Hi guys, About to try and convert my OWB 29er to an E-bike

[BrandonNorCal]

Hi,
I love my Mountain bike but just haven’t been able to get out and ride for the past couple of years and so I’m going to try and convert it to an E-Bike instead of buying another bike. Should be a fun bike if I can make it happen with help from the folks here. It’s a OWB 29er currently with a White Industries ENO singlespeed drivetrain that I hope to salvage my crank arms and rear singlespeed hub from with the option to add gears later. Those plans might change depending on how impractical that becomes but I have to start with something. I plan to buy a 1000W BBSHD kit and I guess I’ll end up trying to get a 52v Jumbo shark battery depending on fitment but just a quick look at the frame and It seems like I’ll have room for most batteries.

Let me know what you think of this bike in it’s current form as suitable for an ebike build and I hope to get ordering parts soon. Thanks. The pic is a little blurry as it’s an old pic and really the only one I can currently find of the bike (taken in Annadel State Park where I hope to ride it part time)

[73Eldo]

Interesting frame design. Doesn't look like the geometry is unusual just how they got there is. A good thing about it is that you should be able to rotate the motor so its up at least level with the BB which would be great for ground clearance if that is ever an issue for you. With more typical frame designs you end up hanging down a bit or with some designs where the downtube goes straight for a bit it can hang way down to the point you have almost no clearance.

Where were you thinking of putting the battery? It doesn't look like there is room under the downtube if the fork is compressed very far. On top looks like kinda a nut buster especially if you ride off road. Above the crank doesn't quite look tall enough and that is ideally where you would swing the motor to increase ground clearance. Keeping weight down low is best if you are doing things where you need to swing the bike around. Less important if you are just a pavement commuter.

Besides working out what and where for the battery the next issue is what type of bottom bracket does the bike have and how wide is is? Can you take some pics of the crank and BB area looking down from the top? Or flip the bike and take some looking directly down? That is the area where you need a little luck to make things fit. Some designs are no problem while others are a no go.

The BBSHD uses the old school square tapper crank arms with a slightly unusual offset and the sprocket side doesn't have a spider on it, its just a bare arm like the left side but with the right side threads so its not likely that you will be able to re use them. If you want or need something higher quality or a different length there are some options for Bafang compatible but not that many.

[BrandonNorCal]

I think the battery should sit riiiiiiight on that top tubeand at that angle it might not quite be a nut buster but I will figure that out once I mock up a jumbo shark battery. That top tube is 440 mm long and the seatpost sits pretty high . two slimmer custom batteries that sit on each side of the dual top tube would be nice but I don't know how to get custom batteries and I'm just not ready to commit to a custom battery yet. I'll ride it on the street and some MTB trails but even then mostly fire roads.

the bottom bracket is 72mm wide. I think my chainline right now in the rear is 53mm. I'm going to get some pictures when I start tearing it down this weekend. I need to true the wheels and do some general cleaning/prep on the frame.I just ordered the BBSHD motor kit with the mighty mini sprocket and a chain and tensioner.

[73Eldo]

Take some pics for us before you take it apart. Its often easier to eyeball things when the chain ring is still in place. Mighty mini is likely going to put your chain ring at least 10mm further out than any stock ring the bike would have been designed to work with. At least you running a single may help. Are you running a single rear hub or is it a cassette with single spacer? I think the cassettes get you out the furthest but I'm not any sort of expert on singles. I have some single parts that came with one of my Surly's but never ran em in that mode.

Looking at the photo again I could maybe see a triangle pack against the seat post maybe not being a nut buster. Have you seen Grin's offerings? They have some differently shaped packs including some triangle and more flat ones that maybe could be used saddle bag style on yours. Note that they have a $60 hazard surcharge to ship packs to the USA but if they got a shape that works it may be worth it. They seem to have a good rep for quality and service.

https://ebikes.ca/shop/electric-bicy...batteries.html

[BrandonNorCal]

Here are a couple pics I took before I removed the cranks. The second measurement is with the scale as close as I could estimate the center of the chainring. I may have some tricks to get the rear sprocket out far enough if needed. It’s a singlespeed hub with a screw on freewheel. I’ve been dealing with chainline issues since I started mountain biking (Ive only ever built myself singlespeeds) so hopefully I’ll be able to deal with that issue.

My motor kit arrived yesterday so I’m anxious to get the bike completely torn down and clean. I’ll check out the batteries on that website. Getting a suitable battery is my main concern now. Will most batteries come with the correct harness to clip in to the BBSHD? Is that a standard type plug that I would specify when I order the battery?

[73Eldo]

It looks reasonable. Having that angle on the rear chain stay is way better than one that bumps out quick. How many teeth on that existing chain ring?

BBSHD's usually come with what is called an Anderson connector, its black and red. Anderson has a whole line of connectors but in most E bikes use the same one so if it says anderson and it looks right it will probably be right. Many vendors will make adapters. Depending on what your battery comes with I would consider changing the BBS to match the battery rather than the other way around. Its a lot safer and easier to change the connector on the motor side because its not live. The battery side is always live so you have to be extra careful when changing the connector.

I have a Park bike stand so I don't need to build one but I am curious and I'm sure others would like to hear about your stand.

[BrandonNorCal]

Fitted up the motor. I had to use 4mm of spacers to ensure it wouldn’t hit the chain stay. That put my chain line off by about 10mm. I think that’s just too far so I’ll see if I can move the freewheel out a few mm and maybe even dish the rim. The White industries cranks just may work but there is a very very slight clearance issue on the non drive side. Again just a very few mm so I may be able to figure something out. Possibly shave a bit off of the motor cover. Should I be putting this info in a build thread? I’ll get some pics of my bike stand too. Anyone can build one for cheap and I’ve used it while building this whole bike the first time.

[AZguy]

I would try out the chain line the way it is - 10mm isn't that much... mine offset at least that much and I've got no challenges getting all the gears on my 11sp, it shifts very well and I even went from the "stock" 11-42t cassette to 11-51t and still no issues across all gears

It's such a pain to try the other things to address if it shifts fine with the 10mm I'd say run with it

[73Eldo]

The original ring must have been smaller than I thought, it looked like it would have tucked in there better to me. I'm not sure if grinding would help much, the angle its hitting at isn't as sharp as it is on some bikes where a little goes a long way. Did you get a stock 46t ring with that setup? Does that clear the frame the way its installed now? Looks like it might. Its about inline with the seam in the gear case. Lekkie 40t is as small as you can go with that much offset. How big can you go in a freewheel, 18? Does 40 18 get you in the range you want? If you got the stock 46 maybe throw it on and see how it rides. With the help of the motor you don't need as low of gears as you do without it. Maybe a 42 would be fine?

Changing the dish on the wheel won't help unless you have a bunch of spacers on the axle you can move around.

[BrandonNorCal]

Ok looking at the wheel I don’t have spacers on the axle so you are definitely right dishing the rim won’t make a difference. And I already have maxed out my spacers for the back wheel so I can’t mess with it on the rear. Putting the stock 46 tooth chainring brings the chain line back in to what will probably be a good chain line. Roughly the 10mm I was looking for. The biggest freewheel I have is 21 teeth. I have no idea how this motor will perform so I’ll just play with the gear ratios that I have at this chain line. Lekke 40 tooth looks like my next purchase lol.

also the clearance for my cranks where I was thinking of shaving the motor is on the non drive side. My end crank just brushed the motor case. Is there room to grind here?

[AltaBrad]

... also the clearance for my cranks where I was thinking of shaving the motor is on the non drive side. My end crank just brushed the motor case. Is there room to grind here?

I wouldn't grind the motor case. A little grind likely would not affect the strength of the case appreciably BUT how much is "a little grind"? Unless you know the case thickness where you intend on grinding AND you can tell how much you're grinding off then you're just shooting in the dark. If you grind it too thin it might crack. I'd risk that on a well used motor that doesn't owe me anything but you're talking a brand new motor here, right? Investgate what a new case is worth beore making a final decision. And there are warranty considerations too.

Why not grind the crank arm instead? The one in the pic looks fairly meaty to me. Unless it's dear to you for some reason (maybe very expensive?), I'd recommend grinding the crank arm. Don't hack an abrupt notch out of it as that causes a stress point at the notch. It's known to metallurists and welders as "notch defect" and I guarantee you it IS a thing. Feather the grind out so the contour doesn't change abruptly. Leave no scratches, work them out with a medium to fine file, finish with coarse emory cloth or aluminum oxide paper. ALWAYS use a sanding block.

If the crank arm does crack and it's weldable then you can repair the crack and build up the thickness with weld. If it's some unweldable alloy then all you can do is replace it. Costs associated with this option I should think would be less than replacing a motor case. Again and as always, the cost of a weld repair or new arm figures into the decision.

[DaHose]

I'm with Brad. If you can't use a spacer to move the motor over, verify the crank arm is NOT HOLLOW and grind it. If it's hollow, then you would want to grind, and have someone weld it. Honestly, at that point you should just buy crank arms with more offset.

I also REALLY like the geometry on that frame. The center triangle right above the BB looks perfect for a custom shaped battery. Or you hang hang one under the lower down tube, or even directly above the motor. You have a ton of clearance to the tire.

Jose

[AltaBrad]

If it's hollow, then you would want to grind, and have someone weld it. Honestly, at that point you should just buy crank arms with more offset.

Jose

The possibility of the crank arms being hollow didn't cross my mind. I agree with Jose. If hollow then:

1. move the motor over with a spacer
2. buy 2 arms with more offset.
3. if not fussy about mismatched arms then from a spare arm make just 1 arm with the required offset... set the arm on a big solid anvil and whack it with a big hammer OR finesse it in a hydraulic press OR if it's steel then cut it, move it out and weld it together again... know any blacksmiths in your area? an experienced blacksmith with a forge furnace can work wonders, heat it red hot and bend to desired shape, cool slowly to prevent hardening and embrittlement.

It's just that looking closer at the pics it looks like the arm has a long way to go before it tightens onto the crank. I am convinced that if you grind on the motor case you'll grind right into the case and the arm still won't tighten onto the crank. Think how hard you're gonna kick your own arse when that happens. We tell ourselves "nah, it isn't that much" because we're looking for a quick 'n easy solution.

Thoughts on using a spacer to move the motor over....

It will definitely move the chainline out. If you can deal with that then realise whatever you add to one side of the BB (bottom bracket) the same amount must be subtracted from the other side else the motor clamp might be too narrow which would necessitate reworking the motor clamp.

Also, the spacer needs to be attached solid to the BB . If not then guaranteed it will eventually wear loose and the motor will wobble around, guaranteed. Yes, you will be able to re-tighten it but eventually re-tightening won't work because the mating surfaces will no longer be parallel. Been there, done that, you don't wanna go there.

Unless you can determine the dimensions of the spacer on your own you should take the frame with the motor and crank arms installed to a machinist and show him what you're up against. He'll measure things accurately and scratch his head bit but he'll make you a very accurate spacer. Tell him the spacer OD needs to be 1/4" bigger than the BB OD. That will allow 4 nice little fillet welds, each 1/2" long, spaced 90 degrees apart on the circumference. A continuous weld around the circumference would be more waterproof but the crank bearings will be sealed inside the motor so water isn't an issue. A continuous weld around the full circumference might cause heat distortion so avoid it. Besides a few coats of paint on it will seal any leaks. Yep, you're gonna burn some paint off that beauty frame but get used to it or forget about custom DIY installs and just go buy one ready made off the showroom floor for twice the money.

[BrandonNorCal]

I don't think the crank arms are gonna work. That part of the bottom bracket is affixed to the motor and as far as I can tell doesn't move right or left its just always in the same place relative to the motor so for now I don't get to use my sweet White Industries crank arms. No biggie. I'll use the ones that came with it until I get some blingy ones that are compatible. The aluminum crank arms aren't hollow but I'm just not up for grinding them right now.

[AltaBrad]

Wise decision! And remember... you're gonna be moving so fast nobody is going to notice you're using blingless crank arms anyway :)
They'll just hear a whoooosh as you go by and maybe see a streak of color and they'll say like "wtf was that, a low flying jet?"

[BrandonNorCal]

Allright. The bike is coming along very slowly but now I can say I have all the components necessary to get this runing EXCEPT FOR THE BATTERY. I'm still not sure what battery to buy and haven't really done the research to do a custom one. I'd still like to get the battery low or under the seat but again I haven't even made a cardbord cutout of any of the shark or triangle batteries available much less a custom one. I had a pretty bad over the bars spill that shook me up so I've kind of just been avoiding bikes for a couple weeks but now that the handlebars and stem came in i'm ready to get back to it. Here is a quick mock up. Obviously its not ready to ride but it gave me an idea of what the finished product will look like and I'm pretty stoked at how it looks. Those aren't the final tires and probably not the final wheelset but they are definately serviceable and I don't have a problem running them for awhile while I work out any gearing or alignment kinks. The motor is mounted solidly and I'll start with the chainring that I have. I was able to knock 2mm off of the alignment so its about 8mm off right now. also I have a chain tensioner that isn't shown here but if the eccentric hub works properly and doesn't rotate under electric torque then i may not need it. as with all my bikes I'll be using OURY grips. any suggestions for the color?? My first instinct is to go glow in the dark ha ha! I had red on there but not sure if red grips and red bars is enough pop.

[73Eldo]

I'm not sure about the grips. I had to zoom in to see the bars are red so I don't think red grips would be good plus I have not seen a red plastic that looks like that red anodizing. I think you should try and find silver brake levers and a silver seat post. Maybe some gray grips? That kinda go with the silver? Do some gray wall tires so those will tie in the grips?

For a big ass battery maybe mock this up? This looks like its got the mounting slots all around so it could easily go upside down from how things usually mount. Note that Grinn is in Canada and they have a surcharge to ship batteries to the USA. Not usually a deal breaker for a unique quality item but may not be worth it for something you can get other places or lower end stuff.

https://ebikes.ca/shop/electric-bicy...e-battery.html

Some of the sharks look like they could fit too but again upside down and those don't give you many ways to attach them since they have that dock cradle thing on the bottom.

[BrandonNorCal]

Well it's finally up and functional. What a blast. here is a photo from this weekend's first trail ride. I got to use my nice cranks after all. it was really easy to file the backs down enough for clearance and there is PLENTY of meat left on the crank. 16 mile ride mixed between getting to the trails/ steep fire roads and actual technical trails. I have a question about how much charge I have left on the battery after that ride. does this look like just under half of the battery or is there a voltage that I just need to call it quits at. I never felt like I was struggling or losing power.

the battery is in the only real place it can fit on the frame and I did get the GITD grips. yes they got dirty right away. yes they glow like crazy when I turn the garage lights off. I'm still working on cable routing and maybe putting the controller lower on the bars.

I guess I'll start posting in a differenbt section now that it's built and i've introduced myslef!