Let's build an ebike together!

[WalkaboutStache]

I have been thinking about this obsessively for the past few days and decided it is time to tap into the collective hive mind. As any dicussion of bikes goes, lets start with specs:

Rider spec


The rider is a former bike fanatic.  I have since fallen off the wagon, so to speak, but used to commute daily on a bike until I moved to very bike unfriendly Hong Kong.  I am now in rural Hawaii, and this is again on my radar. Former commutes used to be 20km each way from Leiden to the Hague on very used, very crappy used bikes that eventually fell apart, and 10km each way from Finsbury Park to Canary Wharf on an awesome fixie that I spec'ed myself. 

Commute spec

Current potential commute is 2-3 times a week, 26 miles each way.  Downhill on the way to town, uphill back with a 4,000 ft (1km, give or take) elevation gain on long-ish, glentle-ish slopes.  I don't have to look pretty when I arrive, so sweat is no issue, but I do want some help on that climb to make it sustainable.  I am likely to need a trailer for my medium wolf school dropout furry companion because she is awesome (but I know this may be a pipe deam).

Bike spec

As a baseline, the off the shelf solution seems to be a Radpower cargo or commuter bike, which would come at USD 1500.  Based on my fuel costs, this would break even at 150 trips.

So far, I have found a brushless rear wheel conversion kit on eBay for about USD 153:

https://www.ebay.com/itm/Voilamart-Electric-Bicycle-E-Bike-26-Front-Rear-Wheel-Motor-Conversion-Kit/322247604604?_trkparms=aid%3D555017%26algo%3DPL.CASSINI%26ao%3D1%26asc%3D20160406134228%26meid%3De46b5c9022ec453d813d12c954fc35ba%26pid%3D100625%26rk%3D1%26rkt%3D7%26itm%3D322247604604%26pmt%3D1%26noa%3D0%26pg%3D2499334&_trksid=p2499334.c100625.m3682

A good battery will run between USD 350 and 500 (I have not quite settled on one yet).

I can probably find a used bike for USD 200 or under on craigslist near me, but with rim brakes.  I have always used rim brakes on all my bikes, but I am not sure they would hold for an electric, especially since it is pretty wet where I live.

So I would be looking at 1/2 price of the new one so far, though I would be missing out on a sturdy cargo frame and regen braking, plus potentially needing disk brakes. I couls cut a corner and get something like this for USD 350, which all the components I need (I think) and save about USD 500 on the Radpower.

https://www.ebay.com/itm/Cannondale-F7-Mountain-Bike-24-Speed-16-5-Frame-SRAM-Hardtail-Nice/114010764441?hash=item1a8b923499:g:wgQAAOSwIuBd8TOq&shqty=1&isGTR=1#shId

Facepunches and suggestions welcome.  I have been out of the bike DIY for a while but am ready to get my hands dirty again.

[BikeFanatic]

I will add more when I am not at work, but for now I will say 4000 foot climb you will want a direct drive hub motor as opposed to a geared motor. You did not say your weight, but if you are over 150 pounds and climbing hills with a trailer then you can easily burn out a geared hub motor. I would go with higher watts, like 500 to 1000 watts. With a direct drive you can touch the motor and feel if it is overheating, some drill holes in the cover for airflow. I get my stuff from EBIKES.CA  or grin cycles in Canada, they are great and answer questions, also there is an expat in China cell man, he sells great kits too I have to remember his name, he sells great batteries packs. If you are really DIY you can use Cheap Lipo used for remote control helicopter and adapt to your kit. I remember now the guy in China is EM3ev google that site and look around there.

[WalkaboutStache]

Thanks!  I was leaning towards the direct drive. I have my eye on a steel Cannondale bike I have seen on CL for 150 and will contact the guy today to see if it fits me.

[robartsd]

I think your project sounds like fun.

I want a RadWagon. I'm not sure how much it would actually reduce our use of a car. I'd estimate a cargo bike could replace 20-50 mi/year of car trips that I make that would be difficult to do without an e-bike. While I don't think the electric assist would help me personally use a bike more, it could make cycling a much more viable option for my wife. I think having an e-bike for her would likely enable switching a few hundred miles each year for trips I would bike by myself but that we drive when together. Driving costs saved might be on the order of $100/yr - at 10+ years ROI it doesn't really make financial sense. There is some potential that my wife would make frequent use of an e-bike to replace trips she currently makes alone in the car - perhaps enough to bring the ROI of a RadWagon into the 3-4 year range. I should probably plan some trips together using the local e-bike share to get a better idea about how an e-bike might change her use of bikes for transportation.

[BikeFanatic]

I have my eye on a steel Cannondale bike

yes Steel works better than aluminum frames for hub motors, steel can be streatched a little if the dropout is too  tight a fit.

[BikeFanatic]

I want a RadWagon. I'm not sure how much it would actually reduce our use of a car. I'd estimate a cargo bike could replace 20-50 mi/year of car trips that I make that would be difficult to do without an e-bike.

An Ebike is worth it even if you do not save money. Makes  a ten mile trip into an adventure. It is a pretend motorcycle!
I have been riding Ebikes for years, since 2003, when the Voloci came out. 2019 was the first year since then that I do not have a working Ebike. I missed it so much! But at least I get my exercise biking to work every day, more fun with the Ebike especially in winter.

[AccidentialMustache]

I have a rad wagon. I *will not* buy another direct drive e-bike. If the motor isn't assisting, you have a fairly hefty parasitic drag before you even start to talk about the extra mass you're carting around too. Regen *may* be helpful for you on the downhill, but only if you don't charge the battery before. You would have to know how far to charge it ("charge to 50%, build the other 50% up via regen on the downhill run), and their default charger will not help you with that. You have to be "braking" to charge the battery although you can tune the breaks if you're careful to engage the regen before they actually touch the rotor.

Running at lower power settings, I would expect that you'd be fine with any sort of motor aiding you on the climb. The motor putting out 25% rated power does not care if you're going up, down, or sideways. Rad includes warnings about not running at the full 750W for "extended periods" due to overheating, and let's not forget your battery range won't support that anyway.

I wouldn't get a extended frame cargo bike for hauling a dog. One of the dutch-style basket ones maybe. I like the idea of a kid trailer more though, because the tricycle arrangement (your rear, their 2 side wheels) will be more stable for when the furry load shifts around to look at a squirrel.

Now, don't get me wrong. I do love my rad wagon. I just hate the parasitic drag. They pitch regen as awesome and it ... just isn't. Its a gimmick.

For a long commute application, especially since you need to climb one way (home) -- if you run out of juice now you're climbing an effectively steeper slope due to the drag and the mass and that's going to suck a lot.

[BikeFanatic]

The direct drive motor is heavy and the resistance when there is no throttle is there, but if you give a little throttle the resistance disappears. I do love the geared motor for the ability to pedal freely without motor “resistance” but I blew one on a hill in the mountains it was a big long rather steep hill.

[robartsd]

I want a RadWagon. I'm not sure how much it would actually reduce our use of a car. I'd estimate a cargo bike could replace 20-50 mi/year of car trips that I make that would be difficult to do without an e-bike.

An Ebike is worth it even if you do not save money. Makes  a ten mile trip into an adventure. It is a pretend motorcycle!
I have been riding Ebikes for years, since 2003, when the Voloci came out. 2019 was the first year since then that I do not have a working Ebike. I missed it so much! But at least I get my exercise biking to work every day, more fun with the Ebike especially in winter.

I'm plenty happy with my current bike for 10 mile adventures. I don't need a new $1500 toy; but if I decide to get myself a new $1500 toy anyway, RadWagon is pretty high on the list of options.

The direct drive motor is heavy and the resistance when there is no throttle is there, but if you give a little throttle the resistance disappears. I do love the geared motor for the ability to pedal freely without motor “resistance” but I blew one on a hill in the mountains it was a big long rather steep hill.

Being more massive and having a larger shell area, direct drive motors likely can withstand more power output for a longer period simply because they can dissipate more heat a lower temperatures.

For the situation the OP describes, I do think a geared motor may be the better choice.

[WalkaboutStache]

Thanks, everyone.  It turns out that r/ebikes has a fairly detailed guide on bike and kit manufacturers and they lean towards the DIY crowd.  If anyone is thinking about a build, that is a good resource to have.

I am now looking for a suitable bike to convert - eyes on Craigslist.

[TrMama]

Thanks, everyone.  It turns out that r/ebikes has a fairly detailed guide on bike and kit manufacturers and they lean towards the DIY crowd.  If anyone is thinking about a build, that is a good resource to have.

I am now looking for a suitable bike to convert - eyes on Craigslist.

I'm not sure how much your dog weighs, but if he's more than about 40lbs, I'd prioritize disc brakes over rim brakes. Going downhill with a weight behind you will wear the pads and rims quickly. It's also disconcerting to not be able to stop so easily.

I bike sometimes with a heavy grocery trailer and rim brakes, but *luckily* the store is downhill from home. So I don't really touch the brakes when I'm hauling loaded.