Karon commented that we rarely ride the Cannondale anymore and I had to agree. While it’s fine on the flat, we now struggle on anything over a gentle gradient and it’s been putting us off taking it out. I had a ‘spare’ Bafang BBS01 250W motor in the shed and an old 36V battery that still has a bit of life in it, so I decided to see if I could fit it on to the ‘Dale.
Points to note fitting a BBS01/2 – Note that the supplied brake levers with sensors are only suitable for hybrids and MTBs with cable brakes, not road bikes with drop bars. Sensors to fit non-standard or hydraulic levers can be bought separately. Personally, I am ok with not using brake sensors and fitting them neatly to road levers would be a challenge. The motor will still operate without brake sensors/levers fitted. It’s quite easy to ride without the sensors… if you want to stop the motor, just stop pedalling.
Third party brake sensors. They are glued to the brake lever housing and a magnet is glued to the lever. When the brake is activated, the sensor cuts power to the motor.
It was actually pretty straightforward on our Cannondale but this is the fourth fitting of a BBS01 I have done. I first needed to remove the original stoker’s chainset and front derailleur – as shown in the videos. Once this was done the Bafang motor and integrated bottom bracket slides in from the drive-side. The cable guide under the BB made it tight but I used a rubber mallet to drift the motor into place and the rear gear cable was still free to move.
The original Cannondale BB was an ISIS drive and the Bafang is a square taper (diamond) as can be seen above and in the picture of the cranks below. The drive side uses the right hand crank that comes with the motor. On a solo the left hand crank would also be used, but on a tandem with left side timing chain, the stoker’s left crank may need replacing with a square taper crank and spider for the timing chain unless the original BB is also a square taper. I ordered a left hand tandem crank from Spa Cycles, square taper, black, 5 arm, similar to the unchanged pilot’s timing chain crank/spider, but the replacement spider was 110 bcd and the old spider was 104 bcd, so I also had to buy a 42T 5 hole 110 bcd chainring to fit the new crank/spider.
The Bafang cranks – note the square taper axle pattern. The stoker’s timing chain crank for the left side from Spa Cycles.
The Bafang DPC18 display with control buttons. This is fixed to the handlebar but can straddle the stem. It has a USB outlet to the rear which is handy if you use a navigation device or phone on long rides.I originally utilised the bottle cage mounts and a heavy duty zip tie to mount the battery on the downtube under Karon, but she lost her bottle cage. After putting the timing chain on, I realised there was enough space on the lower spar, so moved the battery and reinstated Karon’s bottle cages. I used rivnuts to attach the battery mounting bracket to the lower spar on the frame – see later in this article.The stock 44T Bafang chainring. I have not fitted the chainring cover. Fitting the motor meant losing the triple chainset. I do have an adapter in the shed for a smaller (down to 38T), though if we need to reduce the gearing a little, I replaced the 11-32 cassette with an 11-36. That enables us to keep the top end the same while extending the bottom end of the gear range. Having the motor means there’s less need for very low gearing.
Chain alignment isn’t really an issue when swapping out a triple chain-ring for a single Bafang one.
The replacement left hand crank for the stoker with 5 arm 110 bcd spider. 42T chainring on order. The insulated ‘lump’ on the wire anchored to the seat tube is the power cable that connects the battery to the motor. While one can wire the power cable directly into the battery bracket housing, I chose to add a connector between them. This makes removing the motor for maintenance or part replacements a lot easier.Typical rear part of the battery mounting bracket with cable arrangement. The pin type will vary depending on battery housing. It may come with a fuse as shown here, or the fuse may be housed within the battery. Without the additional connector described in the previous photo, it would be necessary to dismantle the mounting bracket and disconnect the battery lead for motor removal.I already had a spoke magnet for the trip computer for Karon (she likes to see speed and mileage), so I aligned the Bafang speed sensor to that. The single magnet will activate both. The speed sensor is an essential part of the system and if it does not align with the magnet and ceases to function, the motor will cut out after a couple of minutes.I kept the bars relatively clean by utilising a couple of unused plastic bar accessory clamps that I cut down and then mounted the controls and throttle alongside the stem. The wiring harness includes connectors for the brake levers/sensors which I have not fitted, so I covered the connectors with weatherproof tape and tucked them out of the way under the cross-bar bag.
I decided not to try adding brake sensors. I had them on an MTB but removed them after a while and found I hadn’t needed them. Generally, when you brake, you stop pedalling, and if you stop pedalling, the motor stops powering, so the sensors to cut power are almost redundant anyway and the extra cables etc. are just clutter.
The clamp, complete. The T section pulls out and the remaining tube can be cut to size.I also replaced the large plastic knob with a an allen bolt.After a test ride, I moved the controls next to the hoods and put the cables under the bar tape. With the throttle next to the stem I didn’t feel I had enough leverage when using it pulling away at a junction. Having the controls next to the hoods should allow me to keep a good grip and control over the bike and still make power level changes/throttle use.
Our first ride was short and all felt ok, but I wasn’t completely happy with the controls and throttle next to the stem. A second, longer ride confirmed that it was a little shaky trying to use the throttle to pull away at a junction, so on returning, I moved them next to the hoods.
The final piece of the retrofit e-assist: I swapped out the 10 speed 11-32 cassette for an 11-36. 36 is as big as you can go with the standard 105 rear mech without a hanger extension.
While the zip-ties to hold the battery mount in place worked ok, I didn’t like the look of the ties wrapped around the frame, so I removed the mount and put three rivnuts into the frame.
The rivets make for a much tidier and stable finish.No zip-ties! I also got rid of the others on the down tube which heldthe cable that runs from the motor to the bar-mounted display and controls, replacing the zip-ties with guides made from black ‘Sugru’ mouldable glue. I also used Sugru to form a seal on the battery mounting bracket where the power cables pass through the end of the bracket. It will help keep water out of the internals of the bracket in heavy rain.
