E-BIKE TECH CORNER

Q:  I’m looking to purchase a new e-bike to chase my daughter around on her regular bike, and I need to know what type will be best for me. There are a few hills to battle with in my neighborhood, and I’ve heard about e-bikes having an overheating problem. What do I need to know, and how can I prevent damage to whatever e-bike I decide to get?

A: Too much load on an e-bike motor can get it hot enough to trigger an error code that will usually trigger a fail-safe mode. It’s one of the most common problems people find with budget-brand e-bikes. Truthfully, the majority of the bikes that can experience this issue are hub-drive systems. Simply knowing what the realistic capabilities of a hub drive are will help you know if one is right for you. The more informed you are, the better the chance you’ll make the right purchase for your style of riding. 

POINTING THE FINGER AT HUB DRIVES

Similarly to combustion engines, electric motors struggle to dissipate heat as more load is applied. Excessive loads, in the case of electric bikes, comes almost exclusively in the form of hills. Steep hills can be too much effort for the average 250-watt hub drive to handle without any assistance from the rider. Some bikes do have more powerful motors, even up to 750 watts in many cases. However, they’re mostly used in heavier bikes, which somewhat offsets the gain in power. 

In most cases, 250 watts is enough power to comfortably propel a 50–75-pound bike and its rider on flat ground until the battery runs out. Hills are a different story, though, and in extreme cases hub drives can only handle a couple of minutes of steep climbing before an overheating error might stop you. Most companies use a failsafe error code that will put you in a limp mode or just cut power until it cools down. 

If you bring your bike to the point of an error too many times, you run the risk of wearing out the motor and other components much faster. Usually, the insulation around the copper coils that make up the bulk of an electric motor is the first thing to breakdown. As more load is applied at lower speeds, the more the other components start to breakdown. Sections of the copper windings will also start to char after a while.

DON’T EXPECT A FISH TO CLIMB A TREE

Many (no-name) hub-drive systems found on cheaper e-bikes do not utilize the advanced technology that is available. Often, the basic electric motor and sensor technology used doesn’t lend itself to the demands of making long climbs on steep hills. That basic technology we’re referring to is spec’d on bikes usually costing under $2000. 

The number of mid-drives that have overheated are negligible when compared to hub drives. Mid-drive e-bikes are better able to hold their own on rides with massive elevation gains. Still, we have seen it occur. It doesn’t mean they don’t get really hot, though. And in just about every overheating mid-drive case, it was an extremely long climb in Turbo mode just trying to let the motor do all the work, and often with a heavier rider aboard.

TIPS FOR KEEPING IT COOL

We’ve seen many hub-drive bikes that use a throttle, which is often overused, particularly on steep hills. Remember, spending $2000 on an e-bike doesn’t make it a motorcycle, and it doesn’t take too long of laying on the throttle for error codes to start showing up. Therefore, putting more effort into pedaling up hills will be the best way to prevent getting that error code—and provide a better workout! Just as important, giving the rear hub and brake can add some life to the overall system.

Everyone knows that many people are getting back into riding bikes with the help of e-bikes. And knowing how to best utilize the bike’s drivetrain is one of the most important things to understand when it comes to riding hills. If you’re one of those riders, you may not even be familiar with modern shifters and how they work, but proper shifting technique will be key for both you and your bike’s powerplant. Our best advice is that you get the best advice on how your drivetrain works (via your local dealer, friends, YouTube), because it will enhance your riding experience for the better. 

Being in a gear that allows your legs to spin at a relatively high cadence will give you the best chance of helping the bike get up hills. Cycling science tells us that it is easy to put more power out at a higher cadence. In other words, try to spin your legs a little faster as opposed to a little harder. As much as you can, try to feel a bit of resistance on your legs when climbing. If you start getting too tired, be sure to take a break—for you and the bike!

Like we said, it doesn’t take long for most hub drives to get warm on steep hills, but they do cool down quickly. A two- to five-minute break is a fair amount of time to let it get back to proper operating temperature. If you start to get errors on flat ground with minimal load, you may have a separate problem, at which time you should consult a shop. 

FINAL THOUGHTS

Usually, companies don’t tell the whole story when it comes to overheating. We’ve read catalog copy that inferred all over-heating problems to using the bike in extreme conditions of “the peak of summer heat.” Sure, hot weather can impact the motor’s performance, but that’s not the whole truth. We hear of such “power failures” occurring on a weekly basis. Luckily, many people figure it out and quickly adapt their riding, while others are left angry that their machines don’t do what they thought it would. 

Hub-drive e-bikes are sold in mass quantities, and this analysis isn’t about throwing shade on them. Truthfully, their benefits outweigh this one weak point, but it’s important to know about their shortfalls before buying one. Whether mid- or hub drive, e-bikes come in many different styles and price ranges with a equally wide range of quality. Do the research and take your time in deciding which bike is best for you and how you plan to ride.