Surly Pugsley fatbike with BBHSD and 52V 13.5 ah Panasonic Shark Pack

[jdaun]

My daily commute is 13 miles each way, and I found myself making excuses for driving my car instead of biking, especially with snow on the road. I own a Surly Pugsley fatbike that doesn't see much use, so converting the Pug to an eBike seemed like the perfect solution to create a monster commuting machine that can bomb through nearly any road/weather conditions.

Donor bike: Surly Pugsley (with aftermarket rack):







Finished build:






I purchased the "Bafang BBSHD Mid Drive Ebike Kit" from LunaCycle including the following components:
* BBSHD 100mm motor
* Luna Shark Pack 52v 13.5ah battery
* Luna full color display
* Stock 46t steel chain ring
* Bafang eBrake levers
* Bafang BBSxx Left Thumb Throttle
* 52V 3amp Luna mini charger
* Programming cable
* Bottom Bracket/Lockring wrench

Other items I needed for the build:
Several small stainless washers, for the retaining bracket bolts (explanation below)


The Pugsley has a 100mm bottom bracket, so I ordered the 100mm BBSHD. I thought the chainstay might interfere with the motor, and it did, but only slightly. There's a German guy on the internet who intentionally dented his chainstay with a hammer to work around this problem ... you do NOT need to do that! Here's what I did instead:

The motor kit included several bottom bracket spacers. I used one of the ~2mm spacers to bump the motor out a few millimeters on the drivetrain side. This allowed the motor to clear the chainstay beautifully:





View from top, better view of motor and chainstay:





This reduced the spacing between the retaining bracket and motor housing on the non-drivetrain side, so the ~5mm spacers included with the kit were now too thick. I substituted small ~2-3mm thick stainless-steel washers (purchased at local hardware store) and the retaining bracket tightened down nicely.

Using the stock 46t steel chainring, this setup provided a chainline that is reasonably straight with the chain positioned in the middle gears of the cassette, which seems ideal for me:




Because my Pug frame is small, and the downtube bottlecage bolts are close to the seattube, I bolted the Shark battery on upside down to make it fit. This means I push the battery down to remove it. This puts the key for the battery lock on the drivetrain side, near the bottom.

The eBrake levers are not fancy, but they do a fine job. It takes very little pressure to stop electricity flow to the motor - nice.



Things I may change in the future:
* Upgrade to a nicer Luna chainring when the 46t wears out, probably a 42t. Need to verify how this may change the chainline. For now, the 46t chainring seems fine, I haven't had any issues.
* Experiment with the programming: right now I only use PAS1, because PAS2+ deliver more power than I am comfortable with. I'd like to have smaller power increases between PAS levels. Also slightly smoother throttle response.
* Modify the battery mounting bracket (by drilling additional mounting holes) so battery can be mounted right-side up.
* Experiment with a twist throttle, probably a left twist, half grip.

[Eric Luna]

nice build thanks... i believe surly pugsley was the first fat bike... i had one back in the day and electrified it with a mac motor up front :) must be sweet with a bbshd.

Thanks for sharing.

[jdaun]

Eric - yes, I've put 200+ miles on this build in the last 2 weeks, and the Pugsley with a BBSHD rocks!

It handles my 13 mile commute with almost no pedaling ... I charge the battery to 80% and throttle almost all the way, at average speed of 20mph. Then recharge at work, and repeat for the ride home.

Made a few updates ...

1. Added 5" wide DIY fenders. Constructed from 1/8" black corrugated plastic, 1/2" wide aluminum strips and a few rivets. Got all the materials at Home Depot, total cost around $17 plus about 90 minutes of time. Love 'em!
2. Drilled an additional hole in the battery mounting bracket, allowing the battery to be mounted "right-side-up". This looks better (in my opinion) and is slightly more functional.
3. Reprogrammed the controller to give less power in the lower PAS levels, and smoother throttle response.

Did I mention this thing rocks?!?!?!?

[having trouble uploading pics ... will try to add them later ...]

[mtm408]

Love to see a picture of the DIY fenders. Nice job on the build!

[jdaun]

Front fender uses corrugated plastic ~5" wide, riveted to a couple pieces of flat aluminum stock (bend the aluminum with hands/pliers as needed).
Fender is attached to fork at top using a small metal "L" bracket and a bolt.
At bottom, it's attached using a U-shaped aluminum brace - this goes around the plastic on the outside.
Also a piece of aluminum that runs on the underside of the plastic, front to back - this is so the fender maintains it's shape.
This inside piece of aluminum is riveted to the L bracket through the plastic at top, and riveted through plastic to the U bracket at bottom.




Rear fender is a ~4" wide piece of corrugated plastic.
On top, it's zip-tied to the underside of the rear rack.
There are also 2 allen bolts used to secure the fender inside (underneath) the chainstay bridge, and the seatstay bridge.

[mtm408]

Creative and simple! Thanks for sharing.

[Lookseasy]

Nice build. I have the same bike in medium with Nuvinci hub. Should I keep the stock levers and add the adapter or are the included levers fine? Might go smaller chain ring also but you are getting by fine on the stock? Nuvinci is right twist shift so I will go left throttle, you think the twist is better than thumb? Thinking of battery on my rack to keep bottle cages. I run panniers so top of rack is available, bad idea? Are you running stock performance settings or did you have them upgrade? Have you fooled with programming yourself, how complicated is that? My commute is 11 miles one way, battery size suggestions? Thanks for any thoughts, sorry for so many questions but I have been mulling this over for years and seeing your build on basically my bike has got me motivated.

[ykick]

Good job on the fenders. The wider the tires the more we need ‘em.

I’ve used coroplast for fenders on several bikes and eventually discovered long spokes slip inside and help hold shape. A touch of glue will usually hold them in position.

I suppose stiff solid wire would work as well? Variety of ideas to toss out there…

[jdaun]

I realize this is REALLY late reply, but here are my responses to Lookseasy's questions after 1500+ miles of riding ...

• The included ebrake levers are fine for everyday use. If you're heavy-duty offroading, you may want beefier levers.
• The stock chainring SUCKS. Chain always falls off. I'm using a Luna BBSHD Bling Ring with great results. 42T is the smallest chainring you can use on a BBSHD on a Pugsley ... anything smaller and your chainline will be messed up.
• I use left throttle, and it works great.
• I ordered kit with stock performance settings, but tweaked the programming to get smoother throttle response, and smoother progression of the 9 assist settings. There are threads on this forum describing how to do it, wasn't too difficult. Save a backup file of original settings before you start messing with it, so you can revert if necessary.
• My commute is 12 miles one way, the battery I'm using gets me there no problem with no pedaling, but won't get me home (I charge battery at work for commute home). My battery 52V 13.5ah Shark Pack. If you have the money, going bigger is always better :)

[Kocho]

For the "stock" Bafang brake levers, I don't like them very much, mainly because they are too long. I am used to 2 finger braking, or even 1, and with these it is more like 4 fingers - if you use only one or two or three, the others will be in the way as the brake lever closes near the handlebars. Meaning you have to kind of let go off the handlebars with all fingers in order to sqeeze the brake. My levers are mounted as far inside on my bars as the bar bends would allow and they still protrude too far out. Other than that, they seem to function OK, but are not adjustable and a little too close for my long fingers.

Maybe I'll cut an inch or two from the lever ends to shorten them... But I need more time to see if that initial impression of mine is really true.

[Rider]

I'm having this same problem. Has anyone come up with a two-finger lever that will simply install in the Bafang mount with cutoff sensor? Thx.

[Paddler]

Hi jdaun,

I have a Pugsley I'd like to convert to an ebike. Any suggestions about how to proceed? I don't need to go more than about 15MPH, but intend to tow my canoe behind the bike. Also, what kind of backrack do you have? Any modifications you had to make?

[ykick]

BBSHD use 30T Mighty Mini. Should be a great eBike

[kbunning]

Thinking about doing the same thing with my Pugsley. Any other suggestions?

[BigFatDummy]

I'm in the same boat. Building out a Pugsley with a BBSHD but having trouble figuring out if I should go with the 100mm or the 120mm... OP said he p[ut the 100mm on but I've read other users go with the 120mm and used spacers but no word on how that affects the chain line.

[smogli]

Has anyone built up a Karate Monkey with the BBSHD? I'm wondering if there is a chain stay issue with that bike too, and what size motor to get. Thanks