Shimano Hydraulic Brake Hose and Connector Standards Guide

Types of Shimano Hydraulic Brake Hoses

Shimano offers two types of hydraulic brake hoses:

1. SM-BH90 (High Power)¹
2. SM-BH59 (Standard)²

These hydraulic brake hoses are shared between road and MTB systems.

Although they look nearly identical at first glance, they differ in hose rigidity. Shimano categorizes the SM-BH90 as “High Power” and the SM-BH59 as “Standard” in terms of stiffness.

Note that you must use the hydraulic hose recommended for your brake lever set. You cannot choose BH90 simply because you want higher stiffness.

Differences Between BH90 and BH59

Let’s compare the differences between BH90 and BH59.

The major differences are the hose inner diameter and the corresponding connector insert.

As shown in the table above, the BH90 has a 0.2mm smaller inner diameter. Therefore, it requires a slimmer compatible connector insert.

Shimano genuine parts use different colors to avoid incorrect insertion: silver for BH90 and gold for BH59. The lengths also differ, so pay close attention.

What Happens with Different Inner Diameters?

Even though the outer diameter is the same, the smaller inner diameter of BH90 means the hose walls are thicker. Think of it like comparing thick-walled and thin-walled hoses.

The difference in wall thickness affects how the hose behaves under pressure.

In a hydraulic brake system, squeezing the brake lever increases hydraulic pressure, which is transmitted to the caliper pistons. At that moment, pressure also builds inside the hose.

The thicker-walled BH90 resists deformation and transfers power more directly. In contrast, the thinner-walled BH59 can expand slightly, causing a small loss in hydraulic force.

This explains the difference in rigidity between BH90 and BH59.

Types of Shimano Hydraulic Brake Connecting Bolts

Shimano hydraulic brake hoses come in two types: BH90 and BH59. However, the connecting bolts that link the levers and calipers to these hoses come in various types, as shown below:

The specific combination of levers, brakes, and connecting bolts depends on the component series.

Even within the same category and generation of shifting systems, compatible connecting bolts can differ. Be sure to refer to the [Shimano Hydraulic Disc Brake Hose Compatibility Information]³ before making a purchase.

How to Choose Shimano Hydraulic Brake Hoses

If Buying the Hose Only

When purchasing just the hose, make sure it matches your brake lever and caliper. If you’re using a genuine Shimano hose, the part number is usually printed on the outer surface of the hose—check that first.

If you’re unsure which hose is compatible, you can search for the brake lever or caliper model on Shimano’s official website, or refer to the [Shimano Hydraulic Disc Brake Hose Compatibility Information]³ to find the right hose for your brake model.

As noted in the comparison earlier, BH90 and BH59 use different connector inserts, so be careful not to purchase the wrong type.

Note that the olive is the same for both BH90 and BH59.

If Buying a Hydraulic Hose Set

When buying Shimano hydraulic hoses, pay special attention if you’re purchasing a hydraulic hose set that includes multiple parts.

Shimano’s hydraulic hose sets typically include:

1. Hose
2. Connector Insert
3. Olive
4. Connecting Bolt
5. Hose Cover
6. O-Ring
7. Insert Installation Tool

As mentioned earlier, connecting bolts vary depending on whether they are for the lever or the caliper.

Shimano’s hydraulic hose sets use part numbers like SM-BH00-AA-BB or SM-BH00-ABB, where “A” and “B” indicate the type of connecting bolts.

“A” refers to the connecting bolt on the lever side, and “B” refers to the one on the caliper side.

For example, the popular road hydraulic hose set SM-BH90-JK-SSR means: BH90 hose with a JK bolt on the STI (lever) side and an SSR bolt on the caliper side.

In the case of MTB, the current M9100 series uses SM-BH90-SBM, which means: BH90 hose with a straight bolt on the lever side and a BM (banjo style for BR-M9120 caliper) on the caliper side.

You can find the exact hose set model number that matches your brake system in the [Shimano Hydraulic Disc Brake Hose Compatibility Information]³. Look up your brake model and purchase the appropriate hose set accordingly.