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External Junction B (SM-JC40)

The junction box SM-JC40 is used externally, when internal cable routing or an internal junction box (SM-JC41) is not possible. It is usually placed underneath the bottom bracket, fixed to the frame using a screw.

External Junction Box B - SM-JC40

Details & specifications

Shimano model codeSM-JC40
Shimano model nameJunction B (external)
Weight8 g
SeriesUltegra 6770, Ultegra 6780, Ultegra R8000, DURA-ACE 9070, DURA-ACE R9150
Downloads Junction B Manual
View on Amazon (new tab)  |  eBay (new tab) Chain Reaction Cycles (new tab)

Shopping links

Are you looking to upgrade your bike using this component? We've added shoppings links to this component's Amazon and eBay pages. Click the images below to view the Amazon product page or eBay search results.

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Installation

The SM-JC40 is installed underneath the bike, below the bottom-bracket. It attaches using a mounting bolt and takes up to four e-tube wires.

SM-JC40 installation SM-JC40 wire installation