# the wife's eBike build



## cfanto (Oct 13, 2010)

Converted the wife's Specialized Myka to an eBike...
While my son & I vowed we'd never use one ourselves on the trails, it was an option I considered for the wife as she's always wanted to join us on MTB rides but her fitness level & lack of exercise has dissuaded her from going. Unfortunately, she doesn't get the chance to ride often enough to build up her endurance. The intent is NOT to use the throttle at all (I've actually got it disconnected) - only the pedal-assist system to help her up the hills, so she'll still get her exercise in as she still has to spin her way to the top - just with less effort.

We're actually quite pleased with the build. The bike looks & sounds stealth - you can't immediately tell it's motorized and it's incredibly quiet.








DONOR BIKE:
Make/Model: 2013 Specialized Myka Sport, size: extra small
Cassette: Shimano HG-61, 9spd, 12x36T
Rear Deraiulleur: SRAM X7, 9spd (non-Type 2)
Shifter: SRAM X9, twist shift, 9spd
Brakes: Tektro Drako, hydraulic (converted from V-Brakes to hydraulic disc's)

THE BUILD:
The motor is a Bafang BBS02 48V, 750W mid-drive system ordered as a complete kit from Luna Cycles. I was actually looking for a 500W unit, but no one seems to stock them anymore. And the 1000W BBSHD would be way too much ebike for her. Also, knowing the stock 46T chainring would put too much strain on the motor for most of our Bay Area hills, I added the optional Race Face 34T Narrow-Wide chainring & adapter. While a 30T would actually be more ideal, I believe they only make a 30T kit for the BBSHD.




















Driving the motor is a 52V, 13.5Ah slim line battery pack made up of quality 18650 cells - supposedly the same Panasonic cells used by Tesla. This battery pack was actually designed to be mounted on a bike-mounted rear rack. With the wife's Specialized Myka being an extra-small sized frame, there was no room to frame-mount the battery & adding a rear-rack would only be a last resort as having dead weight sitting rearward with a high center of gravity will affect the handling of the bike. So instead, I opted to run the battery in my old Osprey Zealot hydration bag. The battery weighs ~8lbs. but when carried in the pack, it doesn't weigh much more than when it's fully loaded w/ 3L of water, tools & other gear. However, I may end up purchasing Luna Cycle's Mighty Mini Cube battery pack which is only 3lbs & rated for 6Ah as I'm thinking the 13.5Ah is a bit overkill (based on today's testing).




















INSTALLATION:
Fairly straight forward - remove the crankset & bottom bracket & then install the motor unit, speed sensor, & finally, the control/display unit. Since I have a bike stand & all the necessary bike tools, installation was actually quite simple & quick. The only thing that really took the most time for me to do was soldering the battery connectors & heat-shrinking all the cabling. I actually purchased the optional hydraulic brake motor cut-off kit - what a gimmicky POS! Plus the odd shape of the brake levers made it difficult to mount the magnet - which I guess you're supposed to attach via zip ties?!. So into the parts bin it goes - maybe I'll try to pawn it off on fleaBay later. Also glad I didn't waste money on the shifter motor cut-off kit (which kills the motor momentarily when it detects shift cable movement to allow shifting under your own power) - the bike shifts smoothly even while under power - no heavy clunking or crunching of the chain or gears while shifting.

TESTING:
Initial testing of the bike on the streets, pedal-assist works fine. You have to pedal a good cadence for PAS to work - cadence too low, PAS won't kick in. When you stop pedaling, the motor stops as well. The unit also shipped with a thumb-throttle (which I mounted upside-down for safety reasons). However, I felt the throttle applied way too much power and doesn't apply it gradually which results in instant wheelies - which scared the sh1t out of me the first few times. The throttle works more like an on-off switch rather than an accelerator - the wife & I didn't see a need for it, so I left it mounted but disconnected.

Today we actually went out for a hill climb on a trail that the wife usually dreads. In the past, she's had to make several (long) rest stops & most of the time ends up walking half-way up the hill. While it typically takes me less than 18min to climb to the top, it's usually more like 45-50 mins with her. But today, she pedaled her way to the top on Pedal Assist Level 1 with a big smile and made only a couple of short stops basically just for water breaks. During these short stops I touched the motor to see how hot it was running (I haven't done the aquarium temp mod yet) but it was always just barely warm. She's really loving her 'new' ebike... & I am too since now we can now enjoy the ride(s) together.


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## kneecap (Dec 20, 2003)

Pretty cool, did you do a lot of research before the purchase?
Was the complete kit expensive?


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## rider95 (Mar 30, 2016)

A great way for the wife to now be included in your rides , Soon you will be planning your weekends with ways the wife can use her e bike she looks really happy lol e bikes will do that.


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## cyclelicious (Oct 7, 2008)

Good job. I hope your wife continues to ride... she does look very happy


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## rider95 (Mar 30, 2016)

Why use such a big battery?? and 52v ? why not a 36v bottle type?? or 46v it will fit better and in the right place on her bike .


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## cfanto (Oct 13, 2010)

kneecap said:


> Pretty cool, did you do a lot of research before the purchase?
> Was the complete kit expensive?


Yeah, did some research. But there wasn't a lot of info regarding mountain biking up long climbs using PAS - seems like everyone just wants to throttle their way up to the top. Based on the research, it looked like 500W @ 48V would be more than capable for what we were looking to do but getting information regarding battery capacities was a crap shoot. All the times given for a given capacity were primarily for street use/commuting. So I ended up going a bit overboard w/ the battery capacity. Based on yesterday's ride, an 6-8Ah battery would've sufficed.

Regarding pricing - I initially looked at fleaBay kits. I could've probably picked up a 750W, 48V kit w/ a slim "Dolphin" style battery for ~$950. But more researching led me to order from a reputable company due to everyone else's frustrations - most of these guys/gals ended up paying way more than if they bought a kit from a reputable company. Typcially, the no-name batteries are a crapshoot & the motors from overseas have no guarantee they have the updated controllers even if they claim so. IIRC, I paid ~$1200 for the entire kit. However, if I actually went with the 6Ah Mighty Mini cube battery & did away with the hydraulic brake motor cut-off kit, I would've saved over $100.


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## cfanto (Oct 13, 2010)

rider95 said:


> Why use such a big battery?? and 52v ? why not a 36v bottle type?? or 46v it will fit better and in the right place on her bike .


Yeah, I over did it with the battery. I could've gone away w/ a smaller capacity such as Luna Cycle's Mighty Mini 6Ah battery: 
52v Mighty Mini Cube Ebike Battery Pack Panasonic PF 6ah - Luna Cycle

As for voltage, there were plenty of 36V 500W mid-drive systems around, but I felt that was more suited for commuting. I knew some of the long hill climbs we were going to run into in the mountains was going to put a lot of strain on the motor so I made sure I went with at least a 48V system as it would be more efficient by drawing less current, therefor less heat, than a 36V system would. This would help save the controller as the MOSFETS are the ones that usually gets fried from pumping too much amps thru them & overheating. The controller is capable (I believe) up to 60V, so driving the motor w/ 52V (fully charged is ~57.4V) would provide a bit more performance while drawing even less amps & heat.


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## fos'l (May 27, 2009)

Great idea; I do the same on some longer rides with my wife. So you know, I got a Luna 30 tooth chainring for my BBS02; it fits without an adapter and completely transformed my bike for off-road use.


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## NEPMTBA (Apr 7, 2007)

Nice build and report...
...more power to you and your wife!


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## rider95 (Mar 30, 2016)

The GF n me were riding the bike path sunday when we saw a Sondors yellow fat tire bike the guy said he only paid $500 for it !!!! I have been promising to convert her bike to elec for a year now but cant get my BMC motor back from High Power Cycle . So now she is like its only $500 I want one !!!! . And for my next builds I will be using Luna also I an tired of the crap HPC sold me at a higher price . And Luna has up grades for the Sondors !!


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## formula4speed (Mar 25, 2013)

Any concerns about the motor getting smashed by a rock or a log? Seems pretty low to the ground for a MTB.


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## WoodlandHills (Nov 18, 2015)

Mine is no higher and I've never hit anything. Some folks have added skid plates around the motor, but I would worry about restricting the flow of cooling air in summer. I think eventually someone will build an MTB frame specifically for mid-drive motors allowing us to put it into the triangle...... Some are close already, you just need offset the seat tube to the rear a bit at the BB and use a curved downtube as is the latest fashion anyway.


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## Sanchofula (Dec 30, 2007)

Humble pie time, but I am on the exact same path for my wife. 

I'm a strong rider and she is not, her fitness level is not good, so when we ride together it has been on a tandem. Tandems are great fun, we love riding together, BUT they limit what you can do because the stronger rider pulls the weaker rider along; also tandems don't handle as well as a bike.

So after reading about the Specialized ebikes and talking with a friend and his wife, I started thinking that this might be something worth considering. I don't think we'll do a custom build, I am leaning toward the full suspension specialized 6fatty because it has good geometry, fat tires for mixed surfaces, and it's a nice clean package.

This morning I suggested selling the tandem to fund an ebike ... she didn't seemed displeased with the idea


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## WoodlandHills (Nov 18, 2015)

Yours is the most common reaction from MTBers I meet on the trail: they say "maybe now I can get her to ride with me!". I know that my wife asked me to build one just for her.......


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## Bigwheel (Jan 12, 2004)

Nurse Ben said:


> This morning I suggested selling the tandem to fund an ebike ... she didn't seemed displeased with the idea


Actually motorized bicycles are a lot like a tandem in that they are a little heavy and rely on a stoker, in this case a very fit stoker, to balance the scales. But I wouldn't be surprised if your wife is thinking more about seeing the trail in front of her than your back!

Don't be afraid of doing a refit of a regular bike, its not as custom as you think. With the mid drive BBS02 it is pretty much plug and play. The best thing about it is you get a throttle mode also along with the pedal assist. Especially in tight situations it can help make a difference, especially with someone not as sensitive to crank timing (which you have had control of on the tandem) and allows for easier take offs. e bike throttles contrary to popular opinion are not the devil if used in conjunction with pedaling. If you read the ride reviews on the Levo one of the complaints is that they don't "stall" well due to the PAS being slow to come back on when you start to pedal out, blipping a throttle in that situation makes it better, then continue on pedaling.

Figure about $1200 for a complete system and add it to the b+FS bike that fits her the best. Also there is no need to go $$ on the componentry because even the mid grade stuff works fine these days and there is no need to count grams.


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## Sanchofula (Dec 30, 2007)

WoodlandHills said:


> Yours is the most common reaction from MTBers I meet on the trail: they say "maybe now I can get her to ride with me!". I know that my wife asked me to build one just for her.......


For a long time it was not a problem, I was riding mountain unicycles and she rode abike, though I still had to wait for her and I was able to ride more difficult terrain, she did well enough that we could ride together.

When I got the tandem we alternated between bike/muni and tandem, so she was riding with me anytime she wanted, but since I started riding bikes she is no longer able to keep pace so the only time we ride together is on the tandem.

I kinda like her, so I miss not riding with her...also, to be quite honest, tandem riding is hard and I'd rather ride my bike


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## cfanto (Oct 13, 2010)

*Just A Quick Status Update*

Just a status update regarding the LunaCycle 52V, 13.5Ah slim line battery pack...

A buddy of mine had been wanting to go out riding but was concerned about ankle pain & didn't want to put a lot of load on the foot so I told him he could try my wife's converted e-bike. Needless to say, he had a blast as he pedaled up the hills, sweeping back down for us & then charging back up again a few times on some of the longer climbs... though watching him pedal by while struggling up some of the more rocky, technical climbs was pretty demoralizing . And since PAS literally made the hills feel like pedaling on flat ground, he had no issues w/ ankle pain. He tried the different PAS levels & pretty much found the sweet spot at level 2. By the end of the 15+ mile out and back ride, I was surprised to find that the battery was only down to ~78% (and this was with him occasionally playing around with the throttle).

While the 13.5Ah slim battery pack works great, I clearly could've gone with a LunaCycle 6Ah or 7Ah Mighty MiniCube... esp. if the bike is kept in PAS-mode only.
In this blog, the tester was able to fit a Mighty MiniCube in his front jeans pocket, eventually tossing it in a saddle bag. I think the Mighty MiniCube is gonna be on my Fathers' Day wish list.


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## fos'l (May 27, 2009)

Those mini-cubes seem like a good solution to various fitment challenges. Monday morning quarterbacking, but if one purchases two of those, use one or the other, then take both for longer rides.


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## Bikedriver (Jun 11, 2016)

Very cool! Nice work. 

I know what you mean regarding your wife. I rarely, pretty much never, rode with my girlfriend....She just didn't like it. Here is the build she has been riding starting about 6 months ago. She really enjoys riding now. Of course, it's not magic, it doesn't allow her to ride extremely technical terrain with me, and never will, she simply doesn't have those life long skills and that certain passion for off road one needs. However for road, dirt roads, and very easy trails, getting her on an ebike has been really fantastic, we go often now and we can more or less always stay together. The best part - Always a big smile on her face.


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## bsrhoad (Mar 21, 2014)

Same with my wife. She really enjoys riding, but hates the long climbs. This really limited the routes we would take when riding together. This spring we purchased her a Cube Hybrid Reaction, which has 4 levels of pedal assist (eco, tour, sport, and turbo) but no throttle lever. Now she can join me for those all day epic rides, with 1000+ meters of climbing, and at the end of the day still have a big smile on her face. Worth every penny...


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## hummer boy (Aug 23, 2004)

Just curious, did you ever buy the mini cube? 


Sent from my iPad using Tapatalk


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## cfanto (Oct 13, 2010)

hummer boy said:


> Just curious, did you ever buy the mini cube?
> 
> Sent from my iPad using Tapatalk


Unfortunately, not yet... I've been working on some upgrades to the fatbike & downhill bike.


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## PinoyMTBer (Nov 21, 2013)

Cfanto: Wow! I just realized who you are...Funny! I found a group of eMTB riders locally and it's been an awesome time! Let's ride again sometime.


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## jsalas2 (Nov 29, 2008)

Gonna do a similar build with backpack battery,was trying to figure out where the pack connects to the bike. Where does the wire hang while riding, will it disconnect in case of a fall. Yours are the only good pics that I have found with the battery in the pack. Thanks, Jesse.


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## cfanto (Oct 13, 2010)

jsalas2 said:


> Gonna do a similar build with backpack battery,was trying to figure out where the pack connects to the bike. Where does the wire hang while riding, will it disconnect in case of a fall. Yours are the only good pics that I have found with the battery in the pack. Thanks, Jesse.


I have the battery cable from the motor running along the bottom tube (adjacent to the cabling for the display, throttle, etc.) and have the XT90 connector hanging off the right side of the headtube. The battery cable from the backpack comes down from the left shoulder harness (right shoulder harness is reserved for water bladder hose) to the left side of the bike then around the front of headtube to attach to the XT90 connector that's on the right side of the frame. I do this as it seems to keep the cabling out of the way than just running it straight down. Hope that make sense.

In the 1st pic w/ the wife, you can see the cable from backpack fishing around the front of the headtube. And in the 2nd pic, you can kinda see the yellow XT90 connector dangling by the headtube area.

I've seen another guy run the cable up the seatpost. But it would seem to me that the cabling would get in the way every time you mount/dismount the bike or maybe the cabling rubs against your legs while pedaling.

Hope that helps!


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## jsalas2 (Nov 29, 2008)

Yes, helps allot, now that I know where to look, I see it now. Was thinking the same about it being in the way, along the seatpost.


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