Does it make any sense to build your own E-mtb?

highroad 2

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I am looking to buy another E-mtb for a friend to ride.
Another Bosch CX assisted bike would make a second battery available when needed.
I do not care for the Bosch small chainring design and prefer the Brose, Yamaha normal sized chainrings.

Bottom of the line full suspension Santa Cruz's, Stumpjumpers,......
cost $3000.
Say a mid drive Bafang or E-rad motor, controller and battery cost $1500.

These bikes weigh 30 pounds and the after market mid drive weighs 15 pounds.
My Haibike and Levos weigh around 50 pounds.
I could carry the battery in a back pack to get some weight off the bike.

It appears that it only makes sense to build your own e-mtb if you already have a good donor.

Or if you can save significant weight and cost, and get more miles per charge.

Please let me know your experience building your own

Highroad

The Bafang and E-rad motors seem to be well below the bottom bracket and I bump the bottom of the motor often when crossing over larger logs.
 

WoodlandHills

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You will be hard put to find any new MTB suitable for an ebike conversion: the down tubes connect to the bottom bracket horizontally at the front requiring any BBSxx motor to hang down like an udder. For this reason cheaper older used bikes make better candidates and lead to the big advantage of DIY bikes over OEM, their lower cost. Of course any bike you build you will know how to repair which is another savings too.
 

Phantastic79

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My eV10 is not bad. 47lbs and handles beautifully
Although I did have to fabricate the BB controller cover to hide the controller and wires. But overall I think the the build is pretty clean and could outperform most off the shelf Ebikes.

You could put this setup on a 20lb bike and have a 30lb ebike but you won't have as much plush suspension travel, which I think is more beneficial, but that's just my opinion.

2012 eV10
 

eFat

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I would not want a battery in my backpack.

As you said, if you already had a suitable bike maybe but otherwise...
 

highroad 2

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I would like to build a bike only if I can find a bike that the motor is not hanging down like an "udder".
I would like a modern bike with at least 160mm suspension travel and plus sized tires.

Any suggestions on bikes that would work.

I do not want a throttle, so pedal assist only and not much if any more power than the production bikes.

I like the idea of Phantastic's downhill bike because the motor looks like it is well out of harms way and lots of suspension travel which at my age I would set up for a plush ride versus the capability to jump off tall buildings.

Phantastic
How is it riding with the battery in a back pack?
What does the battery weigh and what range to you get?
Which motor did you use?
Does it have torque and cadence sensing or are those features overrated?

I do not want to reinvent the wheel on this potential build so please share what has worked or not worked for you.

Thanks
Highroad
 

Phantastic79

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There are many Other frames I could have used but I got a smokin deal on this V10. Also I really liked the way my nomad rode and wanted to Upgrade to a V10 instead of using a more Ebike friendly frame. The more ebike friendly frames have larger Triangles so you could mount the Battery there. But honestly I think it is more beneficial to get as much weight off the bike as possible.

Riding with the backpack is not bacd at all for me. I use a 20ah battery and I think it weighs like 10lbs. I carry my camelback in the backpack also. so it is pretty significant in weight. However I use an EVOC blackline MTB pack and it breaths very well and has really comfy straps. I don't mid it at all and if it gets tiring on the climb I rest the backpack on my seat. You can get a smaller or bigger battery or even attach it to the frame if you dont want to use the backpack. I have a small one I attach to the downtube for testing that weighs 3lbs and can get me about 10miles of range.

Bike is just throttle. Adding a cadence sensor would be nice and a torque sensor would be even better. May have to do that in my next revision. Honestly since I built the bike which is still in prototype mode I want to ride it every spare moment I get. So i haven't carved out more for additional modification time. It's just freakin awesome.

Most people Opt for a BBSHD, which is a great motor. However on many high end frames you will have to Grind off the ISCG tabs for it to fit. It is plenty powerful enough and the cadence sensor pedal assist is pretty cool. I was going to go that route but there's hella wires with that setup and I wanted to keep the bike as clean as possible. I only have a throttle cable to the bars and a batt cable to the seat. I dont even have a display, which is not that useful. I generally know how much juice I have left and If I really want to know I'll look at the battery display in the backpack. Knowing you speed is irrelevant to me as I'm not trying to race and cannot ride the bike as fast as it will go anyways.

Range all depends, but on trails I get around 30 miles. I need to work on programming the Controller to only put out 25% of power. I think that will give me enough assisted juice and will extend my range by like 30%+ but I'm not quite sure.

Motor is a Luna Mini Cyclone Deluxe. A little more expensive but is much cleaner and has waaaay better mounting brackets. I still had to fabricate and 3d print a frame protector to keep the Motor from cracking the frame under load and the bottom bracket controller cover but this motor made my job much easier.

I definitely could have used a lighter bike and Possibly got away with a sub 30lb Ebike(Probably carbon hardtail) but I think the additional weight is offset by the additional suspension which makes the experience much better.
 

highroad 2

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Seems like Kranks bikes also use the V-10 bike to motorize.
I had no idea what the ISCG tabs are but google does.
How does a 20ah battery compare to the 500wh battery that comes with the Bosch CX I currently ride.
Your battery weighs about 3 #'s more than the Bosch 500 so I makes sense you get more range.
Is it a simple matter of ordering and installing torque and cadence sensors of your Luna motor
 

Phantastic79

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I believe I have a little over a thousand watt hours on my battery.

But I see what you're trying to do. And I've also considered it the easiest way to accomplish what you were thinking is to Simply use a bbshd controller on this motor which I believe is totally doable. I was also going to hide the controller under the bottom bracket as well. But the motor came with a controller and I didn't want to bother with more fabrication. again the problem with this is you will have many more wires and your bike will look Messier. Unless you take it to the next level and take your frame down to a frame shop and they can route some internal wires. There's a guy out here in the Bay Area that quoted me about a hundred bucks for a port on the carbon frame. He's a guy that specializes in carbon frame repair and paint. You could just order the Cadence Sensor and torque sensor and make it work for this motor but it would require a bit of engineering. Totally doable though
 
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