Fixing a flat on an e-bike is the same basic job as on any bicycle, with three differences: the wheel is heavier, the tires are often wider and stiffer, and a hub motor wheel has a motor cable and large axle nuts that a normal bike does not. This guide covers the tire and tube work itself. If the flat is on a rear hub motor wheel, take the wheel out with our rear hub motor wheel guide first, then come back here.
Before you start
- Read the size on the tire sidewall. You will see something like 20 x 4.0, 26 x 4.0 or 27.5 x 2.4. A replacement tube has to cover both numbers: the same wheel diameter and a width range that includes your tire. Fat tires need fat-tire tubes; see fat-tire e-bikes 101 if you are not sure what you have.
- Check the valve type. Most e-bikes use Schrader valves, the same style as a car tire. Buy the tube with the same valve, or it will not fit the hole in the rim.
- Plan for the wheel. A front wheel without a motor usually comes out in a minute. A hub motor wheel takes longer, so give yourself time and a clear floor.
What you need
Two or three plastic tire levers, a new tube in the right size or a patch kit, a floor pump with a pressure gauge, and a rag. For a hub motor wheel you also need the correct axle wrench (hub motor nuts are commonly 15, 18 or 19 mm) and a torque wrench, because those nuts have a specified torque. Do not use a screwdriver or knife as a lever; Park Tool warns that sharp tools can damage the tire or tube.
Step by step
- Turn the bike off and remove the battery. A throttle that gets bumped while your hand is near the spokes can spin the wheel. If your battery is built into the frame and is not meant to come out, switch the system off and make sure nobody can switch it back on while you work.
- Hold the bike steady. Use a work stand or one of the methods in how to hold an e-bike safely for repair.
- Take the wheel out. If the bike has hydraulic disc brakes, do not squeeze the brake lever while the wheel is out. Shimano's brake manual explains that the pistons will push out further than normal; slide a pad spacer, or a folded piece of thick card, between the pads.
- Let every bit of air out. Press the valve pin until the tire is completely soft all the way around. Even a little air left inside makes the tire harder to remove.
- Free both beads. Push each edge of the tire (the bead) toward the middle of the rim, all the way around. The center of the rim is deeper, and moving the bead there gives you the slack you need.
- Lift one bead over the rim. Start opposite the valve. Hook a lever under the bead and pull it down, then hook a second lever a couple of inches along and do the same. Once a section is over the rim, slide one lever around the wheel to release the rest of that side.
- Pull the tube out, starting opposite the valve and lifting the valve out of the rim last.
- Find the cause before you fit anything new. Pump the old tube up and find the hole. Lay it against the tire to locate the matching spot, then check that part of the tire inside and out for a thorn, wire or glass. Run a gloved hand carefully around the inside of the tire. Check that the rim tape covers every spoke hole. Two small slits side by side usually mean the tube was pinched against the rim, which points to pressure that was too low.
- Patch or replace the tube. Follow the instructions on your patch kit, or use a new tube. If the tire itself is cut right through, replace the tire too, because a new tube can push out through the cut. Our guide to replacing the tire and tube together covers that job.
- Give the new tube a little air. Add just enough to hold its shape. Put the valve through the rim hole, lined up with the pressure label on the tire sidewall so it is easy to find later, then tuck the tube inside the tire all the way around.
- Refit the bead by hand. Start at the valve and work both ways with your palms, finishing opposite the valve. If the last part is tight, push the bead you have already fitted down into the center of the rim to gain slack. Use a lever only for the final few inches, and check the tube is not caught between the tire and rim.
- Check the bead at low pressure. Inflate a little and look at the thin molded line just above the rim on both sides. It should sit at the same height all the way around. If it dips into the rim anywhere, let the air out, work that section, and try again.
- Inflate to the pressure printed on the tire sidewall. Never go above the maximum printed on the tire or on the rim, whichever is lower.
- Refit the wheel and check before riding. On a hub motor wheel, tighten the axle nuts to the torque in your bike or motor manual, never just hand-tight (the rear wheel guide has the details). Remove any pad spacer, squeeze each brake lever several times, refit the battery and test the brakes and motor at walking pace before you ride off.
Safety notes
- Keep your face away from the tire while it is inflating to full pressure. A bead that is not seated can blow off the rim.
- If the same tire keeps going flat in the same spot, something is still in the tire or the rim tape has moved. Look again before fitting a third tube.
- Wide, heavy e-bike tires lose air quickly with a small hole. Check pressure every week or two.
Flat tire fixed but the bike still will not go? Start with our free e-bike diagnosis, which works through the free checks before suggesting any part.