It can’t be easy to make a trail bike. You’re forced to settle on one design that should somehow climb like a goat, yet also eat up rough descents with ease. Recent geometry trends have vastly improved rider weight balance and overall handling, but Rocky Mountain’s 2021 Instinct offers solid modern geo and enough adjustability that anyone should be able to tune this bike to their terrain or riding style.

2021 RMB Instinct, side, on trail

*Please note the saddle and rear tire in this photo are not stock parts. All other photos show the complete Carbon 70 build spec.

Rocky Mountain has honed their linkage and frame geometry to make the new Instinct a well-balanced, stable and versatile trail-gobbling machine. I’ve had the Instinct Carbon 70 since the snow melted in B.C., and despite losing a few weeks to a rib injury, I’ve now tested it on many different trails and experimented with its geometry adjustments.

Even without its adjustable geo I’d call the Instinct a solid contender in the ‘one bike for everything’ class, but with the variable chainstay length and Ride 9 chip, the Instinct offers something some bikes don’t – multiple personalities and plenty of opportunity for fine-tuning.

2021 Rocky Mountain Instinct Frame Details:

2021 RMB Instinct, frame closeup

Check out my launch article for complete details on the 2021 Instincts, but here’s some key notes on the new design: The Instinct Carbon 70 features Rocky Mountain’s recently revised Smoothwall carbon frame, offering 140mm of rear travel (with 150mm forks on all models). The XL, large and medium frames roll on 29” wheels, but RMB runs 27.5” wheels on XS frames and smalls get the option of 27.5” or 29”.

The new Instinct’s Smoothlink linkage was redesigned to improve pedalling efficiency and handle rough descents better. The Instinct’s tune is different from RMB’s Altitude enduro bike, prioritizing all day pedaling performance over big hit capabilities. The re-shaped front end tubing and dual bearings at the Instinct’s chainstay/seatstay junction both improve frame stiffness.

2021 RMB Instinct, actual weight

Rocky Mountain keeps their weights well within reason: the medium Instinct Carbon 70 weighed in at 31.81 lbs (with pedals).

Suspension Setup:

2021 RMB Instinct, rear shockWith its revised linkage the new Instinct runs similar air pressures to Rocky Mountain’s Altitude, requiring more psi than the usual ‘body weight’ setup. You’ll have to look at Rocky’s setup chart to find your starting point, but beyond that the Instinct doesn’t require any special tuning. I weigh 145 lbs and I’m running 180psi in the Fox Float DPX2 rear shock. My compression is two clicks from wide open, and I started with the rebound at 11/15 clicks toward the Fast end. I did play around with the rebound on the Instinct, and I’m glad I did… more on that later.

2021 RMB Instinct, fork crown

Upfront I’m running the Fox 36 Fit 4 Performance Elite fork with 70psi (within recommended range) with no tokens. I have the HSC wide open, and +2 clicks of LSC. Rebound is close to the recommended numbers with the LSR at 9/15 and HSR at 8/9. The fork setup seems pretty bang-on, as I’ll generally use about 90% travel but will bottom out on a fast rough run or during a hard G-out.

Geometry:

2021 RMB Instinct, Ride 9 chip

Given this bike’s ‘Trail’ designation, Rocky Mountain did a great job of finding a comfortable, versatile geometry range for the Instinct that keeps up to modern trends –  and is adjustable in two ways. The 2021 Instinct features Rocky Mountain’s Ride 9 chip, which alters the bike’s geometry and shock rate, and a chainstay flip-chip that shortens/lengthens the rear end by 10mm.

2021 RMB Instinct, angle, right

In fully Slack mode (Pos. 1) the Instinct’s reach is 456mm, head angle is 65.1°, seat angle is 76.1°, and the BB has a 43mm drop. In the steepest mode (Pos. 9) reach increases to 468mm, the steering angle steepens to 66.2°, the seat mast tips up to 77.2°, and the BB lifts considerably to a 28mm drop.

The bike’s rear end length and wheelbase only changes by 2mm with the Ride 9 chip, but the 10mm chainstay flip chip lets the rider play with noticeably different Short and Long modes. The shortest rear end setting is 436mm, and the longest is 448mm. Check out RMB’s website to see geometry specs for every Ride 9 chip position.

Ride Impressions:

2021 RMB Instinct, Steve Fisher, long slab

Since we’re on the topic of geometry, I’ll start my ride impressions there. I’m 5’10” and find the medium Instinct 29er very comfortable. The 456mm reach in fully Slack mode feels great, putting me in a centered body position but not stretching my arms out too much to whip the bike around when needed. I conducted most of my test in the Instinct’s slackest Pos. 1, as that suits my steep, rough local trails.

I really like this bike fully slacked out; it offers near-enduro handling (particularly in Long mode). That said, its mid-range travel makes for a very fun bike that will smash through rough trails but won’t let you get lazy about it! I’d say a 65.1° head angle is perfect for this bike – fairly slack but never cumbersome for technical trail riding.

While it contributes to the bike’s stable ride, the Instinct’s BB sits pretty low with the bike slacked out. I was regularly tagging cranks on low-lying obstacles, so you do have to pedal carefully on rougher climbs.

2021 RMB Instinct, Steve Fisher, climbing 1

Even in Pos. 1, the seat mast on the Instinct is steep and puts you in a good position for pedalling. As today’s bikes get better and better with their front-back balance, I find myself staying in the saddle more on climbs, and the Instinct was no exception. Traction on both wheels is very good, and only the steepest uphill pitches required a stand-up effort rather than a slight forward lean.

For my last few rides, I put the Instinct’s Ride 9 chip into Pos. 7. The 464mm reach felt longer right away but I quickly got comfortable with the change. It’s lengthy but not too long, so I still found the steering comfortable on descents. The increased reach definitely shifts you into a great position for powerful pedalling: I was happy with the bike slacked out, but it only climbs better as you steepen the angles. Pos. 7 leaned me just a little bit more forward, and it really emphasized the bike’s climbing prowess.

2021 RMB Instinct, Steve Fisher, climbing, side

The slightly steeper 65.8° head tube angle is noticeable, but I found it helped more on the climbs than hurt on the descents. The steeper and shorter settings (I was in Short mode while testing Pos. 7) make the Instinct whip around switchbacks, yet it’s modern geo keeps the bike a long way from ever feeling twitchy.

The BB lifts to a 34mm drop in Pos. 7, and I did still tag a pedal here and there but definitely less so than with the Instinct slacked out. I certainly didn’t notice a huge loss of stability at high speeds, but lower is definitely better if downhill thrashing is your cup of tea.

My legs are a bit long for my height, but I have no issues with the Instinct’s standover clearance. Up front the stack height (610-619mm) gives the bike a fairly aggressive stance, even in Slack mode.

Short/Long Modes:

2021 RMB Instinct, dropout flip chip

The Instinct is already a very well-balanced bike in short mode. At 436/438mm RMB isn’t offering the stubbiest rear end on the market, but they’ve struck a suitable balance between agility and stability/traction. Climbing traction is already very good, and given its generous reach the Instinct provides that ‘dead between the wheels’ feel across its range of settings. In short mode the Instinct easily handles tight switchbacks, just like you’d expect a trail bike to.

On descents the rear end feels quite fitting for the bike in short mode. The Instinct pops around tight corners pretty well considering its modern dimensions, and it offers good stability from its fairly lengthy wheelbase and low BB (when slacked out).

While flipping the dropout chip makes a noticeable difference, the Instinct doesn’t feel like a whole different beast in long mode. It definitely enjoys a little boost in stability, and it does slow down a bit in the corners, but it doesn’t suddenly become an enduro bike.

2021 RMB Instinct, Steve Fisher, climbing 2

What I find interesting is how much I like the longer rear end for climbing. Again, cornering is a bit slower, yet I haven’t ridden a single switchback that made the bike feel awkwardly long. Where I really appreciate the longer rear end is on steep climbs. With the increased wheelbase, it seems like your body positioning would have to be way off to hamper traction. When a steep climb forces your weight backwards, the rear wheel only seems to gain traction and the front end doesn’t want to lift like it would on older, shorter bikes.

When descending the longer rear end feels great and provides impressive stability at high speeds. The longer chainstays do slow down your turns a bit, but I found only the tightest technical corners required a little extra swing of the hips. On faster flow trails or any kind of berm, I didn’t feel like long mode was slowing me down at all.

With the Instinct, terrain will most likely dictate the rider’s preference for short or long mode. If your home trails aren’t particularly steep or rough, I’d say short mode offers the best all-around geometry for trail rambling. However, if you have some gnarly trails at hand, the Instinct in long mode offers the most stable ride I’ve yet experienced from a mid-travel bike.

Suspension – Climbing:

2021 RMB Instinct, Steve Fisher, climbing 3While I’d gladly say the Instinct is the best pedalling Rocky Mountain I’ve ridden yet, I still prefer to climb with the rear shock in firm mode. RMB’s linkage is initially very active and moves freely to smooth out small bumps, which it does well, but I find using the shock’s firm setting greatly reduces pedal bob. Even in firm mode, traction on technical trails is very good and if you hit something hard, the Fox DPX2 shock will still open up to absorb it.

2021 RMB Instinct, linkage

While the initial stroke is soft the Smoothlink linkage doesn’t wallow under pedalling efforts, using about 50-60% travel on a singletrack climb. I also noticed the Instinct’s stand-up pedalling performance was very good, resisting heavy bobbing under hard efforts (with the shock in firm) and maintaining forward momentum well. If you choose to climb technical trails with the shock in medium or open mode the linkage will keep you floating along at half travel, and you’ll get optimum traction for a small sacrifice in pedalling efficiency.

Most of my test was ridden in the slackest/most progressive Ride 9 chip Pos. 1, but I jumped to Pos. 7 for my last several rides. Moving towards Pos. 9 does make the shock more linear, but while climbing the Instinct’s linkage refused to acknowledge this, keeping me cranking along at roughly half travel.

Descending:

2021 RMB Instinct, angle, left

Given the steep terrain in my area I really wanted to keep the Instinct in its slackest position, but I have had issues with other RMB bikes ramping up too much for me in that setting – I’m a lightweight at 145 lbs. I was pleased to find the Instinct’s linkage felt less progressive than the Altitude, and I had no trouble bottoming out the bike in the slackest Ride 9 chip position. Both bikes come with one spacer in the rear shock, and I regret not pulling it from the Altitude but don’t feel the need with the Instinct.

Now I don’t want to suggest the Instinct is too soft or squishy: There’s still enough mid-stroke support to give the bike RMB’s characteristically lively ride, and it does take a good thump to squeeze all the travel from the rear end.

2021 RMB Instinct, Steve Fisher crashing

*Good thing this was the last photo I wanted! Broke my wrist on this one, so you won’t see any more product reviews from me until fall.

After a few rides I found the rear end quite poppy and decided to dial that back. I slowed down the rebound by 5 clicks and it did what I wanted in an obvious manner – the bike felt much more plowy through chattery rough patches, and much less bouncy. The rear tire was rolling through bumps instead of hopping along on top of them, and I felt a noticeable improvement in traction and handling in rough sections. I added two clicks back (faster) after that lap and the ride is nicely balanced now, sucking up repeated hits nicely but still feeling lively and poppy. I start out with every test bike near or within recommended suspension settings, but I liked the Instinct with a bit less rebound, and will keep that in mind for future RMB reviews.

2021 RMB Instinct, Steve Fisher, steep rock

Anticipating a more linear shock rate, I added 5psi to the Instinct’s rear shock when I moved into Pos. 7. Under impacts I noticed the bike dove a bit deeper into its travel more easily, but only to a point: Even in Pos. 7 the end-stroke ramps up nicely, so the few psi I added left me with nearly equal bottom-out resistance as Pos. 1.

RMB says the Instinct was built with the same stiffness as the Altitude enduro bike, and while the mid-travel Instinct takes a bit more body language to mash through rough terrain, it holds its line pretty well.

Components:

2021 RMB Instinct, Fox 36 forkI was pleased to find the 150mm Fox 36 Fit 4 Performance Elite fork could easily be set up soft enough for my liking. I’ve found other Fox forks hard to bottom out, but even with my air pressure within Fox’s recommended range, I got every millimeter from this one on those harder hits.

2021 RMB Instinct, rim

I’ve now ridden several sets of Race Face’s AR 30 rims without doing any notable damage, but I’m really impressed with them after this test! I thumped a sharp rock really hard on one ride, slashing the Instinct’s rear tire and letting out a cringe-worthy noise, but I can’t even tell where the rim took the impact and it’s still straight as an arrow. Good stuff!

2021 RMB Instinct, drivetrain

As for the Instinct Carbon 70’s XT drivetrain and Trail four-piston brakes, I can sum it up with ‘no complaints’. Shifting is reliable and crisp, and the brakes are on the grabby side but I appreciate their stopping power and can modulate them well enough.

2021 RMB Instinct, bar, brake and grip

The Instinct’s cockpit offers a nice stubby 40mm stem, and while I wouldn’t say no to an 800mm wide bar I’m fine with the 780mm Race Face Turbine R handlebar.  The Ergon GE1 EVO grips are also a nice ergonomic touch.

I’ve had no issues with the crank or BB, and I’m always happy to see good ol’ Maxxis Minion DHF/DHR EXO tires on any bike. Quick note – I don’t think any trail-rated tire would have survived that rock smash I sliced the rear on!

2021 RMB Instinct, seat and postI have not had good experiences with Race Face’s Turbine R dropper posts. The medium Instinct’s 150mm model was, unfortunately, no exception. The posts almost always stick on the first lift fresh out of the shed, and frequently top out below maximum height or stick down while I’m out on the trail. On the positive side, I do find the WTB Volt Race saddle agreeable with my behind.

2021 RMB Instinct, with eagle

The Instinct Carbon 70 retails for $6899. Frame sizes XS/S/M/L/XL are available. The Carbon 70 model is sold in two colorways – Violet Hills/Enter Sandman/Black Dog (as tested) or Ice Ice baby/UD Carbon Matte/Black Dog.

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