New build Cannondale F7

[Stogie-boy]

Hello Forum members. After searching for specific builds for the bike I own, as well as topics pertaining to other concerns, I am making my first post.

I have been researching for several weeks regarding kit conversions vs. purchase of a pre-built "brand name" ride. Along with this I have done several test rides of various manufacturer's bikes. After the test rides I have come away with the general impressions that I like the look, the overall unity of the design, in many cases the performance related to shifting and integration of the drive function, but do not like the prices or the lower power/torque offered. Unfortunately I have not found a way to ride an adapted bike with the BBSHD motor. Given this, I am considering a conversion of my Cannondale F7 mountain bike. In doing the basic research I have come across a few concerns that I would like to get input form more experienced individuals on the forum. Of course if someone reading this has converted this model of bike, please jump in.

First, my F7 has a 73mm BB. In looking at the BBSHD motors I see the units are designed for 68mm-73mm, 73mm-100mm, and finally 120mm BB dimensions (I am referencing info provided by Luna Cycle web site). Unfortunately, LC is only currently showing the 72mm-100mm option on the site (I may be able to find the other dimension kits in other places, but my questions spring from this). In the event one purchases the 73mm-100mm motor setup with the intent to install onto a 73mm BB, what issues might this present pertaining to:

• Chain alignment to the rear sprocket assembly - I have read many posts where this alignment has lead to issues with chain throws and breaks. Is this more of a concern when adapting this larger specked unit to its lower range? If so, is it a better idea to purchase the 68mm-73mm unit? Is one looking at a rear sprocket re-build to make the ride as sound as possible?
• Spacers - The motors come with a set of spacers to adapt to various install scenarios, and I have also read there may be a need to purchase additional spacers when installing the 73/100 to a 73mm BB. I am always concerned when a mechanical spacer is used in a an install. Is this a point of weakness or does the addition of spacers introduce other performance issues related to stress? Is this also less visually appealing once the install is complete?
• Chainrings - The motor kits typically come with a steel chainring. I have read many people opt for an after-market machined chain ring vs. the stock steel unit. Can the addition of the right/proper chainring address issues with chain alignment in any way? Obviously alignment is what it is, but thought I would ask.

I am sure the final performance of any do-it-yourself build is heavily impacted by the knowledge of the builder and the parts used. My intent is to have a finished product that looks and rides as tight as possible and to avoid creating a Franken-cycle. I welcome all thoughts and comments.

** One last, somewhat unrelated thought. I am relatively new to the e-bike scene, but I have noticed a general scarcity of the Bafang BBSHD mid-drive kits when searching the web (in particular the 68/73 sized units). Is this typical or a recent development? Are other factors impacting this (tariffs, interest, new designs emerging, etc.)?

Cheers!

[SRG]

I'm not an ebike expert. I do have a BBSHD kit on a Cannondale Moto (FS downhill/freeride bike).

I don't think you want the 73/100 kit. You will have to use spacers to make up the extra width. To keep the chainline straight, the spacers will end up on the left. That will push the crank arm farther out on that side.

I used the stock SRAM parts on my bike, no issues. Your stock chain will likely be too short. I added a couple of links to mine.

You don't want to have to use extra spacers - see above.

People (me included) use the fancy chainrings because the Bafang steel one is ugly/cheesy/cheap. I have the Luna one, it's offset to the left is the same as the Bafang one and as far left as it can go, which is what you want for best chainline.

[Stogie-boy]

Thanks for the reply, SRG. Your thoughts are right on, as I exchanged some communication with LC tech support and they made the same recommendations. You say you purchased the LC chainring, can you tell me which one? I'm now hung up on chainrings and chain concerns and am curious about the best choice there. Are you running on your stock chain? In the area I ride I will be pulling a lot of hills, so want to maximize torque to the crank and it's my understanding tooth count may come into play.

Thanks!

[zmarkjam]

Hi Stogie-boy, I checked the Luna site this morning and the BBSHD 68-73 is back in stock. Consider ordering quickly as they get snatched up quickly. As far as chainrings go, I use the Lekkie 42 on my trail bike. 42 is the smallest ring that will wrap around the motor housing and give a good chainline (both Lekkie and Luna Eclipse). On all three of my bikes I switched to a Sunrace 8-speed cassette 11-40 tooth. Here's some pics of my bikes. Finally, soon after you get your bike finished, ditch the soft aluminum crank arms and get some Shimano Steps cranks. Good luck with your build.

[zmarkjam]

Sorry, here's the pics

[Stogie-boy]

Thanks, Zmarkjam! These are all things I am contemplating related to fine tuning when building. Your pics are awesome and since you have 3 builds I assume you are sold in the e bike concept! Curious about your battery setups, is there a reason you have gone with the types you have vs. tube-mounted that typically come with many of the kits? Is this a voltage wH thing, or aesthetic, or other? Thanks!

[zmarkjam]

Thanks, I am definitely invested. Between the three bikes I have 5000 trouble free miles. I went with soft pack 52V batteries for several reasons. First, I wanted large capacity batteries in the frame. The green hybrid bike has a 24Ah triangle battery in the frame bag, and the full suspension mtn. bike has a 17Ah triangle battery. Hard mounted 52V batteries don't come in these sizes. Second, I wanted an effective, versatile way to carry extra batteries for extended range rides and also be swappable between the hybrid bike and the mtn bike. For this I have 2 extra soft pack batteries (one 14Ah and one 17Ah, both rectangle). On the hybrid bike I installed a Topeak rack with a locking track system for their bags which slide on and lock to the rack. I have two bags, one briefcase bag for the extra batteries and a trunk bag with panniers for shopping or luggage. With all 3 batteries I have 55Ah of juice and can switch batteries in seconds. For the mountain bike, I carry the extra 17Ah rectangle battery (total juice 34Ah) in a Camelback with a connector leash, also switchable in seconds. Third, I like the XT-90 connector much better than the blade connectors of the frame packs. The XT-90's can handle 100 amps and have anti-spark suppressors built in. Finally, triangle bags may scream "something", but they don't scream "huge battery on board", I like the aesthetics. Pics attached.

[SRG]

SB - Yes stock SRAM chain. I did have to add a couple of links. The chainring is the Luna 42t one. If I were doing more tight/steep trails and wanted a lower gear, I would see if I could go bigger on the cassette's low gear.

The standard Dolphin/Shark type battery works fine for me, but my mount is much more secure than just the 2 screws of a water bottle mount. The battery I have is 48v/13.4ah and takes me 30+ miles of mixed riding at lowish PAS levels and some use of the throttle.

[Stogie-boy]

Zmarkjam,

That's a lot O' power, and it gave me more to consider related to battery options. I truly appreciate you and SRG taking the time to reply with such great details. I'm close to making a buy...

[Stogie-boy]

Hey guys. I ordered and received two BBSHD kits from Luna for the conversion of my F7s. Started the build today and ran into a few issues. Thought I would present then on this thread and get your thoughts. First, my kits did not include the spacers for the motor. I've emailed Luna about the issue, so I'm kind of stuck until that gets resolved. On a second issue I'm wondering if either of you installed a shift sensor on your bikes. I've researched this topic and it appears a special tool is recommended for cutting the outer cable jacket, as well as some parts for sealing the cable jacket to the sensor. How did you guys deal with this on your install? Is the sensor a good idea? Did you run into any issues? Thanks!

[zmarkjam]

Hey Stogie-boy, glad to see you're starting your build. As far as the spacers go, are you talking about the ones to move the drive side away from the chain stay (right side), or the ones between the triangle mounting plate and the motor (left side). If it's the left side, then washers from the hardware store will work fine. If the right side, you may be in for a wait from LUNA as I saw in their parts section the spacers are out of stock. Maybe the ones for the kit are out too. If LUNA tells you it could be a while and you need them, don't worry I can send you some. Just PM me with your address or phone or both and I'll get them in the mail. I have various spacers from 2mm 1mm and 1/2mm.(pics attached) As far as the gear sensor goes, I don't use one. I have a motor cutoff on the left brake handle so I can cut the motor without engaging the brake. Make gear changes seamless for me.

[Stogie-boy]

Of course the spacers I need are the right side... (Couldn't be easy

[Stogie-boy]

... sorry about the abbreviated post above for some reason most of my response text was cut off. To continue, the spacers I need are on the right side. I too saw the out-of-stock post on the Luna website just like you did. Zmarkjam, It's very generous of you to offer your parts for my use! As soon as Luna responds I will let you know if I need them. I did a quick measurement of space between the motor and the chain stay and it looks like I will need to compensate approximately 8 mm with the spacers. Of course if I have to dip into your inventory I will gladly send back the spacers I use once Luna sends me what they owe me from the kit . Also, can you tell me any more detail of the motor cutoff you are using. Where you purchased and make/model?

Cheers!

[max_volt]

Standard bb spacers should be available locally @ lbs or rei.

[zmarkjam]

I use the standard Bafang brake lever with motor cutoff wire built in. They came with my LUNA kits. If I could put it in my budget I would get the Tektro Dorado E725 hydraulic brake set. Another option is the handlebar mounted cutoff button. As far as how I use it, when the brake lever is pulled, the motor cuts off before the brakes are engaged so I can cut the motor without braking. Then it's simple: pull the lever, shift the gear, let go of the lever. The brake lever is only for mechanical (cable) brakes. For hydraulic brakes there are other options. I'll add links.