Velotric E-Bike Brake Service: Hydraulic Brake Adjustment & Pad Replacement

Every Velotric e-bike model—whether the Discover 1, T1 ST, Nomad 1, or Voyager—uses hydraulic disc brakes. Over time, pads wear, levers soften, and rotors may run out of true. You can handle pad swaps, lever adjustments, and even a basic bleed at home with the right tools. This guide walks each task in order of difficulty, with model-specific notes where they matter.

What You’ll Need Before You Start

Gather these items before pulling the bike off the stand:

• Hex wrenches (4 mm, 5 mm) for caliper bolts and lever clamps
• T25 Torx bit for rotor bolts (most Velotric rotors use T25)
• Pad spacer or a spare old pad to prevent caliper pistons from popping out
• Mineral oil (Velotric uses mineral oil, not DOT fluid; Tektro and Zoom brakes usually take Tektro or Shimano mineral oil—confirm your model)
• Bleed kit compatible with your brake brand (Tektro M275/Zoom HB-100 or similar)
• Rotor truing tool (or a clean adjustable wrench reserved for this job)
• Isopropyl alcohol and clean rag for rotor and pad surface cleaning

Model variation note: Early Nomad 1 models shipped with Tektro M275 brakes; later units and the Discover 1 often use Zoom HB-100. Both operate identically for pad replacement and bleeding, but bleed-port sizes may differ slightly. Check your caliper body for a brand stamp before buying a bleed kit. If you grab a Shimano bleed kit for a Tektro brake, the thread pitch won’t match and you’ll strip the port.

Step 1: Replace Worn Brake Pads

Pad replacement is the most frequent brake service. You’ll know it’s time when braking feels less positive or you hear a metallic scraping sound (the wear indicator rubbing the rotor). Do not ride with pads worn past the indicator groove—you risk damaging the rotor.

Remove the old pads:
1. Remove the wheel or use a pad spacer to keep the pistons from closing. On most Velotric models you can leave the wheel in place, but you must remove the caliper from the adapter (two 5 mm bolts) to access the pad-retaining pin.
2. Use a 4 mm hex to push out the retaining pin from the top of the caliper. Some calipers use a split pin; pull it straight out.
3. Slide the pads upward. Note the orientation of any anti-rattle springs or shims—photograph for reference.
4. If the pistons have extended at all, gently push them back into the caliper body using a plastic tire lever or the old pads as a buffer. Do not pry directly against a piston.

Install the new pads:
1. Insert the new sintered or resin pads (Velotric ships bikes with sintered pads; either works, but sintered last longer in wet conditions).
2. Reinstall the anti-rattle spring the same way it came out.
3. Push the retaining pin through the pad holes and caliper body. Secure with the cotter-pin or retaining-clip.
4. Reinstall the caliper onto the adapter. Torque bolts to 6–8 Nm (finger-tight plus a quarter turn is fine if you don’t have a torque wrench, but check manual for exact spec).

Verification step: With the wheel spinning freely, apply the brake firmly three times, then spin again. If you hear a constant scrape, the caliper isn’t centered over the rotor. If the lever feels spongy, you likely pushed air into the system when you retracted the pistons—move to the bleed procedure in Step 3 before riding.

Common mismatch warning: Aftermarket pads labeled “compatible with Tektro” may not fit Zoom HB-100 calipers without filing the backing plate. The pad shape is similar, but the retaining-pin hole can be off by 1–2 mm, forcing the pin in at an angle that cracks the pad backing. Stick to pads sold as Tektro M275 or Zoom HB-100 specific. Velotric sells direct replacements for each model; check your order page or contact support with your bike’s serial number.

Bedding in new pads: Before riding, pump the brake lever several times until firm. Then ride gently in a flat area, applying gradual pressure to bed the pads to the rotor. Avoid hard stops for the first 10–15 braking cycles.

Step 2: Adjust Lever Reach and Caliper Centering

After new pads, you may need to adjust lever throw or center the caliper. Velotric owners sometimes report a rubbing sound after a pad change—usually a centering issue, not a bent rotor.

Lever reach adjustment: On Tektro and Zoom levers, find the small dial (often a 2 mm hex or a twisted knob) near the lever pivot. Turn it clockwise to bring the lever closer to the bar, counterclockwise to push it away. Adjust so your finger sits at the middle of the lever when braking. Do not crank it all the way in—you need enough travel for the pad to push fluid and compress.

Centering the caliper (fix rotor rub):
1. Loosen the two caliper mounting bolts about one full turn—just enough to let the caliper wiggle on the adapter.
2. Spin the wheel. As the rotor passes through the caliper, it will self-center against the fixed (non-moving) pad.
3. Squeeze the brake lever firmly and hold it. While holding the lever, tighten the caliper bolts to 6–8 Nm.
4. Release the lever, spin the wheel, and listen. If still rubbing, repeat. A faint, periodic “swish” is normal; a constant scrape means the caliper is still not square over the rotor.

Practical implication: If you tighten the caliper bolts without holding the lever, the caliper will lock in an off-center position. You’ll chase the rub for hours, possibly convincing yourself the rotor is bent when it’s actually fine. Always re-center after any pad change, even if the old pads seemed fine.

Step 3: Bleed the Hydraulic Brakes (When Air Gets In)

You’ll need a bleed when the lever feels spongy or pulls all the way to the bar. This happens naturally as brakes age, or after a pad change if you pushed fluid back into the reservoir. Velotric hydraulic systems are closed and easy to bleed with a simple two-syringe kit.

Bleed procedure for Tektro / Zoom brakes:

1. Remove the brake pads and insert a pad spacer (or the old pads) to prevent pistons from closing.
2. Attach a bleed syringe filled with fresh mineral oil to the caliper bleed port (usually a 7 mm or 8 mm wrench). Open the port one quarter turn.
3. Attach a second empty syringe to the lever bleed port. Open that port slightly.
4. Slowly push oil from the caliper syringe upward through the line. Air bubbles will exit into the lever syringe. Continue until no air and only clear oil flows.
5. Close the lever port first, then the caliper port. Remove the syringes.
6. Clean any spillage immediately—mineral oil can damage paint.
7. Reinstall pads and pump the lever until firm.

Pro tip: If you only have a single syringe, you can use a gravity bleed: hang the caliper above the lever (or remove the caliper and hold it high), open the caliper port, and let oil drip through while periodically tapping the hose. This is slower but works for minor air.

Trade-off to consider: A full syringe bleed pushes oil from caliper to lever, which dislodges stubborn air pockets near the lever pivot. A gravity bleed clears line bubbles but often leaves tiny air trapped at the master cylinder, giving you a lever that feels 80% firm but never fully solid. If you’re bleeding because the lever pulls to the bar, use the two-syringe method—gravity won’t cut it.

Step 4: True a Bent Rotor

A wobbling rotor causes pulsing brakes or constant rub even after centering. Velotric rotors are 180 mm front and rear on most models; they’re thin (1.8 mm) and can bend if the bike falls over or you hit a rock.

Check trueness: Spin the wheel and look down the rotor from above. A wobble of more than 1–2 mm needs straightening.

Verification step before truing: Mark the rotor at the high spot with a piece of tape. Then check if the wobble is consistent across the full rotation or jumps at one specific point. A consistent wobble is a simple bend. A sudden jerk at one spot means a dent or crease—that rotor is beyond truing and needs replacement. Truing a creased rotor can crack it mid-ride.

Straightening method:
1. Use a rotor truing tool (Park Tool DT-2 or similar) or a clean adjustable wrench that matches the rotor thickness. Never use a screwdriver—you’ll gouge the surface.
2. Identify the high spot (where the rotor bends toward the caliper). Place the tool on the rotor just below the high spot and gently bend the rotor away from the caliper—about as much force as bending a paper clip. Overbend slightly, then check again.
3. Work in small increments; a rotor can crack if you bend it too far in one pass.
4. After truing, re-center the caliper as described in Step 2.

When to Skip DIY and Visit a Shop

Not every brake issue belongs in a home workshop. Hand the bike to a Velotric dealer or a reputable shop if:

• The lever pulls to the bar and bleeding doesn’t firm it up. This points to a leak at a hose fitting or a worn master cylinder seal.
• Rotor is warped beyond repair (deep scratches, cracks, or a wobble over 3 mm). Replace the rotor; truing won’t fix structural damage.
• Caliper pistons are sticky or leaking. Mineral oil on the outside of the caliper means a seal is compromised.
• You’re unsure which mineral oil grade to use. Using automotive DOT fluid will destroy the seals—a shop will know the exact spec.

Hydraulic brakes are the single most important safety system on your e-bike. If a task feels beyond your comfort level, paying a mechanic for a proper bleed or rotor replacement costs far less than a crash.

---

All Velotric models share the same hydraulic disc architecture, so the steps above apply across the lineup. Start with pad inspection every 300–500 miles, and you’ll catch wear before it becomes a rotor-damaging problem.

Explore This Topic

• Back to Velotric Brakes
• Back to Velotric E-Bikes

Related guides in this cluster:
– Sondors E-Bike Brake Service: Adjustment, Pad Replacement & Bleeding Guide
– Super73 Brake Service: Hydraulic & Mechanical Brake Adjustment Guide
– Aventon E-Bike Brake Service: Hydraulic & Mechanical Adjustment Guide
– How to Adjust & Replace Brakes on Lectric E-Bikes: Step-by-Step Guide