the rear rack with the cables exiting downward (with a drip loop). I also dismantled and applied silicone to the joints of the controller, as recommended by ebikes.ca.

Charger error

Eager to get my ebike charged to be able to try out the next day, I ended up soldering the connections to the charger last night in the wee hours of the morning. I managed to wire the connector on my battery box with the polarity backwards. When I connected the charger to the box, I heard an unpleasant pop sound and immediately knew I had screwed something up. I sent an email to Ping, and he responded later with a reassuring "Don't worry, we will help you solve the problem". Ping helped diagnose the problem as being the charger and said he would send me a new one, no charge, even though I explicitly said I had caused the fault. My experience with Ping as an eBay seller so far has been outstanding.

A Home for a Battery: The Case

Since my LiFePo4 battery is made up of what are known as prismatic cells, essentially foil packets which are bound together with duct tape, sturdy protection is essential. I chose to go with a pre-made plastic case designed to protect sensitive instruments rather than make my own, as this seemed the easiest route to ensure waterproofness. The case is by Pelican and is the 1300 size. This model of case seems to fit the battery perfectly, but note that Ping can make your battery into any shape or size you want if you ask. I used a waterproof cable gland to make the transition through the wall for the power cable. I used the connector provided with the charger to charge separately. A highly recommend getting a crimper designed specifically to crimp the Anderson Powerpole connector, as this provides a perfect, professional crimp every time. Though it cost nearly $50, I think this is worth it for the ease of use alone, not to mention reliable connections.