Cotic RocketMAX Gen4 Mullet Silver review

Santa Cruz Nomad S Carbon C Mx Mountain Bike 2023

The RocketMAX from Cotic has always done well in our Enduro Bike of the Year test, consistently impressing across a variety of terrain. The fourth generation of the British brand’s enduro bike improves on previous scores thank to a host of changes that help to make it a serious bit of kit when pointed down the hill. While the 160mm of rear-wheel travel and steel front triangle remain, the new RocketMAX is compatible with longer-travel forks. It also comes as a full-blown 29er or with mixed wheel sizes (29in front wheel, 27.5in rear) and is offered in more sizes. There are also direct-to-consumer, easy-to-customise build options, which are a massive plus when shopping on a budget. Add to that a quality finish and a ride that’ll have you grinning from ear-to-ear every time you swing a leg over the RocketMAX, and you’ll soon see why we scored it as highly as we did in Bike of the Year 2023.

Cotic RocketMAX Gen4 Mullet Silver frame and suspension details

Cotic Rocketmax Gen4 Mullet Silver Full Suspension Mountain Bike

The external cable routing looks neat and tidy, and should prove easier to work on for home mechanics. It wouldn’t be a Cotic if there wasn’t some steel involved. The RocketMAX Gen4 frame’s front triangle is crafted from custom Reynolds 853 steel tubing, while the rear swingarm is made from 6066-T6 aluminium. In the mixed wheel-size configuration seen here, there’s clearance for a 27.5×2.8in rear tyre (with a 29in wheel fitted, it’s 29×2.5in – the 29er version doesn’t use the angled headset needed to alter the geometry for the mullet setup). Cotic gives you a choice of rear-wheel travel, which is dictated by the stroke length of the shock. You can opt for 150, 155 or the 160mm-travel option (which uses a 65mm stroke shock), which is what I tested. The 160mm of travel is delivered using Cotic’s ‘droplink’ system – a single-pivot design with a linkage-actuated shock – which is said to have 30 per cent progression across the range of travel.

Cotic Rocketmax Gen4 Mullet Silver Full Suspension Mountain Bike

A small chain guide helps to keep the chain in check. For the fourth generation of the RocketMAX, Cotic tweaked the droplink design, keying the links to the axles in a bid to limit flex or twist when the bike is ridden as hard as it has been designed to do. This latest iteration of the frame has also been altered and beefed up to handle the rigours of bigger-travel forks with stiffer 38mm stanchions (upper tubes). Home mechanics will rejoice at the fact the cables are (mostly) routed externally for easy access. The rear derailleur cable does run inside the seatstay though. Other details include the 3D-printed upper chainguide for a bit of extra peace of mind, threaded bottom bracket and a bottle cage mount.

Cotic RocketMAX Gen4 Mullet Silver geometry

Cotic Rocketmax Gen4 Mullet Silver Full Suspension Mountain Bike

Cotic offers the RocketMAX Gen4 with 29in wheels, or in a ‘mullet’ configuration Cotic has switched to what it calls the ‘C’ sizing model (think along the lines of Specialized’s ‘S’ or Merida’s ‘Agilometer’ sizing, which puts more of a focus on difference in reach and front centre, rather than purely seat tube lengths). The RocketMAX Gen4 is available in five sizes (C1-C5). You still get the brand’s ‘Longshot’ geometry, which is designed to balance stability and agility, and bikes are built around short 35-45mm stems (depending on your size and preferred fit). To maintain the slack 63.4-degree head angle (I measured it to be slightly slacker than Cotic claims) with the smaller rear wheel in place, an angled headset is used.

Cotic Rocketmax Gen4 Mullet Silver Full Suspension Mountain Bike

Cotic’s own bar and stem are decent bits of kit that do the job nicely. Compared to the 29er RocketMAX, however, this slackens the seat tube angle by one degree. I measured my test bike’s effective seat tube angle to be 75.8 degrees with the saddle set to my preferred pedalling position. The stack height is 647mm (the 29er’s stack is 639mm), which is around 20mm higher than the Nukeproof Mega 297 Carbon Elite and Vitus Sommet 297 AMP, which were also contenders in the Enduro Bike of the Year test. In this configuration, the C2 frame has a middling reach of 451mm and a lengthy front centre (the horizontal measurement from the centre of the bottom bracket axle to the centre of the front wheel axle) of 805mm. The rear centre (effective chainstay length) of 448mm is long compared to many medium-sized frames, especially with a smaller 27.5in rear wheel fitted. The 343mm bottom bracket height (and 32mm of drop) helps to keep weight low for improved stability.

Seat angle (at 720 BB-saddle height) (degrees)74.874.8975.275.275.2
Seat angle (at 815 BB-saddle height) (degrees)74.574.574.974.9749
Head angle (degrees)63.563.563.563.563.5
Chainstay (mm)448448448448448
Seat tube (mm)390417444471496
Top tube (mm)599621639660679
Head tube (mm)100110120130130
Bottom bracket drop (mm)3232323232
Wheelbase (mm)1,2331,2571,2791,3031,322
Stack (mm)638647656665665
Reach (mm)435451473492511

Cotic RocketMAX Gen4 Mullet Silver specification

Cotic Rocketmax Gen4 Mullet Silver Full Suspension Mountain Bike

The Cane Creek DB Kitsuma coil-sprung shock offers loads of external adjustment to help dial it into the terrain. Thanks to its online, direct-to-consumer sales model, Cotic offers plenty of possibility to customise builds along the way. My test bike started as an ‘Enduro Silver’ build (£4,649). However, Cotic switched the fork to the RockShox ZEB Ultimate (170mm of travel), added Hope Fortus 30 wheels, included a OneUp dropper post and Magura MT5 brakes, and bolted on a pricier Cane Creek DB Kitsuma coil shock. WTB supplies the tyres, though Cotic offers alternative options if you’d rather something different. While I was happy with the Verdict up front, I couldn’t get along with the Trail Boss rear tyre and wanted something that would offer a bit more traction under braking. Cotic was quick to send out a replacement Judge, which made a big difference on steeper trails.

Cotic RocketMAX Gen4 Mullet Silver ride impressions

Cotic Rocketmax Gen4 Mullet Silver Full Suspension Mountain Bike

Through the turns, the RocketMAX Gen4 feels brilliantly balanced and eager to go fast. I rode the Cotic RocketMAX Gen4 Mullet/Silver on a wide variety of trails around the South West of England and South Wales. These varied in gradient, speed and terrain. They included man-made tracks littered with high-speed impacts, rock gardens and big jumps through to steeper, natural, technical trails where the roots and rocks were plentiful but speeds a little lower – along with everything in between.

Cotic RocketMAX Gen4 Mullet Silver setup

Cotic Rocketmax Gen4 Mullet Silver Full Suspension Mountain Bike

No tools are required to twiddle the Kitsuma shock’s damping dials. After a bit of back and forth with Cotic, the bike was shipped with a 350lb spring fitted to the Cane Creek Kitsuma rear shock. This gave me 31 per cent sag (I weigh 68kg, kitted up). The Kitsuma shock offers a serious amount of adjustment (high- and low-speed compression and rebound damping), though to get the RocketMAX to feel as I preferred, I ran all but the low-speed rebound fully open (this was set with five clicks from fully closed). Up-front, I set up the 2022 ZEB Ultimate fork with 52.5psi, with two volume spacers fitted. I left the high-speed compression fully open, but had 17 clicks of low-speed compression damping (from closed) and 12 clicks of rebound. I dropped the stem down the fork steerer a little (I’m a big fan of brands that leave enough fork steerer to enable riders to play with bar height). After a bit of playing around, I settled on leaving one 5mm spacer beneath it.

Cotic RocketMAX Gen4 Mullet Silver climbing performance

Cotic Rocketmax Gen4 Mullet Silver Full Suspension Mountain Bike

Aside from the weighty WTB tyres, the RocketMAX Gen4 feels relatively eager when pointed uphill. Uphill, the RocketMAX Gen4 feels more eager than some of its competitors. Because I have quite short legs and a long torso, the seated position of the RocketMAX Gen4 worked well for me. While the seat angle isn’t the steepest on paper (my saddle height is lower than the one Cotic uses to measure its seat tube angles – 695mm versus 720mm), it never caused me any issues. Sure, it’s not as steep as some that feel really keen on super-steep climbs, but it still works just fine. It helps that there’s enough stretch in the 621mm effective top tube to pull your weight further forwards, and the rear centre is long enough that weight remains well distributed between the wheels.

Cotic Rocketmax Gen4 Mullet Silver Full Suspension Mountain Bike

The short seat tube lengths of the RocketMAX mean you can fit a dropper post with plenty of travel. This becomes particularly apparent on really steep, technical inclines where you can simply sit and spin your way up with no fear of the front wheel lifting or wandering as you navigate obstacles. The rear end remains calm while pedalling sat down, too, with only minimal movement from the shock as you spin the cranks. That meant at no point did I need to reach down and use the shock’s climb lever. The WTB rubber isn’t the fastest-rolling out there, but it’s a trade-off I’m happy to make for the traction on the way back down.

Cotic RocketMAX Gen4 Mullet Silver descending performance

Cotic Rocketmax Gen4 Mullet Silver Full Suspension Mountain Bike

There’s now the option to buy a Fox 38 or RockShox ZEB Ultimate fork (as seen here). Barrel headlong into steep, technical terrain, and the RocketMAX oozes poise and control from the get-go. The high front end and supple RockShox fork enable you to weight the front of the bike with utter confidence, keeping the tyre stuck to the trail when you need to. Off the brakes, trucking into choppy terrain, both the fork and shock are suitably supple and do a fine job of sucking up trail chatter and maintaining traction, the rear end pattering over bumps with plenty of control.

Cotic Rocketmax Gen4 Mullet Silver Full Suspension Mountain Bike

Shimano’s SLX drivetrain offers great, reliable shifting and won’t break the bank. The well-centred ride position leaves you in a neutral position on the bike, only needing to put in small inputs when you need to correct your position on the trail or angle the tyre more to improve grip. Alongside that high front end, the healthy 1,253mm wheelbase on my C2 test bike really bolstered stability. Even when riding trails blind for the first time, I could push that bit harder thanks to the sure-footed feel the RocketMAX delivers.

Tight and technical

Cotic Rocketmax Gen4 Mullet Silver Full Suspension Mountain Bike

Hope wheels are part of the customisable build package if you’re looking to add a little bling. On steppy, rocky tracks that are steep enough to see you dragging the brakes more often than not, the back end of the RocketMAX isn’t as forgiving as some. Being more precise with your braking does help in these situations, though there’s no denying that the best bikes in the category deliver a little more comfort in terrain such as this. Thankfully, it doesn’t detract massively from the RocketMAX’s overall capability. When things got twisty and tight, I had no issues manoeuvring the bike – despite the length and slack head angle, I never felt as though I had to muscle it about to stick on my desired line. It helps that there’s plenty of support and progression built into the rear suspension, really giving you something to push against when loading the bike in order to negotiate tricky obstacles or turns. If and when the time comes to loft the front wheel in the air, the long rear centre means it won’t pop up with quite the same ease as shorter equivalents. However, you soon get used to this and it doesn’t detract from the on-trail agility.

Rocket by name, rocket by nature

Cotic Rocketmax Gen4 Mullet Silver Full Suspension Mountain Bike

Hope Fortus wheels are solid and dependable. We had no issues with these during testing. On faster trails, the RocketMAX Gen4 was able to carry impressive amounts of speed where other bikes hung up or felt a little lethargic. This is most obvious when sling-shotting from turn to turn. Here, the Cotic’s ride position, and the balance and support through the suspension, mean you can slam into turns at warp speed, load the bike up and it’ll fire out the other side faster than a circus clown out of a cannon. There’s a chance you’ll have the same goofy clown smile plastered over your face too. At pace, the RocketMAX Gen4 feels steadfast and a comfortable place to be. Sure, there’s a little more feedback and chain slap when battering through rock gardens compared to some plusher bikes, but if you have the bottle, it’ll get you through just about anything without deviating from your chosen line.

How does the Cotic RocketMAX Gen4 Mullet Silver compare?

Bird Aeris 9 Shimano 12-Speed Full Suspension Mountain Bike

The Bird Aeris 9’s industrial looks will appeal to many, as will the brand’s sales model, which enables you to customise your build. Compared to the Bird Aeris 9, a bike that’s sold online, direct to the consumer, the RocketMAX Gen4 feels more lively and exhilarating to ride. That’s not to say the Bird is in anyway bad, because it’s a great bike. However, although it feels similarly poised through the turns, it doesn’t seem as engaging when being pushed hard. The RocketMAX Gen4 is easier to generate speed on, too, when pumping through undulations. That said, although the back end of the Bird feels a little more muted, it manages to take the edge off nasty bumps when skidding down nasty rocky trails. Both are certainly impressive enduro bikes and both brands offer a brilliant opportunity when it comes to speccing the bike how you’d want it. However, for me, the RocketMAX’s ride feels that bit more exciting.

Cotic RocketMAX Gen4 Mullet Silver bottom line

Cotic Rocketmax Gen4 Mullet Silver Full Suspension Mountain Bike

There’s more than enough control in the suspension to ensure hefty landings will be absorbed deftly. The RocketMAX Gen4 Mullet Silver is a proper winch-and-plummet mountain bike. It’s mild-mannered enough on the climbs that you don’t feel as though you’re rinsing energy unnecessarily, and when it comes to riding downhill in the right hands, this thing can really fly. Yes, there are quieter, arguably smoother bikes when the going gets really rough, but the RocketMAX Gen4 still impresses when it comes to its speed-carrying ability. Through the turns, the speed and composure is hard to fault. Naturally, some of the appeal here has to lie with the easy-to-customise build, which is a real plus if you know where on the bike you really want to splash the cash. Overall, Cotic’s changes to the Gen3 RocketMAX have really paid off.


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