E-BIKE TECH CORNER: Securing Your Headset

If you have the questions, we have the answers

SECURING YOUR HEADSET

Q: I’ve recently purchased a raised stem for my Rad Power fat-tire bike. I wanted to bring my arms up a little further from the ground for more comfort. The stem feels much better for me than the old one, but now I have a substantial clunking noise in the front end of my bike. I made sure everything was tight, but I can’t get rid of this noise when riding. I’m new to working on my own bike, but need all the tips I can get.

A: This can be an issue when changing out the stock stem. Usually, the reason people can’t get their headset secure is that there are not enough headset spacers, often because aftermarket stems can’t be guaranteed to be the same size as the one you pulled off. Meaning, it could be taller, shorter or could be using a cap that is countersunk, making you think it’s tightening properly, but it may not be.

It may appear that the steerer tube is sunk into the stem appropriately, but sometimes it isn’t quite enough. This means the cap is only tightening up itself to the fork steerer tube and not the entire headset as needed. 

Essentially, what you want is the fork itself to be securely snug to the head tube part of the frame. Stem spacers come in different sizes, and having the correct number of spacers play an essential role in achieving this. You may need to add another small headset spacer. Not too much, though, just enough to get the handlebar stem cap above the fork steerer tube about a few millimeters. Many companies say 3mm is a safe amount for the stem to still have a good grip on the steerer tube.   

It’s important that the fork steerer tube is below the stem as shown.

Now, having the fork steerer tube sunk below the stem you can begin the tightening process. First, you’ll tighten the top cap and, as a general rule, somewhere between 1–2 N/m is enough. That is if you have a torque wrench. If you don’t, it means it’s just barely tight enough to be snug. Too tight and you’ll put more pressure on the bearings and wear them out much faster. Essentially, your goal is to pull the fork snug to the head tube by tightening the top cap. Again, it doesn’t take much tension to get it secure.   

Wrong!

Once you have the top cap tight, you can sit on the bike and get your handlebars aligned with the front wheel. When they’re where you want them, you can tighten the bolts on the side of the handlebar stem. Typically, the side pinch bolts need 4–6 N/m of torque to be securely tight and maintain alignment of the handlebars and front wheel.

FAT-TIRE BLUES

Q: I just bought two new e-bikes for my employees to use for going out to lunch and running errands. I got those bikes that have the motor in the rear wheel with tires that are over 4 inches wide. “Fat-tire bikes,” as many refer to them, and as much as they fit my needs, we recently got flat tires on both bikes. Looks like thorns were the culprit. I found out how hard it is to take the rear wheel off and put back on.

After you’ve installed the new stem at the height you want with the steerer tube sunk correctly as shown in picture two, this will be the first bolt you’ll need to tighten at roughly 1–2 N/m (not very tight).

Actually, what really happened was that I gave up! I brought the bike back to the shop I bought it from, in pieces, and kindly asked if they could “take care of it for me.” It was way too much for me to do by myself. Are there any tire liners you recommend preventing me from getting flats? Or, maybe a way to change the tire by myself a little easier?

A: Full-size fat-tire bikes on average weigh somewhere around 75 pounds, and changing a tire by yourself without a stand is challenging, particularly the rear tire. Even if you do have a stand, it can take two people to get it into the stand. A decent stand that can hold one of these bikes can cost around $300.   

Finally, make sure your handlebars are aligned with the front wheel, and then tighten the pinch bolts on the side of the stem (about 4–6 N/m).

If you are going to change the tire without a stand, it would be best to have a friend to help lift the back end up while you pull the wheel out. Always remember to cut the zip-ties that secure the power cable to the frame first. Some of that cable is going to be connected to the rear wheel and will need to be disconnected/pulled apart before you can remove the rear wheel. We’ve attached pictures, which illustrate what we mean if you don’t know where it disconnects.   

First you’ll want to cut the zip-ties that hold this cable to the frame and disconnect it as shown. Some just pull it apart; this one needs to be unthreaded first.

As far as liners go, we’ve had really good luck with Tannus liners, which are foam liners about 15mm thick in the center to about 5mm thick on the sidewall. They massively limit thorns from puncturing your tube, and by the time you have a shop install them, it will be cheaper than buying a quality stand for holding your bike. Plus, you’ll minimize the chance of even getting a flat tire. Even many shop mechanics give each other a hand to make it go faster, because it’s heavy and takes some coordination to even do it at all. 

Second step is to loosen the nuts on each side of the wheel (usually an 18mm socket or open-end wrench), but be ready with one hand to hold the wheel, because sometimes the wheel is ready to fall out immediately after loosening the nuts.

Some of you might be aware of tubeless setups that some fat-tire rims are capable of, but most entry-level fat-tire e-bike rims and tires are not tubeless compatible. If your wheels are not tubeless compatible, you would need to buy separate tires and rims or different wheels to make it work. If you have a mid-drive fat-tire bike with tubeless-ready wheels, it would be worth converting. Just make sure you keep the tire topped off with the recommended amount of sealant as time goes by, or you could be left stranded with the flat-tire blues after the sealant dries out. Both Cushcore and Vittoria make tubeless inserts that can help keep you rolling if you suffer a flat.

Reinstalling the wheel will sometimes require pulling the derailleur back to let the directionally shaped rear axle back to where it came from—into the axle dropouts.
After you’ve got the wheel securely held up into the dropouts, you can tighten the nuts and reconnect the power cable and reinstall new zip-ties to hold it to the frame and out of the way of being damaged.
edit