The Waterloo-based Trek Bicycle Corp. is warning the owners of some 2012 models to stop riding their bikes until they are inspected.

The reason behind the warning is that several models are being recalled due to a safety hazard. The concern is over a defective bolt that secures the seat saddle clamp to the seat post on Trek 2012 FX and District bicycles. If the bolt breaks, riders can fall, company officials said.

Trek has fielded at least four incident reports, including one minor injury. The rider was treated for a broken tooth and a lip injury, according to the U.S. Consumer Product Safety Commission and Health Canada.

The voluntary recall involves about 27,000 bikes, which were sold at stores between May and September 2011, they said..

Trek issued a statement to buyers on its website: "We sincerely apologize for any inconvenience this problem might have caused you. We value you as a customer and want you to enjoy your Trek bicycle. We hope that after your Trek bicycle is repaired, you will continue to safely enjoy cycling."

The recalled models include:

• 7.5 FX including WSD and Disc models
• 7.4 FX including WSD models
• 7.3 FX including WSD and Disc models
• 7.2 FX including WSD models
• Livestrong FX including WSD models
• Livestrong District
• 9th District
• District

Affected bike owners should contact a Trek dealer for a free replacement bolt. Consumers may also call 800-373-4594, weekdays between 8 a.m. and 6 p.m. CST.