Review: Merida Reacto 4000

The Reacto forms part of Merida's range of aero race road bikes boasting efficient teardrop tube profiles, with direct mount brakes, internal cable routing, and an integrated seatpost which features Merida's S-Flex technology for some added comfort in the saddle.

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The Frame

Merida have clearly poured development time and some good thinking into the design of the Reacto frame. All the tubes have been shaped to maximise airflow efficiency. The tear dropped profiles follow NACA (National Advisory Committee for Aeronautics) Fastback design principles to ensure the aero effect is real. The rear or "tail" of the tube profile is D-Shaped in an effort to keep the airflow stable without causing turbulence and to keep the tube dimensions UCI compliant.


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Further aerodynamic gains are achieved by joining the seatstays lower down on the seat tube. This reduces the size of the frontal area and with the stays positioned wide, they stay clear of the rear wheel to help manage the airflow and turbulence in that area. The carbon fork's legs are widely spaced for the same reason, with the crown integrated into the frame. The head tube has a bit of an odd shape from some angles, but by looking at all the other design touches, I have no doubt that the size and profile plays it's part in the bike's low drag.


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The Reacto comes with an internal seatpost clamp that is placed inside the top tube and works fastens with an expanding wedge. The carbon seatpost is also tear drop shaped with its own clever design touches. The S-Flex seatpost, as Merida calls it, features a cut out near the top with an elastomer fitted to allow some flex and add comfort to the ride. The S-Flex seatpost comes standard with a reversible head and integrated bracket for a Di2 battery. The reversible head will allow you to setup the bike in an aggressive position over the pedals, if you'd like to use the Reacto for time trials.


It is no use having tubes that slip through the air when other components and cables are undoing all the good work. With that in mind, the cables are routed internally, entering the frame at the top tube just behind the stem. As this is already "dirty air" the exposure of the cable up to this point will have little impact on drag. The front and rear brakes are direct mount with the front brake in a conventional position rather than tucked away behind the fork, as preferred by many other aero bikes. According to Merida, the difference in drag is minimal. The rear brake, however, is hidden behind the bottom bracket. Going this route has allowed Merida to do away with the seatstay bridge in an effort to keep the bike clean in that area, and in doing so further improving the Reacto's aerodynamic efficiency.


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Furthermore, the Reacto includes an inline quick release for the direct-mount caliper, barrel adjusters for the the front and rear, a stem top cap with integrated cable guides, chainstay protection, and a chain catcher as standard.


A not so obvious aero trick lies in the frame's geometry. With a shorter head tube compared to their Scultura (170mm vs 159mm comparing 54cm frames) and a longer reach (390mm vs 400mm) the Reacto will enable the rider to sit lower on the bike reducing the impact of the rider on the overall aerodynamics.



  • Colourblack / green
  • Frame sizes47cm, 50cm, 52cm, 54cm, 56cm, 59cm
  • Frame sizesREACTO CF3
  • ForkReacto Carbon pro-direct
  • Derailleur frontShimano 105 D
  • Derailleur rearShimano 105 SS
  • ShiftersShimano 105
  • Brake leverShimano 105
  • BrakesShimano 105-direct
  • ChainwheelFSA Gossamer Pro 52-36 (BB386)
  • ChainKMC X11
  • HubsFormula Road Bearing
  • RimMerida Expert 35 CW
  • FreewheelShimano CS-5800-11 11-28
  • TyresContinental Ultra Sport II 25 fold
  • SpokesBlack stainless
  • Handlebar stemMerida Expert Carbon OS -5
  • HandlebarMerida Compact road OS
  • HeadsetFSA No.47/48
  • Seat postReacto carbon Race [Di2 ready]
  • SaddleMerida Sport Pro
  • Weight8.90 kg
  • Recommended PriceR 29,999.00


On the Road

First ride out and it was obvious that the all the features employed by Merida have resulted in an aero bike that is quite comfortable on uneven roads with no sign of the sting that plagued early aero road bike efforts. On longer rides, the bike gave nothing away to other full carbon race bikes and there is a balanced feel between the front and rear end.


Getting out of the saddle and on the pedals shows just how reactive a stiff the frame really is with every pedal stroke resulting in forward motion. However doing this does trade in some of the comfort provided by the seatpost - the overall feel is not harsh, but the seatpost definitely plays its role in the comfort built into the bike.


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With Cape Town's South Easter howling away during my test period, the Reacto proved itself stable and manageable in crosswinds. This helps a great deal as some bikes and deep section wheels can be quite tiring to keep under control when the wind is out in full force. I tested the Reacto with the a review pair of Mavic Cosmic Pro Carbon SL C wheels. The combination of wheels and tyres dropped nearly 850g from the bike's overall weight and added a turn of speed and burst of acceleration, whether from standstill or out of a corner, elevating the bike to another level. The wheel's retail price of R 32,700 does make it more expensive than the bike, but for a tad over R60 000 you will then have yourself a very capable, fast and comfortable aero bike.


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With the stock wheels fitted, climbing is good and on par with other 105 specced road bikes that we have been riding the last couple months. Attacking the twisties was a fun affair with the bike's geometry playing into the hands of those not afraid to get their knee out. Fortunately staying clear of feeling twitchy or nervous at speed. Keep the momentum going and the Reacto will zip along cutting through the air at a rate belying its stock weight.


The Reacto 4000 comes with 52/36 tooth chainrings which helps on longer, steeper climbs. The Shimano 105 groupset performed flawlessly, with the only kink being the rear brake that could do with a bit more oomph. In wet conditions, initial braking felt a bit more gritty thanks to more dirt collecting on the pads and it would be interesting to see the effect this will have on running a carbon rim brake wheelset over a full season. The top end model and the official Merida team riders do ride carbon wheels so I'm sure it has been tested to its max and found to be a non-issue.


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Merida has shown with the Reacto that an aero bike can be comfortable and doesn't have to weigh a ton. Advances in technology and years of carbon know how has certainly played its part to close the comfort and weight gap between standard and aero frames. With a solid base specification, the Reacto 4000 offers excellent long term upgrade potential.



Vanzyl, Jan 05 2017 09:50

not a merida fan but thats hot!!!!

Zorro5614, Jan 05 2017 10:14

More a Scultura man

Cadre, Jan 05 2017 10:37

not a merida fan but thats hot!!!!

I bought mine around a year ago. Frame colours are inversed on mine. Very happy with the bike. Best thing about it, must be the value for money. For me it ticks all the boxes. And yes, it does turn heads. Downside though....some chick wanted to take a photo of the bike at Suncoast Casino one weekend...she did the unthinkable....she asked me to move out the frame as she only wanted a picture of the bike. I am psychologically scarred for life.

mecheng89, Jan 05 2017 11:36

I bought a 2016 Reacto 5000 in December 2015 and the bike has been bitter sweet to me. 


The bike standard is quite "heavy" for a full carbon bike. I suspect this is down to the heavy wheels. The aero position does place an awful lot of load on your shoulders and triceps, but I believe this is nothing a bit of TITS and some resistance training can't solve. SICK speed on the flats and descents! 


Planning on purchasing carbon seat, stem, handlebar and wheels within the next 12 months, will give feedback once all the parts have been purchased. 

shaper, Jan 05 2017 12:01

Nice looking bike, but heavy!!

Zorro5614, Jan 05 2017 12:07

You could get it to 8kg with new saddle, seatpost, stem, handlebars and wheels

Dexter-morgan, Jan 05 2017 12:09

I think it will be my next road bike.

myth125, Jan 05 2017 04:30

I have the 7000e.  Amazing road bike, super comfortable for an aero bike and, as others have mentioned, great value for money...

Forbsie, Jan 08 2017 09:24

Got mine in December.................. amazing!!!!!!!!! 

mecheng89, Jan 08 2017 12:03

You could get it to 8kg with new saddle, seatpost, stem, handlebars and wheels

That's my plan. Then the rider must drop a few kgs too!