Dedicated Subsystem WorkbenchPlatform Gen: 2017–2026

2025 Triumph Bonneville T100 / Street Twin / Speed Twin 900 Tire Sizes, Cold Pressures & Gearing Ratios

OEM tire sizes, front cold PSI (), rear cold PSI (), sprocket teeth count, final drive ratio, and chain pitch for 2025 Triumph Bonneville T100 / Street Twin / Speed Twin 900.

Technical PassportOEM VERIFIED

Engine

900cc

Cooling

Liquid-Cooled

Final Drive

520 Chain

Engine Oil

3.20 L (3.38 US qt)

Spark Plug

NGK LMAR8A-9

Front Tire

100/90-18 (T100) / 100/90-18 (Street Twin)

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Gen 2017–2026

Factory Platform Compatibility: All workshop fluid capacities, maintenance milestones, torque specifications, and consumables on this specification sheet are factory-identical across model years 2017 through 2026.

Select Model Year:(Active: 2025)
10 Production Years (2017–2026)

2017 2018 2019 2020 2021 2022 2023 2024 2025 2026

Suggested Items3 Verified Workshop Consumables Available for this Job

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Tire Engineering & Multi-Scenario Pressure Matrix

ETRTO Validated

Inflation targets calibrated across operating modes, verified rim width ranges, and certified alternate sizes.

Shop Direct-Fit Tires

Multi-Scenario Inflation Pressures

Solo Street / CommutingCold Baseline

Front: Not Available

Rear: Not Available

Two-Up Passenger & LuggageMax Load

Front: Not Available

Rear: Not Available

Off-Highway / Terrain Pressure

Maintain OEM cold baseline for street transfers; adjust -2 to -4 PSI for loose terrain.

Rim Geometry & ETRTO Envelopes

Front Wheel

OEM Rim Width:Not Available

Permissible Envelope:Not Available

Rear Wheel

OEM Rim Width:Not Available

Permissible Envelope:Not Available

Operating outside ETRTO envelope width alters crown radius, accelerates shoulder wear, and impacts lean stability.

Factory Dimensions & Verified Alternates

Factory Standard Sizes

Front:100/90-18 (T100) / 100/90-18 (Street Twin)

Rear:150/70 R17

Shop In-Stock Matched 2-Tire Sets→

Verified Alternate Fitments

Factory standard sizing recommended.

Alternate profiles verified for swingarm, chain guard, and fender clearances.

Final Drive Gearing & Speed/RPM Calculator

Chain Drive

Factory reduction ratios, interactive sprocket gearing simulator, 6th gear cruising RPM matrix, and swingarm chain adjustment tolerances.

Launch Full Gearing Simulator Shop Chains & Sprockets

Factory Pitch / Size

520 Pitch

OEM Sprockets

17T Front / 41T Rear

Factory Final Ratio

2.410 : 1

Factory Link Count

110 Links

Tensile Rating

Not Available

Quick Gearing Presets

Front Countershaft SprocketStock: 17T

17 Teeth

Factory teeth count

Rear Driven SprocketStock: 41T

41 Teeth

Factory teeth count

Drive Ratio & Torque Impact

Calculated Final RatioStock: 2.410

2.412 : 1+0.07%

Drivetrain Torque Delta

+0.1% Rear Wheel Torque Increase

Quicker throttle roll-on response and aggressive low-to-mid range launch. Reduces top speed in each gear proportionally.

Countershaft Speedo Variance:-0.1%

At 70.0 mph indicated speed, true vehicle ground speed is 69.9 mph. Speedo calibrator module recommended.

Cruising Engine RPM in 6th Gear

60 MPH

Stock: 2,985 RPM

2,987 RPM

+2 RPM

70 MPH

Stock: 3,482 RPM

3,485 RPM

+3 RPM

80 MPH

Stock: 3,979 RPM

3,982 RPM

+3 RPM

Calculated using factory 6th gear ratio (0.923), primary reduction (1.681), and 150/70 R17 rolling circumference.

Chain Sizing & Swingarm Slack

Recommended Drive Chain Length:110 Links

Fits within factory swingarm axle slot adjustment range. Retain stock 110 links.

Factory Swingarm Slack Tolerance

Measure slack at midpoint between countershaft and rear axle on the bottom strand with the motorcycle on its side stand unladen.

Master Link Requirement:Not Available

Recommended Hardware: •

Shop Chain Breaker & Rivet Tools Find Direct-Fit Gearing Sets

Factory Chassis Geometry

Chassis Alignment, Drive Tension & Rear Axle Calibration

Precision workshop alignment tools, dynamic drive tension tolerances, and axle spindle calibration for the 2025 Triumph Bonneville T100 / Street Twin / Speed Twin 900.

Factory Swingarm Slack Tolerance

Not Available

Test Condition: Measure midway on lower chain run with bike on side stand (unweighted).

Measured Chain Slack

30 mm

10mm (Too Tight)Factory Window: 25 - 35 mm65mm (Critical Slack)

PASS: IN FACTORY SPEC(30 mm / 1.18 in)

FACTORY TOLERANCE CERTIFIED: Chain tension is in optimal balance. Allows complete swingarm articulation through the entire suspension stroke without countershaft binding or excessive snatch on deceleration.

Precision Alignment

Rear Axle Caliper Alignment

Why mechanics never trust swingarm stamped notches: Factory stamping tolerances can be off by up to 3mm, causing the rear tire to "dog-track" and chew through tire shoulders.

LEFT PIVOT TO AXLE:

215.0 mm

RIGHT PIVOT TO AXLE:

215.0 mm

PERFECT WHEEL ALIGNMENT (PASS)Δ 0.0 mm

Rear axle is square to the swingarm pivot within 0.5mm. Sprocket and chain tracking run in direct true plane.

Wear Limit Diagnostic

21-Pin (20-Pitch) Chain Stretch Test

Pull chain tight and measure distance across 21 consecutive pins with a vernier caliper. Standard new length = 317.5 mm; factory discard limit = 323.0 mm (1.5% stretch).

MEASURED 21-PIN DISTANCE:

317.5 mm

Stretch: +0.0 mm (0.0%)

Remaining Chain Pin/Bushing Life:100% (GOOD)

Three Professional Workshop Alignment Techniques

Method 1 — Swingarm Pivot to Axle Center (The Gold Standard):

Insert a precision rod or vernier caliper measuring from the center dimple of the swingarm pivot bolt to the center dimple of the rear axle on both left and right sides. Both sides must match within 0.5 mm. This mechanically guarantees that the rear axle is perfectly perpendicular to the motorcycle chassis centerline regardless of factory swingarm stamping defects.

Six-Step Workshop Chain Adjustment Protocol

Rear Axle Nut: Not Available - Refer to Factory Workshop ManualAdjuster Locknut: 16 - 22 N·m

1Loosen Axle Spindle Nut

Loosen the rear axle nut 1 to 2 full turns (Not Available - Refer to Factory Workshop Manual). Keep it snug enough so the wheel does not cock sideways freely.

2Back Off Adjuster Locknuts

Back off the jam locknuts on both the left and right adjuster bolts by 2 to 3 turns using a 12mm or 14mm box wrench.

3Turn Adjusters in Small Increments

Turn both adjuster bolts equally. One full 360° turn of an M8 bolt moves the axle by 1.25 mm. Adjust 1/4-turn at a time.

4Kick Tire Firmly Forward

Kick the rear tire firmly toward the front of the motorcycle to ensure the axle blocks are solidly seated against the bolt heads.

5Torque Rear Axle Nut to Spec

Torque the axle spindle nut to exactly Not Available - Refer to Factory Workshop Manual. Always use a calibrated 1/2" torque wrench.

6Crucial Re-Check of Slack

Torquing down the rear axle nut frequently tightens chain slack by 2 to 4 mm! Always re-check slack after full torque is applied.

Official NHTSA Safety Recalls & Technical Bulletins

0 Open Campaigns (Clean)

U.S. Department of Transportation compliance database (Title 49 U.S.C. Chapter 301).

Verify VIN on NHTSA.gov

No Active Federal Safety Recalls Reported

The U.S. DOT National Highway Traffic Safety Administration (NHTSA) records zero open safety recall campaigns for the 2025 Triumph Bonneville T100 / Street Twin / Speed Twin 900 platform. Always check your individual 17-digit VIN at an authorized dealership or via NHTSA.gov for individual recall completions.

OEM Workshop Archives

Official Factory Service Bulletins & Field Updates

2 Documented Bulletins

Bulletin #SRAN-560Safety Recall 19V-133 / SRAN 560: Bonneville T120 / T100 / Street Twin Steering Headstock Tidy & Clutch Cable Routing

Source: RCLRPT-19V133-9239.pdf

Mandated Torques:Headstock Tidy Cable Guide Screws (2x M5): 3 N·m (27 in-lb)Handlebar Upper Riser Clamp Bolts (4x M8): 26 N·m (19.2 lb-ft) (Front bolts tightened first to ZERO GAP)Headlamp Bowl Mounting Bracket Screws: 7 N·m (62 in-lb)Clutch Lever Pivot Bolt: 3 N·m (27 in-lb) / Locknut: 6 N·m (53 in-lb)

Consumable Specs:Coroplast High-Adhesion Anti-Abrasion Textile Harness TapeMolybdenum Disulfide Cable LubricantCorrugated Flame-Retardant Wire Conduit Sheath

Genuine Part Numbers:T2070054 (Countermeasure Headstock Tidy Bracket - Left)T2070055 (Countermeasure Headstock Tidy Bracket - Right)T3010114 (Coroplast Protective Sheath Wrap)T3020058 (Guide Fasteners M5)

NHTSA Recall 19V-133Triumph Campaign SRAN 560

Triumph Bonneville T120 / T100 / Street Twin Steering Headstock Tidy & Clutch Cable Routing

Electrical short-circuit countermeasure: Replacement headstock tidy bracket (T2070054), harness separation, and handlebar clamp sequence (26 N·m).

CLICK ANY ROUTING COMPONENT TO VIEW ANTI-CHAFING BRACKET SPECIFICATIONS AND HANDLEBAR CLAMP TORQUES

Select a component above to inspect headstock tidy replacement hardware, wiring sheath repairs, and handlebar riser clamp sequence.

Bulletin #SRAN-641Safety Recall 24V-785 / SRAN 641: Bonneville T120 / T100 / Speed Twin 900 Alternator to Regulator Connector Thermal Relief

Source: RCLRPT-24V785-3629.pdf

Mandated Torques:Regulator/Rectifier Frame Mounting Screws: 7 N·m (62 in-lb)Left Engine Alternator Cover Bolts: 9 N·m (80 in-lb) (diagonal pattern)Battery Ground Cable Terminal Stud: 4.5 N·m (40 in-lb)

Consumable Specs:DeoxIT High-Conductivity Contact Lubricant & SealantCoroplast High-Temperature Wiring TapeAlternator Cover Gasket (T1260262)

Genuine Part Numbers:T2500412 (Alternator Terminal Wire Alignment Clip Kit)T2500415 (Sealed 3-Pin Alternator Output Connector)T1260262 (Alternator Casing Gasket)