---
product_id: 12975928
title: "Wolf Tooth Components 25mm Long B-Screw for Adapting Old deraileurs When"
brand: "wolf tooth"
price: "£6.09"
currency: GBP
in_stock: true
reviews_count: 9
category: "Wolf Tooth"
url: https://www.desertcart.co.uk/products/12975928-wolf-tooth-components-25mm-long-b-screw-for-adapting-old
store_origin: GB
region: United Kingdom
---

# Premium 18-8 stainless steel 25mm precision length M4 x 0.7mm metric threading Wolf Tooth Components 25mm Long B-Screw for Adapting Old deraileurs When

**Brand:** wolf tooth
**Price:** £6.09
**Availability:** ✅ In Stock

## Summary

> 🔧 Upgrade your drivetrain, dominate every trail with precision!

## Quick Answers

- **What is this?** Wolf Tooth Components 25mm Long B-Screw for Adapting Old deraileurs When by wolf tooth
- **How much does it cost?** £6.09 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.co.uk](https://www.desertcart.co.uk/products/12975928-wolf-tooth-components-25mm-long-b-screw-for-adapting-old)

## Best For

- wolf tooth enthusiasts

## Why This Product

- Trusted wolf tooth brand quality
- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **Race-Proven Reliability:** Trusted by riders to fix bent screws and conquer muddy trails without compromise
- • **Optimized for Large Cogs:** Specifically designed for Wolf Tooth GC 40 & GC 42 cogs to unlock bigger gear combos
- • **Precision Threading & Size:** M4 x 25mm screw with fully threaded shaft for secure, exact adjustments
- • **Perfect Fit for Shimano MTB:** Seamlessly replaces stock B-limit screw for flawless derailleur tuning
- • **Durable Stainless Steel Build:** Corrosion-resistant 18-8 stainless steel ensures long-lasting performance in all conditions

## Overview

The Wolf Tooth Components 25mm Long B-Screw is a premium stainless steel replacement screw engineered to optimize Shimano MTB derailleurs when paired with large Wolf Tooth GC 40 or GC 42 cogs. Featuring precise M4 x 0.7mm threading and corrosion-resistant 18-8 stainless steel, it ensures reliable, durable performance and perfect derailleur adjustment for serious mountain bikers pushing gear limits.

## Description

When using the Wolf Tooth GC 42 (50-3898) or GC 40 (50-3899) replacement cogs with a Shimano rear derailleur, a longer B-screw will be needed for proper adjustment. High quality 18-8 stainless steel screw is compatible with most Shimano mountain bike derailleurs. Replaces stock B-limit screw on Shimano MTB derailleurs Use if you are using Wolf Tooth GC 42 or GC 40 large cogs High quality stainless steel

Review: Perfect for Shimano B Screw - I used this to replace the B limit screw on my Shimano derailleur after it was bent in a particularly muddy mountain bike race. It works perfectly!
Review: For those lower gears - If you want to thumb your nose at Shimano’s claimed largest sprocket size, get this. As long as your derailleur hanger has a large-enough flat for it to bear against, it will work fine for up to 40- or 42-tooth cogs. Some people turn it around, so the head of the screw meets the land to provide support.

## Features

- Replaces stock B-limit screw on Shimano MTB derailleurs
- Use if you are using Wolf Tooth GC 42 or GC 40 large cogs
- High quality stainless steel

## Technical Specifications

| Specification | Value |
|---------------|-------|
| ASIN | B00LMY7BA0 |
| Best Sellers Rank | #167,621 in Sports & Outdoors ( See Top 100 in Sports & Outdoors ) #25 in Front Bike Derailleurs |
| Brand | Wolf Tooth |
| Color | Silver |
| Compatible Groove Diameter | 4 Millimeters |
| Customer Reviews | 4.5 out of 5 stars 241 Reviews |
| Drive System | Bicycle Derailleur Drive System |
| Exterior Finish | Stainless Steel |
| Fastener Size | M4 x 25mm |
| Fastener Type | Screw (M4 thread size) |
| Finish Types | Stainless Steel |
| Global Trade Identification Number | 00812719020152 |
| Grade Rating | Premium |
| Head Style | Phillips |
| Head Type | Phillips |
| Included Components | Miscellaneous Rear Derailleur Part |
| Item Diameter | 4 Millimeters |
| Item Dimensions | 4 x 2 x 0.25 inches |
| Item Weight | 4.54 g |
| Item dimensions L x W x H | 4 x 2 x 0.25 inches |
| Manufacturer | Wolf Tooth |
| Material | Multi |
| Material Type | Multi |
| Maximum Shear Strength | 550 MPa |
| Metal Type | Stainless Steel |
| Model | BSCREW25 |
| Number Of Items | 1 |
| Number of Pieces | 1 |
| Part Number | BSCREW25 |
| Point Style | cylindrical |
| Screw Head Style | Phillips |
| Screw Point Style | cylindrical |
| Set Name | Single Screw Set (M4 x 25mm) |
| Set Screw Thread Type | M4 x 0.7mm |
| Size Name | 4mm x 25mm |
| Thread Class | 2B |
| Thread Coverage | Fully Threaded |
| Thread Size | 4mm |
| Thread Style | M4 |
| Thread Type | Metric |
| UPC | 812719020152 |
| Unit Count | 1.0 Count |
| Warranty Description | Limited Warranty |

## Product Details

- **Exterior Finish:** Stainless Steel
- **Head Style:** Phillips
- **Item dimensions L x W x H:** 4 x 2 x 0.25 inches
- **Material:** Multi
- **Thread Size:** 4mm

## Images

![Wolf Tooth Components 25mm Long B-Screw for Adapting Old deraileurs When - Image 1](https://m.media-amazon.com/images/I/61DD++TmylL.jpg)

## Customer Reviews

### ⭐⭐⭐⭐⭐ Perfect for Shimano B Screw
*by D***C on July 5, 2024*

I used this to replace the B limit screw on my Shimano derailleur after it was bent in a particularly muddy mountain bike race. It works perfectly!

### ⭐⭐⭐⭐⭐ For those lower gears
*by A***T on October 8, 2022*

If you want to thumb your nose at Shimano’s claimed largest sprocket size, get this. As long as your derailleur hanger has a large-enough flat for it to bear against, it will work fine for up to 40- or 42-tooth cogs. Some people turn it around, so the head of the screw meets the land to provide support.

### ⭐⭐⭐⭐⭐ Problem solver
*by B***D on July 17, 2025*

Exactly what I needed for a 9 speed SLX derailleur to run a larger 40T granny gear. Nice Allen head with good threads and fit.

## Frequently Bought Together

- Wolf Tooth Components 25mm B-Screw
- Wolf Tooth Components Roadlink
- Wolf Tooth GoatLink for Shimano

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*Product available on Desertcart United Kingdom*
*Store origin: GB*
*Last updated: 2026-06-30*