Replacing the brake cables on the Shimano BR-R7100 [paid link] is a critical maintenance task that directly impacts braking consistency, lever feel, and safety. As part of the Shimano 105 R7100 series, these hydraulic disc brakes rely on precisely routed and tensioned cables within the STI lever and hydraulic hose system. Though this model utilizes hydraulic fluid to transfer braking force, the term “cable” in this context refers to the mechanical routing elements tied to the STI lever action, specifically the internal routing through the frame and hose replacement when necessary.
Replacing the brake cable or hydraulic hose should be done with care and an understanding of the model-specific layout. This guide will take you through the tools, removal, installation, and bleed process essential for ensuring a responsive and powerful brake feel.
Tools Required
- 4mm and 5mm hex keys [paid link]
- Shimano TL-BH62 hydraulic hose cutting tool
- Shimano TL-BH61 barb and olive press tool
- Shimano hydraulic mineral oil [paid link]
- Shimano funnel (e.g., SM-DISC)
- Bleed block and clamp
- Clean rags and isopropyl alcohol
- Replacement Shimano SM-BH90-JK-SSR hydraulic hose
- New barb and olive kit
- Bleed kit [paid link] with syringe and funnel
- Torque wrench [paid link] (range up to 7 Nm)
Understanding the BR-R7100 Hydraulic Brake Cable System
The Shimano BR-R7100 [paid link] system features a full hydraulic disc braking system, with braking force actuated through mineral oil [paid link] pressure generated by the Dual Control Lever (ST-R7170). The “cable” replacement involves hydraulic hose servicing, typically SM-BH90 series hoses. This model uses a straight insert (banjo not supported), and hose routing is internal on many modern road frames.
It’s important to distinguish that the mechanical shifting cable (if using a non-Di2 version) is separate from the brake hose and unrelated to brake performance. For Di2 setups, only hydraulic hose routing is necessary.
When Should You Replace the Hose on Your BR-R7100 Brakes?
- Visible damage or cracks in the hydraulic hose
- Spongy lever feel due to internal leakage or contamination
- Swollen or soft hose indicating degradation
- Poor braking power despite a recent bleed
- Hose length adjustment after bar swap or frame upgrade
Step-by-Step Brake Hose Replacement Procedure
1. Preparation and Setup
Begin by clamping the bike in a stand. Ensure the brake lever is level [paid link] to facilitate bleeding later. Remove the wheel and brake pads, then insert the bleed block. Clean the caliper and lever area thoroughly using isopropyl alcohol.
2. Disconnect the Existing Hose
At the caliper end, use a 5mm hex key [paid link] to remove the hose fixing bolt. Gently pull the hose free. At the STI lever, remove the lever hood, unscrew the compression nut (usually 8mm or 5mm hex depending on lever design), and detach the hose.
Keep a rag below the lever to catch residual mineral oil [paid link]. Avoid getting oil on brake surfaces.
3. Measure and Cut the New Hose
Lay the new SM-BH90 hose alongside the old one to match length. Cut using the Shimano hose cutting tool to ensure a clean end. Never use pliers or scissors, which can deform the hose.
4. Install New Barb and Olive
Using the Shimano TL-BH61 tool, press the new brass barb into the hose. Slide the olive onto the hose before inserting the barb into the STI lever port. Thread the compression nut and torque it to Shimano’s specified value (usually 5-6 Nm).
At the caliper end, re-insert the hose, fit a new olive and compression nut, and torque appropriately. Double-check for hose alignment and ensure there’s no kinking or twisting.
Bleeding the BR-R7100 Brakes Post Cable Replacement
Replacing the hose introduces air into the system, which must be removed through a proper bleed procedure. Use Shimano’s funnel-type bleeding kit:
- Open the bleed port on the lever, screw in the funnel, and fill it with Shimano mineral oil [paid link].
- At the caliper, attach a syringe with mineral oil and open the bleed nipple.
- Slowly push oil through the system until air bubbles stop appearing in the funnel.
- Close the caliper bleed valve, remove the funnel, and reinstall the bleed port screw.
- Clean the system thoroughly and reinstall the brake pads and wheel.
Post-Installation Testing and Final Adjustments
After reassembly, pull the lever several times to check for firmness. If the lever pulls to the bar or feels inconsistent, repeat the bleeding procedure. Spin the wheel and engage the brake to ensure proper rotor alignment. Look for any rubbing or sponginess.
Check torque on all fasteners after the system is sealed and test ride the bike in a safe area to confirm performance.
Customization and Optimization Tips
- Shorten the hose as much as frame geometry allows to improve responsiveness.
- Consider internally routing the hose with frame guides or port systems for a cleaner setup.
- Use frame grommets and protective sleeves to prevent hose abrasion and reduce rattling.
- Periodically inspect the lever and caliper connection points for weeping or loosening.
Compatibility Notes
- The BR-R7100 [paid link] is compatible with the ST-R7170 STI levers and uses the same SM-BH90 hydraulic hose system as Shimano’s higher-end road disc components.
- Always use Shimano mineral oil [paid link]; do not substitute with DOT fluid.
- Hose fittings (barb/olive) must match Shimano specs. Third-party fittings may lead to failure.
Conclusion
Replacing the brake cable—or more accurately, the hydraulic hose—on your Shimano BR-R7100 brakes is a manageable task with the right tools and approach. Doing so can restore lost braking power, refine lever feel, and extend the lifespan of your braking system. With proper bleeding and careful routing, you’ll achieve smooth, reliable braking performance ride after ride.
Frequently Asked Questions
1. Can I reuse the olive and barb when replacing the hose?
No. Shimano recommends using new olives and barbs for every hose installation to ensure a leak-free seal.
2. What happens if I cut the hose too short?
A hose that’s too short can cause binding during steering and compromise braking performance. Always measure carefully and allow extra slack if unsure.
3. Do I need to bleed the brakes every time I replace the hose?
Yes. Air is introduced when disconnecting the hose, so a complete bleed is necessary to restore performance.
4. What torque settings are recommended for the BR-R7100 hose connections?
Typically 5–7 Nm, but always check Shimano’s latest technical manual for model-specific torque values.
5. Can I use BR-R7100 hoses with other Shimano calipers?
Yes, but only if the calipers use the same SM-BH90 hose system. Compatibility with non-series components should be verified.
6. How often should I replace my hydraulic brake hose?
Shimano recommends inspecting the hose annually and replacing it if there are signs of wear, damage, or degraded performance.