Bike Review: KHS Sixfifty 6555+E

Founded in 1974, KHS’ goal from the beginning has been to distribute moderately priced, high-quality bicycles. Since their earliest days, the brand has desired to be a player in every segment of bicycles. To this day, they’re still owned by the same family, and now they’ve stepped into the e-bike market with a line of four bikes—two of them aimed at off-road—with the SixFifty 6555+E being their sole full-suspension mountain bike entry.


KHS chose a double-butted, custom-formed aluminum frame over carbon, but they’ve somehow managed to make a bike that isn’t too expensive as far as the full-suspension e-bike field goes, and still kept it well under 50 pounds. 

The bike is set up with Fox Float suspension, including an e-specific 34 fork in the front and DPS rear shock that offers 150mm of travel in the rear. Overall, it’s a pretty plush ride. There are some bikes going up to 180+mm of travel, but 150mm of well-set-up travel makes for an amazing ride that isn’t crazy tall.

The front end is pretty slack to make it forgiving over big bumps. The head tube angle is 67.5 degrees on all sizes of the frame.

A very compact SunRace 11-46T cassette offers all the range you’ll need.


WTB Scraper rims are laced to Formula TD711 hubs with thru-axles and Boost spacing for added rigidity and strength. The drivetrain is a Shimano XT shifter and derailleur. There’s a KMC chain that’s not e-specific but designed for high rigidity and light weight, and a SunRace cassette that makes for a 1×11 setup that never runs out of useful range. The derailleur hanger is replaceable.

“It climbed up the hill like a sprightly mountain goat!”

A relatively long-travel, 100mm dropper seatpost gets the seat out of your way for descents and technical stuff and raises back up for the climbs. Although, we found this one to be very slow in actuating. It’s been better than getting off the bike and manually dropping/raising the seat, but not as instantaneous as we’d like. This is a better setup for when you know the trail like the back of your hand and can anticipate the adjustment a few seconds ahead.


There are a lot of e-mountain bikes using the Shimano E8000 motor. It’s a good choice for many companies, because it’s small, light and powerful, and Shimano is very flexible about battery choices. KHS has used a standard 504 Wh battery in the 6555+E.

The front end of the KHS is very forgiving on trails.

We made a big mistake by trying to tweak the settings for the E8000 via the E-Tube app in the field. Turns out that the bike needed a firmware update, and on a cellular connection, it wasn’t about to happen. We canceled the firmware update and rode the software stock. When we got back to the office, it was handled quickly via Wi-Fi. Make sure you check that before you leave to see if there are any updates, or you’ll regret it when you get to your trail. As always, we tweaked the Trail mode setting to make it higher and closer to the middle range. Every E8000 motor we’ve ridden has needed this.

While we’re on the subject of the app, in case our friends at Shimano happen to be reading this, the user interface leaves something to be desired. It wasn’t clear that we have to be in the app to connect, not first connecting via the phone’s Bluetooth settings. Once in there, it’s hard to tell how to change the settings. We’re familiar enough now after riding dozens of bikes with E8000 systems, but the average consumer who is using one for the first time may get stuck.


The 6555+ is a solid, trail-oriented bike with 150mm of travel that is good for up to expert-level riders. The $5700 price point and generally lighter weight of the bike makes it an attractive option but at that price, it’s definitely intended for the more serious rider.


Firing up the system requires care. It’s actually better if you turn on the E8000 when you’re off the bike and holding the brake. The torque sensors zero out when you first start the system, so if you touch the pedals or cranks, or if the bike simply rolls a bit, you’ll get an error message, and the bike won’t get any power assist until you turn the system off and then turn it back on again and let the sensor zero out. 

On our initial ride we headed to a climb that most bikes either loop out on or suffer from back-wheel slips. The KHS has great geometry that let us lean over the front end easily, and it climbed up the hill like a sprightly mountain goat! Helping that stability is the 438mm-long rear end and a moderate stack height. Even though the Kenda Havok tires have fairly small knobs, we ran lower air pressure because of the high volume of plus-sized tires, and that offered enormous grip.

Descending that same steep section, we weren’t sure how well the brakes were going to do. The rotors are 180mm and 160mm, where many e-MTBs these days run 200mm up front and 180–200mm rear. Our fears were unfounded, however, and thanks also to those tires, braking felt perfect. 

We had carefully set sag to about 25–30 percent, ran the shock wide open, and that worked really well on even the bigger bumps and drops on the trail. Small bumps simply disappeared, the ride was plush and forgiving, and the bike felt planted when cornering hard. 

With a relatively slack front end, the bike has snappy steering. It didn’t feel like we were steering a barge, and it was quite responsive. Point, pedal and you’re there. We looked forward to every ride with this bike, and it’s definitely a go-to for our local trails.


For a first-time effort, the KHS proved a really good bike. Of course the brand has years of experience designing traditional mountain bikes. In this price range, this is one of the best and lightest bikes we’ve ridden. There seems to have been little compromise made to make this bike handle at the level it does. We think they’ve hit their goal of providing a high-quality bike for a moderate price.


KHS SixFifty 6555+E

MSRP: $5700

Motor: Shimano STEPS E8000

Battery: Shimano, 504Wh, lithium-ion

Charge time: 4-5 hours

Top speed: 20 mph

Range: 20–40 miles

Drive: Shimano XT

Brakes: Shimano MT501 hydraulic disc brakes 180mm front/160mm rear

Controls: Shimano STEPS E8000

Fork: Fox 34 Float, e-specific, Performance, P-S Speed-Ped, 150mm, Grip 3Pos, 15QRx110, Boost, 1-1/8–1.5 taper

Rear shock: Fox Float DPS.P-S.A.3pos LV

Frame: 6061 aluminum with double butted top and down tube

Tires: 27.5” Kenda Havok Pro EMC, 120 TPI, folding

Weight: 49 lb.

Color choices: Black

Sizes: S/15, M16.5, L/18, XL/20


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