Rear disc brake and magnet sensor clearance issues on Giant Talon 3?

[Brushy82]

Hey everyone, hello, my step son has brought a conversion kit for his mountain bike. He is having trouble with rear break disk hitting the frame and brake calliper hitting the casing for the magnets in the rear tyre

My bike's a Giant talon 3 M 27.5 2000w motor from TDR.

 

[Greg Watts]

Hey everyone, hello, my step son has brought a conversion kit for his mountain bike. He is having trouble with rear break disk hitting the frame and brake calliper hitting the casing for the magnets in the rear tyre My bike's a Giant talon 3 M 27.5 2000w motor from TDR.

Welcome to the forum, @Brushy82. Right, so there are actually two separate problems here that need dealing with one at a time.

The disc hitting the frame is a rotor clearance issue. The Giant Talon 3 27.5 comes stock with a 160mm rear rotor, and the TDR 2000W hub motor kit is designed for 6-bolt disc brake compatibility. The hub motor axle is much wider and chunkier than a standard hub, and if the disc is fouling the chainstay it usually means either the wheel isn't seated properly in the dropout, the rotor needs to be a smaller diameter, or a spacer/dishing adjustment is needed. Worth checking the wheel is fully pushed home in the dropouts first.

The caliper hitting the speed sensor magnet casing is the more interesting problem. The TDR kit uses a 12-magnet pedal assist sensor crank sensor, but it also comes with a speed sensor that typically mounts on the rear wheel. On many of these conversion kits the speed sensor disc or magnet ring adds bulk to the hub/rotor area that the stock caliper position doesn't account for. The fix is usually a brake caliper adapter that pushes the caliper outboard to clear the sensor housing.

To give more specific advice I'd need to know what year the Talon is and which exact TDR kit variant he has. Can he post a photo of the rear axle/hub area? That'll make diagnosing which adapter or spacer is needed much quicker than guessing from a description.

 

[Brushy82]