1st e-bike conversion, talk me up, or talk me down!

[Clyde]

Greetings and Salutations!

So I've recently begun obsessing over e-bikes after selling off the 2008 Ninja 250 that was my daily driver for several years. My thinking is that I could use it for my short work commute during the summer, and let my 12-year-old ride it to school if that ever happens again during the school year. There are, of course, lots of decent and reasonably priced bikes available lately. The Civibikes Cheetah is beautiful, and I'm intrigued by the Super 73 minibike style rides, as well as the Luna fixie and BABE, but that's just by way of introduction. I've had bikes apart before, and used to wrench on my Honda XR75 back in the day, so I'm comfortable enough around bikes and tools, although I've never removed a bottom bracket. How hard can that be?

In my shed I have a lightly used, 2002 Trek Clyde: https://www.bikepedia.com/QuickBike/BikeSpecs.aspx?item=37639. It's a aluminium framed retro-cruiser with a Shimano Nexus 4-speed IGH, ProMax V brakes, and not much else. Tires are 26 x 2. Considering that the least expensive e-bike on my radar is around $1700, which would only get me a hub motor and mechanical disk brakes, a 750 or 1000W mid-drive conversion kit @ $800 - $1000 seems like a reasonable avenue to consider. It would give me the flexibility to build something else later on, and take advantage of the existing IGH for now, as I enter the e-bike world.

So right off the bat, and armed with an Internet education, I've got some worries:

1) The Shimano Nexus 4-speed IGH was discontinued in 2005, apparently over reliability issues. Here's the specs: https://www.sheldonbrown.com/nexus4.html
2) The 2nd top tube and curved down tube limit my options for battery placement. I don't want a rack-mount battery.
3) The curved down tube will make mounting a mid-motor a bit challenging, as it continues forward from the bottom bracket before curving upwards. I'm guessing this will require rotating the motor so that the bit that normally extends forward from the bottom bracket is rotated downwards a bit. Probably not a clearance issue.
4) The existing V-brakes are likely barely sufficient at best. I've read that some retain the V-brake on the rear, and install a hydraulic disk up front, which I guess is an option, but hits the budget a good whack.

So... Am I buying trouble? On the right track? Living in a fantasy utopia of my own imagining?

TIA

 

[Dewey]

You might consider a triangle battery, like one of the tri 48v batteries from ebike marketplace, they post the dimensions on the site so can measure up your bike’s frame triangle. A disk brake would require a new fork presumably, you could also ask on the endless sphere and electric bike.com forums. Rotating the motor down would probably work, although it would mean you couldn’t use a bsb-1 stabilizer bar/torque arm for the mid-drive. I’d read this article https://www.electricbike.com/mid-drive-kit-igh/, not sure I would push 1,000w through a Nexus-4, but a used Nexus-3 26” wheel and shifter should be easy to get.

 

[Clyde]

Thanks Dewey! I'll have a look at ebike marketplace triangle batteries. As I look at the picture again I'm thinking a Shark battery may still fit on the seat tube, as they're 14.48" long. Need to measure that, I guess. I'll check out the link re: the torque arm. That may put paid to my little adventure right off the bat. Much appreciated!

Caught a video of a Bafang BBSHD install on a fat bike with a similar down tube and the motor rotated to compensate. Didn't see any reference to a stabilizer/torque arm, unless that's the Y-shaped mount that prevents the motor from rotating?

 

[TimJohn]

Just like to add...don't put a BBSHD 1000w motor on this bike of yours without disc brakes. Asking for trouble, it will go but just as important it has to stop!

 

[Dewey]

Clyde, the kit comes with the Y shape mount you mention but it doesn’t work very well, you are forever removing the crank arms to tighten the BB lock rings. But a BSB-1 stabilizer arm with a hose clamp is just the thing to keep it from rotating, however it holds the motor at a certain angle and from your description your frame may or may not accommodate it, worth a try making a cardboard cut out of the motor at a 40 degree angle to see if it could fit on the frame. https://california-ebike.com/shop/bsb-1-bafang-stabilizer-bar-bbs0102-bbshd/

 

[Clyde]

Just like to add...don't put a BBSHD 1000w motor on this bike of yours without disc brakes. Asking for trouble, it will go but just as important it has to stop!

Thanks Tim. I only consider the 1000w BBSHD, as I've heard that the BBS02 has issues with a nylon gear. I'd likely leave in in class 1/2, and unleash it on a future build with better anchors.

 

[Clyde]

Dewey, that does look like a better solution than the supplied motor holder. Simple as it is, I bet I could get someone to cut one out for me with the correct angle for the motor. Thanks! As for the Nexus 4, I hear that the guts from a Nexus 3 fit in the same hub, so I could break it and replace should it come to that.

 

[AHicks]

If I could, I would suggest that you sell that bike for what you can get for it. Then get a donor bike with disk brakes. In the grand scheme of things (like when it's time to sell it) you'll be further ahead.

 

[Clyde]

Thanks for responding, AHicks. I'm willing to hear that. I guess my thinking was that the motor is the lasting investment, with my existing bike serving as a cost-free donor to get the project off the ground cheaply. If I decide the whole enterprise isn't for me, I convert my bike back to acoustic, sell the Bafang, and I'm only out the depreciation. When/If I want upgrades, I can revert my bike and install my motor kit on something else. If an e-bike without disk brakes is truly an abomination I can accept that, but by the time I obtain a donor with disks and a motor kit I'm well within striking distance of the cost of an acceptable, purpose-built bike.

 

[Katysax]

Disc brakes are definitely preferred but are not the end all and be all. I’ve had a couple of ebikes with rim brakes, and I had one with cheap disc brakes. They were all problematical. You can do OK with rim brakes if you put on really good pads. I’d rather have rim brakes with good pads than cheap disk brakes. High quality disk brakes are the best, but you can make rim brakes work.

 

[Dewey]

It is a sellers market right now, lots of demand for bicycles, anecdotally I've read of other people getting good prices selling their bikes used. Rim brakes are a problem if you ride at Class 3 speeds or in the rain when they don't work as well. I have rim brakes on my lower power Bafang 350w conversion, the shop swapped out the pads for Shimano Deore pads and they work fine in the dry, but I'm considering getting a Sturmey Archer drum brake for the front to make it an all weather commuter. Virginia passed revised ebike legislation this year requiring Class 3 ebike riders to be 14 or older so your plan to limit it to Class 2 makes sense. With a 48v battery you would need to program it to 15A current/20mph speed to keep under the 750w Class 2 power/speed limits, and presumably change the throttle setting to not exceed the speed setting, but I don't know if that would make the transition between throttle and PAS jerky or what happens when voltage drops as the battery empties, might be good to ask BBSHD controller programming questions on Endless Sphere.

 

[Browneye]

Building one is not a cheaper way to get a ebike. Just sayin'.
And as mentioned, disc brakes are a reasonable requisite for an ebike.
Ebikes are really fun!

 

[Clyde]

I'm kind of attached to the bike, and have no plans to sell it regardless of how/whether this project proceeds. Maybe if I cool my jets for another year someone will offer up a mid-drive, disk brake, 750w+, hardtail, belt drive, IGH, fat tire bike with style for under $2 grand...

 

[AHicks]

2000. not too hard if you were to lower the priority for a belt driven IGH....

 

[Clyde]

That seems to be the way things are moving. I wouldn't be surprised to see prices for belt drives come down quite a bit. Hate to buy something now only to have those really nice options become affordable soon after.

 

[rich c]

I'm kind of attached to the bike, and have no plans to sell it regardless of how/whether this project proceeds. Maybe if I cool my jets for another year someone will offer up a mid-drive, disk brake, 750w+, hardtail, belt drive, IGH, fat tire bike with style for under $2 grand...

The way this ole world is going, who knows what waiting a year will be like. I'm 67, and thinking having fun right now should be a little higher priority that it used to be. Besides, waiting a year would reduce my eBike riding time by around 3,000 miles.

 

[AHicks]

That seems to be the way things are moving. I wouldn't be surprised to see prices for belt drives come down quite a bit. Hate to buy something now only to have those really nice options become affordable soon after.

With a philosophy like that, you could be waiting long enough where you wouldn't be able to ride this new technology you're waiting on.....

 

[Clyde]

No doubt. No doubt. I do tend to delay gratification while I analyze a toy purchase/project to death, but I also find that that's all part of the fun of toys. Should I die before I obtain an e-bike my afterlife garage is already adequately stocked.

Having another look at the bike, anyone think a decent 48v battery might fit behind the seat post? Hadn't considered that placement. I measured the seat tube from the lower top tube to the bottom bracket, and it's a meagre 12". Looks like I'd gain an inch or two flipping the battery around back.

 

[Dewey]

Having another look at the bike, anyone think a decent 48v battery might fit behind the seat post?

It's an option but for a larger heavier battery I caution against putting that amount of weight that high up, it may topple and/or affect handling, inside the triangle, low and center, is best, but on a rear rack if you need to. I've seen conversions with a battery in a front basket but that works best if the basket is fixed and mounted to the frame not the handlebar else the weight will pull the handlebar around to either side.

 

[Clyde]

Sorry. I meant 'seat tube', not 'seat post'. So in front of the rear wheel. Tape measure time!