Squeaking or weak disc brakes are a common complaint on e-bikes and regular bikes alike. Most of the time they come down to three things: dirt on the braking surface, worn pads, or a worn rotor. They cost very different amounts to fix, so we always start with the cheapest one and only move on if it doesn't work.
Our take, Joe: "On my Abound, the pads wore thin at about 1,400 miles, and by then the rear rotor was grooved. I replaced both."
Before anything else: if the brake lever feels soft, sinks toward the handlebar or the caliper is leaking fluid, stop here. That's air or a leak in the hydraulic line, not pads or rotors, and it's a job for a shop.
Step 1: Clean the rotor and pads (about $30)
Try this when: the brakes squeal or feel weaker than they used to, but the pads still have plenty of material (more than about 1 mm, roughly three business cards stacked).
Road grime, rain spray and brake dust build up on the rotor and pad surface and cause most squealing. The first wet ride of the Sacramento season is a classic trigger.
What to do: we use SILCA Ultimate Brake + Drivetrain Cleaner. SILCA says it's safe on both pads and rotors. Follow the directions on the bottle, rinse well, let everything dry, then bed the brakes back in, which SILCA recommends after cleaning. Aventon's bed-in method: ten times, get up to 15 to 20 mph and brake evenly down to walking pace without skidding, releasing while you are still moving. Do it on a quiet street.
Oil on the pads and rotor (chain lube overspray, brake fluid, a rag with grease on it): Aventon says fresh contamination can sometimes be cleaned off with rubbing alcohol or by lightly sanding the surface of the pads. If the squeal is still there, Tektro's rotor manual says to replace the pads and the rotor. Skip to steps 2 and 3.
Step 2: Replace the pads (about $35 for both wheels)
Move on to this when: the squeal or weak braking comes back after a clean, the pads are under about 1 mm of material, or you hear grinding (that's the metal backing plate on the rotor).
TRP makes the Tektro E10.11 pad for most original-equipment Tektro 2-piston brakes, including the HD-E3520, HD-M280 and HD-T280. Aventon fits the HD-E3520 to the Abound, Aventure 2 and 3, Level 2, Pace 500 and Pace 4. Our Brake Pad Refill Kit has two sets of E10.11 resin pads plus alcohol prep pads, a lint-free cloth, two pairs of gloves, two spare zip ties and a card that links to our step-by-step guide. Only need one wheel? Single sets of E10.11 pads are here.
How to do it: see our step-by-step guide, E-bike brake pads for Aventon: when and how to replace them.
Not sure which brakes you have? The model is printed on the caliper (the part that grips the rotor). Email us a photo of it and we'll tell you.
Step 3: Replace the rotor (only if the rotor itself is the problem)
Tektro's rotor manual gives three reasons to replace a rotor:
- It's too thin. Tektro's minimum is 1.5 mm for a rotor that started at 1.8 mm. You need a caliper or micrometer to measure it; if you don't have one, a shop can check it in a minute.
- The braking surface is uneven. On Joe's Abound, the rear rotor was grooved by the time the pads wore out.
- It's bent and you or a bike shop can't straighten it.
Our advice: fit new pads with a new rotor. Old pads are worn to the shape of the old rotor.
Which rotor: check the size stamped on your rotor and count the bolts. For a 180 mm, 6-bolt rotor we keep the Tektro TR-52 in Sacramento ($32.99). Joe's original Abound uses a 180 mm rear rotor; Aventon lists a 180 mm front and a 203 mm rear for the Abound SR and LR, so on those the TR-52 fits the front only.
For a 203 mm rotor, like the rear on the Abound SR and LR, we carry the TRP RS02M, 203 mm 6-bolt ($58.49). It's 1.8 mm thick, the rotor thickness Tektro specs for the HD-E3520 brake. Need any other size? Email support@breaktimebicycle.com with your bike model and the size and bolt count stamped on your rotor, and we'll match it.
The short version
| Symptom | Start with |
|---|---|
| Squeal, pads still thick | Step 1: clean |
| Squeal comes back after cleaning | Step 2: pads |
| Pads under 1 mm or grinding | Step 2: pads (clean the rotor too) |
| Oil on the pads and rotor | Clean once; if the squeal persists, steps 2 and 3 |
| Rotor too thin, uneven or bent | Step 3: rotor and pads |
| Soft or sinking lever, leaking fluid | Stop. See a shop |
Questions?
Email support@breaktimebicycle.com with your bike model and a photo of the brake. We answer within one business day, and we'd rather point you to the $30 fix than sell you the $100 one.
Ride on,
Break Time Bicycle Co.