We’ll make this a great experience

It’s our mission to provide you with world-class hospitality every time you visit us online or in-store. We’ll always take care of you. It’s the Trek way.

Awesome free shipping options

All accessory orders over $49 ship to your home for free, and all accessory orders ship free to your local retailer for in-store pickup.

30-day Unconditional Guarantee

If for any reason you’re not 100% happy with your online order from trekbikes.com, you can return it in like-new condition within 30 days. No questions asked.

Learn more

Trek 2018 Session 0-Degree Head Angle Headset Assembly

Model W557045

Original replacement headset assembly for your Session.

Product details

Complete headset assembly
0-degree offset headset is stock on Session models
Only for use on 2018+ Session Carbon models

Manufacturer part #	10100025000010
Steerer outer diameter	28.6mm (1-1/8")
Crown race inner diameter	39.8mm
Cup Insertion OD	49mm Top/56mm Bottom
Stack height	9mm
Bearing type	Sealed
Headset type upper	Unthreaded semi-integrated
Headset type lower	Semi-integrated
Material	Aluminum

We reserve the right to make changes to the product information contained on this site at any time without notice, including with respect to equipment, specifications, models, colors, materials, and pricing. Due to supply chain issues, compatible parts may be substituted at any time without notice. Prices shown are manufacturer's suggested retail prices.

Weights are based off pre-production products at time of publication. Weights may vary in final production.