The Merida Reacto 4000 is a mid-range aero road bike with disc brakes, the most affordable model in a range topped by the pro-level Reacto Team. Equipped with Shimano 105 and fairly modest aluminium wheels, the Reacto 4000 offers a superbike-adjacent experience on a rather more real-world budget.
At current prices, it’s one of the better equipped bikes in its class and while it’s excellent in standard form, the frameset is good enough to justify significant upgrades down the line.
Merida Reacto 4000 frameset
The Reacto 4000 gets Merida’s second-tier CF3 carbon and its frame weighs a claimed 1,165g plus 490g for the fork, around 200g more than the top-level CF5.
Material aside, the more affordable 4000 is virtually identical to the flagship bike, with the same ultra-modern frame design that ticks off just about every on-trend aero bike feature. There are truncated aerofoil tube profiles throughout with a particularly narrow down tube and a dedicated aero seatpost. Meanwhile the seatstays are dramatically dropped and the top tube is horizontal.
Like many race bikes with discs, the Reacto’s tyre clearance is healthy, with a maximum official width of 30mm.
The cables are neatly hidden from view but mercifully Merida hasn’t gone overboard with the integration, instead opting for the FSA SMR cable routing system, essentially a conventional stem with a removable cover on its underside that conceals the cables on their way into the upper headset cover.
You’ll still need to disconnect things to change the upper headset bearing, but it’s a less restrictive approach than some fully integrated designs while still looking ultra clean.
Like other Meridas, the Reacto features brake heatsinks that sit between the calipers and the frame and fork. I’m pleased to report the rear one doesn’t stick out as much as the older design still seen on some bikes including the Scultura Endurance, so it won’t take chunks out of your shoes if you pedal a bit heels-in.
The Reacto 4000 is a seriously handsome bike with a finish that combines glossy red sections with matt black for an effect that’s anything but budget.
Merida Reacto 4000 build
The Reacto 4000 has a full Shimano 105 R7000-series hydraulic disc groupset with the KMC chain being the only substitution.
This being a race bike, Merida opts for a semi-compact 52/36 crank but lets you down gently with a reasonably generous 11/30 cassette so you’ve still got a pretty low gear when you need it.
The rear derailleur is the larger capacity GS version too, meaning you can fit an even bigger cassette if the mountains beckon.
If there’s one part of the build you probably won’t get too excited about, it’s the wheels. They’re Merida-branded aluminium rims on nameless hubs and there’s absolutely nothing wrong with them, they’re just not very special.
The internal rim width of 19mm is well suited to the range of tyre sizes you’ll put on this bike however and you can even run them tubeless if you want to, although doing so will necessitate new rubber; the standard tyres are basic Continental Ultra Sport III clinchers – a sensible but budget-oriented choice, and one that isn’t tubeless-ready.
I’ve covered the clever stem above, and the rest of the finishing kit is well chosen too. The aero seatpost deserves a special mention for its neat integrated rear light.
As noted in our review of the Team edition bike, this runs on a triple-A rather than being USB-rechargeable, but I’d argue not having a built-in battery makes it more future proof, and it’s nice to have as a backup regardless even if you’re running external lights as well.
Another nice bonus that comes as standard is the compact multitool tucked under the saddle.
My size medium test bike complete with that light and multitool (but no pedals or other extras) weighed 8.7kg which doesn’t sound all that impressive, but is pretty typical for a mid-range aero bike with discs.
Merida Reacto 4000 geometry and sizing
| Frame size | XXS | XS | S | M | L | XL |
| Reach (mm) | 377 | 384 | 390 | 395 | 400 | 409 |
| Stack (mm) | 517 | 529 | 542 | 557 | 571 | 593 |
| Seat tube (mm) | 470 | 500 | 520 | 540 | 560 | 590 |
| Top tube (mm) | 520 | 536 | 545 | 560 | 575 | 590 |
| Chainstay (mm) | 408 | 408 | 408 | 408 | 408 | 408 |
| Head tube angle (°) | 70.5 | 72 | 72.5 | 73.5 | 73.5 | 74 |
| Seat tube angle (°) | 74.5 | 74 | 74 | 73.5 | 73 | 73 |
| BB drop (mm) | 70 | 70 | 66 | 66 | 66 | 66 |
| Head tube (mm) | 105 | 112 | 128 | 140 | 155 | 176 |
| Wheelbase (mm) | 985 | 983 | 990 | 990 | 999 | 1,010 |
Merida’s sizing runs big so pay close attention to the numbers here. With 395mm of reach and 557mm of stack, many brands would call our medium test bike a large – it’s a similar size to a typical 56cm bike.
Leaving that aside, the geometry is pretty typical race bike fare, with steep angles and a short wheelbase of 990mm on the medium.
Riding the Merida Reacto 4000
The days of aero road bikes being little more than time trial bikes with drop bars are thankfully behind us and the Reacto is a refined and well-rounded ride, one that inherits more of performance special sauce from its superbike big brother than you might imagine for such a reasonably-priced build.
It’s the kind of bike that seems to egg you on, ruthlessly converting hard efforts into speed and offering an exciting, engaging ride.
Specialness is so subjective and it’s hard to separate out the preconceptions you have about a brand from what you’re actually experiencing on the road.
For me, the Reacto has that indefinable quality that separates great bikes from those that are merely competent. Sure it’s about a blend of well-judged ride quality and stiffness, but it’s also something more nebulous, let’s call it verve.
Maybe it’s because the bike looks so good – the finish could belong to a more expensive machine. The Reacto oozes speed whether it’s in motion or not – you won’t be able to help casting one last look back as you stroll into the café.
But the ride is what really matters and the Reacto is just thoroughly good at being a bike. It has a strong sense of purpose without being one dimensional. It’s fun to throw around and ride hard, but it also doesn’t wear you down the rest of the time.
Merida Reacto 4000 verdict
You could spend more money to move up the range and get yourself a slightly posher groupset, but the Reacto 4000 is a brilliant bike in its own right, and that cash might be better saved for a future wheel upgrade.
In standard form the Reacto 4000 is solidly good value for money and will leave few riders wanting. Add some deep section clinchers and premium tubeless road tyres down the line and you’ll have yourself an everyday superbike without the price tag.
Merida Reacto 4000 specs
| Frame | Reacto CF3 IV |
| Groupset | Shimano 105 |
| Brakes | Shimano 105 hydraulic disc |
| Crankset | Shimano 105 52/36 |
| Cassette | Shimano 105 11-30 |
| Bars | Merida Expert CW |
| Stem | FSA SMA ACR |
| Seatpost | Merida Team CW |
| Saddle | Merida Expert CC |
| Wheels | Merida Expert aluminium clincher |
| Weight | 8.7kg |
| Contact | merida-bikes.com |
Merida Reacto 4000 alternatives
Merida Reacto 5000
An extra £250 gets you an upgrade to Shimano Ultegra with an otherwise nearly identical spec. It’s not quite the full groupset however – the crank is non series. The £2,950 Reacto 6000 goes the whole hog and also switches to Fulcrum Racing 800 DB clinchers.
- Price: £2,550
Merida Scultura 4000
If aero isn’t your thing, the Scultura 4000 is the Reacto’s all-rounder race bike counterpart. Shallower wheels aside, the spec is all but identical to the Reacto 4000’s.
- Price: £2,150
Review images: Joseph Branston. Product images: Merida
