Swytch Bike Install – Converting a road bike into an e-bike

So this week has been an interesting one; we have a Swytch bike install kit to fit to a customers bike. For anyone not familiar with Swytch, the company offers kits to convert almost any standard bikes into electric pedal assist. They also offer specific kits for bikes such as the Brompton. The kit consists of a three main parts. A brushless hub motor pre-built into a wheel size of your choosing, a removable battery pack and a crank sensor. Also in the box, the charger well as a selection of items to make the final result look neat and professional. Swytch also offer a small selection of accessories such as throttles as well as brake sensors and spare battery packs.

Starting off – Mounting the Swytch bike wheel

After checking the box to make sure all parts are present and correct and a scan through the quick start guide, its time to get the bike up in the stand and begin. The bike in question is a small size Cannondale Synapse road bike, alloy frame with carbon forks. The model comes with rim brakes and 700c wheels. With the 25 section Continental Gatorskin tyre and tube moved over to the new Swytch wheel and test fitted we come up against our first hurdle. The axle has two flats milled onto them, exactly like Shimano and Sturmey Archer rear geared hubs do. Geared hubs such as the Swytch exert torque (a turning force) on the axle when power is applied. These flats prevent it from spinning in the frame. The issue is the width of the flats is 10mm but the fork dropouts are 9mm. The wheel physically wouldn’t fit. A quick look on the FAQ section on the Swytch website found nothing so dropping back out to Google took me to their Zendesk help page.

swytch motor axle
swytch bike wheel install

The official way around this is to remove just enough metal from the two flats to allow the wheel to slot into the forks. The instructions suggest a file but in practice you’re filing hardened metal, the file just skims across the surface. I opted to use a small rotary die grinder fitted with a sanding disc to do the job. The disc allowed a high level of control and keeps the flats strait and parallel, taking turns to take the same amount from both sides. After two or three sessions the wheel now fits.

Fitting the Swytch Bike Pedal Sensor (PAS)

The PAS is the part that tells the brain of the system when to apply power and when to not. It does this by sensing when you are peddling. A ring of twelve magnets attached to the crank move past a stationery sensor fixed to the frame. When a magnet passes the sensor, a pulse is sent to the main control unit which in turn starts the electrons flowing into the motor. There are a few different designs of PAS for the Swytch, this one came with the “Universal Indented” type suitable fore fitting to indented crank arms. After a little fiddling, the unit was fitted using the cable ties provided and the sensor fixed to the frame. This part is probably the most tricky to get right as everything needs to align correctly for it to work.

swytch pas sensor mounting

Handlebar Mount

Now I fit the final part, the handlebar mount. It clamps over the bars at two points, a strap then passes underneath the bar stem for extra support. All cables are colour coded so there was no chance of getting things wrong. Cable ties attach them to the frame. Sadly the ones supplied weren’t long enough for the oversized down-tube used on this bike, longer ones needed to be sourced.

swytch bike battery pack mount
View of swytch bike battery pack mounted

With the battery charged and slotted into place it’s ready to go.

Are you thinking of buy a Swytch kit for your bike and need assistance fitting it? If so please get in touch.

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