Gearing is one of the simplest, highest‑impact changes you can make to your bike. This guide focuses on 300 2‑strokes and 350 4‑strokes, so you can choose, fit, and test the right combo for your terrain.

What is Enduro → Hard Enduro Basics →

Quick Picks

  • 300 2‑Stroke (tight/technical): 14×52 or 13×50
  • 300 2‑Stroke (mixed): 14×50 (stock on many bikes)
  • 350 4‑Stroke (technical): 14×50
  • 350 4‑Stroke (mixed/open): 14×48 (common stock)
  • Rule of thumb: -1 front ≈ +3 to +4 rear teeth. Start at stock, then adjust one step.

Enduro Tires: get grip right too → · Deep dive: Hard Enduro Tire Systems

How Gearing Works (Fast)

Gearing ratio = rear teeth ÷ front teeth. Higher ratio = lower gearing (more torque, lower top speed). Lower ratio = taller gearing (more top speed, less snap at low RPM).

  • Lower gearing (bigger rear or smaller front): Better control on steep, rocky, muddy and slow terrain. Perfect for hard enduro.
  • Higher gearing (smaller rear or bigger front): Better for fast, open trails and sand; requires more clutch at low speed.

Step‑by‑Step: Choose Your Ratio

1. Define your terrain

  • Mostly technical/slow? Aim lower (e.g., 3.70–4.00).
  • Mostly open/fast? Aim higher (e.g., 3.40–3.60).

2. Start from stock

Stock gearing from the makers' 2027 owner's manuals:

  • KTM 300 XC-W: 14×50 (3.57).
  • KTM 300 EXC, EU models: 14×42 (3.00).
  • KTM 350 EXC-F: 14×48 (3.43).
  • Husqvarna FE 350: 14×46 (3.29). The FE 350 Pro: 14×52 (3.71).

Check your own manual. Stock gearing varies by model and market.

3. Make one change at a time

  • Try +2 rear teeth or -1 front tooth; test the same loop.

4. Check chain length and clearance

  • After a change, check the axle still sits inside the adjuster range. The chain section below explains why.

5. Test, then fine‑tune

  • Evaluate clutch use, stall risk, climb control, and cruising RPM.

Pro tip: Carry a spare 13T countershaft sprocket. It’s cheap and quick to swap. On a 48–52 rear, one less front tooth equals about 3.7 to 4 more rear teeth.

Proven Setups by Bike Type

These are starting points. Ratio = rear teeth ÷ front teeth.

300cc 2‑Strokes

  • 14×50 (3.57): Excellent all‑rounder for mixed enduro.
  • 14×52 (3.71): Hard enduro and slow, technical terrain; improved lugging and control.
  • 13×50 (3.85): Maximum low‑end for very steep/rocky; watch chain slider wear.

Explore 2-stroke bikes →

350cc 4‑Strokes

  • 14×48 (3.43): Stock on the 2027 KTM 350 EXC-F. Balanced for mixed terrain.
  • 14×50 (3.57): Adds technical control and tractability without killing cruise speed.
  • 13×48 (3.69): Strong low‑end feel; mind chain slider wear vs. a rear‑only change.

Explore 4-stroke bikes →

Related: If you’re choosing a 300 2‑stroke for hard enduro, read the Buyer’s Guide for platform differences and recommendations.

Ratio Benchmarks and Use‑Cases

Front Rear Ratio Best Use
13 46 3.54 Open terrain, faster flow
13 49 3.77 Mixed terrain, more punch
13 50 3.85 Technical climbs, hard enduro torque
13 52 4.00 Very steep/slow, maximum control
14 48 3.43 Versatile, trail + liaison
14 50 3.57 Technical trails, strong lugging
14 52 3.71 Hard enduro focus, low‑speed precision

Remember: -1T on the front ≈ +3–4T on the rear. For example, 13×48 (3.69) sits close to 14×52 (3.71).

Chain Length, Fitment and Wear

  • Chain length: A bigger rear sprocket needs more chain. A smaller front needs slightly less. KTM's 2027 manual says: "The wide adjustment range of the chain adjusters enables different secondary ratios with the same chain length." After a big change, check the axle is still inside the adjuster range before riding.
  • Slider wear: A 13T front can wear the chain slider faster. If you can, add rear teeth instead.
  • Alignment and tension: After changing sprockets, set correct slack and verify alignment to protect the swingarm, guide, and bearings.
  • Replace as a set: KTM's 2027 manual says: "Always replace the front sprocket, rear sprocket, and chain together."

2‑Stroke vs 4‑Stroke Gearing Feel

  • 2‑Strokes: Snappy, benefit from slightly lower gearing to keep the motor in the meat without excess clutch.
  • 4‑Strokes: Broader torque, tolerate a wider range of ratios; engine braking helps on descents.

Skill support: gearing works best when your controls are calm. Sharpen throttle control, clutch control, and rear brake control in the Hard Enduro Training Plan.

Testing Protocol (10‑Minute Loop)

KTM's 2027 manual links gearing and heat. For slow riding or hot weather, it says to adjust the gearing. The engine oil gets hot if you use the clutch a lot because of "an excessively high secondary transmission". KTM means gearing that is too tall for the terrain, so the fix is lower gearing: a bigger rear or smaller front sprocket.

  1. Warm up, then ride a short loop with climbs, slow turns, and a brief fast section.
  2. Note clutch use, stall risk, and lugging at low RPM. Aim to reduce clutch work.
  3. On the fast section, check comfortable cruise RPM and noise levels.
  4. If you’re slipping the clutch a lot in the slow bits, go lower. If you’re revving out on the fast bits, go taller.

FAQs

  • Do I change the front or rear first? If you need a big change fast, swap the front (cheap, quick). For fine‑tuning and longevity, add teeth to the rear.

  • Will 13T chew my slider? It can increase wear. Inspect the slider regularly.

  • What about sand/desert gearing? On fast sand, go taller (e.g., 14×48) to keep revs down. If you crawl through soft sand and slip the clutch a lot, gear lower instead (see KTM's heat advice above). Pair with the right tire/mousse setup; see Enduro Tires.

  • Best spare to carry for races? A 13T countershaft sprocket in your kit and a few extra chain links in the van.