Carbon revolution? New 2021 Kellys THEOS F eMTB featuring REIN4CED’s steel-carbon composite and a 720 Wh battery
200% more impact-resistant, 200% more durable and without any added weight compared to conventional carbon frames: the frame of the newly developed Kelly THEOS F 2021 is made of a thermoplastic steel-carbon composite called FEATHER, supposedly ringing in a new era in ebike technology. Read on to find out what this promising bike is all about.
Admittedly, Slovakian bike brand Kellys wasn’t on our radar until now. Their previous eMTB range wasn’t able to capture our attention, but all that has changed with the 2021 Kellys THEOS F. For those who’ve never heard of Kellys: founded 30 years ago by the brothers Peter and Brano Divinec, the brand’s headquarters are an hour’s drive northeast of Bratislava and today their full range of bikes is available in around 30 countries. One of Kellys’ goals is to offer leading technology at affordable prices. This also applies to the new Kellys Theos F, which will be available at prices starting from € 4,999. It’s not only the design and development of the bikes that takes place at the company headquarters, but also their assembly, allowing them to be more flexible, faster and cheaper in terms of production compared to most bike brands that don’t do this.
The first details about the 2021 Kellys THEOS F eMTB
The new Kellys THEOS F will be available in two travel length variants: the two THEOS F90 and F70 models come with 180/170 mm travel whereas the entry-level THEOS F50 offers 150/140 mm travel. All models are based on the same frame, the only difference being that the travel of the THEOS F50 is reduced. All THEOS F models roll on mixed wheel sizes with a 29er up front and 27.5″ wheel at the rear. Kellys have not released any details about the motor, but it is said to be Shimano’s new 2021 model, which the Slovakian brand are combining with a 720 Wh battery developed in cooperation with BMZ. The Kellys Re-Charge K1 battery can be removed out of the bottom of the frame, similar to the Specialized Levo. Designing it this way is said to cut down on weight while offering improved stiffness since the downtube isn’t structurally weakened by any openings to the side, as is the case with most ebikes featuring a laterally removable, integrated battery. The motor is rotated by around 45 degrees to be able to remove the battery out of the bottom of the frame and keep the centre of gravity as low as possible. As already mentioned at the start, Kellys want to revolutionise the market with the so-called FEATHER steel-carbon composite that the frames are constructed using an automated production process. The production also takes place in Europe.
REIN4CED’s steel-carbon composite FEATHER in detail
The new Kellys Theos F range was created in close cooperation with Belgian tech company REIN4CED, the frame of which is made from a thermoplastic steel-carbon composite. According to the manufacturer, this material is twice as impact-resistant and durable as normal carbon without any weight disadvantage. The so-called FEATHER material is also claimed to be recyclable. REIN4CED is an independent Belgian tech company that cooperates with the Netherlands Aerospace Center (NLR) and the Fraunhofer Institute for Chemical Technology (ICT), among others. Kellys are the first bike manufacturer to use this technology on an eMTB. GHOST Bikes and the Accell Group are also listed on their website as partners of REIN4CED. However, it is not yet known when we will see more bikes made of FEATHER come to market.
What makes FEATHER so unique is that the carbon fibres are reinforced with micro steel fibres. These wafer-thin fibres are claimed to distribute forces more evenly and over a larger area in the event of a crash or impact and thus prevent delamination or cracks. According to Kellys, this technology is already being used in the aerospace industry. GPS satellites, for example, have to be extremely durable because they are constantly being bombarded by space debris. The biggest hurdle was to scale the manufacturing process down to bicycle parts. After all, the wall thicknesses of bicycle frames range within a few millimetres. Besides, the individual layers of traditional carbon frames are placed in their moulds by hand. This is no longer possible with FEATHER. In contrast to conventional carbon frames, FEATHER relies on thermoplastic polymers instead of liquid resin as the binding material, the properties of which also act as a structural material. These plastics can only be deformed via the application of heat, which is why Kellys use robots to heat and shape the material.
200% more impact-resistant, 200% more durable without any weight penalties compared to conventional carbon frames – it sounds promising. However, it is unclear which grade of carbon Kellys are using as a reference for these claims. When asked, we were told that it refers to the highest available grade. However, since there are big differences among bike manufacturers and their respective manufacturing processes, different resins and methods of layering, the figures communicated by Kellys probably serve more as an indication. However, given the sales prices of the THEOS F range, FEATHER technology is all the more appealing. The flagship model is claimed to weigh around 22 kg in size medium – considering the 720 Wh battery capacity and € 7,999 price point, that definitely sounds promising!
In the past year, we tested over 30 carbon bikes on the roughest trails and we never encountered any defects in the carbon frames, though we did break a few carbon rims. As such, we have to ask ourselves whether we even need a more impact-resistant and durable composite material? Kellys’ answer is a clear yes! Because many riders still hedge doubts about the durability of carbon or are afraid of crashing and of carbon parts that suddenly fail. In the event of major crash or impact, the rider usually can’t tell whether carbon parts are damaged or not. Often, the damage isn’t apparent and can lead to failure at a later point in time. This is exactly where Kellys want to ease their customer’s minds with the new FEATHER technology.
2021 Kellys THEOS F: models, prices, geometry, maximum permissible weight and availability
The THEOS F is available in a total of 3 models, and the shorter travel, entry-level THEOS F50 comes in a choice of two colours. Kellys are currently only making two frame sizes, M and L. The geometry looks very up to date and promising for the bikes’ intended use. The THEOS F is said to hit the market in February 2021, but according to Kellys, the date depends on the availability of certain components. The approved payload of the bike is 120 kg, i.e. the maximum permissible weight of the THEOS F is around 145 kg.
THEOS F90 – € 7,999
FRAME Kellys THEOS F series – Thermoplastic Hybrid Steel-Carbon Composite aka FEATHER by Rein4ced assembled by advanced robotic manufacturing/Think Link, 170 mm rear travel, integrated removable battery/Made in EU
MOTOR 2021 Shimano motor
BATTERY Kellys Re-Charge K1 Li-ion internal removable 720 Wh/capacity 20 Ah, co-developed by Kellys-BMZ
FORK Fox 38 Float Factory, Kashima Coat, 180mm, Float Evol/GRIP2 damper
REAR SHOCK Fox Float X2 Factory, Kashima Coat, 2-Position Open-Firm
SHIFTERS Shimano Deore XT Di2 SW-M8050 Firebolt, 11-speed
REAR DERAILLEUR Shimano Deore XT Di2 M8050
BRAKES Shimano Deore XT M8120 Hydraulic Disc F/R
WHEELSET DT Swiss H1700 Spline 29/27.5 Disc F/R
TIRES Schwalbe Eddy Current Evo SuperTrail 29×2.60 ADDIX Soft/Schwalbe Eddy Current Evo SuperGravity 27.5×2.80 ADDIX Soft
THEOS F70 – € 6,199
FRAME Kellys THEOS F series – Thermoplastic Hybrid Steel-Carbon Composite aka FEATHER by Rein4ced assembled by advanced robotic manufacturing/Think Link, 170 mm rear travel, integrated removable battery/Made in EU
MOTOR 2021 Shimano motor
BATTERY Kellys Re-Charge K1 Li-ion internal removable 720 Wh/capacity 20 Ah, co-developed by Kellys-BMZ FORK Rock Shox Zeb, 180 mm, DebonAir/Charger R
REAR SHOCK Rock Shox Super Deluxe Coil Select R SHIFTERS Shimano Deore SL-M6100-IR Rapidfire Plus, 12-speed
REAR DERAILLEUR Shimano Deore XT M8100 BRAKES Shimano MT420 Hydraulic Disc HUBS Shimano Deore MT410-B Disc
RIMS KLS Bender Disc
TIRES Schwalbe 29×2.60 Eddy Current Evo SuperTrail ADDIX Soft/Schwalbe 27.5×2.80 Eddy Current Evo SuperGravity ADDIX Soft
THEOS F50 – € 4,999
FRAME Kellys THEOS F series – Thermoplastic Hybrid Steel-Carbon Composite aka FEATHER by Rein4ced assembled by advanced robotic manufacturing/Think Link, 170 mm rear travel, integrated removable battery/Made in EU
MOTOR 2021 Shimano motor
BATTERY Kellys Re-Charge K1 Li-ion internal removable 720 Wh/capacity 20 Ah, co-developed by Kellys-BMZ
FORK Rock Shox 35 Gold RL, 150 mm, DebonAir/Motion Control
REAR SHOCK Rock Shox Deluxe Select R, DebonAir SHIFTERS Shimano Deore SL-M4100-R Rapidfire Plus, 10-speed
REAR DERAILLEUR Shimano Deore M5120
BRAKES Shimano MT420 Hydraulic Disc HUBS Shimano Deore MT410-B Disc
RIMS KLS Bender Disc
TIRES Schwalbe 29×2.60 Eddy Current Evo SuperTrail ADDIX Soft/Schwalbe 27.5×2.80 Eddy Current Evo SuperGravity ADDIX Soft
Our opinion on the 2021 Kellys THEOS F
Price, geometry, looks, integration and technical features – the facts and details of the 2021 Kellys THEOS F are very promising. So is the new FEATHER material. Even if we’re convinced that properly handled carbon products are very safe as they are, the carbon-steel composite promises to lift the bar and eliminates any safety concerns carbon sceptics might have. We are very excited to see how the bike will perform on the trail – as soon as the first test bikes become available, we’ll be sure to let you know!
More info: www.kellysbike.com
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Words: Robin Schmitt Photos: Kellys
