Project View

Cinder Cone high speed commuter

Smithers BC

Published: 2024-04-29

GMAC

Fast

Powerful

Trailer

Mountain Bike

I turned my old Kona Cinder Cone hardtail into an excellent commuter with a bunch of components from Grin.
I think that a barrier for a lot of people who might be interested in converting a bike (certainly me!) is a distaste for protruding clamps, wire bundles and zap straps. I set out to make this bike as close to the slickness of a factory ebike as possible, while still enjoying all the advantages of Grin components (power, customizability, future-proofing, regen braking, throttle and torque sensing . . . ). I got most of the wiring inside the bars, concealed the torque arm, and streamlined the battery mount. See what you think from the photos.
It has a 10t Gmac motor capped electronically at 1500 watts (which it easily reaches), a 52 volt battery, Erider bottom bracket torque sensor, and other components explained below. I charge to 85% with a Satiator to prolong the battery life. I can ride at 40-50 km/h anywhere my car goes now, and get to work non-sweaty if desired. I have programmed a fully street legal mode in case of compliance issues, and an offroad mode (which I use most of the time). I think of it as a wolf in sheep's clothing.

motor and torque arm

I chose a Gmac motor for plenty of power and torque on hills, and regen braking. I wanted a rear motor because I also use the bike for logging road and trail access for hiking trips, and a front motor would have spun out too easily on hills.

I hate bulky clamps, so I modified the torque arm so that it rests on the rear disc brake adapter bar and screws into the forged dropout for stability in both directions. The arm has aluminum plates epoxied on both sides to give more threaded length to the screw holes and provide the necessary spacing. — Modified torque arm

I had to upsize to a 180 mm brake disc so the calliper would clear the motor, but this does a nice job of camouflaging the motor. — Motor and torque arm installed in frame

I slightly ground down the threads on the motor axle so that the adapters for a Bob trailer can fit over the axle ends. This doesn't affect the thread where the axle nuts are. I drilled into the ends of the motor axle and tapped the holes to receive the screws that hold those adapters on. Why are Grin's axle nuts not rustproof? There is just enough room to loosen the axle nuts and remove the wheel without taking off the trailer adapters. — Axle trailer mounts

Controls and wiring

I took a long time to get the wiring as tidy as possible on this bike. I ordered a new stem and larger diameter handlebars to allow space for wires and connectors inside both.

The bike has a CA3, high power light with high and low beam, ebrake levers, a throttle for power and brake control, and a multi-switch all from Grin on the bars. Bar ends, comfy grips and a mirror complete the cockpit. — Handlebars

The CA3 and light are mounted directly on the Ergotec stem. I cut a rectangular hole in the top of the stem to house the wiring projection of the CA3. I like this sleeker and harder-to-damage mounting of the CA3. The light comes off with one screw for trail and summer use. — Light and CA3

All the wiring from the CA3 goes inside the stem. Wire connections are mostly inside the handlebars, which are drilled for wire entry and exit from the stem, brakes, and throttle. The light plugs into a connector on the bottom of the stem for easy removal. I had to invent a tensioning system for the headset since the star nut had to come out for wire clearance. — Concealed wires

I initially ordered Grin's battery triple bob to mount the battery, but even that felt a little marginal for this big battery on bumpy logging roads, and I hate visible hose clamps, and it left the fingers that engage the battery to its mount exposed to get grit in them. So I found a chunk of aluminum extrusion from a junked Zellers door and cut it to match the battery mount plate. I drilled and installed 5 rivnuts into the bike's downtube, and screws into these pull the extrusion plate down hard onto the tube so that the fins on the extrusion are slightly sprung around the tube. It is rock solid and covers and supports the whole plastic battery mount.
The wires from the CA3 to the motor controller go through the stem and down the head tube, and exit out the bottom. Then they enter a channel along the edge of the battery mounting extrusion and are concealed by some car door rubber weatherstrip. Yes, it is a pain to get this whole mounting system and wires installed neatly. But the battery comes off as normal and never has dirt in the fingers that engage its mount plate. — Battery mount and wires

I cut short the Grin throttle and modified the clamp for it so I could still use most of my fattened grips which I love, and have space for bar ends (I know they are uncool now!). The throttle controls power and braking once ebrakes are engaged. I almost never use the physical brakes except to stand still at a light. — Throttle and bar end

Rack and wheels

I mostly use this bike for commuting on pavement, but also for backcountry access on trails and rough roads, so it had to convert quickly to rough surface use.

I wanted the rack to come off with no tools for rough road use. This rack only clamps to the top of the seat tube, but with heavy panniers it was too bouncy. So I added some tent pole sections that plug into the unused v-brake bosses on the seatstays and support the rack, but don't affect its removal at all. — Rack

I found some burly old 36 spoke wide mtb rims and painted them white to contrast with the 2.4 inch Schwalbe Supermoto X tires. These are semi slick, but seem to still work pretty well on anything but mud. They are the widest tires that will fit in my frame, and are super smooth and nice to ride on pavement with potholes. In the winter I switch to studded tires, a little smaller diameter.
The rear fender was a cast off from a friend. I painted it and the frame with a home mix of Tremclad colours and it looks pretty good. It is very close to the fat tires but works fine and doesn't bounce on rough roads. — Wheels and fender

I didn't like the front fender sitting up at the top of the fork, so I epoxied some brass threaded inserts into the grid in the rear of the fork arch and made an aluminum bracket to screw in there and hold the fender close to the wheel. You can still pull it off the bracket in a second as it was designed to do on the original. — Front fender