2014 Diamondback Overdrive EXC Review

The Diamondback Overdrive EXC is a trail ready hardtail electric bike with large 29 inch wheels. It’s great for cruising around town or taking dirt paths and is capable of higher top speeds in pedal assist, up to 28 miles per hour. With a mid-drive motor system from TranzX and support from Currie Technologies, this bike combines the racing heritage of Diamondback frames with proven electric bike systems and support. The balance is great because all of the heavier parts of this system are mounted low and center and the efficiency is also impressive because the motor drives the same chain that you pedal with as a rider. As a result, it benefits from mechanical advantage depending on which gear you choose from the 10 speed cassette. One of my favorite features is the RockShox air fork suspension which includes rebound adjustment and lockout so you can reduce bob when riding on flat hard surfaces. The one thing I really wish this ebike had however, would be rack attachment points on the rear seat stays. The bike is fast, efficient and better suited to roads or hard trails so why not make it into a rugged commuter with lights and a rack? While it’s true that you could always use a beam rack, in my experience those just aren’t as sturdy and can get knocked right or left more easily than a traditional frame mounted rack.

Driving this bike is a 350 watt geared mid-drive motor from TranzX. It’s relatively small and seems well protected at the bottom bracket because the front chainring extends below and has an aluminum bash guard to protect its teeth from rocks, roots or curbs. I like mid-drive electric bike designs because they can be fast or strong depending on which gear you choose at the rear but one disadvantage is potential gear grinding. Some fancier systems from Bosch or Impulse actually detect when you’re switching gears and tell the motor to ease off but that is not the case here. As mentioned in the video review above, I’ve found that the best way to shift is actually to tap the brake levers (which cuts power to the motor temporarily). Ultimately, this TranzX Currie motor is part of a mid-level or “value” system but it’s definitely not the lowest end in my experience it operates smoothly, relatively quietly and is capable of those higher top speeds in pedal assist. The control system that powers the motor measures your torque and cadence which makes it feel fluid and another big advantage of this mid-drive is the front and rear quick release wheels. This feature makes changing flats or just getting a standard bike tuneup easier and less intimidating for shops that might be used to servicing only normal bicycles.

Powering the motor and display system on the Diamondback Overdrive is Lithium ion battery pack that mounts directly on top of the downtube, where you might be used to seeing a water bottle cage. This design is good for several reasons, it keeps weight centered on the frame compared to a rear rack which might produce more flex in the frame and it also protects the pack itself in the event of a crash. The battery offers 48 volts of power and 8.8 amp hours of capacity which is quite good and the 2 amp charger that comes with the bike can fill it up either on its own or while still attached. The battery pack also locks to the frame for security which is nice if you use it around town. In terms of chargin, the pack reaches ~80% in roughly two and a half hours or 100% in about five hours due to leveling towards the end. While I’d prefer a battery pack that’s more integrated into the downtube vs. the large square one used here, I understand that it helps to keep the price of the bike and replacement packs low. The two big complaints I have with how this one works however is that it has to be activated before the display panel can be turned on (most mid or high-level ebikes don’t have two switches like this) and there isn’t a spot for mounting a bottle cage because that’s where the battery already is. When riding off-road in places like Colorado, Utah or Arizon where it’s dry and hot, water is very important and it just bums me out that there isn’t space for it with this battery pack and that they didn’t try to fit one on the seat tube. You might do best with a CamelBak or that beam rack idea mentioned earlier.

Turning this bike on is a two step process. Once the battery is charged and mounted you have to press a rubber power button on the right side of the battery for a couple seconds and then press a second power button near the left grip on the button pad for two more seconds. From there, the LCD screen turns on and does a quick countdown… then, finally you’re ready to get going! From here, at any time you can twist the throttle and get up to ~6 mph (20 mph if you pedal along). This two-step throttle system sort of threw me off at first just like the two step power-up because I’m used to many ebikes having a throttle that will go to 20 mph with or without pedaling. As I understand it, the throttle here is meant to serve primarily as a boost for helping you ascend short climbs while pedaling in lower levels of assist. In practice, that method works pretty well but it makes me question the need for a throttle at all, especially considering that it compromises the right grip a bit which you could be squeezing tightly while navigating rough terrain. One thought I had was that maybe they could use a trigger throttle instead so that both grips are consistent and stable feeling? Back to the display, it has a built in light sensor or you can activate backlighting at any time by using the button pad. The LCD display shows speed, battery level, estimated range (based on the battery’s state of charge) and assist level 1-4. This display is actually one generation old from what I’ve observed on other ebikes and doesn’t have two support arms like the newer Currie Technologies displays. That’s usually not a huge deal but might be more vulnerable if this bike is crashed while riding off-road. The display isn’t removable and doesn’t seem to swivel easily like the new two-arm systems but it performs just fine otherwise.

My feelings are mixed on the Diamondback Overdrive EXC… I love that it will be available through more retail outlets because it’s a Diamondback product and that it uses a mid-level drive system and battery but I feel like the price is a bit high considering the IZIP E3 Dash is very similar but goes for $200 less. In fact, the Dash has rear rack mounting points and the new display system I just mentioned. The lack of rack mounts and bottle cage bosses bother with the Overdrive me but I do like that the frame comes in two sizes and the air suspension fork is light but sturdy. There aren’t many 29er electric bikes out there and this one would be perfect for mixed terrain commuting, even with a beam rack or backpack. The large wheels are smooth and efficient and the higher top speed could make short work of longer rides… especially with the lockout. I personally think the bike looks cool and with the hydraulic disc brakes and grippy aluminum alloy pedals, it handles very well and I believe you can even have aftermarket lights wired in to run off the main battery source. This bike isn’t exactly cheap and that sort of pushes me towards the Haibike XDURO 29″ for ~$700 more. That bike has a much more sophisticated motor motor system but still no rack mounts, no throttle and a lower top speed of 20 mph vs. 28 mph. It really depends on what your riding needs are but the Overdrive EXC will definitely perform in a wide range of conditions and brings something new to the market in terms of speed, efficiency and serviceability.

Pros:

• Available in two sizes for improved fit, both are high-step which provides stiffness and come in the gloss red color scheme
• Light weight RockShox XC30 air suspension fork with lockout for riding on pavement and flats as well as rebound and compression adjustment for trails
• Battery can be charged on or off the bike (store in neutral temperatures and top off after each ride for maximum life) connects easily to frame and locks securely, the built-in LED charge level indicator is useful when the pack is off the bike
• Solid warranty, available at lots of locations throughout the USA for easier test riding, fitting and future service
• Excellent weight distribution with the mid-frame battery pack and center drive motor, this improves balance and handling, especially off-road
• Mid-drive motor leverages the 10 speed cassette for improved efficiency and range, great for climbing with lower gears
• Throttle adds power dynamically (up to 20 mph) when pedaling, great for overcoming small hills when using a lower level of assist
• Front and rear wheels offer quick release for easy trail maintenance – changing tires, fixing spokes etc. and makes the bike less threatening to traditional bicycle shops who may have never serviced an ebike
• Removable battery reduces overall weight of the bike when transporting on cars etc. and also frees up the triangle section of the bike for easier mounting from hang-style racks
• Solid one year electronics warranty serviced by Currie Technologies, should get good service for tuneups and mechanical fixes from Diamondback retail outlets
• The 29er wheel size offers the best rolling momentum and smoothest feel on bumpy terrain, takes a bit more energy to get them going but then they coast very nicely and have a high attack angle for riding through obstacles
• Nice component upgrades including the SRAM X7 10 speed cassette, locking grips, aluminum alloy pedals and RockShox suspension fork – wires are integrated through the frame for durability and a nice clean aesthetic
• Hydraulic disc brakes operate without requiring much effort, they are smooth and provide quick stopping power while also cutting power to the motor, matching 180 mm rotors are large for added strength
• Remote button pad on left bar is well sealed against water, blends in with the bar and is easy to reach while riding – intuitive menus make operating the bike while riding fairly easy

Cons:

• The throttle can only reach ~6 mph if you’re not pedaling along, it cuts out abruptly and leaves me wishing it could hit 20 mph on its own
• Display panel is not removable, that means it will take more exposure to the elements when parked outside and may be tampered with more easily
• Display panel only attaches to the handle bars with one support arm (some newer displays use two) could be a little more vulnerable when trail riding if you slide out on the bike
• Value drive system with larger front ring and simpler control sensors than higher end systems like Bosch or Impulse, the motor doesn’t kick in or stop as quickly and it also can’t sense when you’re shifting gears
• The rear seat stay bars lack side bosses for mounting a rear rack in the most secure way, you could still make it work with the middle hole but this might take the place of a rear fender, also there are no bottle cage mounting points on the frame, consider using a CamelBak
• In order to operate this ebike the battery pack has to be turned on before the main display is activated, this takes extra time and can make you wonder if the battery is charged or if the bike has an issue (if you forget to activate the pack first)