What It Is

Guided Alignment System (G.A.S.) bottom brackets are a two-piece system for threaded frame shells where the system space is constrained with respect to the bearing size and crank spindle. *I.e. it can’t have the drive-side and non-drive-side bearings in the drive-side module, like our best-in-class Module One, Module 45 and Module 47 bottom brackets. This ITA (Italian) standard has a high-precision sleeve fit which guides and aligns the two bearing holding modules (bearing cups) in exacting (or very-good) alignment for reduced friction, greatly extended lifespan and no chance of creaking. This ITA-70 version fits frame frames with a Italian threaded frame shell that is 70 mm wide. It is suitable for 24mm crank spindles (typically Shimano), or 24/22mm (GXP).

Why It’s Better

This is a bottom bracket made to Formula One standards and it’s the precision that makes the difference. The very close sleeve fit with a deep overlap between the two parts ensures they mount and remain in line. The extremely high-accuracy with which the bearing seats are machined to keeps the bearings themselves in exceptional alignment.

The unit is machined from lightweight, high-stiffness, 6000-series aluminium. The bearings themselves are very high-grade items from Japanese specialists, with a choice of seals. When they eventually require servicing or replacement, the design gives easy access and either bearing can be replaced without uninstalling the entire bottom bracket.

SN-Vitae bottom bracket casings come with an 2-year warranty.

Choice of Bearing Seals

Contact (DD) Seals

Contact (DD) seals are better for year-round riding and lower maintenance because the seal is in contact with the inner race of the bearing. This makes it extremely difficult for contaminants like dust, dirt, and moisture to reach the inner parts of your bearing whilst doing an excellent job of sealing lubricants inside your bearing.

Non-Contact (VV) Seals

Non-contact (VV) bearing seals are recommended for racing bicycles that are regularly serviced. Non-contact seals do offer lower friction but are also a less robust barrier to dirt and water. They should be considered consumable-like.

*Contact seal bearings are advisable if you race and train on the same bike.

Compatibility

Frame BB Shell Type:	ITA - Shell widths of 70 mm
Crank Spindle Diameter:	24mm (Shimano), or 24/22mm (GXP).

What’s Included?

Module Casings:	2x module casings parts (drive-side and non-drive-side) manufactured from 6000-series aluminium, anodised for a long-lasting smart finish.
Bearings:	2x High-grade NSK Japanese bearings. Select from either Non-Contact (VV) or Contact (DD) Seal Types.
End Caps:	2x Plastic End Caps for location within the bearings / fitment to the crank spindle.
Installation Tools:	Included free with each BB purchased on the SN-Vitae website.

Guided Alignment System (G.A.S.) Technology

Central to the G.A.S. bottom bracket design is the two-piece system that has a high-precision sleeve fit system aligning the two bearing holding modules in exacting (or very-good) alignment for reduced friction. When this optimal bearing bore alignment is achieved, this greatly increases the bearing life and reduces unnecessary frictional losses that often occur through bearing misalignment.

Installation

Ensure your bicycle's bottom bracket shell is free from obstructions such as cable guide screws protruding into the bottom bracket shell.
Ensure the bottom bracket threads are clean.
Installation and removal must be performed with the supplied specific tool – The 3X Tool.
Installation MUST NOT and cannot be conducted with plastic end caps installed in the bearings. Remove the End Caps before commencing installation.
Warranty will be void if there is evidence of impact damage or use of a hammer/mallet during installation.
Check dimensions for tolerance - for instance shell width.
Install module sections to torque setting of 40 Nm.
It is advisable that all all G.A.S. bottom brackets are installed using anti-seize (nickel based is best) on the threads and interface between the drive-side and non-drive-side modules.