Shimano Deeper Sunken Nuts for Carbon Forks - 18 mm
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Product Information
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Designed for road cyclists and mechanics working with carbon fork installations, these genuine Shimano sunken nuts provide a critical 18 mm depth to ensure a secure and reliable anchor for rim brake calipers. They are specifically engineered to accommodate the thicker crown construction of modern carbon fiber forks, though users must verify their fork's specific reach requirements before purchase to avoid fitment issues.
All features
| Model Part Number | 8557401 |
|---|---|
| Brand | SHIMANO |
Extended Product Information
FAQs
Can I use these on an aluminum fork?
While technically possible if the depth matches, these are specifically optimized for the recessed crowns found on carbon forks.
How do I measure my fork for the correct nut length?
Measure the distance from the rear of the fork crown to the front recessed hole. The nut should be long enough to allow the brake bolt to catch enough threads for a secure hold.
Is this a single piece?
Yes, this is a single 18 mm sunken nut component.
Do I need a special tool to install this?
Typically, an Allen key is used on the brake bolt side to tighten the assembly once the nut is placed.
Does this prevent the brake from centering?
Properly seated, this nut provides a stable anchor point that assists in maintaining brake alignment.
Troubleshooting
Nut does not fit through the fork hole
Check for excess carbon resin or paint in the fork crown hole and clean it out before attempting re-insertion.
Brake caliper feels loose after tightening
Verify that the 18 mm depth is sufficient; if the bolt bottoms out, you may need a different length, or ensure the nut is seated fully against the crown.
Pros and Cons
Pros
- Ensures secure brake caliper mounting on deep carbon forks
- Genuine Shimano component ensures compatibility
- Robust construction for long-term safety
- Precision-machined threads for smooth installation
Cons
- Specific to 18 mm requirements; not universal
- Requires proper fork crown clearance measurement
- Not intended for use with non-standard brake mounting systems
Setup, Compatibility & Care
To install, slide the nut into the rear of the fork crown hole. Ensure that the internal threading is clean of debris or excess carbon resin before threading in your brake bolt. Apply a small amount of anti-seize compound to the threads to prevent long-term bonding to the caliper bolt. Compatibility is generally restricted to standard road calipers; always check your fork manufacturer's documentation regarding the required nut length, as carbon forks vary significantly in thickness.