BMC has released a brand new 29in cross-country race hardtail, the Twostroke, to sit alongside its full-suspension XC bike, the Fourstroke.
The Twostroke will be offered in both aluminium and carbon, and is designed for the rigours of modern XC and marathon racing.
Six models will be available, ranging in price from €1,199 to €3,999, bucking the trend for super-pricey top-flight race bikes.
BMC Twostroke design
XC hardtail designers have a number of competing demands when it comes to designing a bike. They need to keep the bikes light and stiff, for the most effective responses to pedal inputs on punchy climbs, while also ensuring the bikes are able to cope with technical courses and keep riders fresh during long days out.
The old adage used to be that races were won on the climbs and lost on the descents, but BMC reckons nowadays races are won on both the climbs and descents, so bikes have to be as capable up as they are down.
In a slightly surprising move, BMC has moved away from the elastomer based softtail design of its previous XC hardtail, the Teamelite, instead opting for a traditional rigid frame.
With cross-country courses getting tougher and fast riders still demanding compliance from their bikes, BMC recognises the need for a compliant frame.
It says that modern frame design and construction methods, along with the latest generation of voluminous XC race tyres, give all the comfort and control needed on a hardtail, though.
BMC’s Twostroke concept was for a light, stiff and responsive frame that gives “explosive accelerations and precise handling” while still being up to the task of everyday racing and riding.
At the same time, it’s borrowed the ‘Tuned Compliance Concept’ from its road bikes for the Twostroke’s carbon frames, seeing a fine-tuning of the carbon layup to provide the ideal amount of vertical deflection.
This is realised through the chainstays, which are designed to give that vertical deflection along with the use of a D-shaped seatpost and seat tube, which BMC has found to aid fore-aft deflection, again boosting comfort.
Alloy frames use a hydroformed, ‘smoothwelded’ construction method and come with a 31.6mm round seat tube.
Further reflecting the development of cross-country, BMC says that it’s given the Twostroke ‘radical geometry’ in order to allow you to hit the race course with the utmost confidence.
This effectively means slack head angles, 44mm short-offset forks, a steeper seat angle and short chainstays.
BMC Twostroke frame details
The Twostroke certainly has a distinctive look, with the top tube and seatstays merging in to one continuous line.
BMC says that it’s removed unnecessary curves from the design and took aesthetic inspiration from the Lockheed Martin X-35 fighter jet, no less!
In another slightly surprising move, BMC hasn’t built the frame down to the sub-kilo weights we’ve seen from the likes of Specialized and Orbea, with a medium carbon frame coming in at a claimed 1,037g.
This is because BMC wanted the frames to be stiff and robust. This translates in to wide chainstays that are high in profile, along with a straight, oversized down tube to give torsional stiffness and strength.
Alloy frames come in at a claimed 1,850g for a medium.
BMC Twostroke finishing touches
The straight down tube means that in a crash the fork crown is likely to hit the down tube. As such, the Twostroke comes with an integrated fork stopper to prevent this from happening.
Frame protection continues further back, with an integrated chain-suck plate, chainstay protectors and a chain guide, along with helicopter tape pre-installed on the down tube.
While the aforementioned D-shaped seatpost and tube might aid deflection, the shape, in theory, means no dropper posts will fit. However, BMC recognises that some riders will want that flexibility.
As such, a shim will be available to reduce the seat tube so it will accept an internally routed 27.2mm dropper post – something that’s having a bit of a resurgence thanks to the growth of the gravel market and it’s requirements for skinny droppers.
Frames are 1x specific, have a 160mm Post Mount brake bracket, provide clearance for 52mm tyres and hold two water bottle cages. The carbon frames take a PF92 bottom bracket, while alloy frames take a threaded BB.
BMC Twostroke geometry
Both the carbon and alloy frames share their geometry. Bikes are available in XS to XL, and details for a Large are detailed below:
- Reach: 465mm
- Seat tube: 480mm
- Chainstays: 425mm
- Head angle: 67 degrees
- Seat angle: 75 degrees
- Wheelbase: 1,161mm
- Stack: 608mm
- BB drop: 64mm
BMC Twostroke models
BMC Twostroke 01 One
This top-level carbon bike is built with a 100mm RockShox SID Select fork, a SRAM X01/X1/GX Eagle groupset with a 34t ring on the carbon cranks and DT Swiss XR 1700 wheels with 2.25in Vittoria Barzo tyres.
Brakes are SRAM’s Level TLM units, while the finishing kit is largely BMC branded componentry. The bike is a claimed 9.33kg.
BMC Twostroke 01 Two
The second tier carbon bike gets a RockShox Reba RL fork, a SRAM GX Eagle groupset and DT Swiss X 1900 wheels with the same Vittoria tyres.
Finishing kit is courtesy of BMC, while SRAM Level TL brakes complete the build.
BMC Twostroke 01 Three
This model gets a RockShox Recon Silver RL fork, a NX/SX Eagle groupset, Alex MD25 rims on Shimano hubs and Shimano Deore brakes.
BMC Twostroke 01 Four
The entry level carbon bike gets a RockShox Judy Silver TK fork, a Shimano Deore 12-speed groupset and Shimano BR-MT400 brakes. It receives a round 27.2mm seatpost within the shim.
BMC Twostroke AL One
The alloy frameset is built with a RockShox Recon RL fork with a remote lockout lever. It has a mixed SRAM NX/SX Eagle groupset and Shimano Deore brakes.
BMC Twostroke AL Two
The entry-level bike in the range has a RockShox Judy TK Remote fork, a Shimano Deore 12-speed groupset and Shimano BR-MT400 brakes.