E-Bike Parts

Hydraulic Brake Components

Calipers, hoses, olives, bleed kits and mineral oil / DOT fluid.

Hydraulic disc brakes are standard on mid-range and better e-bikes because they stop a heavy bike with less hand effort and stay consistent as pads wear. They also need occasional service that cable brakes do not: a bleed when the lever goes spongy, a new hose when one is cut or kinked, a caliper when a piston sticks or seal leaks. The parts are not expensive, but they are brand-specific in ways that matter. On an e-bike the extra weight and speed make healthy hydraulics even more important, so do not put service off.

The big divide is fluid. Shimano, Tektro, TRP and Magura systems use mineral oil; SRAM, Avid, Hayes and Hope systems use DOT fluid. They are not interchangeable, and putting the wrong fluid in a system ruins the seals. Within a brand, hoses, olives and barbs vary by model and hose diameter, and bleed kits need the right adapters for your lever and caliper ports. Calipers must match the rotor size and mount you already have, and a replacement caliper from a different brand generally means replacing the lever and hose too.

Bleeding is a learnable job with the right kit and a patient hour, and it fixes the most common hydraulic complaint. Hose replacement and caliper swaps are a step up, because they involve cutting, fitting a new olive and barb, and a full bleed. If the brake has been contaminated or the caliper is leaking fluid onto the pads, stop riding it until it is sorted. Confirm fluid type and part numbers on your bike before buying anything.

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Hydraulic Brake Components

Mineral Oil Hydraulic Brake Bleed Kit for Shimano/Tektro/Magura (generic)

Bleeding hydraulic brakes at home is a reasonable job for an e-bike owner, and the generic bleed kit makes it possible: two syringes, hoses, a bleed cup and a bag of adapters that thread into Shimano, Tektro and Magura levers and calipers. Most kits are sold with or without a small bottle of mineral oil. It pays to get a kit that includes the Shimano funnel and the M5/M6 fittings for Tektro calipers, since those are what most e-bikes have. Follow the manufacturer's bleed procedure; each brand differs slightly.

Best for: Owners of Shimano, Tektro or Magura mineral-oil brakes · Fixing spongy levers or after shortening a hose · Riders who want to do annual brake maintenance themselves

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Hydraulic Brake Components

Shimano Hydraulic Disc Brake Mineral Oil, 100 ml

Shimano's own mineral oil is what goes in any Shimano hydraulic brake, and it is also commonly used by owners of Tektro and Magura brakes after checking compatibility. The 100 ml bottle is enough for several bleeds on a two-brake bike. The important thing to know is that mineral oil and DOT fluid are not interchangeable; putting DOT in a mineral-oil brake ruins the seals. If your levers say Shimano, Tektro or Magura they almost certainly take mineral oil, but read the lever cap. Keep the bottle sealed and away from heat.

Best for: Bleeding Shimano hydraulic brakes · Riders with Tektro or Magura mineral-oil systems who have confirmed compatibility · Anyone refreshing spongy brakes on an e-bike

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Hydraulic Brake Components

Tektro HD-E350 E-Bike Hydraulic Disc Brake Set

The HD-E350 is one of the most common hydraulic brakes fitted to e-bikes as original equipment, and it is sold as a complete front/rear set for upgrades and replacements. What makes it e-bike specific is the lever: it includes a motor cut-off switch with a lead that plugs into most controllers. The two-piston calipers, pre-bled hoses and resin pads are the same proven Tektro recipe used across their range. It is a meaningful upgrade from mechanical discs on a heavy bike and a direct replacement when an OEM Tektro lever or caliper fails.

Best for: Replacing damaged OEM Tektro hydraulic brakes on an e-bike · Upgrading mechanical discs on a conversion or budget e-bike · Riders who want cut-off levers and hydraulics in one purchase

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How to choose hydraulic brake components

Fluid type

Mineral oil for Shimano, Tektro, TRP and Magura; DOT fluid for SRAM, Avid, Hayes and Hope. Use the brand's recommended fluid where possible; never mix.

Bleed kit adapters

Kits differ by the threaded fittings at the lever and caliper. Buy a kit listed for your brake brand, or a universal kit that includes the right adapters.

Hose, olives and barbs

Hose diameter and fitting hardware are brand- and model-specific. Replacement hose kits should include the correct olive and barb for your lever and caliper.

Caliper fit

Match mount standard (post mount or IS with adapter), rotor size, and piston count to your existing setup. Pads and rotor clearance follow from the caliper model.

Cutoff sensor compatibility

If you replace the lever, make sure your e-bike's motor cutoff sensor can still be fitted or is built into the new lever.

Compatibility notes

Mineral oil and DOT fluid are never interchangeable; confirm the fluid type printed on your lever or caliper before buying any fluid or bleed kit.
Hose fittings, olives and barbs vary between brands and models; confirm the specific part number for your lever and caliper.
Calipers are mount- and rotor-size specific; a swap may need a different adapter. Confirm on your bike.

Installation considerations

Remove pads before bleeding and insert a bleed block; fluid on pads ruins them.
Work cleanly: DOT fluid strips paint and mineral oil contaminates pads, so cover the frame and rotor.
Route new hose with enough slack for full steering lock and secure it so it cannot rub the tire or motor.
After any bleed or hose change, pump the lever until firm, check for leaks, and do a careful test ride at low speed before trusting the brakes.

Maintenance tips

Bleed when the lever feels spongy or reaches the bar; on a commuter that is typically every year or two.
Clean caliper pistons gently with the brand's fluid on a swab when you change pads to keep them moving freely.
Inspect hoses for cracks where they bend at the lever and caliper, and replace any that weep fluid.

E-Bike Brake Rubbing

Frequently asked questions

How do I know if my brakes use mineral oil or DOT?

It is usually printed on the lever reservoir cap or the caliper body. As a rule, Shimano, Tektro, TRP and Magura use mineral oil; SRAM, Avid, Hayes and Hope use DOT. Confirm on your bike before buying fluid.

Can I use a universal bleed kit?

Yes if it includes the right adapters for your brand's lever and caliper fittings and you use the correct fluid. Brand-specific kits take the guesswork out.

Why is my lever spongy?

Air in the system, usually from a slow leak, a hose cut or a long period of neglect. A bleed fixes it; if it goes spongy again quickly, look for a leak at fittings or the caliper seals.

Can I replace just the caliper?

Within the same brand and model family, usually yes, with a fresh olive and barb and a bleed. Across brands, the lever and hose generally need to change too.

How often should e-bike hydraulic brakes be serviced?

Check pads monthly and bleed when the lever feels soft; for most commuters that is roughly annually. Heavier, hillier riding means more frequent checks.