Most commercial courier companies can transport bicycles, but pricing varies—it’s worth getting multiple quotes. You’ll likely need to provide the package dimensions (length, width, height) and estimated weight.
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The Bike Hub community recommends these couriers:

Packaging Tip: Securely box your bike to prevent damage—couriers are not responsible for packaging and will insist on your bike being boxed. Your local bike shop can assist with proper boxing.

The couriers above also handle smaller items. However, for parts and accessories, counter-to-counter services may be a more convenient and cost-effective option:

These services offer fixed pricing and easy drop-off/pick-up but have weight and size limits, making them unsuitable for complete bikes.