I'm driving a deathtrap that probably needs to be rebuilt

I put together my ebike about a year and a half ago to get to and from work (27 miles total). It hasn't gotten a whole lot of use, mostly because it's unreliable and probably dangerous.

Details:
- Cheap aluminum mountain bike (probably needs to be replaced)
- 48V 1000W front wheel hub motor
- 20AH battery (I think)
- Crappy rim brakes
- Stock chain drive
- Max speed of 30mph
- Don't remember details of the controller

I have a few concerns with this setup. 1) I don't know if the aluminum frame can handle the torque of the motor and I don't have a torque arm, 2) the rim brakes loosen constantly and it takes me way too long to come to a stop when I hit the brakes as hard as I can, and 3) with the chain drive I have, I can't pedal fast enough to assist the motor at top speed, which means the battery often dies before I get home from work.

When I first put this ebike together, I did a lot of research on the electric components, but clearly not enough on the bicycle portion. As a result, I'm pretty happy with the motor, controller, and battery, but I think I might need a whole new bike. Reading guides and forums again, I realize I should have made sure my bike had a steel fork, disc brakes, and I think a chain drive with a bigger front gear? Unfortunately, the hub motor/front wheel I own does not have disc brakes and I'm not sure how they would be installed.

I am comfortable investing $1000 into rebuilding this ebike into the safe, reliable commuter vehicle I wanted it to be. Can someone please help me with this?

http://endless-sphere.com/forums/viewtopic.php?f=3&t=70169

Rim brakes are easy to fix. Mostly you just need some good pads, and then simply get used to the idea that if you run at 30 mph, then you need to do some maintenance, like tightening up the cable as the pads wear away.

YES,, you need a damn torque arm!!!!! And two c washers if you have that front motor on an aluminum fork.

http://endless-sphere.com/forums/viewtopic.php?f=4&t=15163&hilit=Ebikes+ca+c+washers


http://endless-sphere.com/forums/viewtopic.php?f=4&t=15167&p=225525&hilit=Ebikes+CA+torque+arms#p225525

Too bad you chose a front motor, but just the motor is pretty cheap if you want to switch to rear motor. That would make a fork swap allow front disc.

If the bike has the disc mounts in back, get a disc wheel for that one too. Disc requires less fuss than rim brakes IMO.

If you can weld, then get a steel bike, and build something like this. Hell, I weld like a monkey on LSD but I built this with a 100 buck wire feed welder.

http://endless-sphere.com/forums/viewtopic.php?f=6&t=67049

But if that is not possible, seriously look at spending some real money on the bike. Lots of good bikes out there to convert. IMO, longtails for the win. Look at Edgerunners, Surly, Yuba mundo etc. Long bikes handle speed really well, and they can carry a pizza home.

1. Why not just buy a newer bike if you have 1k to spend. Test ride at shops/craigslist find one you like works on your roads. At 48v should have steel dropouts and torque arms. Better to buy used a bike shop probably won't like servicing your conversion.

2. Or go cheaper old steel mtb on craigslist. 80's/90's $100-150 good cantis or v-brakes, test ride some old rim brakes stop fine. Good steel smooth ride vs cheap aluminum. Get a non-race bike slack angles more comfort.

3. Or upgrade current bike with brakes, gearing etc will cost in the hundreds with tools, you'll still have aluminum harsh ride, soft dropouts, more work. And the same crappy chinese bearings, headset, etc. it sounds like anyway, good luck,

Lucky to be alive. Go charge your battery. How since you fully charged your battery. We are trying to save the battery first. A front 1,000 watt motor on aluminum forks, really. Aluminum feels unsafe with a rear motor on 25mph. A fork motor most fill scary flexing and all at 30 mph.
Second get an old comoly frame bike, specialized, trek ect 60~100 usd. Rim brakes are fine, like the newer side pull. Buy some koolstop pads. I look at the shift, brake cluster and how my throttle fits before I buy. Look for a 48t front ring and buy a 11t freewheel. Torque arm. Maybe 220usd. with improvements.

Thanks, everyone!

Wesnewell, thanks for the thread. That covers some basics I wanted to confirm.

Dogman dan, that is one kickass bike. Nice work! Thanks for all the suggestions. I appreciate that you took the time to consider multiple approaches to my situation.

Oobagooba, thanks for your multiple suggestions, too. Options are always good

999zip999, those are some useful tips. Thanks! I've kept the ebike plugged in for the most part, so I assume the battery is still in good shape. And yeah, I had no idea how dangerous it was. I'm just glad I'm finally listening to the community here and getting proper safety advice.


I think I'm going to spend some time scouring Craig's List for a deal on good a steel bike. Whatever I find that I really like, I'll just build around that. I got pretty much everything answered, but can anyone recommend a solution for the chain drive (if I'm using the correct term)? I still want to make sure I can pedal assist this newly built ebike at top speed.

EDIT: Maybe I just need a larger chainring?

Thanks again, everyone!

gmessad said:

... I got pretty much everything answered, but can anyone recommend a solution for the chain drive (if I'm using the correct term)? I still want to make sure I can pedal assist this newly built ebike at top speed.
EDIT: Maybe I just need a larger chainring?

Click to expand...

You got some help from people smarter than me so i will be short. As 999zip says can go 11t rear, 48 front more top end. Or find a bike with high top gear.

Before buying gears or tools know what type rear hub, freewheel or cassette. Freewheel more common on steel bikes but not always. Could find a nice 90's mtb with cassette.

Same for front chainring, many different bolt patterns. Find the bike you like, measure bcd, get the right ring. Might need tools to change out, crank puller etc.

Meanwhile if bored you could get some Park tools cheap on ebay and practice on your current bike with some cheap gears. New brake pads, etc. Give you some time to find a new bike. Then swap parts over if they fit.

For sure i'd get steel fork, good headset, couple torque arms with 48v front, good luck

http://www.amazon.com/gp/product/B00K60C67Y/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=B00K60C67Y&linkCode=as2&tag=xbnijgbr-20&linkId=KC5MTN63KDRZBGVY
https://www.endless-sphere.com/forums/viewtopic.php?f=31&t=29129 < My favorites, but both are torque arms worth considering.

An aluminum frame should be fine for a rear motor in most cases. Sure, steel is better, but don't sweat it. Unless your bike is made by Huffy or Next, it's probably Fine, or at least OK enough.

As an upgrade, a good craigslist bike like a Trek 820 and a rear motor would be a good start. You might be able to reuse the rest of what you have.

As for pedaling to help the motor at top speed, forget it. You can't produce enough power to help the bike in any meaningful way at 30mph. If you're in good athletic shape, you can produce about 100 watts continuously. the bike should be sucking down around 1000 watts at 30mph. At best, you'll add 10% range if you want a very hard workout.
If you want to go further, just go slower, or get a bigger battery. At 20mph you more than double your range. And at 20mph, pedaling does have a big impact on range.

As for brakes, a front disk is helpful at 30mph, but you're still in the range were rim brakes are equal to and sometimes better than disks. Get some Kool-Stop™ rim brake pads, some Jagwire™ cables if yours are old or cheap, and then never worry about stopping again.

To pedal, and actually help above 20mph, you need some serious gearing, like 52T/11T. Over ~18mph with 48/14T it's a waste of energy for me.

You can find 48t front on some mtb and they sale 11t freewheel for the motor. They sell 7,8 and 9 sp. freewheel with 11t.

Aluminum frame is fine, if you get a decent one. Not one of those floppy thin tubed ones you get on a 150 buck wall mart bike. But a cheap ass steel bike can be a great starting point.

With up to $1000 to spend, lots of options. You could get a pretty nice aluminum bike, and still replace the motor for a rear one, including some good torque arms to go with the alu frame.

But again, if you can snag a nice longtail on craigslist, go for that.

Re the pedaling at speed, this is a problem. My cruiser won't pedal much past 20 mph, 48 tooth front ring, and 14 in back. Converting a beach cruiser to a larger chain ring up front is not always easy. You have to find a bottom bracket to convert a one piece crank to square taper. Or, find a ten speed so old it has the one piece crank on it. I just scored mine last week, a 70's Schwinn varsity. Soon my bike will have a 52 tooth front chain ring.

If you like that beach cruiser approach, cruisers work really well with a front hub. Check out the Micargi's for example. http://pacificbeachbikes.com/shop/beach-cruisers/puma-3-0-red-micargi-bicycles/