TESTED - Crestline Bikes RS 50/75 eMTB 6

Featuring Bosch's Performance CX Race motor and suspension tuned by Cascade Components, the RS 50/75 is made for aggressive, e-versed riders wanting to get the most out of their eMTB in every situation.

In less than a year, Crestline Bikes has emerged as one of the most exciting small-batch mountain bike companies. They burst into existence with their RS 205 VHP downhill bike and wasted no time releasing two e-bike models a few months later: the RS 50/75 and RS 75/50. Built around the same frame, each model uses different stroked shocks and custom-tuned suspension by Cascade Components to achieve different travel amounts. 

Beautifully crafted machines featuring Bosch's latest Performance Line CX Race motor, a big 750Wh battery, and loads of adjustability, we jumped at the opportunity to test the shorter travel RS 50/75 model. Not a bike developed to persuade uncertain riders to join the electric movement, the RS 50/75 was made for aggressive, e-versed riders wanting to get the most out of their e-bike in every situation. 

RS 50/75 Highlights

  • Full carbon frame
  • Size-dependent rear wheel size 
  • Aftermarket swingarms available for 27.5" & 29" 
  • 150mm of rear travel // 160mm fork travel
  • Rear travel is adjustable between 150mm, 163mm, and 175mm with different stroke shocks
  • Available in three sizes (reach adjustable by +/-5mm w/ aftermarket headset)
  • 85Nm Bosch Performance Line CX Race motor
  • Removable 750Wh Bosch Powertube battery
  • Compatible with 500Wh and 625Wh batteries
  • Kiox 300 display integrated into the top tube
  • System Control unit integrated underneath the top tube
  • Bluetooth wireless Mini Remote
  • Straight 56mm head tube
  • 12x148 Boost rear hub spacing
  • Weight (size RH-3, no pedals): 54 lbs (24.4 kgs)
  • MSRP: $12,996 USD



  • Geometry provided a balanced body position that was comfortable for descending and climbing
  • Highly capable and versatile bike— from mellow flow trails to steep and technical descents.
  • Bosch Performance Line CX Race motor 
  • Clean and simple cockpit 
  • Adjustable and adaptable frame to match rider or terrain
  • Silent on trail
  • Premium price point
  • Bosch CX Race motor could be too much power for some 
  • Only one colorway and build kit

Frame Details

Like Crestline's RS 205 VHP downhill bike, the RS insignia on the 50/75 and 75/50 is an acronym for 'Racing Sport.' Borrowed from the automotive world and an ode to Audio and Porsche's highest-performing models, the RS naming on Crestline Bikes represents their limited-produced, premium, full-carbon frames. Made by VIP Composites out of Vietnam, Crestline uses VIP's highest-end modulus carbon and layup models to achieve the best strength-to-weight and stiffness-to-flex ratio. 


The RS 50/75 is the shorter travel configuration Crestline offers, and the name represents the bike's stock 150mm of travel and its ability to run 175mm of travel. The RS 75/50 uses the same frame but comes set up with 175mm of rear wheel travel and a 180mm fork, with the option to run 150mm of travel. 


Adjustability is a major highlight of Crestline Bikes. Regardless of which travel amount riders choose directly from Crestline, the inverse amount is possible via a different shock stroke and a flip chip in the lower eyelet. The frame uses a 230mm shock length, which comes in various stroke lengths. This means that riders have a few travel amounts between 150mm and 175mm to choose from. Geometry is preserved when changing rear travel because the eye-to-eye remains the same. 


Additional adjustability is provided by the straight 56mm head tube that can fit a variety of reach or angle adjust headsets. Rides have only three frame sizes to choose from, so tossing in a reach-adjust headset does help accommodate shorter and taller riders or those who fall between sizes. 


Crestline recommends sizing down with their frames. The sizing recommendation is based on the philosophy that the added weight from an e-bike motor and battery increases the weight and traction on the front wheel. Thus, riders can ride a smaller frame and still receive good front wheel grip while ending up with a bike that is easier to maneuver in steep or tight sections. 


Frame size dictates the wheel configuration of the RS 50/75. The RH-2 frame only comes with mixed wheels, RH-3 comes in either mixed or dual 29" depending on the stock travel amount, and RH-4 only comes with dual 29" wheels. For riders who prefer a setup outside Crestline's recommended wheel configuration, aftermarket one-piece swingarms are available for 27.5" or 29" wheels.


The final adjustment riders have at their disposal is the ability to use aftermarket batteries of different sizes. The bike comes with a 750Wh Bosch Powertube battery. Dropping the battery requires removing two screws near the bottom bracket to undo a small door. Riders prioritizing maneuverability over range can install a smaller battery and save some weight (750Wh battery = 9.9 lbs // 625Wh battery = 8 lbs // 500Wh battery = 6.6 lbs). Or, riders who want to go longer between charges or take two batteries on epic rides can opt for a second battery. 

At the end of the day, the value of all these adjustments is that they give riders the ability to dial in their setup to best match riding style or terrain. And since Crestline only offers top-tier builds on a premium frame, having multiple bikes in one with the addition of a few extra components does help lessen the blow to your bank account. 

Suspension Details 

The RS 50/75 uses a familiar dual-link suspension layout that sees two links rotate around a virtual pivot in opposite directions. A highly tunable design with an extensive race pedigree, Crestline worked with Cascade Components to dial in the kinematics. The goal wasn't to recreate how a dual-link platform performs but to offer a combination of suppleness and support to complement various riding styles and abilities.


Bosch Performance Line CX Race System

Crestline is one of the few brands sporting Bosch's limited-edition Performance Line CX Race motor. The main difference between the Race and standard CX motor is the weight (Race is ~140 grams lighter), the addition of Race mode, and a jump from 340% to 400% support ratio. Designed for eMTB racing, Race mode delivers all 85Nm of torque in a faster, more powerful support profile. It also features Extended Boost, which causes the motor to continue working for up to a meter after you stop pedaling. 


Underneath the top tube is an integrated System controller that turns the system on/off and enables connectivity to Bosch's eBike Flow app. Connecting to the app allows riders to check battery health and range, look at ride-time stats, conduct over-the-air updates, customize riding modes, and plan routes. A newer feature is the eBike Lock function, which disables the motor if someone tries to steal your bike. It also turns your phone into a system key, requiring Bluetooth connectivity for the motor to begin providing support. 


Integrated into the top of the top tube is a Kiox 300 display that clearly (and in color) shows such metrics as speed, cadence, power, range, and battery percent. Navigating through the near-endless data screens is done via Bosch's Bluetooth wireless Mini Remote. The sleek remote is also used to engage walk mode and cycle between the riding modes: Eco, Tour+, eMTB, Auto and Turbo. When tuning each mode in the eBike Flow app, riders can adjust max power, max support level, acceleration, and speed.


Finally, the system includes a wireless speed sensor on the valve stem, eliminating extra wiring in the swingarm.  

Build Kits

Crestline produces its bikes in limited batches. The first batch (which has sold out) included 50 RS 50/75s and 50 75/50s. The second batch arrived last month and included 100 RS 75/50 complete bikes. At this time, about half have sold, and the rest are available on crestlinebikes.com. The following batch is expected towards the end of this year.


Our impressions below detail how the bike performs in a smaller travel configuration and with different components than what is currently available. We periodically rode the bike in the 75/50 setup, but for our testing terrain, we opted for the shorter travel version. We tested a one-off build that shares some similarities with the latest SRAM CX Race build, but component performance will not be a focus of this review. Instead, we will focus on the Bosch CX Race system and suspension performance since those are constants regardless of which build kit riders receive. 


Can you buy a frame only? With so much adjustability designed into the bike, we asked Crestline if they will offer frames only so riders can go wild with their personalized builds. A tricky question to answer due to the high costs of importing just a frame with a Bosch system (upwards of $7,000 USD), Crestline is currently figuring out how they can economically offer frames in the future. But, for those seriously interested in getting a frame now, reach out to Crestline, and they will do what they can to get you rolling. Crestline is happy to support the demand if more riders are interested and willing to pay a premium for a frame only.

On The Trail

All our time on the RS 50/75 was spent around Southern California during the peak of summer. Home to many trails of varying terrain, summer conditions are mostly dry, sandy, and blown out. Plenty of harsh hits and braking bumps were on the menu during testing, and the bike consistently rose to the occasion. The RS 50/75 didn't need much tweaking out of the box, as the taller Renthal handlebars and wireless cockpit felt comfortable and looked great. We did add a 5mm spacer under the stem to raise the front for comfort, and we adjusted sag front and rear to achieve a balanced ride height. 

With Crestline being a smaller brand, we were surprised at the fit and finish of the RS 50/75. The cable routing was clean and tight; the battery was easy to remove if needed; a small rear fender helped prevent mud and debris from stocking piling on the rear shock; and a proper chain stay protector mitigated noise without additional mastic tape. And throughout testing, the bike remained extremely quiet. The attention to detail on the RS 50/75 matched bikes produced by companies that have been making bikes for decades. Props to Crestline for coming out swinging and crafting a thoughtfully designed frame!

Descending Performance 

With gravity at our backs and our favorite technical descents ahead of us, the RS 50/75 was an absolute treat to ride. The rear suspension felt limitless when charging over rocky terrain, and the roomier cockpit allowed us to stand in a natural position over the bike. This poised riding style offered great traction and control, and no trail was off-limits. A composed monster at speed, the bike was eager to take on big hits, rocky steeps, or marathon-long descents. 


With so much capability on gnarly trails, we came to realize the RS 50/75 bears a fun and poppy personality with the proper setup. Crestline suggested running 30% sag in the rear, which gave the bike the stable and planted feel we admired. Curious how the bike would ride with a firmer setup, we dropped sag to 24%. The result was a more playful bike that was eager to jib or pop off little jumps. With two setups for two riding styles, we see more aggressive riders choosing less sag to keep the RS 50/75 alive and active, while those looking to hold on and plow would be best suited running the recommended sag. 


The standout characteristic of the RS 50/75 was the confidence-inspiring feel created when pushing the bike's limits. When on pace, the bike was extremely predictable with no surprises up its sleeve; we could load up the rear suspension and blast into compressions without fear of an unsuspected bottom out. With the rear suspension being so predictable, the RS 50/75 welcomed lines that seemed off-limits on other bikes. We loved being able to drive wide and high into corners and carry maximum exit speed. 


Cresline did a wonderful job making the RS 50/75 a weapon on trails with loads of elevation drop. At the other end of the spectrum, down tight or flat trails, the bike did require more rider input to keep charging forward. At slow speeds, the bike became laborious to navigate. Not a huge surprise, considering the weight and wheelbase of the RS 50/75 don't exactly slot it into the featherweight class. With this knowledge in our pockets, we were conscious of how we entered awkward sections or approached tight inside lines. Additionally, the CX Race motor sprung into action through tight or flat corners, allowing us to rely on its power to pull us through lulls in the trail. Perfect for those moments when you botch a section and need to find your flow again. 

Climbing Performance 

This was our first time riding an e-bike with the Bosch CX Race motor, and let us tell you, it's called race for a reason. Right off the bat, we found ourselves climbing in Turbo mode most often (creatures of habit?). However, after only a few ascents, Turbo mode proved too powerful. The Extended Boost feature caught us off guard more than a few times, leading to some interesting line choices and even running off the edge of the trail a few times. We hopped into the Bosch app and backed down the acceleration, which allowed us to push harder on the climbs without the bike pulling out from underneath us. But ultimately, AUTO mode became our new go-to, allowing us to focus on the trail and execute the moves needed to clean technical climbs. Or, it allowed us to sit back and enjoy a long fire climb with a friend. With AUTO mode operating in the background, the thought of which mode you should be in or how much battery you have remaining is eliminated. Just start riding; it's almost too easy. 


The RS 50/75 had excellent small bump compliance, making long stints in the saddle comfortable. The large 750Wh battery offers more than enough range to accomplish as long of rides as your heart desires. Most of our rides were not massive all-day excursions but consisted of 6-8 laps with 500-800 ft of climbing per lap. This typically resulted in burning two bars out of five on the battery display. Compared to other eMTBs, the RS 50/75 was fairly fuel efficient when it comes to smiles per mile, offering riders plenty of range. 


The 64.5-degree head tube angle translated to a nice feel on the front wheel without the chopper effect when climbs became slow and steep. The seat tube angle on the 50/75 is not the steepest seat tube on the market, but after dialing in the ride modes, the bike really came to life. We could stay seated more, which increased the traction and stability when on the technical climbs. The 50/75 is not the lightest e-bike we've ridden, but the power on tap from the CX Race motor kept the bike from showing its weight on climbs. Having the options to adjust the ride modes along with the reach adjustment options in the headset, you can feel confident knowing the correct setup is out there to match your terrain. 

Bosch e-System Performance

Crestline is one of the few companies producing bikes with the Bosch CX Race motor. Not only was the Race motor an impressive beast during testing, but the rest of the system was executed flawlessly. The wireless Bosch Mini remote made for a clutter-free cockpit, and the wireless speed sensor on the wheel further eliminated any extra e-related wires. The Powertube battery also created a clean downtube with no extra frills or keys to remove the battery. The Smart System from Bosch is new for this year and allows you to hook up your phone and really explore the possibilities of the system. From adjusting your ride modes to tracking your ride time, the Bosch app allows you to gather data like never before. 


The placement of the Kiox 300 display in the top tube took time to get used to compared to the handlebar-mounted version. But after a few rides, we enjoyed its location because it kept us looking down the trail instead of catching glimpses of the screen while riding. The hidden-in-plain-sight location of the System Control unit under the top tube was the perfect way to tie the clean cockpit together. The only downside was when you needed to activate the Bluetooth setting, you would have to mildly contort your body to make sure you were in the right setting. 

Overall, Crestline came to play with its first e-bike. The powerful motor with a large battery and neatly integrated e-components provide riders with class-leading performance. 


What's The Bottom Line? 

The RS 50/75 is built for riders who want to maximize their ride time on the trail and push the boundaries of what they thought was possible to ride on an eMTB. A great option for all-day lappers trying to ride every trail under the sun or those seeking massive e-adventures, the bike can handle the wildest descents and rip back up the burliest climbs. The only knock on the bike is the lack of multiple build kits and colorways and the expensive price tag. Of course, that comes with the territory of riding a high-end, boutique bike. For those who choose to play ball, the RS 50/75 delivers a highly capable ride quality with thoughtful frame details and endless adjustability. 

For more information, please visit crestlinebikes.com


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