Skip to main content
Due to the unfortunate COVID-19 Pandemic, we are currently experiencingunprecedented volume of online orders.
As we are doing our very best to process them quickly, 
please expect to see some delays at this time.
Thank you for your understanding and patience.

Trek Seat Mast Cap

Trek Seat Mast Cap
Please select options


Trek-compatible seat mast cap

Offered in white and black and a variety of lengths and offsets, the mast cap includes hardware compatible with round saddle rails only. 7x10mm carbon rail-compatible hardware sold separately.

Key features:

- Ultra-light carbon construction
- One bolt head design offers easy fore-aft and infinite angle adjustment
- Compatible with all Trek road bikes with round seat masts
- 175mm and 135mm lengths
- 5mm and 20mm offsets
- Aluminum clamp

Part Numbers

Option UPC MPN Store SKU
Black / N/A / 135mm / 20mm 601479788828 559538 654-0050+2
Black / N/A / 175mm / 20mm 601479788798 559539 654-0049+3
Black / N/A / 135mm / 5mm 601479788811 559540 654-0046+1
Black / N/A / 175mm / 5mm 601479788804 559541 559541