--(A Practical Guide Based on Real Customer Cases and Technician Experience)
Hydraulic brake olives are small but critical components in MTB and e-bike brake systems. When riders talk about SHIMANO BH59 vs BH90, they are usually trying to solve one of these problems:
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“Why is my lever leaking after I cut the hose?”
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“Why is there no braking power after installation?”
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“Which olive do my brakes actually use?”
If you’re confused, you’re not alone—customers ask us these questions every single day.
In this guide, we will explain the real technical difference between BH59 and BH90, how to identify the correct type, and why almost all BUCKLOS, ZOOM, and IIIPRO brakes use BH59.
(Full compatibility list included below.)
1. What Is a Hydraulic Brake Olive?
A brake olive is a small brass compression ring that seals the hydraulic hose to the brake lever or caliper.
When the compression nut tightens, the olive bites into the hose and creates a leak-proof seal.
Because hydraulic pressure is high, the wrong olive—or an olive installed incorrectly—will cause leaking, spongy brakes, or complete loss of braking force.
Here is a the decomposition Diagram of the brake olive:
2. BH59 vs BH90: The True Technical Difference
Although BH59 and BH90 look similar, they are not interchangeable.
BH59 Olive
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Thicker wall
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Softer brass
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Designed for lower to mid-pressure systems
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Easier to compress
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Used on most entry-level to mid-level hydraulic brakes
BH90 Olive
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Thinner wall
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Harder material
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Designed for higher-pressure braking systems (e.g., Shimano SLX/XT/XTR)
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Requires more precise compression
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Only for BH90 hoses
Because the hardness and wall thickness are different, mixing them will cause:
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Oil leakage
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Poor pressure sealing
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No braking force
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Olive damage during tightening
3. Why Most Brakes Use BH59 (Including 90% of Our Store Products)
Based on our real product compatibility and customer installations, BH59 is the correct olive for nearly all BUCKLOS, ZOOM, and IIIPRO hydraulic brakes.
This includes:
BUCKLOS
HB-323
HD-M735
HD-E735
HD-E635
MT200 (BUCKLOS version)
ZOOM
HB-875
HB-876
HB-876E
HB-775E
HB-100
DB-680
IIIPRO
IV2
IV4
E4
PEERAGE4
E500
All of the above use BH59 olives.
NOTE：
Only a very small number of Tektro systems require a different type: HB-CP4
4. Most Common Customer Questions About BH59/BH90 (Real Cases)
These are the top questions we receive from customers worldwide:
Q1: “After cutting my hose and installing the olive, why is oil leaking from the lever or caliper?”
Typical causes:
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Wrong olive (BH90 used on a BH59 system or vice versa)
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Hose not pushed all the way in
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Olive is damaged during tightening
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Compression nut overtightened or undertightened
Q2: “How do I know which olive type my brakes use?”
For our store:
If your brake is BUCKLOS / ZOOM / IIIPRO — the answer is BH59.
Q3: “Why do my brakes have no pressure after installation?”
Usually because:
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The olive didn’t fully bite into the hose
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Hose is cut unevenly
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The insert pin is not fully seated
Air entered the system (requires bleeding)
Here is the difference：
BH59 vs BH90 Olive & Insert Pin Dimensions (Industry Standard)1. Olive Dimension
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Insert Pin Dimension
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5. Most Common Installation Errors (Based on Real Customer Support)
We regularly help customers fix these mistakes:
❌ 1. Olive crushed during installation
Happens when the compression nut is overtightened or misaligned.
❌ 2. Hose not cut straight
A diagonal cut prevents the olive from sealing properly → instant leaking.
❌ 3. Mixing BH59 and BH90
This is one of the most common reasons for leaking and weak braking.
❌ 4. Hose not inserted fully
Even a 1–2 mm gap can cause total loss of braking force.
6. Material: Why We Use Brass Olive Heads
All our BH59 olives use high-quality brass (brass olive head) because:
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Brass forms a reliable compression seal
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Corrosion-resistant
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Suitable for MTB and e-bike vibration environments
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Easy to install and durable over time
This is the same material standard used by major brake manufacturers.
7. Full Compatibility List (BH59)
To make installation easier, here is the complete list of brakes in our store that use BH59:
If you bought your brakes from our store, 99% probability they require BH59 olives.
8. Can You Mix BH59 and BH90? (Answer: No)
Mixing the two types will cause:
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Oil leakage
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Spongy lever
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Weak braking power
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Olive failure
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Possible damage to the lever port
Always match:
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BH59 olive → BH59 hose
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BH90 olive → BH90 hose
Although BH59 and BH90 olives share similar outer diameters, their height, wall thickness, and insert pin length are engineered specifically for different hose wall thickness and system pressure.
In our store, over 90% of hydraulic brake systems (BUCKLOS, ZOOM, IIIPRO) are designed around BH59 hose specifications, which is why we standardize on BH59 brass olives and BH59 insert pins across most models.
9. CTA – Shop BH59-Compatible Brakes and Olive Kits
Since almost all brakes in our store use BH59, you can easily find the correct parts here:
👉 All BH59 brake systems (BUCKLOS / ZOOM / IIIPRO)
👉 BH59 Olive + Insert Kits
👉 Hydraulic Hose Replacement Kits (BH59 compatible)
Here is the BH59 olive brass head replacement guide：
10. Final Tips From Our Technician Team
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Cut the hose with a proper hydraulic hose cutter
(if you might also need the Internal Cable Routing Tool Kit insert into the bike frame)
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Insert the pin fully before tightening
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Tighten the compression nut slowly to avoid crushing the olive
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If a leak appears, never re-use the same olive—replace with a new one
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Always confirm the olive type (BH59 vs BH90) before installation
With correct installation and the right olive type, your brake system will stay sealed, firm, and reliable.
