Archive: Rocket 275 (Gen2)

Cotic Rocket 275 in Matte Bright Orange

Discontinued, superseded by Gen3. This page is kept as an archive record for owners and for anyone researching an older Cotic Rocket.

Years of production: 2015-2017

This is the Rocket Gen2, the first Rocket on 27.5" wheels. The original 26" bike is on the Rocket 26 (Gen1) page, and the other generations are in the Rocket archive.

It was a race proven Enduro weapon, which the Cotic Racing team took to multiple UK Gravity Enduro podiums in 2013, 2014 and 2015, to the PMBA Enduro Series overall championship titles in 2016 and 2017, and also campaigned in the Enduro World Series.

Finishes: Matte Bright Orange and Matte Bright Green.

droplink

The Rocket used our droplink suspension layout, which brings together the grace, durability, clean lines, fun and interactive feel we put into all our hardtail frames, and adds a whole truckload of speed and rock pounding performance.

Reynolds 853 delivers a fantastically robust and durable front end, and includes our signature Ovalform top tube. Our custom designed heat-treated seat tube gives incredible stiffness at the suspension pivots to give you the confidence you need when pushing on.

Steel is also used for the seat stays, as its strength lets us minimise the size of this part of the frame, maximising ankle, heel and calf clearance. Custom ultra slim titanium droplink pivot fittings complete the picture.

The swingarm is 7000 series aluminium. It allows us to create the complex shaped CNC machined parts required to thread through the area between the tyre and chainrings, and still get as much structure as possible in the brace area for great stiffness at the back of the bike.

The details and latest trends are all covered: taper steerer compatible head tube, Syntace X-12 142 x 12 bolt thru back end, 27.5" wheels, ISCG05 mounts, sealed, capped and shielded pivots, right down to the precisely located hose routing, semi-internal gear routing and Stealth dropper compatibility.

In short, it's a brilliant all round mountain bike, with crisp climbing performance and a wonderful lightness of touch when pinging between lines. This is all allied to a swaggering, "let's do this" attitude when you're flying back down the other side of the hill. It feels just as happy whipping between the trees as it does flat out on an uplift day.

Frame details

Cotic OFI bike fit with long cockpit, corrected seat angle for dropper posts and carefully placed BB to combine stability with a fun, interactive feel
Reynolds 853 Ovalform and DZB tubed front end brings precision, durability and strength
44mm standard head tube designed with an external bottom cup for taper steerer compatibility and a zero stack top cup for minimal stack height
Custom Cotic designed 35mm heat treated cromoly seat tube for super stiff support for the main suspension pivots
31.6mm seatpost size is dropper seatpost compatible. The frame has external and internal "Stealth" dropper post remote routing
ISCG05 mounts on a regular threaded bottom bracket bring drivetrain security and reliability
Rear mech cable routed internally through the steel seat stay for clean lines and low noise
2x drivetrain compatible. Routing and swingarm clearance in place for double chainsets and a Shimano Side Swing front entry front mech
7005-T6 aluminium swingarm with Syntace X-12 142 x 12 rear axle
15mm pivots for the BB and a droplink thru axle style linkage clamp keep the frame solid front to rear
Clearance for big tyres: 2.5" DH tyres run with plenty of clearance
One bottle mount
Geometry for speed, fun and interaction using 150 or 160mm forks. 66° head angle and low 13.3" BB with a 150mm fork
Later rated and retested for use with a 170mm fork
150mm of Cotic droplink suspension brings precision, fun and interaction via a strong progression rate on the linkage driven single pivot layout
Sizes: Small (16"), Medium (17.5"), Large (19") and XL (20")
Weight: Gold spec bike 30.3 lbs without pedals

Complete bike builds

All our bikes were hand assembled to order in Sheffield. Specifications changed without notice, so bikes shown in videos and photos may feature a different spec to the ones below.

Platinum build

Shimano XTR M9000 mechanical 1x11 drivetrain, XT 11-42 cassette
Race Face Next SL Cinch 175mm carbon cranks, direct mount 30t chainring
Deore XT M8000 brakes, 180/180 rotors
Fork options: RockShox Pike RCT3 2018 Boost 160mm, Cane Creek Helm 160mm, or Cane Creek Helm 170mm
Cane Creek DB Air IL shock
Hope Tech Enduro wheels
WTB Vigilante 27.5x2.3 TCS Light High Grip front and Breakout 27.5x2.3" Tough Fast Rolling rear, set up tubeless
Joystick Analogue Carbon bar (800 x 20 rise, 223g) and Joystick Builder 50mm x 10 degree stem
Race Face Turbine dropper seatpost: 125mm drop on Medium, 150mm drop on Large and XL
Cotic Cromo rail saddle
Hope headset
Pedals not included

Platinum customisation options: choice of disc brakes (two Shimano and two Hope options); Hope/WTB Ci24 carbon wheels; an 11-46 cassette for easier climbing gears, or the Hope 10-44 cassette to save weight; and a Cane Creek DB Coil IL or Fox Factory Float X2 shock.

Gold build (SRAM Eagle)

SRAM Eagle GX 12-speed, 10-50 cassette
SRAM Eagle GX cranks, 175mm, 32t X-Sync 2 chainring, GXP BB
Deore XT M8000 brakes, 180/180 rotors
X-Fusion Sweep Roughcut 160mm fork, 15mm axle, taper steerer
Cane Creek DB Air IL shock
Hope Tech Enduro wheels
Handlebar of your choice: Cotic Calver (780 x 25 rise), or Joystick Analogue Carbon (800 x 20 rise, 223g, +£100)
Stem of your choice: Cotic 35mm or 45mm, Race Face Ride 60mm or 70mm, Hope AM 50mm (+£50), Joystick Builder 50mm or 35mm (+£50)
Race Face Turbine dropper seatpost: 125mm drop on Medium, 150mm drop on Large and XL
Cotic Cromo rail saddle, Hope headset
WTB Vigilante 27.5x2.3 TCS Light High Grip front and Breakout 27.5x2.3" Tough Fast Rolling rear, set up tubeless
Pedals not included

Gold build (Shimano XT)

Shimano Deore XT M8000 1x11 drivetrain, 11-42 cassette
Race Face Turbine Cinch 175mm cranks, direct mount 30t chainring
Deore XT M8000 brakes, 180/180 rotors
X-Fusion Sweep Roughcut 160mm fork, 15mm axle, taper steerer
Cane Creek DB Air IL shock
Hope Tech Enduro wheels
Handlebar, stem and dropper post choices as on the SRAM Eagle Gold build
Cotic Cromo rail saddle, Hope headset
WTB Vigilante and Breakout 27.5x2.3" tyres, set up tubeless
Pedals not included

Gold customisation options: choice of disc brakes; Hope/WTB Ci24 carbon wheels; Cane Creek Helm or RockShox Pike forks; an 11-46 or Hope 10-44 cassette; and a Cane Creek DB Coil IL or Fox Factory Float X2 shock.

Silver build

Shimano SLX M7000 1x11 drivetrain with SLX M7000 11-42 cassette
Race Face Affect Cinch 175mm cranks, direct mount 30t chainring
Deore M615 brakes, 180/180 rotors
X-Fusion Sweep RL2 160mm fork, 15mm axle, taper steerer
X-Fusion O2 RCX shock, Cotic tune
Shimano Deore M618 hubs on WTB ST i25 TCS tubeless ready rims
Handlebar and stem choices as on the Gold builds
X-Fusion Manic dropper post, 125mm drop
Cotic Cromo rail saddle, Cane Creek 10 headset
Continental Trail King Pure Grip 2.2" tyres
Pedals not included

Silver customisation options: a Hope headset; choice of disc brakes; Hope wheels or Hope/WTB Ci24 carbon wheels; the Roughcut HLR damper, Cane Creek Helm or RockShox Pike forks; an 11-46 or Hope 10-44 cassette; and a Cane Creek DB Air IL, DB Coil IL or Fox Factory Float X2 shock.

Geometry

The chart is a guide to frame size. OFI geometry means that the frames are low and long, with plenty of standover room. You can either have a regular position coupled with a small and chuckable frame, or go for the next size up and go long and racey without feeling like you're riding a gate. All measurements are static.

Frame Size	Small	Medium	Large	XL
Seat Tube (centre-top)	400mm	440mm	480mm	503mm
Chainstay Length	433mm	433mm	433mm	433mm
Head Tube Length	100mm	110mm	120mm	130mm
Usual Height Range	165-173cm	170-182cm	178-191cm	183cm +
Stem Length	35-60mm	35-60mm	35-60mm	35-60mm
Frame Wheel Travel	150mm	150mm	150mm	150mm

The angles and BB drop depend on the fork:

Fork	Head Angle	Seat Angle (effective)	BB Drop
150mm	66.0°	74.4°	-3mm
160mm	65.5°	73.9°	0mm
170mm	65.0°	73.4°	+2mm

Top tube length, reach and stack (Small / Medium / Large / XL):

Fork	Top Tube (effective)	Reach	Stack
150mm	581 / 599 / 618 / 640mm	418.5 / 433.2 / 448.1 / 468mm	581.7 / 590.9 / 601.7 / 606mm
160mm	581 / 599 / 618 / 640mm	418.5 / 433.2 / 448.1 / 468mm	581.7 / 590.9 / 601.7 / 606mm
170mm	584 / 603 / 622 / 644mm	415.5 / 430.2 / 445.1 / 465mm	587.7 / 596.9 / 607.7 / 613mm

Component sizes

Seatpost diameter: 31.6mm (380mm long minimum)
Front mech: 34.9mm (bottom pull, high band clamp or Side Swing)
Bottom bracket width: 73mm
Bottom bracket thread: conventional English/BSA
Fork: maximum 160mm travel, 551mm axle to crown (without sag)
Chain guide mounting: ISCG05
Headset: 44mm for taper steerer forks: Hope 2H, Cane Creek ZS44 top/EC44 bottom, or Chris King Inset I7
Rear hub: 142 x 12 bolt through
Rear axle: Syntace X-12
Rear mech hanger: Syntace X-12 Type 1 (conventional or Shimano Direct Mount)
Shock: 200 x 57, with 15.75 x M8 fittings at the down tube end and 19.0 x M8 at the seat stay end
Dropper post routing: both external under the top tube, and Stealth via the down tube
Rear brake mounting: I.S., compatible with rotors up to 203mm diameter

Set-up guide: how to set up your Rocket Gen2

The basics

The suspension on a Cotic droplink bike is designed to work at its best when it sags with the rider on board. Sag is the amount the shock compresses with a rider on the bike. The suspension works best with 25-30% of the available travel as sag, with our preferred starting point being 30%.

The Rocket Gen2 has a 57mm stroke shock, so that means 15-17mm of sag on the shock and 32-40mm of sag on a 160mm fork. As a starting point we suggest the middle of those options: 16mm sag at the rear and 36mm at the front.

Setting your shock sag

Put 170psi in the rear shock. Leave your fork as it is (if you've already set it up), or put in the pressure the fork manufacturer recommends for your weight. Turn off any lockout or climb switch on the shock, so it compresses unhindered and gives an accurate sag measurement.

Put your riding kit on, or at least a fully loaded backpack if you usually ride with one, noting how much water you carry: it's probably the heaviest thing you strap to the bike after yourself. Set the saddle to your full pedalling height, then ride briefly somewhere quiet, bouncing on the saddle a couple of times to get the shock compressing.

Stop somewhere safe, get off, and slide the o-ring on the shock down against the seal. Get back on with the saddle at full height and your legs dangling off the pedals, and check the o-ring is still against the seal. Gently get off without moving the shock (dropping the saddle and using a kerb as a step helps). Measure the distance between the o-ring and the shock body, then adjust the air pressure to get the sag you want.

Setting your fork sag

Once the rear sag is set, check the fork. On a brand new bike, start with 60psi in the fork and set all the compression damping to minimum. We recommend 20-25% sag on forks.

In a quiet area, drop the saddle and ride around slowly, bouncing the fork once or twice to free it up. Sit down and, being careful of the spinning wheel, slide the o-ring on the fork leg down to the seal. Stand up slowly into a balanced attack position as if starting a descent, then move rearward and sit down and roll gently to a halt, braking only very gently so the fork doesn't dive. Get off carefully and measure from the o-ring to the fork seal. For a 170mm fork, aim for around 34-42mm of sag (20-25%).

If the fork sag needs altering, alter it and then re-check the rear sag. Repeat until front and rear are both as you want them, within the manufacturer's recommendations for the frame and fork.

Weight distribution

Every bike's weight distribution is different, depending on saddle position, stem length and bar width among much else. With the correct sag at the rear, your fork may end up with more or less sag than you expect because there's more or less weight on it than on your previous bike. That's why we don't recommend particular pressures: always set up by sag measurement, not by a generic shock pressure.

Setting shock damping

Once front and rear sag are set, adjust the rebound and compression damping to taste. If you specified a Cane Creek DB Air IL, Coil IL or Air CS shock, our base set-up was on the shock when it was delivered. The base tunes have been developed since, so the settings below (all relative to the fully open position) are worth trying.

Cane Creek DB Air IL: 1 x large volume spacer, 0.5 turns high speed compression (HSC), 4 clicks low speed compression (LSC), 1.0 turns high speed rebound (HSR), 2 clicks low speed rebound (LSR).

Cane Creek DB Coil IL: 1.0 turns HSC, 5 clicks LSC, 1.0 turns HSR, 2 clicks LSR. If you have picked up a used Rocket Gen2 with a coil shock, contact us for advice on the spring rate you need. Do not keep adding preload beyond 2 turns: that coil-binds the spring at bottom out and can damage your frame.

Cane Creek DB Air CS Piggyback: 1 x large volume spacer, 0.5 turns HSC, 4 clicks LSC, 1.0 turns HSR, 2 clicks LSR.

The Cane Creek Field Tuning Guide has excellent instructions for fine tuning a Cane Creek shock: download it here. Cotic base settings tend to run on the lively, fast rebound side. That may feel different to what you're used to, but stick with it for a couple of rides before changing anything: light rebound damping lets the rear wheel patter and keeps traction better.

For other shock brands. Rebound: start 3 clicks from fully open. The fastest rebound you can run safely is best for traction and a lively feel. If you're being bounced out of the saddle on big compressions, springing back too hard off drops, or the bike bounces back at you on rocky sections, add rebound damping until it stops. Compression and pedal platform: start with it off, or at minimum. droplink is designed not to need a compression damping circuit for good pedalling, and the minimum setting lets the suspension move under bump forces and track the ground better.

Setting fork damping

As with the shock, run the fork damping as light as possible for best traction.

Rebound. Set it in the middle of the range and see how it feels matched to the shock. Try riding it faster than you normally would: it makes a big difference and keeps the bike in balance. After a couple of rides, if the fork kicks back too much at speed on bumpy trails, add rebound damping. If the middle setting is fine, make it faster until it feels sketchy, then go back one click.

Compression. Almost regardless of size, weight or riding style, everyone at Cotic runs the fork's high speed compression fully open or very close to it, and we suggest you start there. If you use the full travel too easily, add one volume reducer to the air spring rather than ramping up the damping. For low speed compression, start in the middle of the range. If the bike feels confident but is uncomfortable or chattery through your hands, reduce it by 3 clicks. If sag and air spring feel right but the fork dives under heavy braking or in steep terrain, add 3 clicks. Keep refining until you're happy.

A bit of advice

Avoid setting rebound with the "bounce in the street" test. It usually produces rebound that's too slow for good grip on the trail, because rebound fast enough for good performance feels too fast in that unhelpful situation. Only start adjusting once you have a feel on the trail.

We recommend starting at 15mm of shock sag and going for a couple of rides. It's a good middle ground: an active, plush feel with a low bottom bracket for confident handling. If you catch your pedals too often, the steering isn't as quick as you'd like, or you don't have the climbing position you want, add air to the shock and reduce the sag by 1-2mm, or reduce the fork sag by a few millimetres to move your weight forward.

It's well worth a couple of hours doing laps of a trail you know well, changing one thing at a time. Turn one damping dial fully closed for a run, then fully open for the next: you'll learn what big changes do, which helps with the subtle ones afterwards. Take notes before tweaking, and always keep a written base set-up you can go back to: fork travel (if adjustable), air pressures, rebound clicks, and compression clicks if adjustable. If the handling just seems to get worse the more you twiddle, return to your base set-up.

We're always happy to help: drop us a line at info@cotic.co.uk.