Suspension school · Tuning by Riding Style

eMTB Trail Setup

The definitive baseline for a 20 to 27kg bike that climbs everything

A full-power eMTB weighs somewhere between 20 and 27kg, roughly half as much again as the unpowered bike it replaced. Setting it up as if it were that lighter bike is the most common mistake we see. The extra mass changes spring rates, damping needs, tyre choice and even which parts of the trail matter most.

Where the Weight Sits, and Why It Matters

The motor hangs at the bottom bracket and the battery lies along the downtube, so almost all of the extra mass is low and central. That is good news for handling, but it loads the rear suspension noticeably harder than the front, and because the weight is sprung mass, the suspension has more to control on every bump. The practical result is that an eMTB needs slightly higher pressures than the charts for an unpowered bike suggest, with the rear needing proportionally more.

The manufacturers agree on the size of the correction. Fox's E-Bike+ setup charts run about 9psi higher on a 38 than the standard chart for the same rider, and RockShox's guidance is simply to add 10psi to the printed fork chart. Treat that as the scale of the adjustment, then confirm with sag rather than trusting any chart blindly.

Baseline Numbers

• Fork sag: 15 to 20% of travel, measured stood up in your riding position
• Shock sag: 25 to 30%, start at about 28% for trail riding
• Fork pressure: your bodyweight chart figure plus 9 to 10psi, then fine-tune to sag
• Low-speed compression: one or two clicks firmer than you would run on an unpowered bike
• Rebound: start with the calculator's suggestion, then adjust on the trail as described below

One convention note before you start counting. This guide counts compression clicks from fully closed, so firmer means fewer clicks out. RockShox Charger 3 and 3.1 dampers are the exception: they count plus and minus around a centre 0, so firmer means a higher plus number. Record whichever your fork uses and stick to it.

Technical Climbing Is Half the Ride

An eMTB will climb things an unpowered bike simply cannot, and most riders end up seeking those climbs out. Steep, rooty, ledgy climbing at 8 to 15km/h is a suspension problem in its own right: the rear shock is your traction device, keeping the tyre pressed into wet roots while the motor delivers torque. A setup judged only on the descent misses half the ride.

• Rear wheel skips and spins over roots: the wheel is not following the ground, open low-speed compression a click and check you have not over-slowed the rebound, a packed-up shock sits deep and skates
• Bike wallows and pedals strike on ledges: sag is too deep, add shock pressure in 5psi steps until it stops
• Front wheel wanders on steep gradients: fix your body position first, slide forward and drop your chest, the fork is nearly topped out on a climb whatever you set
• Leave the compression lever open on technical climbs, the climb switch is for fire roads and tarmac, on a rooty climb it kills the traction you just tuned for

Braking, Dive and the Motor's Mass

Twenty-five kilograms arriving at a corner carries real momentum, and under braking that low-slung mass still transfers forward, so eMTB forks dive harder than the same fork on a lighter bike. Resist fixing this with air pressure, which ruins small-bump feel everywhere else. Add one or two clicks of low-speed compression first, and if you are also using full travel on ordinary drops and holes, fit a volume spacer to add bottom-out resistance without firming the start of the stroke.

Casings Are Part of the Suspension

The tyre casing is the first spring in the system, and at eMTB weights a light casing folds, squirms and punctures. Sensible minimums for a full-power trail bike: Maxxis EXO+ with DoubleDown on the rear if your trails are rocky, Schwalbe Super Trail with Super Gravity on the rear for rocks, Specialized GRID Trail with GRID Gravity behind, or Continental's Trail casing with Enduro on the rear. Pure XC casings have no place under a 24kg bike.

• Front: 21 to 23psi for an 80kg rider on an EXO+ or Super Trail class casing
• Rear: 24 to 26psi, the motor and battery load the rear tyre as well as the shock
• Add roughly 1psi front and rear per 10kg of rider weight above 80kg, subtract the same below
• A stiffer casing such as DoubleDown or Super Gravity tolerates 1 to 2psi less for the same rim protection

Set It, Check It, Then Stop Fiddling

Measure sag in the kit you actually ride in, including a pack if you carry one. Change one setting at a time, in single clicks or 3 to 5psi steps, and give each change at least one full descent before judging it. The calculator on this page gets you to a sensible baseline; the last ten per cent only happens on your own trails.

Once it is right, write the numbers down. Air springs lose a few psi over the weeks, dials get knocked in the van, and a recorded baseline turns a mystery handling problem into a two-minute fix.