RadCity 4 vs. Bafang 750 Watt Mid-Drive Kit

A few months ago, I bought a RadCity 4 electric bike from Rad Power Bikes. I got it for commuting into town (5 hilly miles) and to the office (8 miles, with steep hills).

The bike arrived about a week after I placed the order. It comes in a box, mostly assembled, with the customer having to do the final steps of attaching the pedals and handlebars, and connecting some wiring. The assembly was pretty easy. You don’t need much mechanical ability.

The first thing I noticed about the bike was that it was heavy: about 68 pounds. I considered that a negative, though I later changed my mind, as I’ll describe below.

This bike has a number of pluses, and after 500 miles of riding, I would say it has no serious minuses. Here are good points:

• It rides smoothly. A heavy frame, fat tires, front shocks and smooth motor acceleration all contribute to the feel.
• It has excellent range. (After 27 miles of hills with a 200 pound rider, the battery indicator was hovering between two and three bars, meaning it may have gone another 15 miles.)
• It provides good power assistance even up steep hills. You can set the assist level to 0 (None) through 5 (750 watts). On flat ground, level 2 provides plenty of assist. On steep hills, you’ll want to go to level 5.
• The construction is bomb-proof. With the rear rack welded on, you can load it up with fifty pounds of gear and not feel the weight as you ride.
• It has a lot of thoughtful touches, including:
  • Engine cut-off when braking.
  • Brake lights when braking.
  • A heavy duty rear derailleur guard to prevent derailleur damage if the bike falls over.
  • Comfortable grips and seat.
  • Thick-gauge, heavy duty spokes for durability.
  • Well-designed fenders keep you dry (except for your toes).
• The stem and seat post are adjustable to fit shorter/taller riders.
• The bike maxes out at 20 mph by default, but you can up that to 25 mph by changing a simple setting. It takes about 10 seconds.

A couple of points to note:

• The headlight isn’t powerful enough for night riding if you live in an area with no street lights. You can buy your own and mount it on the handlebars.
• Although Rad says this bike fits riders up to 6’ 5", I had to buy an extended seat post to fit comfortably at 6’ 4". (Hint: you want the 27.2mm width.) The bike as-is works well for people 5’ 6" to 6’ 1".
• The rear hub motor drags when going down steep hills. The drag kicks in when the bike hits its max speed setting (20 or 25 mph). Most people consider this a good thing, because they don’t want to go 35 mph downhill and have to keep hitting the brakes.
• Changing a flat on the rear tire will be difficult because of the hub motor and its wiring.

Overall, this bike is a phenomenal value for commuters and casual riders. At $1,599, it’s $2,000 cheaper than comparable offerings from traditional bike manufacturers. But there’s nothing cheap about the design, construction, or materials. If you’re looking for a commuter or an occasional joy ride, this is your bike. It hauls groceries like a champ too!

One final note: The RadCity has a rear hub motor. I was worried the magnets in the motor might damage electronics in my rear pannier, since they’re sitting just inches from the hub throughout my daily commute. The magnets don’t seem to bother electronics at all. I’ve ridden for weeks with a MacBook Pro and 5TB spinning magnetic drive in the panniers, and neither was affected.

Bafang 750 Watt Mid-Drive

So why would I buy another electric bike if the RadCity 4 was working so well? Because I couldn’t get the RadCity away from my wife.

Also, I’m an aggressive rider. Not rude or agro, but I ride full steam all the time. That’s a habit I picked up during my years as a bike messenger. The RadCity rides like an upright cruiser and isn’t suited to an aggressive riding style.

I had a Specialized Rockhopper Comp 29er mountain bike languishing in the garage. Since I do most of my riding on the road, I knew I’d use it more if I put some slicks on it and added a motor.

I ordered the Bafang BBS02 750 Watt Mid-Drive kit with a 48V 17.5 Ah battery. With shipping, that came to about $1,000. Mounting the battery and motor were surprisingly easy. The hardest part was removing the old stuck bottom bracket. (YouTube has some interesting videos showing creative solutions for stuck bottom brackets.)

Everything in the Bafang kit worked except:

• The included brake levers with engine shut-off are designed for cable brakes. They don’t work with Shimano disk brakes, which have hydraulic fluid in the brake levers.
• The headlight, like the RadCity headlight, is fine for city riding, but not powerful enough for areas that have no street lights.

I spent an extra $20 for the shift sensor, which cuts power for a second when you change gears. This prevents the motor from damaging the rear cassette when you shift under power. I also added the engine cut-off sensors for hydraulic brakes (another $20). These were easy to install.

The Specialized with the new motor and battery weighs around 45 pounds. That’s substantially lighter than RadCity’s 68 pounds. I added an Ibera rack which is almost as strong as the RadCity’s rack.

After 300+ miles on the Specialized + Bafang 750, here are my observations:

• The Bafang motor has considerably more power than the RadCity 4. This is especially noticeable on steep hills.
• While the RadCity power assist maxes out at 750 watts (level 5), Bafang starts at 750 (level 1) and goes up over 1200.
• While the RadCity’s acceleration is smooth, the Bafang motor starts with a lurch when it first engages. This can make the bike harder to control in some situations, and this is why the brake cut-off sensors are important.
• The Bafang’s 17.5 Ah battery lasts about as long as RadCity’s 48V 17.5 Ah battery. I drained the battery on a hilly 41-mile ride, using mostly assist levels 1 and 2. (Caveat: That’s a 200 lb rider doing hard hills in 96-degree heat. On flat ground, this probably would have gone 60 miles.)
• The mid-motor adds some pedal resistance when pedaling without power assist.
• The low mounting of the mid-motor gives the bike a low center of gravity, making it less likely to tip over when you’re walking it.
• The Bafang motor has no speed restriction. When pedaling hard in gear 48/12, I can maintain 35 mph on flat ground. If you’re into speed, you’ll find some YouTubers have gotten the bike well over 40 mph. Top speed depends on your gear ratio.
• I’m not comfortable yet riding this bike on trails. The motor mounts below the hub, making it susceptible to damage. The way it lurches when it engages makes it easy to crash on rocky, rooty, technical trails. It should be fine on gravel and wider dirt trails.

While I do like being able to pedal full force on the Specialized, my first few rides on this bike gave me a new appreciation of the RadCity’s hefty weight. The RadCity is a very stable bike. You want that if you’re a casual rider tooling along at 25 mph.

The Specialized is more nimble, but learning to control it with that powerful motor will take some practice.

UPDATE June 26, 2022

Bafang advertises their controllers as “intelligent,” meaning that they adapt to the way you ride. After 1200+ miles, I can say this is true. Instead of starting with a lurch, the motor now accelerates more smoothly. On the lower assist levels, it cranks out less power once you start turning the pedals at 60+ RPM.

You can still increase the assist level to get more power if you want it, but the upside of the controller NOT providing too much unnecessary boost is that you’ll get more mileage per charge.

I have now ridden this bike on trails and have had no problem with roots, rocks, or anything else that I thought might damage the low-mounted motor. You do have to watch for obvious dangers, but in general the motor position isn’t a problem.

The Bottom Line

If you’re a hardcore rider and you like to tinker with bikes, the Bafang 750 is a great kit that will work on the bike of your choice.

If you’re a casual rider, the RadCity is a phenomenal value with a smooth, stable ride and no hassles. It’s easy to set up, easy to ride, and everything just works.