BBS-02 750w Kona Stinkin'Coiler build


10 kW
Oct 17, 2012
Thought I'd finally post some of my experience with this mid drive kit.

I had been using a 1000w rear hub motor. I am riding technical single track in the local foothills, with some good uphill slogs and good downhill sections. The hub would get hot - although I did abuse it. Problem was the weight and the fact that the chinese rim and spokes were crap. I had the spokes tightened and the wheel trued every few weeks. Finally broke a few spokes and decided to switch over to the Bafang mid drive.

I ordered the kit from GE bikes shipped to the states for $520. The shipping took a few weeks, but I ordered it during the winter months with snow, so didn't matter much to me. When it did arrive I tried to get the lbs to install it. I had a Marin quad xlt quasi downhill bike that I bought intending to use for this BBS drive. I drop the stuff off pumped to ride it the next day and get a call a few days later with the tech saying it doesn't fit. I drop by the shop to see what he was talking about thinking I'd show him - cause I knew it had the right sized bottom bracket. Only to have him show me the attachment points on the frame for the chain guard were in the way of the motor sprocket. Pissed I go home and grab my cross country bike, a Gary Fisher sugar 4. The shop guys have been commenting about not working on ebikes any longer due to reasons unknown to me. (liability? or just don't want to see them on the hills?) I convinced them to at least remove the bottom bracket and I would do the rest. *I didn't and still don't know much about bike repair as you can tell by now. I got a call the next day saying the bottom bracket would need to be drilled out at an extra $50 charge on top of the $30 BB removal fee. This was after the $50 fee for BB removal and cleaning on the Marin. I felt like I was getting in much deeper than planned. Doesn't it always work that way? I also end up having to go to another bike shop to buy a spanner to tighten the BBS bottom bracket for another $20. Anyway, I get the bike home without the bottom bracket weeks after I wanted. It installed pretty quickly and had it all wired up fast. Didn't take more than an hour or so.

For batteries I had been using two 6s Hobbyking lipos in series on the hub motor and would get a good 30 minute ride at balls out pace. 15mins up and about 15mins down. These were velcroed together and placed in the bottle holder of my old bike. I did the same on this setup. I placed the thumb throttle on the left side, since the front derailleur was of no use. I liked having the twist throttle on the right hand side on the hub - more like a motorcycle. Not too big a deal. It did take some getting used to. I programmed the unit for 9 PAS settings. The first few rides went well, more like a bike instead of a motorcycle like the hub. I was gradually ramping up the assist level to find out the distance and speed I'd get starting out on 4. My times weren't nearly as fast as the hub, but I didn't use much battery. I had never used PAS before and it took some real adjustment. I'd pedal the hub until I needed a boost and then hit throttle. I could stay in the correct gear for my legs to help the motor, but with the PAS and the 44 tooth sprocket, my legs couldn't help. On the big hills it was a pain and the times later where the battery ran low, I'd just turn around and ride downhill. That didn't always work due to some uphill sections. I did finally start getting used to the setup and really enjoyed the extra distance the mid drive afforded. The weighting was also much more natural. It felt like a real bike - heavier but with similar balance. The rear hub was much heavier and weighted toward the back. I had some nice wheelie rides climbing hills on that. I finally had a few runs that were faster than with the rear hub. I do like to piss all the local Strava guys off on a few trails. I know some of the riders, so they know its a joke, but there is some cruel humor in blowing by a sweaty lycra caveman. The mid drive is discreet enough that I wonder what these guys are thinking when someone in shorts and sweatshirt passes them. I'm thinking of getting the spandex out so they don't yell at me.

After the first few weeks, the speed sensor went out on me. I don't know if it was too many roots or rocks that bounced it loose or what. The motor still ran, I just had to set everything and go. I couldn't change settings on the fly or check battery/speed any longer. Literally that same week I came burning around a corner and the bike stopped on me. I look down and the rear triangle had broken. This is when I recall the bike mechanic saying the frame might be cracked in the same area as it broke a month or so ago. Not only was the frame broken, but the speed sensor wire was spliced in half. At this point the weather was still marginal and I had to have this bike for the spring and summer.

I abusing our local classified for bikes I finally give up and put some money on a Kona Coiler with a Stinky rear triangle. Hence the Stinkin' Coiler. The kid says its a sweet downhiller and I'll love it. I double check the bottom bracket and frame to make sure it will work this time. I couldn't remove the BBS-02 from the GF sugar for the life of me. The cranks are such soft metal that the crank remover I borrowed from my neighbor just stripped the threads. I also noticed that the standard square taper remover was hitting on the cranks and not completely on the bottom bracket. I would make sure you file this part on your BBS cranks to make sure you can some day remove it. I finally had to pound the right side off after riding until the left fell off. The BB on the Kona came right off and I got the BBS installed just as easily. The Kona is a much better ride than than the sugar for my trails. I can bomb up hills as fast as going down. It has 8" travel on the front and 5" on the rear. My speeds were even higher than before. After getting the KOM's on the trails that I am riding, I've since been able to tone it down and ride for pleasure and safety. I've also been able to ride at least double the distance that the hub motor would take me on the same batteries. I've ridden a few times with 10ah of batteries, but I don't enjoy riding for much more than an hour or so. That setup leaves me with plenty of juice left. I do ride mostly on level 6 assist now.

I would still like to fix the speed sensor. Weirdly enough I now only have two wires coming out of the motor housing. Somehow the speed sensor wires either ended up inside the casing or fell off before I got it installed on the Kona. I didn't see them anywhere on the garage floor, one day I will open up the motor and find out.

The first recommendation I have is to get Crossbreak's adapter if you are going to ride single track. It made a huge difference in climbing hills for me. I could help the motor out and at least be in somewhat of the correct gear for long hill climbs. I've had the motor cut out a few times due to heat and battery sag and it helps to be in a reasonable gear. I've been using a 36 tooth front sprocket, which is perfect for my use. I talked to Crossbreak about even using a front derailleur and having a 24/36 combo, but no longer feel like I need that. If i was into doing longer rides, it might be nice, but I just do after work rides from my house to the hills and home. I did try and replace the Bafang cranks with the square taper cranks I purchased, but ran into the same issues trying to remove the cranks from the BBS. The crank remover would just strip the threads of the BBS cranks.

Second thing is to have the unit programmed for your liking. I do not like the throttle pause. I wanted the throttle to give me power instantly. I pedal up the hill with PAS and when my legs slow down and I need I boost, I want the throttle to give it. I've ended up stopping on a hill more than once because of this. The smaller sprocket has helped this - but it doesn't work for mountain biking. The other programming feature for me would be to have full throttle on all assist levels. I personally only use the throttle now when I really need help. I have grown to like the PAS because it is so much more like a bike. The people I have had try my bike who mock the ebike idea say the same thing - its like they have the wind at their back. They don't notice the motor/electric part at all.

For all the trouble this has been - I have enjoyed getting out on the trails immensely. I look forward to getting on the bike after work and it isn't some sweaty slogfest like I'd been used to be when I had to rely on myself to power me. I get as much exercise as I want to on any given part of the trail. I think it gives me a better workout since I ride further and more often. I've been very happy with the purchase so far. I can't say that I'm excited to see others on the trails with this setup because I'm sure it will get abused quickly around here.