Production Update: ODK 3.0 Disc Brakes Upgraded
Sunday, November 10, 2013 at 10:23PM An electric bicycle can travel much faster than a normal bicycle. The rider maybe carrying a load which will increase the stopping distance. One of the top feature request for the ODK e-bike was to include a rear disc brake.
To incorporate the rear disc brake, the frame needed to be redesigned and a new 3-speed hub was required. The rear dropout now has a horizontal opening with 135mm spacing. Now most all internally geared hubs with disc brakes can be used. This includes 5 to 8 speed hubs and NuVinci N360 hubs.
With this new setup, we decided to equip, as standard, the best disc brakes available for e-bikes with cost not being the major consideration.
We chose to use the Tektro HD-710E which is the latest generation of hydraulic disc brakes designed for electric bicycles. Both front and rear axles use this setup. They are 100% compatible with bicycle standards so they can be serviced at any bicycle shop.
The stopping power is incredible. The rider will feel confident that the bike can stop rapidly under any weather condition. The hydraulic braking system requires much less pressure on the lever to slow the bike down. Modulating the braking level is easier as there is no "squishy" feeling that is normally experienced with cable-pulled disc brakes.
One major advantage of the hydraulic braking system is that both pads move toward the rotor and self-adjust as the friction material wears down. On more basic cable-pulled disc brakes, only one pad moves toward the rotor and the stationary pad must be manually adjusted. This can make cable-pulled disc brakes difficult to adjust, noisy, and eventually give reduced performance.
Here are some features of the Tektro HD-710E which makes it very suitable for high performance e-bikes.
Brake Cut Switch
One feature that all electric bikes must include is a brake cut-off switch. This switch cuts the power to the motor when brakes are used. Most higher-end disc brakes do not have this feature, but it is included with the new brakes.
Brake Pad Material and Size
Above is a closeup of the new brake pad compared to standard brake pad. The surface area is much greater resulting in better stopping power and longer service life between brake pad changes. The pad incorporates a high performance metal ceramic compound which glides more consistently over the brake rotor. There is less of the "scratchy" feeling felt with lower-end disc brakes.
Ease of Servicing
There are now two disc brakes (front and rear) so the stopping duty is better distributed between the two systems. Pad changes are less frequent. The pads self-adjust and require less fiddling to hush a squeaky rotor.
Improved Lever Design
Almost all of the high-end brake levers have very short blades designed for mountain bike use. This setup is not appropriate for road going e-bike. The Tektro HD-710E has a 4-finger blade with distance adjustment to suit the rider's comfort. The large blade has a ball-shaped end. The overall design is also very suitable for winter riding where gloves will be used.
Thicker Brake Rotor
The brake rotor is thicker than a standard rotor and has more metal material. This will help with heat dissipation and reduce the chance of getting warped if bumped. Both front and rear use the same 180mm rotor and pads which cuts down on parts variation.
Fluid Level Window
One impressive feature borrowed from the motorcycle industry is a fluid-level window. There is no need to guess the brake fluid level. The rider can know immediately if the reduced brake performance is the result of low brake fluid.
Slim Profile
One issue with hydraulic disc brakes is their girth. The Tektro HD-710E has a slim profile which allows it to be used with the large 500-Watt BPM motor without touching the side of the hub. The entry angle of the cable hose can be pivoted to fit a bike's unique frame design.