Internal cable routing is awesome for clean-looking bikes, but it can turn a simple brake install into a nightmare. Shimano’s answer? J-Kit brakes. Instead of forcing you to cut hoses and do a full bleed right out of the box, J-Kit systems come pre-bled and capped so you can run the hose through your frame and connect it to the lever in minutes. The best part: you get the exact same brake performance—whether it’s Deore, SLX, XT, or XTR—just in a rider-friendly install package.
What J-Kit Means
Shimano’s J-Kit (sometimes called “Junction Kit”) is basically a shipping/install system. The brakes come pre-bled from the factory, but the hose isn’t fully connected to the lever. Instead:
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The lever is capped and sealed with oil inside.
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The hose is capped and filled too.
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You just push the hose into the lever and tighten the olive/nut.
This way, you can route the hose through tight frames (like full internal cable routing) without cutting or doing a messy full bleed. Shimano calls it “simple hose connection system.”
Which Models Use J-Kit?
Pretty much all Shimano hydraulic brakes—from entry-level Deore to top-end XTR—have J-Kit versions. You’ll often see a part number like:
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BL-M6100 J-Kit (Deore)
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BL-M8100 J-Kit (XT)
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BL-M9120 J-Kit (XTR 4-piston)
Key point: the “J-Kit” isn’t a separate brake, just the packaging/installation style. The caliper and lever internals are identical to the standard version.
Pros & Cons of J-Kit
Pros:
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Super easy install with internally routed frames.
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No full bleed needed if done correctly.
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Clean, beginner-friendly setup.
Cons:
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You still may need a mini-bleed if you don’t seat the hose perfectly.
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Shops sometimes charge extra to “convert” if you accidentally buy the non-J-Kit version for a bike with full internal routing.
Final Thoughts
At the end of the day, J-Kit isn’t a different brake, it’s just a smarter way to install one. Whether you’re running Deore for weekend laps, XT for enduro, or XTR for race day, the performance is identical—you’re simply saving yourself time, frustration, and a messy bleed when routing hoses through modern frames. If your bike has internal routing, J-Kit is hands-down the easier choice. If not, the standard version works just as well. Either way, Shimano’s got you covered.
If you are looking for mountain bike brakes you can shop our full selection here. Remember that we offer free shipping on all orders over $149CAD within North America. All orders are processed and shipped within 24 business hour as well.
Spend less and ride the best with TBS Bike Parts.
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