GEN3 The Flex Review 2021 | Electric Bike Report

Most electric bikes come with multiple pedal assist settings, to get a better understanding of how each of these pedal assist levels perform we conduct what’s known as a circuit test. This circuit test is a 1 mile loop that we ride in each pedal assist setting, this way we can see the average speed each level provides, and also the relationship between pedal assist settings. We also ride the circuit with the bike turned completely off to see how much the first setting does relative to the bike turned off.

The GEN3 The Flex comes with 5 total pedal assist settings, the lowest setting (PAS 1) does a good job conserving battery life. We only rode 0.8 mph faster in the first pedal assist setting over the bike turned completely off. Based on our testing we would probably recommend riding in PAS 2 if you want to conserve battery life while still feeling like you’re on an e-bike.

The biggest jump in average speed was the change from PAS 2 up to PAS 3 where our test rider gained an additional 2.6 mph over the previous setting. Every other jump is below 2 mph. PAS 5 yielded an 18.8 mph average speed, just 1.2 mph off of the bike’s top speed overall. We would consider PAS 5 to be the best option for the speed-hungry commuter.

We conduct a hill climb test on one of the steepest hills in town to get a good understanding of how the bikes we review stack up. The quarter mile hill is known as “Hell Hole” and it ranges from a 12% to 15% grade — in short, this hill is steep and long enough to put even the strongest electric bikes to the test. We do two separate hill climbs during our hill test, one using only the throttle and the other in the highest pedal assist setting (PAS 5 for The Flex). The Flex comes with a 500W rear hub motor capable of producing up to 900W of peak power in short bursts. This motor is capable of producing up to 65 Nm of torque.

When I scaled our test hill using only the throttle it took me 1:38.00 to reach the top with an average speed of 11.1 mph. I noticed a very quick, yet quiet acceleration from The Flex. I nearly reached the top Class 2 speed of 20 mph on the short stretch of flat ground before the test hill, speaking numbers to the acceleration properties of this bike. The bike slowed down quite a bit on the steepest part of the hill but it never sounded like it was going to give out on me.

When I climbed the same hill using the highest pedal assist setting I reached the top in 1:15.00 with an average speed of 14.5 mph. With me pedaling, the bike had no issue getting up to 20 mph on the flat ground below the test hill and I was able to stay in the hardest gear for just under half of the hill before I had to shift down. Realistically, I could have stayed in the hardest gear the whole time but the goal of the test is to test the motor not my leg strength. Because of this, I ended up down-shifting three times, which isn’t a whole lot when you consider the 21 available gears on The Flex.

If I had to describe the handling characteristics of GEN3’s The Flex in one word it would be sporty. This is a bike that allows you to do more than just cruise around, you can explore gravel roads and paved trails with equal capability because of the way the GEN3 The Flex handles. Its fast rolling 1.95” tires have a tread pattern that is somewhat mountain bike-esc, but still smooth enough to have low rolling resistance.

The 100mm suspension fork does a great job of soaking up rougher terrain and keeping the rider comfortable. Between the geometry and componentry of the GEN3 The Flex you can really ride it however you want. With that being said I wouldn’t recommend any advanced or rocky singletrack, while this bike has hints of a mountain bike the uber-rough terrain would be a bit much for its thin tires.

The GEN3 The Flex is a decently comfortable ride, mainly due to its 260mm wide saddle and 100mm suspension fork. The Flex has a sporty geometry and handles as such. It’s easy to rack up the miles and get a fitness-oriented ride in on The Flex. This geometry and ride position is more directed towards the rider who wants to get a good workout in and feel like they’re on a performance oriented e-bike. For the sporty bike that The Flex is, it is plenty comfortable.

The GEN3 The Flex comes with a 500W Bafang rear hub motor capable of producing up to 900W of peak power and 65Nm of torque. Between how quick the motor accelerates and how quiet it is we were quite impressed with it.

Despite being pushed quite hard on our test hill the motor kept quiet and never sounded like it was going to give out on us. This motor feels plenty strong for The Flex’s intended uses, especially when paired up with its fast rolling tires and 21-speed drivetrain. High average speeds are no problem on The Flex.

The Flex comes with a 48V, 10.4Ah battery that is internally integrated into the downtube of the frame and is removable via key. The battery pack is integrated in such a way that makes The Flex look more like a standard bike than an electric one at first glance.

We wanted to see if the battery’s performance matched its looks, so we conducted a range test to see how far the battery would get in the highest pedal assist level and a lower pedal assist level. Our results far exceeded our predictions based on the 10.4Ah capacity. I reached nearly 30 miles in the highest pedal assist setting and our other test rider reached nearly 50 miles in PAS 2.

We were very impressed with these results relative to the size of the battery. So yes, we would say the battery’s performance matched or even exceeded its looks.

The GEN3 The Flex comes with 5 total pedal assist settings and a lever throttle that sits below the LCD display on the left side of the handlebar.

The lowest two levels are great for conserving battery life while the two highest are great for riding at high speeds for long periods of time. PAS 3, the middle setting, walks the fine line between these two settings and combines the best of both worlds. The throttle characteristics are similar to PAS 4 in terms of acceleration and speed; those wanting a quick-accelerating throttle will likely appreciate The Flex’s throttle tune.

The Flex comes with a backlit LCD display that sits on the left side of the handlebars. This display is a little dim on brighter days and can be a bit hard to see at a glance. With that being said the display houses all the settings and data you’ll want and need throughout the ride. This LCD display shows the battery level indicator, speedometer, odometer, trip meter, pedal assist setting and has the ability to turn the headlight on or off. My only complaint about the display is how it can be hard to see at a glance. Aside from that, I think it’s great.

The Flex comes with GEN3’s own mechanical disc brakes, which are hooked up to 160mm rotors front and rear. These brakes feel decently strong and provide good stopping power.

To get a better idea of the true stopping power of the GEN3 mechanical disc brakes, we conducted a brake test. We stopped five total times from the top Class 2 speed of 20 mph and found the average stopping distance. On average, it took 19-feet-5-inches to come to a complete stop on The Flex.

This distance is a little above the stopping distance we are used to seeing, however it still felt like it stopped at a safe distance. The brakes engaged more powerfully than you might think based on our near 20-foot result — the bike skidded decently far after the wheels locked up which added a couple extra feet.

We wouldn’t mind seeing 180mm rotors on future models of The Flex, however it wouldn’t be a deal breaker if they stuck with 160mm rotors, they seem to work just fine.

The Flex is made out of double-butted aluminum alloy. This 6061 alloy frame houses an internally integrated battery in its downtube and is relatively lightweight.

The Flex uses both external and internal cable routing. The external cable routing makes for easier service and maintenance while the internal routing adds to the clean, sleek look of the bike. The frame also comes with a 1-year limited warranty.

The Flex comes with a 100mm suspension fork which adds loads of comfort and off-road performance to the bike. The suspension fork is one of the components that really ties together the ride experience that this bike has.

It gives the front end enough “squish” to feel comfortable and at home on gravel roads and other moderate off-road terrain. On the flip side, it has a lockout dial that allows riders to lockout the suspension for on-road riding. GEN3 made the right move including a suspension fork on The Flex, it’s one of the components that allows the bike to be as versatile as it is.

The Flex comes with a 3×7 Shimano Tourney drivetrain. That’s 21 gears to choose from total. At first I was wondering why they included the 3 chainrings up front, as 3-by setups seem somewhat oldschool in this day and age especially on e-bikes.

My perspective on the drivetrain changed the more I rode the bike, having so many gears to choose from gave me to ride The Flex like you’d typically ride an e-bike, or the option to get a good workout in.

The Flex from GEN3 is plenty comfortable for the style of bike that it is. Despite its sporty nature The Flex is still somewhat upright in its positioning which helps with back and neck comfort.

The upright positioning mainly comes from the 640mm wide handlebar which has a 25mm rise and 15-degree back sweep. The grips are also pretty comfortable, their soft rubber compound is easy on the hands and is easy to hold onto for long periods of time. The suspension fork takes the edge off some of the rougher terrain too which makes the ride that much more pleasant.

The CST All Terrain 26” x 1.95” tires are great for The Flex, they are fast rolling and have enough tread for off-road riding. These tires really seemed to come alive on hard packed off-road surfaces and rougher on-road surfaces.

As a team we’ve put close to one hundred miles in on GEN3’s The Flex and we haven’t punctured these tires. They’ve proven their worth in the way of reliability and design. The frame has clearance for a slightly wider tire than what comes stock on the bike, however we feel this is the perfect tire width for this bike.

The Flex comes with a headlight and taillight. GEN3 offers a Bike Essentials Bundle but aside from that there aren’t many accessories on their website aside from replacement batteries and chargers. We don’t see this as a bad thing as The Flex comes well equipped as it is.

GEN3’s The Flex proved to be quite the jack of all trades throughout our testing and review process. It didn’t have one specific category that it excelled in, rather it seemed to perform up to our standards in all of them.

The Flex impressed us with its battery range — despite only being a 48V, 10.4Ah battery it exceeded the distance of some higher capacity batteries that we have tested. GEN3 seemed to do a good job of calibrating the motor and battery to work well in unison. Riders who want a long lasting but still relatively light weight bike will probably appreciate what The Flex has to offer.

The 21-speed drivetrain was an interesting choice to us at first, however with time we came to really appreciate the fact that The Flex had it. Reason being is you have a gear range that is easy to pedal even when the bike is turned completely off, and a gear range that matches up nicely with the bike when it’s turned on. What I’m trying to say is you’ll have a gear for pretty much any scenario, even if The Flex has run out of battery.

We wouldn’t mind seeing some slightly stronger brakes on the future models of this bike, while the mechanical disc brakes with 160mm rotors did just fine more stopping power never hurts. 180mm rotors, or hydraulic disc brakes would be a great addition to The Flex.

The fast rolling All Terrain tires from CST were the right choice for this bike, they allow the bike to maintain decent traction on off-road surfaces while still being fast rolling in on-road scenarios. The 100mm suspension fork also adds a lot of comfort and performance to The Flex. Both the tires and the suspension fork allow The Flex to really come alive and be a true sporty hybrid e-bike.

If you are looking for an e-bike that has a wide gear range, is sporty and doesn’t break the bank then GEN3’s The Flex is a worthy option. It’s fun to ride, its motor is quiet and it’s very versatile in the terrain it’s able to tackle.

‘Happy Riding, make sure to let us know if you have any questions down in our comments section or if you think we left anything out in this review of the GEN3 The Flex.