BBS02 mid-drive kit BASIC issues - FIXED on Rockhopper!...

[i-Zapp]

First off, I love this kit. Purchased over a year ago and have put nearly a thousand mile on it (I live in NE Ohio, so no small achievement weatherwise lol). So, kudos to LunaCycle for developing a pretty legit kit right from the getgo.

However, as with most one-size-fits-all "kits", specific adaptation to each bike can be challenging and can make the difference between a good installation experience, and a bad one. In my case I installed the BBS02 on a 29" Specialized Rockhopper with the intention of using it for mostly road commuting and occasional MTB useage.

During the install I immediately recognized one of three serious shortcomings - securement of the motor using the large nut on the lower bracket is a recipe for disappointment. With even mild off-road use the likelihood of those nuts getting loose is nearly 100%. The first mod was creating the large white triangular bracket that attaches to the motor case, the lower bracket, and a two-piece clamp. Solid. 100% not going anywhere.

After finally getting some time on the new setup it wasn't long before I realized that chain drop (chain popping off during bumps) is a huge and extremely annoying problem. This issue stems from the fact that the front derailleur is removed and therefore there is no longer any lateral containment of the chain. Any side to side jostling of the chain and zing the chain falls off. The solution came in the form of 3D printing a guide and mount that conveniently attaches the 2-piece clamp described above. Previously I'd averaged 1-2 drops per ride, and with the guide in place I got NONE ever since even with intentional attempts to drop it going over rough terrain.

The last bit is a battery support. Although the failure mode never actually revealed itself, my anticipation was that the two little water bottle screws holding that big ass battery weren't going to last long given how much the battery wobbles on that skinny attachment plate. In this case the solution was an aluminum bracket that holds the rearmost part of the battery and holds it firmly in place. The design is trickier than it seems because its size is optimized for support and rigidity, but still allows for battery removal (it's tight in there!).

All these parts have been designed in Solidworks (3D design program). With enough interest I could be talked into making more of these in quantity. The challenge is redesigning them to be flexible enough to fit the majority of bikes.

Geo.

[AZguy]

With even mild off-road use the likelihood of those nuts getting loose is nearly 100%.

6000mi of hard pounding on a BBSHD build and the nut has never come loose - blue loctite (not even red)

After finally getting some time on the new setup it wasn't long before I realized that chain drop (chain popping off during bumps) is a huge and extremely annoying problem.

Had this issue with regular chain rings on my mid but once I got settled in with a narrow-wide have never had a chain drop in >3000mi

I have another bike (hub) that has a much worse chain line and it would drop almost every other ride - the narrow-wide helped but I still had a lot of drops... I fabricated something similar to what you did and that helped a ton but if the chain did get dropped it was far more a pain to put it back on with the guide in the way... eventually ended up putting guards on both sides of the ring and after a fair bit of fussing now have a solution that has yet to drop the chain and doesn't interfere with maintenance - has the added benefit of not sucking trouser legs into it too

Although the failure mode never actually revealed itself, my anticipation was that the two little water bottle screws holding that big ass battery weren't going to last long given how much the battery wobbles on that skinny attachment plate.

Conventional wisdom is to simply use a couple of straps around the battery and frame... I was lazy about this for a while and a couple of the tabs broke on the battery mount and the battery case cracked but I've never had any issues with the threaded portions in the frame and I haven't heard that as any kind of frequent complaint (not even sure if I've ever heard of it)

YMMV

[ClimberBill]

Nice job on solving those issues. I like your motor mount addition way more than I like loctite. And the 3D printed guide looks great! Maybe add some stylish lightening holes to your battery support?

[jnitti1014]

I'm interested in buying these! Especially the chain guide

[nondem]

I've got a 2016 Rockhopper Comp 29 myself...if I'm not mistaken that is what you have there...at least the same model/color. I'm looking to do the BBSHD conversion myself. If you could tell me the exact model /size motor you bought it will save me some nail-biting. I'm concerned about the issues with chainring clearing the chainstay and getting the right width etc...
Of course I'm obviously interested in the re-enforcements you have done but the first step is getting the right motor. :)

[73Eldo]

It doesn't look like the original poster has been online here since the day of that post so I would not get my hopes up too high that they will respond.

We can figure out a few things...... That build used the BBS02 which only comes in the 68-73 narrow style. The HD has a slightly larger diameter gear case which can cause issues with some frames but it doesn't look like that one kicks out very far or vert fast so should not be an issue. I would get some spacers like what come in the Luna install helper kit just to have them on hand if needed. In the photos there didn't appear to be any length issues getting both nuts on so I would not expect an issue with the HD even if you need a couple MM's of spacers because the HD's shaft is longer than the 02's even with the 'narrow' model.

Chain ring looks like its coming pretty close to the chain stay. I believe the HD's stock ring puts you in about the same spot. I would likely start with the stock one and see how things align. Most of us end up with a 42t ring. The Lekkie 42t has about 1mm more offset in than the stock one. If you have a lot of room with the stock one then the Luna Eclipse has about 6mm more offset and more color options that can be fun but if you don't have that 6mm of space could be more trouble than its worth especially since the Lekkie is an option.

Those extra brackets and guides are cool and if you have the means to do such things go for it. If you don't I would not worry too much about it. If you have the budget buy the fancy Bafang socket and with that you should have no trouble getting the thing tight. If you don't have or want to spend the money the flat wrenches work OK. The main nut you can use a hook spanner if you have one but the outter lock nut is kinda a unique size and only the $20 wrench fits it well. Get it good n tight and go for a ride then re tighten it and you should be good unless you are really going to pound the thing hard. Note that you will want to own your own crank arm puller tool both to remove the existing arms for the conversion but also to remove the Bafang arms to do things like re torque the main nut and do other major repairs if they come along .

For the chain guide there are companies that make those if you need one. If your bike has a front derailer now you may be able to leave it in place and just set the adjustment stops to hold it in place as a guide. Stop wise you should be able to set it fine because the new ring should be within the range of the derailer but the height could be an issue if its not the type that mounts on a clamp that can be slid up and down the tube.

I currently have 3 bikes with BBSHD's on them and only one has any sort of guide. The one with the guide is a early 1990's mtb and its the derailer. Not sure its needed but it was there and I didn't think it would hurt anything so I left it there. I also have a Surly fat bike that I take off road and a $400 wally world Schwinn that is my 'street' bike and those have no guides at all and almost 2000 miles between them with no chain issues.

When I was first buiding the wally bike which is a 29er that came with a 1x8 I started with the stock 46t ring and a new Sram chain because stock wasn't long enough and stock everything else. 1st gear just looked and sounded unhappy so I adjusted the stop on the derailer to not use 1st. Put a couple hundred miles on it that way while my Luna Eclipse 42t was en route. Went with the Eclipse vs the Lekkie (which is on the fat bike) because I had about 7mm of clearance with the stock ring. Figured that would get me 1st gear back since each gear is about 4mm. Put the Eclipse on and even in 2nd gear the chain wanted to ride up on the chain ring just in the stand. Thought about trying to fit a derailer I had laying around as a guide but didn't think that would be good long term for wear because something wasn't happy.

I also wasn't very happy with how well the 8 speed system shifted. Can you imagine that from a wally world bike? Another guy has the same bike and is fine with his so its got to be low quality control and sometimes you get a good one and sometimes not. I think the issue was in the shifter not having consistent spacing. Since I was unhappy with that setup anyway and had a very well used 10 speed Deore system laying around I swapped that on and its been great ever since. No issues pumping hard in 1st gear. No signs of the chain wanting to climb up the ring. I was a little worried that maybe the magic was using a totally beat 1000+ mile chain but when I replaced it with a new one a month or two ago everything is still fine.

I really don't know why the 8 speed was so unhappy. With the Eclipse I was within a MM or 2 of where the stock ring was. It was a $30 Sram 8 speed chain so its not like I went ultra cheap on the chain or I should have had a mismatch there. It ran fine on the stock ring which was pretty cheap and showed signs of wear in just those few miles where the narrow part of the chain hit the teeth. The stock Bafang ring isn't a narrow-wide. The stock to the bike ring was a narrow wide in as cheap a way as it could possibly be, you kinda had to look at it to imagine what they were going for there. The Eclipse and Lekkis are narrow-wides so maybe a real narrow wide tooth was the issue?

If you want to look up the build I am talking about do a search for Axum. We both did them about the same time on the same bike which was a Schwinn Axum. Actually he had the idea first and I liked it so based on is positive progress at the time I got lucky and found one in stock and converted it right away. He did a BBS02 and I did an HD so there are details to be found in that long thread about the differences between the systems since we both started with identical bikes, those only came in one frame size so not even that variable.

[Dshue]

The kit the OP used is a 750w Bafang BBSO2B. it's the same from any seller. From what I've seen US sellers tout their awesome "warranty" services but are no better than the Chinese Amazon sellers, they just charge you more for the sentiment. Measure the width of your bottom bracket shell to know which width of kit to get. To me it looks like either standard 68mm or 73mm. The chainring in the pics looks to be fairly big so I can't imagine there is any interference issue. To my eyes it looks larger than 44 tooth. I'm with AZguy. If a Bafang stock chainring doesn't let the chain stay on then get a Lekkie narrow wide, or just do the narrow wide from the start. The key is to get the chainring with the most offset possible. Choose a battery voltage, then choose a pack that will fit the frame. Always get the biggest battery you can. Unless of course you only want a light emtb that retains it trail characteristics. Choosing a battery was my most agonizing decision.

[i-Zapp]

I've got a 2016 Rockhopper Comp 29 myself...if I'm not mistaken that is what you have there...at least the same model/color. I'm looking to do the BBSHD conversion myself. If you could tell me the exact model /size motor you bought it will save me some nail-biting. I'm concerned about the issues with chainring clearing the chainstay and getting the right width etc...
Of course I'm obviously interested in the re-enforcements you have done but the first step is getting the right motor. :)

OP here. The part numbers I purchased were:
* BBS02-MTR-SPECIAL (package deal)
* BBS02-CR-48T, any larger and it'd likely touch. But i think the gearing is pretty good for road-riding, although a bit tall for off-road (I'd go with a smaller chainring)

I can tell you the chain ring is VERY close to the frame, but so far no evidence of touching (probably < 1/32" of clearance).

As far as my mods and others' comment re them, there's no way i'd trust a friction joint for holding an overhung motor on a hardtail bike. That's just the engineer in me, and someone who's spent a lot of time breaking things in the woods. I have zero concerns about whether my mid-drive is going to loosen and ruin my ride, even if it's "supposed" to be fine. Re the chain guide, I'm sure you can find one to work on Amazon, but i wanted to design and make something with my new 3d printer at the time. The setup was unrideable off-road without it.

Happy to assist in any other way.

[73Eldo]

Nondem hasn't been here since he asked the question so hopefully he checks back and sees that you are here to answer questions.

[nondem]

Wow...Thanks so much for the guidance from all of you! I'm lucky to find an ideal resource for information about what I'm trying to do.
I was originally going to buy a complete kit but the more I read and think about it I think I should just start with the correct BBHD motor and the helper/install kit to be sure I can get it installed right.
While that is "in process" I'll have time to properly research the rest of the components(by asking questions on this forum). The bike is actually in my shop down the road so I have to go look/take pics and then refer to them when doing research.

My bottom bracket measures 73mm. I've got the "XL" size bike which I hope may make things easier...or at least not harder. I've got to get the tools to pull the bottom bracket...It looks like this bike has the the type that the standard 20 tooth splined socket fits but I'm not 100% sure. It also appears to have the threaded-tapered bottom bracket that these mid-drives were designed for.
I'm wondering if I should get the 68-73mm motor or the 73-100mm and shim it to provide adjustment?

[73Eldo]

Since I Zap did it with a BBS02 I would say just stick with the 68-73. The HD's are about 10mm wider than the 02 so even if you need a few MM's of spacers to clear the larger gearbox you should still have enough threads to get er done. The 100 is an inch wider yet and an inch is a lot of extra to be sticking out one side if you don't need it. He said he used a 48t and its close so I stand by my original recommendation of starting out with the stock 46 that comes with the HD's and see how things align.

XL size frame is good because that should give you a ton of room for battery. Only possible issue would be if you have some really high rise bars you may need an extension cable for all the bar mounted stuff.

What other components are you trying to figure out?

-Since you likely have the space for any battery get the biggest one you can afford. Not many people think they got too much range. If you get everything from one vendor like Luna you should get the correct cables and adapters to plug the battery into the drive. The drive uses a 'anderson' connector. If you are mixing vendors be sure you get the correct adapters or parts to make and adapter or change the end on the drive which I have now done on 2 of my 3. No need to have an extra connection to get wet or just go bad especially if you know how to solder. I also like a traingle bag like Luna sells for the battery. To me makes it look a lot less like an E bike which I like. I got the Luna zip tie bag and punched holes in the bottom to put the Wolf magnet mount in the bag so I don't need the zip ties. Leaves room for a frame pump or what ever if you have extra space. Also keeps the battery from going very far if you crash or lay the bike down for transport. Bag also helps cover some of the wires and you would possibly have the option to stuff/hide some extra wire in the bag if you wanted to. With a battery like the regular Wolf in the Luna bag there is still space for a tube and small tool kit and before I got the rear pack I would stash my wallet and phone in the side pouches.

- charger the basic ones work fine but if you get one that has an adjustable percentage you can in theory extend your batteries life by only going to 100% when you need it or occasionally to let the cells balance. A fancier yet charger will also let you change the charge rates. A lower rate is easier on the pack but a lot slower. There have been times where its really nice to kick it to high to finish or get a quick charge.

-if you have disc brakes I would get the hydraulic brake sensors, the bafang levers really only work well with rim brakes. The hydraulic ones take a little fiddling to mount but can me made to work on any levers which is nice if you like what you have or have ones where the shifter mounts to the brake. If you have rim brakes I would order a new set of pads to make sure you are getting the most performance possible. Older pads get hard and don't work as good. Even if you got discs a spare set of pads will be in your future, you will likely ride faster and more often and just wear em out.

-gear sensor I think is nice. Yes you can get away without it especially if you have the brakes by using them like a clutch but its nice to just not have to worry. I think most of the bad sudden damage to chains and cassettes come from shifting under load which is easy to do with the power these have. If you are getting a gear sensor you will likely need at least some cable ferule ends and the ability to cut the cable. If you don't have the fancy cutter a cut off wheel on a dremel like tool does a nice job. You may also need some extra housing if you have to do some different routing for any reason. You will also want to have a new spare shifter inner wire. If you have a spare the old one will pull out and go back in fine. If you don't have a spare 95.56% chance the end will fray and it won't be usable.

-display. I don't really like the look of the large phone looking ones that go in the middle with their remote buttons. I just don't see a need for a screen that big, there just isn't that much stuff you have to know all the time quickly. Also takes up the best spot if you like to have your phone where you can see it for any reason. That leaves the 500c mini which I really like or the even smaller eggrider 2 which apparently has bluetooth for all kinds of additional features if you are into that. Both of those usually mount on the left and have the buttons on the unit itself. The B&W displays tend to have a few less features than the color ones and cost almost as much so I would not bother with one of those.

-throttle. I think most vendors include the stock universal one and I actually like it on the left between the grip and brake lever. I personally don't like the twist grip ones but some people do like em. I also have one bike with the deluxe left version. Its a much more solid feeling unit and in my head it seemed like it would be a more comfortable design but I really don't like it so I think I would just get the stock one to start with especially if its included.

[nondem]

Once again - thanks for the excellent info. I'm saving all this in my notes.

The 68-73 it is. Sticking to the stock chainring sounds like a good idea. So it is close but fits on the OPers bike assuming his is not an XL I guess there is the risk of there being a problem...I can always get a smaller one if my possibly larger frame is different. I'm using the stock bars for now so there shouldn't be a problem w/the cable length there.

The other components I'm debating are like you said - battery mainly...but also the display, the throttle, brake sensors etc...

I'll get the biggest battery even though I don't see ever needing the max range they seem to provide. I do like the ones that look like they mount directly to the water bottle mounts and have a keyed quick-release - not sure what the difference is between those and the ones in the triangle bag(yet). I'm not clear on if I should get the 52v or 48v batteries but my assumption is that the 52v is the way to go. I am a big guy at 6'2"/260lbs so I know range estimates are likely to be way off either way.

About the The "Hot Rod Program" motor from Luna kit order page/form: I assume it's the same motor but with the Flash updated? I do a lot of stuff with microcontrollers so I can whip up my own cable and tune the thing. I'm just wondering if there is any other benefit to either option.

It isn't clear if how the pedal sensor(the one that mounts on the bottom bracket) plays into a bike w/a throttle? Is it required?

I'm also curious how much drag the mid-drive adds if any to the the pedal action when not using the motor. I know there is quite a bit of added weight but other than that is the pedal-effort pretty much the same as if I were just using that size chainring? I assume it has some kind of sprag/freewheel built in?

I like your thoughts on the display...I only need the bare-minimum of info and a small one will keep my bars as clear as possible. Not to mention it can be upgraded later if I want.

The gear sensor is a tough one...I don't mind using the brake disconnect as a clutch as you mentioned. Having said that - if it's only $45 more and doesn't add a lot of complication to the initial build I may get it.

I really like my OEM Hydrolic brakes and other components so I'll be trying to stick with them where possible. One reason I got the "Comp" version of the Rockhopper is that is comes w/a little better set of components including their in-house "Stout" hubs etc...

The areas I intend to ride don't include the city and the associated restrictions/laws. Just mainly off-road trails and dirt roads where I'm not likely to run into anyone much less some type of law-enforcement that is concerned with ebikes.

I want to actually pedal some so I can continue to get some exersize from riding the bike. I had a Giant full suspension bike before and pretty much rode it into the ground. Then bought this Specialized as a replacement. I had some knee issues that got me off of the bike for years so it only got a few hundred miles on it before being parked. It's in really good shape despite being 5 years old.

I've got a background in electronics and lots of experience w/batteries - just not ebike bats. I'll get a "slow"(Read:Cheap) charger at least at first and manually follow the 80/20 charging rule as much as possible. Getting the larger battery will obviously do better starting at 80% charge. I've had an electric car before so I understand how to best maximize the life of the batteries. I "may" build my own battery pack eventually since the pre-made ones are so expensive but dunno if I should try that first thing.

I need to get the bike up and running so I can start learning the ends and outs and what I really need in my situation. I'll likely get the battery after the mid-drive is already installed because I can more easily slip the smaller purchases by the wife without getting in too much trouble :)

[AZguy]

The "stock" chain rings are on the large side and don't give good low end, but much easier to go smaller later than the other way so not a bad place to start.

52V will give you a battery with more range in the same size, and the "tiredness" that batteries exhibit when they are running down is less - the cost is usually proportional to the number of cells when comparing a like 48 or 52V so you don't pay a "premium"

I wouldn't worry about "hot rod" on a BBSxx, just get a programming cable and you can do what you want since it's just different parameters. I've never met a factory program that didn't have room for improvement and most aren't that good and some are really bad so just plan on tweaking it for your bike and your style of riding. Ludicrous is a different animal but unless you have a really big battery and want to go really fast and be hard on everything no good reason IMO

Most all have a pedal sensor whether cadence or torque (pedal on BBSxx) so it's a moot point. If you want to use pedal assist you need it. I have a throttle but only use it for fine or fast control otherwise leave it to pedal assist and no wrist (or thumb) getting tired

I also like a bare minimum display. All I need is something I can change the pedal assist levels with (the display controls this) and I can't stand having a glowing backlight at night so I go for the monochrome displays that support 10 levels of PAS - some only support 5

Gear sensor is a "why not?" sine they pretty mucht nothing to complexity and if for some odd reason aside from getting dirty they fail or they get dirty and quit sending the interrupt, they "fail safe" - i.e. the bike will keep on running fine, just not interrupt when you shift. I think they provide a lot of value and in the ~7000mi I have on my BBSHD build I've only had it get dirty twice and cleaning it is a five minute job tops

I have on my bike and am a huge fan of hydraulic brakes and wouldn't ever consider going backwards... however brake sensors are a pain with them and I've given up on the sensors... maybe someday I'll put the front one back on

Cheap chargers work fine... If you want them to only charge to 80 or 90% I put a string of five or six 5A Si diodes in series and just use an alligator jumper to bypass however many I don't want in series

[73Eldo]

Hardware is the same hotrod vs street legal. Its just settings you can change with the programming cable if you want to but I find the hot rod is a totally decent place to start. In the Luna world Ludicrous is where you see hardware changes and its not recommended to start there for a first timer. You can buy the upgraded gears right off their site if you think you need em and if you bought the original kit from them and ask and they have stock I believe they will sell you just a controller too even though its not listed on the site. I think they do it that way because its not a bullet proof system you can just crank up to 11 and abuse. It has limits and if they just sold them to any and everyone they would get a lot of people breaking them and other components and blaming them.

Other things to consider about the battery is as it sounds like you are thinking security. One thing to note about the 'shark' packs is they pretty much all use the same key and its a very cheap lock that doesn't take any sort of skills to pick so its not likely to slow down even a casual bike thief but may slow down a random thief. A bag may slow down the random thief because they don't really know what is in there or how it may be secured once the bag is open. To a semi pro the bag may be way better than the keyed shark because they don't know what they may be getting.

The the other thing about different types of battery mounting is charging and storage. Can you charge on the bike? If so then how easy or hard it is to remove isn't really a factor. If you will have to remove it to charge it you will want to consider how easy or hard the process is and what sort of wear and tear it may cause. Is where it will be stored not too hot or too cold? If its nice and stable then it may not need to be removed often. Will you ever have to lift the bike? Up some steps for storage? Onto a storage hook? Onto a car rack? It can be a lot of extra weight and makes it easier to lift if you can easily remove the battery.

The pedal assist in the BBS's is the simple cadence version and its built in so no options there. Some other systems have a torque sensor and some like that better but for mostly street riding I think you can get used to either system. I can see more hardcore offroad maybe the torque would make a difference but if you otherwise like the BBSHD you don't have a choice. The external sensor other than a gear sensor is the wheel speed sensor.

The BBS's have a fairly typical pawl type freewheel between the pedal crank spindle and the bull gear that the chain ring attaches to so the motor can overrun the pedals. The infamous plastic gear that the motor pinion gear rides on has a sprag clutch bearing so the pedals can overrun the motor. If you are not running the motor you are spinning the bull gear which is spinning the pinon gear and shaft but because of that sprag bearing you don't have to spin the motor. There is more drag there than if all that wasn't there but I think all the extra weight adds more drag than that extra gear does. If you wanted an analog experience ditch the battery and save that weight would likely make things feel closer to normal. If the sprag wasn't there then there is a more noticeable drag, you can feel that if you roll the bike backwards because then the sprag engages as does both freewheels so its all spinning.


The basic unit has 4 cables hanging out of it that are maybe a foot long.
-Battery pair with anderson connector.
-gear sensor cable with the 3 pin.
-speed sensor which is a 3 pin with a threaded locking collar.
-main harness which is a multi pin connector (maybe 7?)

The main harness cable is maybe 2 feet long then splits into 4 cables that are maybe 6" long.
-yellow 3 pin brake 1
-yellow 3 pin brake 2
-yellow 3 pin throttle (gender swapped with brakes so not easily confused)
-green 5? pin display. If your display has a remote button unit that will be a tail that comes off the display itself. The programming cables connects to this one too so you disconnect your display while programming.