Friday, July 3, 2015

Maxxis Holy Rollers

Installed new tires on my primary ebike: Maxxis Holy Roller 2.4". These things are awesome. The ride now feels (and sounds) totally different.

I was previously using Continental Double Fighter 1.9" tires, which just didn't have enough traction or air volume.

Thursday, June 25, 2015

Yelm, WA summer pics

This isn't Dallas or ebiking related. I used to live in Yelm, WA, around 45 mins from Mt. Rainer. The famous Ramtha lives here. She has a local store named "JZ Rose" (pictured below).

The pacific northwest area is amazing in the summer. (Recruiting tip: Always bring in out of state candidates to interview in Seattle during the summer months!)

Here are some random pics I took recently.

Carnival in town:

Ramtha's store, JZ Rose:

Railroad grade Yelm to Tenino trail:

View of Mt. Rainer from Yelm in distance:

Yelm to Tenino trail:

My front lawn:

View of huge amounts of logging land in front of my property. Mt. Rainer is behind these trees:

My front yard:

View of house:

Parking on side of house:

Monday, June 22, 2015

West McKinney to the Cotton Mill (East McKinney)

I've found a much better way to work from west McKinney to east McKinney. Here's the route on This route is awesome for ebikes: low traffic, few lights, and wide.

Tuesday, June 16, 2015

New tires

Time for new tires! Maxxis Holy Roller's:

I love these tires for urban riding. They have great traction, low rolling resistance, and low noise. I got the widest tires (2.4") I could squeeze into my hardtail mountain bike frame.

Dallas Trail Mud (of Doom)

We had a strong rain storm pass by McKinney today. Rain is no big deal really, you just go slower and hopefully have some good rain gear on. Easy.

The real problems start once the rain passes and all the silt and dirt on the trails turns to the slipperiest and stickiest mud I have ever seen. 

This stuff is doom to a bicyclist. This type of mud gets into everything: your brakes, fenders, gearing, etc. It's also as slippery as ice. If you see this stuff just be smart and turn around.

Sunday, June 14, 2015

The Battery: The heart and soul of any ebike

An ebike lives and dies by its batteries. It doesn't matter how good the motor is, or the frame, etc., if the batteries suck you're not going to have any fun.

There are many different chemistries, I've personally used LiFePo4 and LiPo:

These are known as "duct tape batteries", for obvious reasons. (Really, they should be called Gorilla Tape batteries!)

The 6 old (but thoroughly proven and battle hardened) hand built batteries to the left are based on A123 M1 LiFePo4 (Lithium Iron Phosphate) cells. Each LiFePo4 battery in the pic contains 30 M1 cells, each cell is (nominally) 3.3V with a capacity of 2.3Ah. Each pack is configured as 6 cells in series (~19.8V) , 5 in parallel (11.5Ah). I always these use packs in pairs. Each pack has an integrated 60 amp fuse.

The two right batteries are actually four Pulse Battery ~22.2V RC LiPo (Lithium Polymer) 5000 mah (5Ah) brick batteries (each pair is taped together). Four of these LiPos give me ~44.4V with a capacity of 10Ah. I usually use 4, 6, or even 8 of these Lipo's at a time depending on the expected travel distance.

Energy wise, each of the 6 packs starting from the left each contain ~227 watt hours, for a total of 227*6=1.362 kilowatt hours of energy. The 2 LiPo packs on the right each contain ~231 watt hours of energy, for .462 kilowatt hours total. In practice only around 80-90% of the total energy is safely usable.

Back in the dark ages of ebiking, way back in 2007, getting good off the shelf ebike capable batteries proved extremely difficult. So I had to improvise and purchase a large amount of these awesome Dewalt 36 volt lithium power tool battery packs from ebay:

I was able to extract ten A123 M1 B cells from each of these power tool battery packs. I eventually purchased and took apart 18 of these guys to build the 6 packs in the pic above.

Carefully soldering my first LiFePo4 battery:

My first prototype battery was only 6 cells in series, 4 in parallel. I later added one more parallel group once I realized that 9.2Ah (2.3*4) just wasn't enough capacity.

Years later, I was able to bulk purchase a large amount of these A123 M1 B cells (from here) to build some packs for a friend:

Thankfully, with the easy availability of RC Lipo packs (at basically every decent RC hobby store) I don't expect to be hand building batteries any longer.


Now that I've got multiple ebikes as backups, I can tear down my primary one to improve various things. I've decided to concentrate on the rear rack, the freewheel, new chain, enable regen (using one ebrake on the front brake), and add a suspension seatpost.

Completed view:

I decided to go with this aluminum back rack (Generic pic from Amazon):

Next weekend I'll add another torque arm (from Grin Technologies) to the front hub motor, for 2 total.

The sound and feel of regen caught me by surprise. The motor now engages (effectively in the reverse direction) whenever I brake the front wheel now. I ride pretty aggressively so this happens constantly. It's like having 3 brakes.