Merida Reacto V4 launched | Mark Cavendish’s new bike gets faster, lighter and more comfortable

Merida’s newly-updated aero road bike, the Reacto V4, aims to combine cutting-edge aerodynamics with the ride quality of a general classification bike.

When Merida introduced the original Reacto back in 2011, it was one of the first manufacturers to bring aerodynamics to a bike designed to be ridden at every stage of a Grand Tour.

Over the years, Merida has fine-tuned the Reacto design, introducing full-cable integration along with a raft of aero updates, and even adding disc brakes and reducing weight along the way.

By 2017, and the release of version three, the Reacto had become the ‘go to’ bike for Merida’s WorldTour team, for riders prepared to sacrifice some comfort in the pursuit of wind-cheating pace.

Merida Reacto V4 2021 — With the new Reacto, Merida has sought to reduce the weight and improve the comfort of its race-focused aero road bike. - Merida

For this fourth version of the Reacto, Merida has looked to tip the balance away from pure aerodynamics to create a bike that has all of the DNA of a pure-bred aero machine, but is an “all-rounder with class-leading aerodynamic performance”. The best of both worlds, then?

While Merida’s rivals in the peloton – Cannondale (with the SuperSix EVO), Specialized (with the new Tarmac SL7) and Trek (with the Emonda SLR) – have all looked to add aero properties to their all-round race bikes, Merida has flipped this around as it's looked to lighten and add all-round abilities to its pure aero-race machine.

There are two versions of the new Reacto frame and eight bikes in total across the range, ranging in price from the £2,250 Reacto 4000 model with Shimano 105, all the way up to the Bahrain-McLaren replica Team-E at £9,000 with Shimano Dura-Ace Di2.

Reacto goes on a diet

Let’s talk numbers. Weight-wise, the previous top-level Reacto CF4 frame tipped the scales at 1,150g for a M/L bike (the equivalent of the V4’s Medium). The new V4 machine’s flagship CF5 frame drops significantly down under a kilo to 965g.

The CF5 frame features on the Team-E, 9000-E, and 8000-E models, while the CF3 frameset features on the 4000, 5000, 6000, 7000-E and Force bikes.

The CF3 has the same stiffness and compliance qualities as the range-topping CF5, according to Merida, but with a little more weight.

The new CF5 fork weighs in at a claimed 457g, whereas the old CF4 came in lighter at 398g. The CF4 had no internal cable routing, though (the brake cable routed through exterior guides), so this is a much cleaner design.

Improving aerodynamics and comfort

Merida tells us it would have been easy to make aerodynamic improvements over the previous model, and it explored designs such as combining the deep aero-shaped seatpost and seat tube of the Warp TT bike to make immediate gains, but that became detrimental to the ride quality.

The new Reacto’s goal was to improve both aerodynamics and comfort, while also dropping weight.

The Reacto V4’s aero improvements come in the form of better integration using Vision’s Metron 5D ACR cockpit. This one-piece bar/stem combo uses Vision’s ACR cable routing design to thread cables and hydraulic hoses through the bar, into the stem and then down into a reshaped head tube.

This provides a 2-watt improvement over the previous design, according to Merida. The oversized head tube also allows better integration with the fork crown, while enlarging the tyre clearance to 30mm also allows for a much smoother transition. The combined effect is another 2-watt gain.

At the rear of the frame, the increase in tyre clearance has also increased the space between chainstays and tyre, and Merida says this also results in less turbulent air created by the spinning wheels, giving another positive effect on aerodynamics.

Where’s the comfort coming from? Merida says it has improved the Reacto’s comfort qualities primarily through the carbon make-up, in order to provide vibration damping and compliance where it’s needed.

Merida has also refined the S-Flex seatpost. This dedicated airfoil-shaped post features a cutaway section into which an elastomer is bonded to reduce road noise and add some flex on rougher road surfaces.

With these improvements, alongside the increase in tyre clearance, Merida claims the Reacto V4 is its most complete bike yet, and in the aero bike class one of the lightest and most comfortable you can find.

Six smart features from the Merida Reacto V4

Vision’s Metron 5D bar/stem system is designed with the Italian company’s ACR system, which fully integrates the cable routing through the unit and channels it down into the head tube, making for a cable-free front end
Like the previous Reacto, Merida has integrated disc-cooling fins into the fork legs and rear stays. These are designed to help regulate brake temperature in the ‘heat’ of competition
The rear mech is held in position using a Shimano-specification ‘direct mount’, making for accurate shifts, improved reliability and a lower profile to better protect the mech in the event of a crash
The S-Flex seatpost combines a deep airfoil shape with a cutaway section and elastomer. This allows the post to flex vertically and the elastomer helps dampen road vibrations, according to Merida
Tyre clearance is up to 30mm without compromising the overall aerodynamics of the Reacto
It’s the bike Mark Cavendish will be racing for Team Bahrain McLaren

Merida Reacto V4 geometry

By and large, Merida hasn’t altered the standard race-orientated geometry of the Reacto, but it has made some changes to the sizing.

The Reacto is now available in six sizes from XXS up to XL. The introduction of an XXS means there's no longer intermediate sizes like S/M and M/L, which should go some way to making size choice simpler.

The reshaped front-end, with its cockpit and fork integration does, however, mean the V4 has a significantly shorter head tube, size-for-size.

Frame size	XXS	XS	S	M	L	XL
Seat tube [mm]	470	500	520	540	560	590
Top tube [mm]	520	535	545	560	575	590
Head tube [mm]	105	112	129	141	156	176
Head tube angle [°]	70,5	72	72,5	73,5	73,5	74
Seat tube angle [°]	74,5	74	74	73,5	73	73
Chainstay length [mm]	408	408	408	408	408	408
BB drop [mm]	70	70	66	66	66	66
Fork length [mm]	384	384	384	384	384	384
Stack [mm]	516	528	542	557	571	592
Reach [mm]	372	373	381	390	394	402
Wheelbase [mm]	985	982	989	990	1,000	1,009

All the small things

Merida has also looked to make improvements in the Reacto’s general usability and performance, with various updates to some of the small details across the bike.

The rear mech now uses the direct-mount standard, which improves shifting accuracy and helps to make wheel changes faster, according to Merida.

Thru-axles: at the front Merida has integrated the threaded insert to fit flush, to reduce turbulence and drag (as small as it might be). The thru-axle lever is also removable and, cleverly, while it’s a 6mm fitment, when removed it doubles up as a 4mm Allen key (that will also work on the seatpost clamp and stem bolts).

The Reacto’s disc coolers remain but with an updated design, designed to cool hot brakes. The second-generation finned system flushly integrates into the front fork leg and inside the rear dropout triangle. Merida claims the coolers reduce brake temperature by up to 35 per cent over a conventional system.

Finally, the seatpost clamp has been redesigned and repositioned to fit flush into the frame to, you guessed it, reduce turbulent air.

The 2021 Merida Reacto range

The new Reacto comes in eight different models, from the £2,250 Reacto 4000 to the £9,000 Team-E.

The premium CF5 frame features on the three most expensive models – the Team-E, 9000-E and 8000-E – and the second-tier CF3 frameset takes over from there, on the 4000, 5000, 6000, 7000-E and Force bikes.