Anytime you get a flat tire on your bike, it can be a minor inconvenience. With an E-bike, it can be more that. This will guide through the procedure to make it easier. I will also give you some tips on how to avoid the flat tire in the first place, and guidelines on flat repairs on other electric-assist bikes.
During the repair, you can patch the tube if you like. I would recommend replacing it with a thorn-resistant tube. The thicker rubber in this tube will help you in two ways. One, thorns and the such will have a harder time putting a hole in the tube. Also, the tire pressure will not drop as easily as the weeks go by because of the thicker-walled tube. You might as well put some green goop (Slime) in there too. It is messy, but any little bit helps. Look into getting some puncture-resistant tires as an extra step against flats.
Don’t forget to check the inside of your tire for the thorn that caused the flat. Check the rim strip to make sure it covers all the spoke nipples on the inside of the rim. Broken or loose spokes can punch a hole in your tube. Look for any other sharp edges before you put the tube and tire back on. After inflating it a small amount, check the beading of the tire on the sidewall to make sure it is centered on the rim so the tire will turn true. Inflate to the correct pressure and give the whole thing the one-over before you reinstall in on your bike.
My E-bike is an eZip. It has an external motor on the back of the bike. Fixing the front tire is the same as a normal bike. Some E-bikes have a hub motor on the front. On a bike like that, the rear tire fix is no different that you are used to. On a bike with a front or rear hub motor, there are some wires that will need to be disconnected before you can remove it from your bike. Most have a plug, but some will require a bit more work. They will also have flats ground on the axle that will need to be lined up correctly when reinstalling the wheel.
Ok, on to the rear wheel removal on your eZip. Currie has supplied each bike with a very (almost too) comprehensive manual. It will help you, but count on your own senses to follow though with the job. Don’t over-tighten any fasteners. Be careful not to lose or strip any of the nuts and bolts. A bike stand will make this job so much easier, but is not required. Use your common sense and take your time. Clean all the grease build-up on the parts too.
My eZip has a horizontally mounted motor (behind the axle), and this is the one we are going to discuss. Some have a vertically mounted motor (above the axle). They are similar in the mechanical procedures. There are differences, so take that into account. Before you start, make sure the battery is out of the bike, or the electrical system is off. Have the correct tools at hand and put aside enough time to do the job right.
First, unhook the brake cable at the noodle (the 90 degree bend) and stirrup. To do this you might have to loosen the ferrule at the brake handle or cable attachment screw on the brake itself. This will allow the brake to open up enough to let the wheel and tire come through the brake pads. Shift the gears so the chain is in top gear (the smallest gear on the gear cluster). Next, loosen the lower motor adjustment nuts (10mm wrench) at the front lower part of the motor plate, all the way. Take out the upper bolt (5mm allen & 10 mm wrench) that holds the motor plate to the frame. At this point you are ready to loosen the axle nuts (15mm). I like to use a short bungee cord to hold the wheel assembly to the rack so it won’t drop all the way down yet. Clip the one tie strap on the motor wire nearest the motor so you can let the motor move away from the frame.
Let the wheel drop down about 2 or 3 inches, but no further yet. You will see a narrow nut (17mm wrench) holding the motor plate to the axle. Remove this, take the small motor drive chain off, and pull the motor free from the axle. Don’t let the motor hang from the wire. Set it on a step-stool or hang it from the rack with some wire or cord. Unhook the bungee cord and pull the wheel free from the bike by pulling rearward on the derailleur so the chain comes free of the gears.
Fix the flat. On both of our eZips, the rear wheel bearings were too dry and adjusted incorrectly. I would recommend cleaning, lubing, and adjusting them at this time. It is up to you, but it will make your bike last much longer. This will require a few bike specific tools and access to cleaning equipment. Take the rim to a bike shop for this if you don’t feel comfortable doing it yourself. In fact, all the bearings (front wheel, steering tube, and bottom bracket) should be dealt with.
The re-assembly is the opposite of what we have done so far. It will take a little time and rework to get the motor chain adjusted to the correct settings. The book calls for 5mm (3/16″) of slack. Just make sure it is not taut or way too loose. I like to tighten the narrow nut (17mm) on the motor plate first, install the rim, and recheck the chain slack. The book calls for a cone (very thin) wrench to tighten that nut once the wheel is back in the frame. Either way, make sure the motor chain is tensioned within spec.
Tighten everything up, making sure the tire is centered in the frame and you like the way it looks and feels. Clean and lube both chains. Replace that tie strap and trim it flush so there is no sharp edge. Rehook your brakes and check their adjustment and where the pads hit the rim. Check your derailleur adjustment for smooth and lined-up shifting. Make whatever adjustments you need, but keep in mind, if you did the job right, it should all line-up the way it did before you started. Give your baby a test ride and feel good about your accomplishment. Great Job.
Any questions? Turbo Bob.
“Sighing for new worlds to conquer, I determined that I would learn the bicycle.”—Francis Willard, How I Learned to Ride the Bicycle.