{"id":4288,"date":"2024-06-24T16:21:25","date_gmt":"2024-06-24T16:21:25","guid":{"rendered":"https:\/\/www.bendingtherules.co.uk\/home\/?p=4288"},"modified":"2026-03-30T08:15:06","modified_gmt":"2026-03-30T08:15:06","slug":"cannondale-e-assist-retro-fit","status":"publish","type":"post","link":"https:\/\/www.bendingtherules.co.uk\/home\/tech\/cannondale-e-assist-retro-fit\/","title":{"rendered":"Cannondale E-assist retro-fit"},"content":{"rendered":"\n

Back in 2024, Karon had commented that we rarely rode the Cannondale anymore and I had to agree. While it was fine on the flat, we struggled on the hills and it was putting us off taking it out. I had a ‘spare’ Bafang BBS01 250W motor in the shed and an old 36V battery that still had reasonable capacity, so I decided to see if I could fit it on to the ‘Dale.<\/h4>\n\n\n\n

Useful videos<\/h3>\n\n\n\n

Bottom Bracket (BB) types<\/a><\/p>\n\n\n\n

Park Tools videos on BBs<\/a><\/p>\n\n\n\n

Some good points on this one and it talks about alternative chainrings.<\/a><\/p>\n\n\n\n

Points to note fitting a BBS01\/2<\/a> \u2013 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.<\/p>\n\n\n\n

\"\"
Third party brake sensors for hydraulic brakes and if you don’t want to use the Bafang cable brake levers. 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. They work, but it adds clutter and they look ungainly. I run the Cannondale without any brake sensors.<\/figcaption><\/figure>\n\n\n\n

Fitting the Bafang was 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 \u2013 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.<\/p>\n\n\n

\n
\"\"<\/figure><\/div>\n\n\n

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<\/a>, 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.<\/p>\n\n\n\n

\n
\"\"
The Bafang cranks \u2013 note the square taper axle pattern. <\/figcaption><\/figure>\n\n\n\n
\"\"
The stoker’s timing chain crank for the left side from Spa Cycles.<\/figcaption><\/figure>\n<\/figure>\n\n\n\n

<\/p>\n\n\n\n

While I had the motor and a spare throttle, I didn’t have the wiring harness or display so those were ordered from Amazon. I like the DPC18 display \u2013 I have one on my MTB \u2013 as it carries more information and has a USB outlet.<\/a> The Bafang BBS01 and 02 motors are very common, so there are lots of spares available on Amazon and eBay.<\/p>\n\n\n\n

\"\"
The Bafang DPC18 display with control buttons. This is designed to 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.<\/figcaption><\/figure>\n\n\n\n
\"\"
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 \u2013 see later in this article.<\/figcaption><\/figure>\n\n\n\n
\"\"
The stock 44T Bafang chainring. I have not fitted the chainring cover. Fitting the motor meant losing the triple chainset. 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.<\/figcaption><\/figure>\n\n\n\n

Chain alignment isn’t really an issue when swapping out a triple chain-ring for a single Bafang one. <\/p>\n\n\n\n

\"\"
The replacement left hand crank for the stoker with 5 arm 110 bcd spider. 42T chainring fitted. <\/figcaption><\/figure>\n\n\n\n
\"\"\/
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. I use a connector outside of the mounting bracket, so I don’t have to disassemble the bracket if I want to remove the motor for servicing\/replacement.<\/figcaption><\/figure>\n\n\n\n
\"\"
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.<\/figcaption><\/figure>\n\n\n\n

As mentioned already, 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.<\/p>\n\n\n\n

The cheap plastic accessory clamp I used to hold the control buttons and throttle, bought from Amazon<\/a>. The ‘T’ section pulls out, leaving the clamp and tube, which I cut down to the length needed for the controls.<\/p>\n\n\n\n

\n
\"\"<\/figure>\n\n\n\n
\"\"<\/figure>\n<\/figure>\n\n\n\n


<\/p>\n\n\n\n

\"\"
I appreciate the throttle is technically illegal in the UK, but I find it essential on hill starts and it helps when trying to pull away briskly at road junctions. Having the controls next to the hoods allows me to use my thumbs to move up and down power levels and use the throttle to help on hill starts and at junctions. It will not power the bike above 15.5mph. With the controls on the left, I have sometimes inadvertently increased the power level when resting on the hoods… my thumb tends to rest against the up switch and if we hit a bump it’s enough to activate the up switch.<\/figcaption><\/figure>\n\n\n\n

The added power from e-assist means that a front double or triple chainring is largely redundant, but with the stock 44T chainring I decided to increase the gear range by swapping the rear cassette for one with a wider range.<\/p>\n\n\n\n

\"\"
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.<\/figcaption><\/figure>\n\n\n\n

I also had a spare inset chainring \u2013 a narrow-wide 38T<\/a> \u2013 which I think is the smallest that can fit the Bafang because of clearances. I fitted this inside the Bafang chaining. If we ever take the Cannondale to a more hilly area, or we ride it with loaded panniers, I can manually drop the chain onto the smaller ring and lower the whole gear range.<\/p>\n\n\n\n

\n
\"\"<\/figure>\n\n\n\n
\"\"<\/figure>\n<\/figure>\n\n\n\n


The chain on the Bafang chainring and on the inner offset, narrow-wide 38T ring. It’s pretty easy to swap the chain from one to the other manually.<\/p>\n\n\n\n

\n
\"\"<\/figure>\n\n\n\n
\"\"<\/figure>\n<\/figure>\n\n\n\n

Here’s a video showing how to fit the rivnuts into place.<\/a> The guy’s voice is a little annoying but the method is good.<\/p>\n\n\n\n

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.<\/p>\n\n\n\n

\"\"
The rivets make for a much tidier and stable finish.<\/figcaption><\/figure>\n\n\n\n
\"\"
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.<\/figcaption><\/figure>\n\n\n\n

I used Sugru <\/a>to make some cable clips stuck directly to the frame. This allowed me to dispense with zip ties for cable management.<\/p>\n\n\n\n

\"\"
The finished set-up without zip ties.<\/figcaption><\/figure>\n\n\n\n

The Cannondale is a light tandem at only 17.5kg in its raw form. The Bafang BS01 can have 5 or 9 power levels to spread across the range, up to the legal 15.5mph (25kmh). I run 9 and usually select power level 6 or 7 to cruise at. This provides assist up to about 12-13mph and on the flat and without a headwind, we usually run faster than that, which means the motor has cut out for much of the time. If we hit a slight gradient, or there’s a headwind which drops our speed, the motor will ‘take up the slack’, but under normal circumstances there’s enough battery capacity to cover us for more mileage than we would usually cover in a ride.<\/p>\n","protected":false},"excerpt":{"rendered":"

Back in 2024, Karon had commented that we rarely rode the Cannondale anymore and I had to agree. While it was fine on the flat, we struggled on the hills and it was putting us off taking it out. I had a ‘spare’ Bafang BBS01 250W motor in the shed and an old 36V battery … <\/p>\n

Continue reading<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"ngg_post_thumbnail":0,"footnotes":""},"categories":[12,7],"tags":[],"class_list":["post-4288","post","type-post","status-publish","format-standard","hentry","category-bikes","category-tech","item-wrap"],"_links":{"self":[{"href":"https:\/\/www.bendingtherules.co.uk\/home\/wp-json\/wp\/v2\/posts\/4288","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.bendingtherules.co.uk\/home\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.bendingtherules.co.uk\/home\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.bendingtherules.co.uk\/home\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.bendingtherules.co.uk\/home\/wp-json\/wp\/v2\/comments?post=4288"}],"version-history":[{"count":21,"href":"https:\/\/www.bendingtherules.co.uk\/home\/wp-json\/wp\/v2\/posts\/4288\/revisions"}],"predecessor-version":[{"id":5341,"href":"https:\/\/www.bendingtherules.co.uk\/home\/wp-json\/wp\/v2\/posts\/4288\/revisions\/5341"}],"wp:attachment":[{"href":"https:\/\/www.bendingtherules.co.uk\/home\/wp-json\/wp\/v2\/media?parent=4288"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.bendingtherules.co.uk\/home\/wp-json\/wp\/v2\/categories?post=4288"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.bendingtherules.co.uk\/home\/wp-json\/wp\/v2\/tags?post=4288"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}