No announcement yet.

Noob Looking for help specing a conversion setup......

  • Filter
  • Time
  • Show
Clear All
new posts

    Noob Looking for help specing a conversion setup......

    Been looking at an e-bike/conversion for the bride. She has a bum foot (chronic stress fracture) and trying to figure out what to do to keep her in the saddle. We were in Portland a couple of weeks ago, and she rented the Raleigh with a Currie mid frame PAS bike for the day so we could ride around downtown. She was pretty much sold after she left me in her dust riding up the hills and over the bridges with 1 foot in a walking cast.
    So...last few weeks I have been trying to figure out if there is an ECONOMIC way to get her on an e-bike. This is not a commuter, this is a rec ride. I ride a fair amount both on and off road and can wrench ok so willing to take on the challenge, she prefers the road or improved (paved) trails and typically rides a max of around 10 miles on a ride.
    Spent the last few weeks looking at the alternatives...not gonna throw down $2K++++ on a rec ride. So, started at the bottom looking up at conversion kits. After doing the homework, have looked at and ruled out hub designs direct, geared and double drive/double torque motors for various reasons.

    Am now looking at the BBS02, and converting her existing bike, a Trek Shift2 21sp step thru frame. The current drive system is bit of a bastard setup, SRAM "Gripshift"3.0 shifters, with the drive system consisting of a Shimano front derailleur (which would go away) w/3 chainrings, a KMC "Z" narrow chain, and a SRAM "X-3" rear derailleur, with a 7spd cassette. The cassette has 14T-34T gearing, with a "Megadrive Superlow 34T" granny gear, on a no-name hub (presume this is a Shimano or clone freewheel/cassette setup). Think the 750W BBS02 should do the job for her, not looking for a super heavy duty off road marathon ride and the smaller motor ould fit her existing bike better...I think...(see below).

    So...what to do now?
    I am guessing I can hang onto the chain/rear drive, yank off the crank arms/chainrings/bottom bracket and front derailleur and throw on the standard BBS02 slung under the front of the downtube...but I don't like to guess or get surprised so want to answer as many questions as possible before pulling the trigger. I've done most of my homework, but still a newbie and don't know what I don't know.

    I measured the bottom bracket at ~70mm wide x 40mm inside dia. with a shell wall thickness of 3mm (eyeballed with a scale, don't have calipers). Will the standard BBS02 fit onto this BB shell?
    I also have 2 cables that run under the BB shell, the front derailleur cable will go away, but the rear derailleur cable will need to stay. It is sheathed and there is a little plastic guide pad screwed into the bottom of the BB shell. These are a total thickness of about 10mm (5mmm sheathed cable and 5mm for the guide pad). So from Center Line of the BB I need 23mm+10mm=33mm to the outside of the cable housing. Will the motor fit over the BB and rear de cable? By my calcs and looking at the BBS02 schematic, there are 29.5mm from the CL of the bottom bracket to the outside face of the motor housing. So... it looks like a tight fit. Pulling off the guide pad gets me w/in a mm....anybody have any help here?

    Next...will the BBS02 play well with this rear drive setup? KMC chains are pretty common, but not so sure about that rear SRAM derailleur and cassette. The granny cog is pressed steel and almost a wide/narrow profile. Not the end of the world if it wears fast, that seems to be a cost of doing a mid drive e-build anyway, as long as they are compatible. I'll cross that bridge when they wear out, just don't want to start the build and then find out I need a whole new rear drive train. Also, looking to go with the standard 42T ring, assume the bigger rings give more speed (which we/she would not need..I'll have a hard enough time keeping up with her on her 52v system), any benefit of going any bigger or with the Lekkie...besides bling (and the blue which she would want is not stocked)?

    Think the bride would like a PAS vs throttle only system, the bar setup she has would mean using the existing right twist for rear derailleur, pulling the left twist and putting a thumb throttle on that side. I test rode a similar setup with what looked to be a DPC-14 display and really like the way it worked. That ride had sensors for brake cutoff instead of the standard replacement Bafang electric cutoff style brake there a pro/con to either?
    Also, looking at displays, the 750W looks really really nice, but at 4.35" between the brackets, it would land just on the curve of her existing bars. Not far in but definitely past the straight section. She also rides with bar hung on front basket, frequently with a dog in it that weighs around 12#. Her basket hangers are about 4.5" spread, I can bend them out some, but the recurve of the bar may still put some pressure on the display brackets. Is this a serious issue? I can always try to find a better bar set for her too, especially if the 750 is that much better than the it?

    Have gone all over the place here...from a mighty mini in a seat bag to now settling on a 52V bottle bat mounted on existing down tube bottle cage bolts as the way to go...sounds like this would give close to a 40mi. range and more power. A smaller 52V would be nice, but no such thing as a skinny mini bottle in the works... eh? The 52v has plenty, probably more go in it than she needs, too bad there isn't a bottle size (5-8a 52v), that's a bit smaller/shorter/less expensive and still looks nice...maybe someday? Also, considering the 52v 3 level charger, sounds like the best bang for the buck.

    So....would all this work? and what, if anything (besides a luna wrench) am I missing or will I need to make this roll down the road? Connectors etc...?

    You should be fine with the 750W, I wouldn't build on that clearance issue though> reroute that cable and ditch the pad or work on a different platform. I guess she probably wants to keep that frame style for ease of saddling? Otherwise I would just look for any steel frame hardtail MTB with decent componetry. Any rear derauller will work - I have used both a budget and high end. The high end (Deore XT) shifts fantastically under power so that is a big perk. PAS has been my favorite so far I almost never use my thumb throttle. I hate grip shift but had it on my last bike and it worked.

    Your BB should measure more like 73mm outside to outside width, that is the standard width. Calipers are nice to have... order some. You will need the tools required to remove the old bottom bracket - park tools - BB extractor and also you'll need the crank puller tool. Other than that there are no other connectors if you are ordering from Luna and have the included pigtails etc to hook battery to BBS02. If it's just a rec ride... dont' need mega battery. I have the BBSHD and 52v shark GA celled pack and am doing 25 miles and it just barely does it from an 80% charge finishing at like 43ish volts.


      Don't worry about the shift cable. Get a complete inner and outer from Amazon, preferably Shimano. They are cheap. Ditch that pad under the BB and then run the complete new cable.

      I have used 3 different left side throttles. The Luna left half twist throttle was the best of the lot. Smooth and progressive it would be an easy swap with the three spd derailleur control you are removing.

      The single greatest complaint with ebikers is not enough battery. My first ride was supposed to be a 1 mile test around the block. It rapidly turned into an around town cruise that drained my 11.5 amp/hour battery. I realized on that first ride that I needed more battery. Take the money you are saving on the BBS02 over the BBSHD and invest in a bigger battery. Look at this one.


        OK, let the fun begin....ordered the BBS02 kit and picked up the left twist throttle per suggestions above. Gonna stick with the 52v, 11.5ah bottle bat though, it looks pretty (and style matters to the bride) and will fit cleanly onto the bottle cage lugs for this first go around. I don't think the she will run out of juice soon with that many Watt hours available. If she does, that is a good problem to have!
        Gonna stick with adapting her Trek Shift2, so will start a thread on the build once the parts arrive. Also going to swap to cruiser style bars and replace the stock 24" wide hybrid comfort bar. Should give her more room for all the stuff she will have on the bars (right twist grip rear shifter, headlight, 750 display, basket, PAS level switch, bell and left side twist throttle grip). Plus, the wider cruiser style bars should help give her more control with a wider grip spread (28" vs 24 on the current ride) and should be able to lower the neck and extend it forward (it has an adjustable neck) and lower the center of gravity on the basket. With the e-kit and the dog, she'll be packing an extra 30-40 pounds on the ride vs empty now.
        I also ordered new cables per suggestions above as well, I doubt the brake lengths will work on the longer bars in any case and the rear de may need to be longer too if it needs rerouted. Hopefully this will end up being a pretty clean build. The looks matter, so cable management will be interesting, this bike has internal cable runs so I'll try to get the wire harness run inside the down tube cable raceway which might be a challenge. Also hope the stock cable harness is long enough with the extended bars. This should be an interesting build, thanks for the helpful suggestions, sure I will be asking for more help as the build progresses.


          The stock cables will be long enough with cruiser bars IF you mount the display off centered to the left.

          Click image for larger version

Name:	image_4801.jpg
Views:	115
Size:	450.6 KB
ID:	38005

          If you want the display centered you will need two 8" extension cables. One for the control switch and one for the throttle. Please note I have been using the magnetic reed switches instead of the supplied Bafang brake levers. These have nice long leads and work very well with cable operated brakes.

          Click image for larger version

Name:	image_7637.jpg
Views:	110
Size:	531.7 KB
ID:	38006


            OK, more than a bit confused...First, this ride does not have hydraulic disc brakes, the ride has cable "V-brake" style rim brakes. The Luna link above calls these: "Bafang Hydraulic and Disc Brake Sensors E-Brake (Pair)"

            Sounds like you are saying these ARE compatible with "cable" style brake systems? If they are....this is unclear on the Luna site, also, if so, it sounds like these may be a better choice than the standard levers. Sound like I may have already potentially screwed up when specifying my order (which has been placed and I believe shipped). I just ordered the "standard" Bafang E-brake levers. Are you saying that these "brake sensors" (ILO the standard brake levers) will:
            A) be compatible with cable style brake cables/levers?
            B) have a long enough wire to "reach" the standard wire harness without an extension (whereas the "standard" levers in the kit may not be long enough?)?

            With regard to the display/controller, are you also saying this will need to be offset to the left "reach" the PAS controller/switch from the left handgrip?

            Sounds like the wire harness and hardware may be tighter than I hoped for or expected. I also have ordered a set of Sunlight bars off Amazon ( which have not yet shipped but are not super wide/deep. They have a 3" rise 8" setback and 27" spread, not as wide or deep as some cruiser bars I have seen.

            Since this is gonna be a comfort hybrid conversion, I believe the cockpit (distance from seat post to head tube is 22 1/4" CL to CL) is not as deep as an Electra cruiser. I didn't want the bars to get too long/deep and impinge on rider with turning radius. I also went ahead and ordered a full set of cables (brake and rear DE) expecting they would be too short or need to be re-routed, but had not anticipated the wires from the kit could also be too this gonna be a problem? It would suck to not have long enough electric cables to reach the standard harness on the new bar set. Also, IF I were to decide to go with the swapping to the sensors vs the brake levers, how is Luna on restock/swapping? I was hoping to avoid this kinda of coordination problem but looks like I may already be in the do-over mode....argh!

            I just checked and the bars have not shipped, so if this is gonna be a problem, can you let me know asap? Gut says we'll need the new bars anyway, but hate to figure this out a day late! arghh... (see note above "Let the fun begin....)"

            Also, I went ahead and ordered the 750C display not the DPC-14 which it looks like you have on your rides, assume these will be pretty similar in cable layout/length...(I hate to assume)...
            Last edited by thedadude; 06-19-2017, 04:30 PM.


              This is text from the Luna page on those reed switches. I underlined the important sentence.

              "Price is for pair Plug and Play into any Bafang controller
              • Compatible with all BBSxx set ups
              • Transforms any brake levered based brake into an ebrake
              • Cuts power the second the brake lever is compressed
              • Uses a magnet attached to your brake lever
              Here it is installed on the backside of my Shimano 3 spd trigger shifter (note the magnet on the brake cable)
              Click image for larger version

Name:	image_2539.jpg
Views:	121
Size:	352.8 KB
ID:	38131

              Most bike handle bars are 24" wide and the harness is designed for that. Most Cruiser bars are 28" wide plus they sweep back besides. I was showing you what I have encountered with a DCP-14 I have no idea what the length of the leads on the 750C are.


                Thanks! I may try and switch to those if the order from Luna has not shipped yet.