I've been reading up on ebikes and options available recently but I feel like I've been drinking from the fire hose and have only scratched the surface on all the information in ES... After my initial research I believe I have a starting plan for my ebike build and have some time available during the holidays to get everything ordered. However, some of the details I am unsure about so I'd like to get some feedback.
Background info: I plan to use the bike mostly for commuting and for casual rides with my 21 year old son (mostly on paved trails but maybe the occasional off-trail ride also. In these cases, I would plan to mostly pedal anyway, with the motor power just to be able to keep up with my son and save face!
). My commute is about 12 miles each way, with rolling hills in eastern Tennessee but nothing too extreme. I plan to pedal but would like to maintain 20 mph, maybe 25, most of the time including on the hills. The longest hill is probably only 1/2 mile long with about a 7% grade. There is a bridge I have to cross that has serious traffic going over 45 mph, though, so I would like to be able to go at least 35 mph to get across the bridge as quickly as possible and just get out of the way of cars. Other than this, I can be on smaller roads or there is a wide enough shoulder that I don't need high speed, and at this point I am not sure if I will feel comfortable riding over 25-30 most of the time anyway. I would like to have enough range that I can do the round trip (~25 miles) on a single charge with a bit of spare in case I need to make a stop on the way home. I'm thinking 30 mile range would be good at an avg speed of 20-25 mph, so probably 1.5-2 kWh is what I estimated for battery capacity. I weigh about 190 lbs and am figuring on about 250-260 lbs for bike and rider carrying a backpack.
I bought a 29er before I learned that a 26" wheel is a better choice. I like the bike and at this point I don't really want to change horses mid stream. It is a Redline Monocog Flight 29er--steel frame with front suspension and disc brakes. It currently is 9 speed in the rear but I will probably change out the shifters with another bike I have and go to a 6-speed freewheel for the ebike conversion, and I am planning to use two gears on the front without a derailleur so I can manually change to the smaller chain ring for leg power-only rides if/when I need to ride home without the motor.
Based on the recommendations I have seen about smaller wheels, I am thinking about using a 26" rear wheel instead of the 29" but with a 38mm wide rim and 2.6" wide tire for a bit of added cushioning since I don't have rear suspension. I will keep the 29" front wheel either way. I think this will probably put the back tire's diameter more into the range of a standard 27.5" wheel, although maybe not quite. I am still somewhat ambivalent on using the 26" vs. 29" wheel. The bike looks fine with a 26" on the back and pedal clearance seems to be ok, especially for mostly on-road use, and with disc brakes I don't have to worry about the brake location. Any experiences from others and special considerations I may not have thought about concerning wheel size (and motor winding) would be appreciated. If I felt confident that the speed and efficiency would not be excessively penalized with the 29" wheel, I would prefer this, but it seems I can expect a hit in efficiency, generate more heat and decrease my range, as well as impacting top speed with the 29" wheel.
For the motor, I am planning to use the Leaf 1500W, and with the 26" wheel I would probably use the 4T winding on the wide rim:
http://www.leafbike.com/products/e-bike ... -1112.html
Peter at Leafbikes recommended the 5T or even 6T motor for uphill performance for the wide 26" wheel, but from what I read it seems like the 4T, with sufficient power (>2kW) and current capacity from the battery and controller would still give plenty of torque and would allow a lower voltage battery to do everything I am looking for. I would prefer to keep the voltage at 52V or less. I plan to use a LiPo battery (probably Turnigy) with about 2kWh (40Ah at 48 or 52V). If I can use a 29" wheel, it seems like the 5T might be a better option but I may need to use a higher voltage to make a top speed of 35mph.
For the controller, I was looking at 18 fet options to provide enough amps to get to a 35mph top speed with the 26" wheel, but I also like the idea of giving myself some room to move up to higher voltage and power levels in the future. I will probably go with the "18fet Silent Controller" from Powervelocity:
https://endless-sphere.com/forums/viewt ... +bluetooth
I like the option on this controller to program it from my smartphone. However, I don't understand the tradeoffs and requirements with different controllers, and don't know if the 18fet is overkill or could negatively impact the performance in some way. If people can comment on this choice for my desired performance, I would appreciate it.
I know I will need torque arms for the build and will also need to get an appropriate charger. I will select the charger once I finalize the motor choice and battery voltage. I am also planning to get the CA3, although maybe not immediately.
Please provide me with any feedback you may have and let me know if there is anything I am forgetting. Thanks in advance for your help!