Stromer ST3 Review

This in-depth review was not sponsored by Stromer, Cit-E-Cycles Electric Bike Shop, or any other third party. It was funded by the display ads and placements on this website and YouTube. I cover as many products as I can, based on what I feel is relevant, interesting, and available. My goal is to be transparent and unbiased with you, this video and writeup are not meant to be an endorsement. I welcome your corrections, additions, and feedback in the comment section below, and the Stromer electric bike forums.

Observations:

• Stromer is a Swiss company that began in 2007 with the introduction of their first models to market in 2009. While all of their ebikes are city/commuting oriented, they do offer a wide variety of fit options including three frame sizes, two frame styles (high-step and mid-step, which they call sport and comfort), two stem options (flat forward or angled upright, which they again call sporty and comfortable), and multiple handlebar styles (shown during the configuration phase of the website once a bike is chosen). Their products are designed to be more like smart electric vehicles than simple lightweight bicycles… but they are still fairly intuitive to power on and ride with assist. They are capable of reaching higher top speeds, have super bright integrated lights, horns, and smartphone apps with alarms and GPS theft recovery.
• The ST3 frame design was borrowed from / inspired by the ST2 and ST5 which I’ve reviewed previously here. The ST5 is significantly more expensive, only offers the high-capacity battery option, may be purchased with an optional a suspension seatpost (made by Kinekt, can be purchased independently for use with the ST3), and uses electronic shifting vs. mechanical. The company also makes an ST2 with 5-speed belt drive, and ST1 with cassette and derailleur. If you like the ST5 looks and appreciate the inverted suspension option, but want to save some money vs. the ST5, then the ST3 is a great option.

Pros:

• Extremely polished product, lots of custom design work here including the hydroformed aluminum alloy frame, stem with internally routed cables, tubular fenders with lowers mount if you get the suspension fork upgrade, and minimalist integrated rack. High quality ALEXRIMS, Pirelli tires, TRP disc brakes, Ergon saddle and locking grips, and Shimano Deore XT drivetrain… they used great parts all around, and the bike is almost seamless.
• Even though this is still a very expensive electric bicycle relative to most that I’ve covered, it’s significantly cheaper than the ST5 but still looks awesome and captures the same experience. You don’t get electronic gear shifting and you have to pay extra for the high-capacity battery pack.
• Considering the wider range of speeds that this ebike is capable of, since it’s a Class 3 product, I really appreciate the wide range of gears. you get an 11-speed cassette with wide 11 to 42 tooth cog spread. This makes the bike easier to start and more comfortable to pedal at 45km 28mph top speeds. Note the little grey lever on the derailleur that tightens the derailleur and reduces chain bounce when in the up position. Pushing it down and forward reduces spring tension to make service easier. The 52 tooth chainring up front has an aluminum alloy guard that protects pant legs and the bottom bracket if you high center on a log or rock. The chainring itself uses a narrow-wide tooth pattern that really locks onto the chain to reduce drops.
• The bike is fairly comfortable, especially if you opt for the more upright stem and pay extra for the suspension fork. Even if you do not, the moped-rated tires are 27.5″ x 2.35″ which provides a lower attack angle and decent air volume for comfort. Note the thicker walls that reduce thorn and glass punctures.
• This is one of the quietest electric bikes I’ve ever tested. The gearless motor does not produce any buzzing or whirring noises the way that most geared motors do. The fenders and rear rack are solid and secure, and the heavier frame seems to absorb vibration and shock vs. transferring it into your body.
• Since this ebike is rated like a moped in parts of Europe, they include a license plate mount, high quality lights, and a horn. The horn sound was updated in recent years to be more pleasant :)
• I like how Stromer designed their stems to hide wires and make mounting a smartphone on top easy! Just remove the rubberized cover and screw on their twist-mount adapter. You might need a special phone case to make it work, but the interface they chose is fairly universal so there should be good options. Since the stem is proprietary, I love that Stromer offers two versions: sport (shorter and more straight) and comfort (longer and more upright).
• The optional air suspension fork looks very cool. It’s a custom design from WREN with decent 30mm travel and extra thick 36mm stanchions that provide stiffness. Note the sturdy 15mm thru-axle up front and wider 110mm Boost hub spacing to improve spoke bracing angle.
• I like that the charger uses a magnetic connector that won’t tip the bike or get bent and broken as easily if it gets snagged. The included battery charger offers 4.5 amp output vs. 2 amps on most competing chargers, and that makes the battery fill faster, which is great when you’re working with a battery that is nearly double the size of most. Having a removable battery makes the bike a lot easier to protect in extreme cold and heat… heat damages the cells over time while cold stunts your range temporarily.
• The battery pack can be charged while mounted inside the frame or stored separately and there’s no dongle required, Stromer also sells a compact charger with smart maintaining feature that will keep the cells from discharging slowly over time if you aren’t riding for months on end.
• I love that Stromer managed to include bottle cage bosses on the downtube for the high-step and step-thu models! THis is great for bringing fluids or a folding lock, I think the could have added a second set on the seat tube as well, but you could always use an SKS Anywhare adapter for that if you need the extra space.
• The OMNI display panel uses color and offers and invert option so you can change from a white background to a black background (which is less distracting at night). It’s fairly simple to use via the button pad near the left grip or via touch screen. I love how easy the button pad is to reach, how simple it is, and that it’s backlit for easy reading at night. I also appreciate that the display is force sensitive because it seems to work with bike gloves.
• The locking features are pretty cool, you can set the smartphone application to lock and unlock the bike based purely on your phone’s proximity… or unlock it remotely for a friend. The bike has a smartphone chip onboard that syncs with GPS for automatic software updates and theft tracking and recovery (which appears to be included free of charge). I was told by a shop tech that registering Stromer products is very easy compared to many other brands, and they have recovered all stolen bikes.
• It’s a minor pro, but I really appreciate the large aluminum alloy pedals that they specced for the ST2 because they provide good traction and a larger surface area than the older alloy cage pedals used on other Stromer ST1 models.
• I was told that every battery that is shipped with a Stromer electric bike, including the ST3, is charged with solar power (which also powers the myStromer AG headquarters in Oberwangen, near Bern / Switzerland).
• Pedal assist feels very responsive because it relies on signals from a TMM4 torque sensor in combination with a gyroscopic accelerometer, the power ramps up quickly and fades out slowly as you stop pedaling… or you can pull a brake lever to cut it more instantly and activate power recoup.
• I believe that the battery packs are cross compatible with other Stromer models, including the ST5. This is great if you’re considering multiple bikes for a family or couple situation. I also want to highlight that the batteries have built-in handles which make transporting much safer and easier.
• Any time you brake with either lever (not just the right one like with ST1 models) power regeneration kicks in and the bike “recoups” some energy, you can also hold the minus button and select from five recoup levels for longer hills to get more energy
• Premium hydraulic brakes with sturdy carbon steel rotors provide excellent topping power. Large 203mm rotors front and rear provide a mechanical advantage over the larger heavier wheels and the extra surface area on the rotors and the front quad-piston caliper help to dissipate heat.
• Stromer is an established brand dating back to 2009 with global distribution, the ST2 received a Eurobike Gold award, Red Dot Quality Seal award, two Testsieger awards, an Outside magazine award, a Taipei Cycle show award and an iF design award and the ST5 and ST3 share many design features.

Cons:

• This is one of the more expensive electric bicycles on the market today, even though it’s not the most expensive in the Stromer lineup. I understand why the custom frame, battery, and control systems come at a price premium, but the $1k suspension fork seems pricey. I wish that in addition to the larger battery pack option, different handlebars, and compact charger option, Stromer would offer the Kinekt suspension seatpost for this bike as they do for the ST5.
• As cool as the suspension fork looks (especially on the black frame), it’s not super adjustable. Basically, you adjust the air pressure inside using a shock pump (the valve is under the left crown cover that twists off). There isn’t a sticker guiding you on air pressure, there’s no compression, rebound, or preload clickers here.
• The kickstand performed fairly well and didn’t rattle while riding on bumpy gravel and up driveways, but it is positioned at the center of the frame which causes pedal lock when you spin the cranks backwards or walk the bike backwards. I’ve become a fan of the rear mounted kickstands that stay out of the way. I also like kickstands that offer some height adjustment, especially tool-free height adjustment as you can see on this ebike.
• The ST3 is a heavy ebike, especially if you opt for the WREN suspension fork! I weighed it at 71.2lbs as shown in the images and video review above. Keep in mind, that’s with the standard 814 watt hour battery pack vs. the heavier 983Wh. I weighed the battery pack at 10.4lbs, the motor is about 11lbs, and I’m not sure how much the fork weighs… but at least the weight is somewhat evenly distributed and kept low on the frame :) I suspect that the tubular fenders and moped rated tires are a big part of why the bike weighs so much, but at least it feels sturdy and comfortable at speed.
• Since the bike is fairly heavy, I chose to remove the battery pack when transporting it on my car rack. The thing is, without the battery pack inserted, the door wouldn’t stay shut. It rained during my drive home with the bike and that water got inside the battery bay which is probably not good for it. Consider tape, a bungee cord, or velcro strap if you find yourself in a similar situation.
• Minor complaint, I noticed that the battery door opens wide enough to make contact with the left crank arm if it’s in the up position. If the battery door is open wide and you back the bike up or spin the cranks, it could scratch the door or cause damage.
• Unless you’re using a phone app, the display is positioned pretty far down and back, which means you’ll have to take your eyes off the road to read how fast you’re going, what level of assist is selected, how far you’ve ridden etc…. I recommend pulling over to read and interact with the display here, or just clicking the left button pad and guessing what level of assist is active vs. glancing down because the screen is also a bit small and prone to glare. It’s not adjustable angle and not removable.
• I wish the smartphone app showed current speed, a range estimate, and offered some sort of trip planning with GPS so you could feel more confident about arriving without running out of battery. This is especially important given the size and weight of the default charger… it’s 2.7lbs and fairly large.
• The integrated lights are awesome, but sometimes it feels like too much! I wish that there was a way to completely shut the lights off so you don’t blind your friends or ruin your night vision on a full moon ride. The headlight is aimable but the 15-LED running light is not. I like the white frame because it’s going to be super visible from the sides, but it would also be cool if the tires had reflective sidewalls or there was some reflective paint or decals on the black frames. Consider using some black reflective stickers to help it stand out more if you frequently ride in the dark.
• I was told by Stromer that the bolts which secure the wheels require a T70 star driver… which is kind of rare. Someone at the shop told me it was a T60 and I couldn’t confirm, this would be a good accessory to pick up when you get the bike (probably online because it is rare), so you can change flats and do basic maintenance, here’s a kit with both sizes for $16 on Amazon and I welcome your comments below to confirm the correct sizing. It would be a bummer to get a flat rear tire and not be able to change the tube just because you didn’t have the correct tool.
• Cogging slows down the rear wheel when motor is not in use vs. a freewheel (metal staters repel the strong rare earth magnets located around the circumference of the hub casing – this is a con for all direct drive gearless motors but more noticeable on high power motors such as the one used for the ST3), a benefit that negates this con somewhat is the active regeneration and regenerative braking. I saw another video review about the bike stating that if regen is active for 2km while you’re coasting down a hill, that will recharge the battery up to 20%.
• Perhaps it was just my demo bike, but the right chainstay did not have a slap guard. Consider using some clear box tape or searching online for a slap guard like this to protect the paint from chips (which happen more frequently at high-speed when using the high gears on bumpy sections).
• I love that Stromer is selling the bike in three sizes, but that really only applies to the high-step frame. It appears that the mid-step is only available in medium. It’s better than nothing, this is a minor complaint :)
• It seems like the display panel takes a while to boot up, it’s not instant (or nearly as fast as Bosch or Yamaha systems I’ve tested), and I think it’s best not to mount or pedal the bike while it is turning on because the TMM4 torque sensor has to calibrate.
• As cool as the USB type A charging port on the headtube is, your cable will be exposed and possibly loose at the front of the bike. I saw another review where the person wrapped it around the stem area, but this could impact steering if you go too tight. I’m mixed on this position, it’s just not very clean. Perhaps a wireless charging dock on top of the stem could be done in the future. That would be super clean and more seamless, but might exclude non-wireless electronic accessories. Maybe just a simple plug input on the back of the stem vs. the front of the head tube?
• Maybe it’s just me or the demo bike I received, but the smartphone app wasn’t syncing with the bike. Whatever the case, I feel that it’s very important to have a shop helping you with this electric bike. Hopefully the shop stays in business and hopefully you can transfer it to a second or third owner someday and still have everything working. It’s just extra complexity and reliance on smartphone apps and even Stromer as a company vs. a stand-alone product.
• I’m not sure of the cause, but the plastic section below the downtube on my demo bike was coming off of the frame a bit. I tried looking closely and pushing up on it, but the piece just seemed to be coming loose? This gave me pause, because the bike was basically brand new and I had barely ridden it. Could this plastic part come more loose over time? Would there be issues with the electronic cables and circuitry inside? Could water get in and run down to mess up the horn near the bottom bracket? It bothered me.

Useful Resources:

• Official Stromer website
• Stromer ebike shop directory to find a Stromer dealer near you for fitting and test rides