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Hope 40T-Rex Ratio Expander Sprocket - 40T-Rex

Hope 40T-Rex Ratio Expander Sprocket - 40T-Rex

The Hope T-Rex Expander Sprocket allows you to upgrade your existing 11-36, 10-speed cassette to p...

Best current price£29.95from Merlin Cycles

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Product Information

Full details

The Hope 40T-Rex Ratio Expander Sprocket is designed for mountain bikers looking to extend their 10-speed drivetrain range from 11-36 to 11-40 without the expense of a full drivetrain overhaul. This lightweight, CNC-machined component offers a superior balance of climbing capability and shifting precision, though it requires precise B-tension adjustment to ensure compatibility with your existing derailleur and cassette stack.

All features

Model Part Number40T-Rex
BrandHope

Extended Product Information

FAQs

Does this work with all 10-speed cassettes?

No, it is designed for specific 10-speed cassettes. Please verify your cassette model for compatibility before purchase.

Do I need a new chain after installing this?

You should check your chain length. Depending on your previous setup, you may need to add links to accommodate the larger 40T cog.

What material is the T-Rex made of?

It is crafted from hard-anodized 7075T6 aluminium for high strength and low weight.

Do I need a special tool to install it?

You will need a standard cassette lockring tool and a chain whip to remove and reinstall your cassette.

Can I use this with a 1x or 2x setup?

The sprocket is generally optimized for 1x configurations, but compatibility may depend on your derailleur's total capacity.

Troubleshooting

Poor shifting into the 40T sprocket

Adjust the B-tension screw on your derailleur to increase the gap between the jockey wheel and the cassette.

Chain skipping or excessive noise

Check that the cassette lockring is fully tightened and that the chain length is sufficient for the larger gear.

Pros and Cons

Pros

  • Cost-effective alternative to replacing a full drivetrain
  • Excellent shifting performance due to targeted tooth profiling
  • Lightweight construction using high-strength 7075T6 aluminium
  • Better B-tension compatibility compared to 42T alternatives

Cons

  • Requires removing a smaller sprocket from the existing cassette
  • Compatibility is limited to specific 10-speed cassettes
  • Demands precise installation and derailleur adjustment

Setup, Compatibility & Care

To install the 40T-Rex, you must remove the cassette from your freehub body and remove one of the intermediate sprockets to maintain the overall stack height. Once the expander is seated behind the remaining cassette cluster, reinstall the lockring and ensure the derailleur B-tension screw is adjusted to clear the larger 40T cog. Always check that the chain length is adequate to accommodate the new maximum gear range. Regular cleaning with a standard degreaser is recommended to maintain the efficiency of the hard-anodized teeth and prevent mud build-up, which can lead to premature wear of both the sprocket and the chain.

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