Converting a Jamis Cyclocross bike - Help needed

I have a 2011 Jamis Nova Race (cyclocross bike) that I use for commuting to work, which is about 8 miles away. My daily route has 2 moderately steep hills in sections that makes very sweaty when I get to work. I'd like to add some electric assist to my bike to ease these hills out so I'm not completely drenched when I get to work. I'm still willing (and want) to pedal, since this has been a great workout for me.



This is my first foray into building an e-bike (built electric longboards before), and I'd like to keep my existing bike setup for cost reasons. I have a few questions and would appreciate any help from the more experienced folks out there!

- Motor: I'm going for a geared hub motor, since I'd like the freewheeling ability. Is 500W sufficient for climbing 7-13% hills with me pedal assisting?

- Front vs. Rear Mount: I have 9 gears on the rear and my forks are carbon composite with "monocoque construction". Are there any good rear geared hub motors that can fit with 9 gears and a disc brake? If that isn't possible, I might have to go with front hub motors. Given my forks are carbon, is it safe to have a 500W front hub motor (geared) with two torque arms?

- Torque Sensor: I'd like to (ideally) have a torque sensor, instead of a throttle, for exercise. Does this add to the complexity and cost considerably? Can I fit a torque sensor without mechanical modifications to my bike? What are some good ones out there?

- Wheels: Is it better to buy a prebuilt electric wheel kit w/ motor and spokes or lace my existing wheel (Alex DH32 26") with the new motor and spokes? What is the complexity of lacing my own wheel?

- Waterproofing: I live in Seattle. So, the entire setup would have to be waterproof. I guess that's not too difficult since a few Bafang hubs I saw were waterproof and I can get a good waterproof case for the battery. If I end up not using a throttle, I don't have to worry about it. Any other hurdles here?

Thanks for your help! Any advice is appreciated (even if you have an opinion on only one of my many questions)

What you need is here. http://www.ebikes.ca/

500w, a 36v battery on at least a 20 amps controller will get you up the hills. 36 x 20 is 720w btw. Look at the Ezee.

How fast are you going up the hill, and for how long is it?
How fast do you ride now pedaling?
How fast to you want to ride with the motor?
How much weight are you willing to add to the bike?

A 250watt motor could work if you only use it for the hill and get one that doesn’t spin too fast. That could be a possible solution. A 500 watt motor is going to give you a lot more power but is also going to give you a lot more weight. A lifepo4 36v20ah battery and motor is going to add 30lbs to your bike. That may not be ideal for your case.

I go a little against the grain here as I like light fast bikes, and I like the motor to be as strong as my legs. So, a 350 watt motor gives me a nice boost. The problem with hill climbing on a small light motor is that it can’t spin too fast at the top end without causing potential overheating problems on the low end (unless you can ensure it will never go below a certain speed when climbing). Then again, my bikes are some of the lightest most pedalable bikes here.

Think about your answers to the questions above…

Wheels: I would lace your own. Wheels are very expensive to ship because of their size, shipping the motor by itself is much cheaper. I took the money I would have spent on shipping and just got a hub motor, and laced it to my own wheel. Cost was about the same, but I got what I wanted, and the quality is much better.
Pre-built Chinese wheels have a habit of falling apart after a few days riding – they spokes are not tensioned very well. Easy enough to fix, but its kinda frustrating being stranded on the side of the road because my wheel was unlacing itself.

Torque sensor generally replaces your cartridge in your bottom bracket.

Thanks for your inputs!

I did some research and have settled on getting a 10T MAC to manage the Seattle hills using 700c wheels. I plan to run it at 48V and 20A. I guess the 10T motor at 48V will have top speed of about 25mph. That is plenty for me, and if I need anything above that, I can complement with my pedaling. I am also planning on getting a Cycle Analyst v3 with a TDCM Torque Sensor from ebikes.ca (which is about a $100 cheaper than the THUNK torque sensor).

A final question: Are the MAC hub motor and controller waterproof?

MAC10T on 48v (14S lipo) will do 30mph on a 700c wheel with ease for commuting. It struggles on 20-30 deg incline if you dont pedal assist. Check the last page of my build thread (in sig) for video and my build steps. I ride a 29er which is a 700c rim (622) with room for fat tires.

The motor and controller are "waterproof" in that it will probably survive heavy rain, but I wouldnt dunk it in a swimming pool or ride on the beach knee high in salt water... I put my 12 FET controller in a waterproof saddle bag to hide all the wires anyway. The unit is waterproofed, but the spaghetti of wires definitely arent.

I also advise you get the 12 FET for 40A. You can tune it down if you want to, but buying an underpowered controller, you cant turn it up.