DIY e-bike. Need your opinion on this build

[jamesbond007]

So, after giving up on my trial for purchasing am out of the box e-bike, I decided to build my own. I figured DIY is way cheaper even if I buy all components, including the bike, brand new and I have the flexibility of expanding and replacing individual parts in the future. So I have narrowed down to these options:


Bike: http://mikesbikes.com/product/specialized-crossroads-225303-1.htm
Motor: https://em3ev.com/shop/bafang-48v-750w-bbs02-kit/
Battery: https://lunacycle.com/48v-pansonic-ga-17-5ah-black-killer-whale-ebike-pack-huge-range/


Of course, I need a charger etc. But am I on the right track for picking the parts?


Just some context. My commute is 23 miles one way and I weigh 185 lbs and am 6'0". I need enough charge to get back home everyday and charge at home. Commute is mostly flat. Just one tiny hill with an elevation of about 120ft (I don't consider it as a hill, actually). I will be on bike trails for 90% of the commute.

[Car Jack]

Flat?

Way cheaper and complete built bike.  I went to the shop and really like this and almost bought it on the spot.  It's only 250 W assist but for flat, that's all you're going to need.  It's also 32 pounds total!  So you can easily carry it up stairs or whatever needed.  I like that it looks like a normal bike.  For under a grand, I can't see building anything.

http://www.ebikesofne.com/EasyGo-Race-p/easygo-race.htm

[jamesbond007]

Thanks for the suggestion. But I am looking for a mid drive motor for a balanced ride. The one you showed is a rear hub motor. It's fine for normal use but if feels like I am pulling a ton of weight with my legs. Also, the battery doesn't seem like it would last 46 miles. That is the reason I was looking into DIY options.

[Goldielocks]

We put a mid drive on a fat bike frame.   
Lots of issues in sourcing our own parts / kit, for a mid drive, and having it work smoothly together, and assemble neatly.   More mechanical skill is needed for a mid-drive kit.

In particular, getting the mid drive gears to align with the crank shaft / other gears was a real headache.  In hindsight, we would just buy a kit already packaged as a set and ready to go.  (one from Luna Cycle). 

OR, get a hub motor kit again which was so extremely easy to install the very first time.   (we paid a shop to spoke it into our wheel, then all was easy to do ourselves).  The hub kit is indeed front-heavy, so no more jumping roots / curbs for me, but I never minded that.   And when a hub drive powers out, it is hard to pedal ( I did not like that).   But the new batteries have better range than 15 years ago when I bought my lead acid ones. 

So, in hindsight, I do recommend hub kits, still, and especially after trying to install a mid-drive kit.

However, you don't have a fat bike frame, so maybe will have an easier time of it than we are with the fat bike mid drive combo.  (Chain came off again last week, still waiting for repair).

[BikeFanatic]

That is a long commute 46 miles. I am not sure that battery will make it. I get 22-25 watts per mile
average, and  I use about 4 amp hours of my 48 volt battery  for my ten mile commute.  you have a mid drive and since you will be assisting I think you will be ok.

[gooki]

Looks like you ebike parts are good. I've done a couple of mid drive builds with the Bafang units, but there were both connected to internaly geard rear hubs (Shimano nexus and alfine). The motors are super quite, and easy to install once you've removed the crank.

If I was spending that kind of money I'd probably drop a bit extra on a bike with better brakes and a better rear derailleur.

[jamesbond007]

Thanks for the responses. It looks like I have to read a bit more.

[Clean Shaven]

I assembled my own ebike too, and posted a bunch about it in this thread:
https://forum.mrmoneymustache.com/continue-the-blog-conversation/electric-bikes/100/

I first tried a rear wheel motor, which had a bunch of problems, and a horrible retailer (Dillenger).  With a rear rack-mounted battery and the rear wheel motor, it was extremely unbalanced towards the rear of the bike.  After forcing Dillenger to take back their pile of shit (had to involve credit card company), I bought a mid-drive kit from Luna Cycle, who were a dream to work with.

From Luna, I bought a BBSHD, with 11.5ah battery (water bottle mount, "dolphin" case), and the fancy Luna charger.  I am using the stock BBSHD 52T metal chainring, which works fine for on-pavement commute use.  I would want a smaller chainring for offroad use.

From Nashbar, I bought a cheap 700c hybrid Schwinn with disc brakes, linked in the thread above.  Highly recommend getting something with disc brakes.  If you get cable brakes (not hydraulic), the Luna kit's brake levers are usable with cable discs, and tie in to the battery cut-off switch.  If you get hydraulic brakes, there is an additional part you will need to make the battery cut-off tie in.  (When you pull the brake lever, it cuts power from the battery.)  I only used the front brake lever from Luna; IIRC they also supply a rear brake lever which also had the cut-off.  Since my bike came with brake levers + shifters integrated into one unit, I am using the stock rear brake lever/shifter assembly.

IMHO the mid-drive is far easily to install than a rear wheel motor, and far easier to deal with removing the rear wheel for any reason (such as flat tires).  The rear wheel motor must be bolted on with nuts, which means that side-of-the-road flat tire changes will require large heavy wrenches.  IIRC, all the rear wheel motors (including the crap one I had) require a freewheel (not a cassette), which must be purchased separately and installed. 

The mid-drive uses the stock wheels, stock cassette, and quick-releases (assuming your bike came with them from the factory, which all these cheap hybrids will).  Flat tire changes are as easy as on a non-motorized bike, other than the bike weighing a lot.  Installation of the mid-drive motor itself is easy, but requires you to remove the stock crank arms and bottom bracket.  My Schwinn weighed a bit under 30# stock, and is about 50# with the ebike stuff (motor, battery, controls, etc), and the misc stuff I added:  rear rack + trunk bag, fenders, spare tube + tools, bottle cage, front + rear flashy lights.  It's very heavy when you pick it up, but the added ebike weight is all down low, and centered well.  It handles well, not rear-heavy or top-heavy at all.

For other comparison to your situation:  I'm your height and a little heavier, and my commute is 18 miles each way, with about 1500' of net elevation difference (probably closer to 1800' total in gain/loss).  Going home is a lot of uphill.  I have to recharge my battery at work; I could not do a round trip on one charge.  With the 17.5ah battery you are thinking about, and having a totally flat commute, you may well be able to do a round trip without recharging at work.

[jamesbond007]

I assembled my own ebike too, and posted a bunch about it in this thread:
https://forum.mrmoneymustache.com/continue-the-blog-conversation/electric-bikes/100/

I first tried a rear wheel motor, which had a bunch of problems, and a horrible retailer (Dillenger).  With a rear rack-mounted battery and the rear wheel motor, it was extremely unbalanced towards the rear of the bike.  After forcing Dillenger to take back their pile of shit (had to involve credit card company), I bought a mid-drive kit from Luna Cycle, who were a dream to work with.

From Luna, I bought a BBSHD, with 11.5ah battery (water bottle mount, "dolphin" case), and the fancy Luna charger.  I am using the stock BBSHD 52T metal chainring, which works fine for on-pavement commute use.  I would want a smaller chainring for offroad use.

From Nashbar, I bought a cheap 700c hybrid Schwinn with disc brakes, linked in the thread above.  Highly recommend getting something with disc brakes.  If you get cable brakes (not hydraulic), the Luna kit's brake levers are usable with cable discs, and tie in to the battery cut-off switch.  If you get hydraulic brakes, there is an additional part you will need to make the battery cut-off tie in.  (When you pull the brake lever, it cuts power from the battery.)  I only used the front brake lever from Luna; IIRC they also supply a rear brake lever which also had the cut-off.  Since my bike came with brake levers + shifters integrated into one unit, I am using the stock rear brake lever/shifter assembly.

IMHO the mid-drive is far easily to install than a rear wheel motor, and far easier to deal with removing the rear wheel for any reason (such as flat tires).  The rear wheel motor must be bolted on with nuts, which means that side-of-the-road flat tire changes will require large heavy wrenches.  IIRC, all the rear wheel motors (including the crap one I had) require a freewheel (not a cassette), which must be purchased separately and installed. 

The mid-drive uses the stock wheels, stock cassette, and quick-releases (assuming your bike came with them from the factory, which all these cheap hybrids will).  Flat tire changes are as easy as on a non-motorized bike, other than the bike weighing a lot.  Installation of the mid-drive motor itself is easy, but requires you to remove the stock crank arms and bottom bracket.  My Schwinn weighed a bit under 30# stock, and is about 50# with the ebike stuff (motor, battery, controls, etc), and the misc stuff I added:  rear rack + trunk bag, fenders, spare tube + tools, bottle cage, front + rear flashy lights.  It's very heavy when you pick it up, but the added ebike weight is all down low, and centered well.  It handles well, not rear-heavy or top-heavy at all.

For other comparison to your situation:  I'm your height and a little heavier, and my commute is 18 miles each way, with about 1500' of net elevation difference (probably closer to 1800' total in gain/loss).  Going home is a lot of uphill.  I have to recharge my battery at work; I could not do a round trip on one charge.  With the 17.5ah battery you are thinking about, and having a totally flat commute, you may well be able to do a round trip without recharging at work.

Thanks so much. Very helpful.