Bombtrack Hook Brakes: GRX, Flat Mounts and 160 mm Rotors
Bombtrack Hook brakes in the saved steel-bike build combine GRX hydraulic controls and calipers with 160 mm SM-RT66 rotors. A separate technical table describes flat mounts and maximum rotor clearance. These entries make a useful brake-identification record when their different roles remain clear, rather than reducing the assembly to one GRX label.
Bombtrack Hook brakes include named controls and calipers
The brake-lever line specifies Shimano ST-RX400 STI hydraulic controls, while the calipers are BR-RX400. The rotor line names Shimano SM-RT66 at 160 mm. Preserve those separate identifiers when comparing an actual bicycle with the saved build; a matching lever cannot establish every other fitted brake component.
This matters especially for a bicycle with replacement wheels or a changed cockpit. The original specification remains useful, but it cannot inspect the installed system or establish its service history. This guide supplies identification information without a bleed, adjustment or wheel-removal procedure.
Flat-mount descriptions and rotor limits answer different questions
The frame and fork tables each print FM 140/160 for their brake mounts. Each also states a maximum rotor clearance of 160 mm. Retain both rows: the mount notation describes an interface, while the maximum entry places a separate stated boundary on rotor diameter for the described frame or fork.
The rear frame mount additionally has a listed thickness of 10 mm. That measurement should not be copied into an order as a universal bolt length. The saved page does not identify the complete fixing or adapter arrangement needed for every possible installation.
Keep the wheel-side attachment in view
Bombtrack Tau front and rear hubs are described as six-bolt disc hubs. That is wheel-side information, distinct from the frame’s flat mounts. A replacement-wheel or rotor enquiry needs the actual hub and its attachment identified as well as the bicycle’s frame and brake record.
The catalogue listing is Bombtrack Hook Bike — Metallic Black. It gives the discussion a particular parent identity, without guaranteeing that an individual offered bicycle retains every saved component. The manufacturer record does not approve a larger rotor merely because an adapter exists.
The historical MY19 Hook image illustrates another build and cannot authenticate hidden fittings. The Bombtrack topic and brand introduction provide family context while the exact component names remain the basis for a specific enquiry.
FAQ
Which rotor diameter is listed for the complete build?
The saved rotor entry specifies 160 mm SM-RT66 discs.
Is FM 140/160 the hub’s rotor attachment?
No. The hub entry separately describes a six-bolt disc interface.
Does the 10 mm rear-mount entry specify every fixing bolt?
No. It is a mount-thickness record, not a universal bolt specification.
Sources
The brake components, flat-mount interfaces and separate maximum rotor entries describe different parts of the published arrangement. See the manufacturer’s saved steel Hook record (https://bombtrack.com/products/bombtrack-hook), captured 26 October 2026 and reread 5 November 2026.
Photograph credits and permissions
Photograph 1
Original title: Bombtrack Hook 2 MY19
Creator: www.velo-radsport.de; creator URI: https://www.flickr.com/photos/velo-radsport/
Copyright notice: Embedded sRGB ICC profile notice: Copyright (c) 1998 Hewlett-Packard Company. This identifies the colour profile, not the photograph author; no separate photographer copyright notice was supplied in the inspected image metadata.
Original source URI: https://www.flickr.com/photos/velo-radsport/47821053362/
License / permission: CC BY-SA 2.0 Generic
License / permission URI: https://creativecommons.org/licenses/by-sa/2.0/
Modification notice: Source-offered 2600 × 1733 original JPEG retained byte for byte with EXIF, IPTC/Photoshop resources, XMP and ICC profile. No local crop, resize, recompression, colour edit or metadata removal. Source EXIF/XMP records Adobe Photoshop Elements 15.0 processing before retrieval.
Source disclaimer: Historical Bombtrack Hook 2 MY19 photograph; MY19 is supplied in the source title, not inferred from upload date. Related Bombtrack brand context only; not proof of the current named build, SKU colour, components, geometry, fit, compatibility, cargo capacity or condition. No endorsement is implied. CC BY-SA 2.0 applies to the unchanged photograph; retain attribution and notices, provide the license URI, and make adaptations available under an applicable share-alike license. No additional restrictions or warranties are implied; other rights may apply. Exact license name: Creative Commons Attribution-ShareAlike 2.0 Generic.