Electric Mountain Bike Maintenance

Electric Mountain Bike Maintenance: Motors, Batteries, Brakes and More

 

 

Key Takeaways
  • Inspect and lube chains frequently as eMTB torque accelerates wear.
  • Flush brakes regularly to prevent overheating on long descents.
  • Monitor tire pressures and wear as wider, softer tires are common.
  • Check connections integrity as motors and electronics are vulnerable.
  • Never high pressure wash motors and avoid submerging components.

 

Proper maintenance is crucial for keeping your electric mountain bike running smoothly and preventing avoidable breakdowns on the trail. Components see considerable stress from the forces and environments involved.

This eMTB maintenance guide will overview best practices for servicing key areas like motors, batteries, drivetrains, brakes, suspension and more. Implementing regular upkeep extends component lifespan and performance.

eMTB Maintenance Overview

Electric mountain bikes have some unique maintenance requirements beyond standard bikes:

  • Motor – Inspection, cleaning, lubrication based on usage hours. Minimal but required.
  • Battery – optimal charging practices maximize longevity. Periodic inspection for damage.
  • Controller – Ensure connections are clean, dry and secure. Update firmware periodically.
  • Drivetrain – Chains, cassettes, cranks wear faster from motor torque. More frequent replacement needed.
  • Brakes – Larger rotors and finned pads help manage heat from added speeds and mass. Maintain for optimal feel.
  • Suspension – Heavier weight distributions and forces require more frequent lower leg and air spring services.
  • Bearings – Hub and pivot bearings see accelerated wear from torque forces and vibration.

While not drastically more intensive overall, eMTB-specific areas do require added attention to keep your ride running strong.

eMTB Motor Maintenance

Motors are quite resilient but do benefit from periodic inspection and care:

  • External cleaning to prevent buildup of grime, which can retain moisture. Avoid high pressure washing directly on motor.
  • Inspect wires and connections integrity. Ensure no frayed wires or corrosion on terminals.
  • Listen for abnormal noises like grinding or whining. Have inspected promptly if any odd sounds develop.
  • Check mount fasteners are torqued to spec periodically. Vibration can loosen bolts over time.
  • Apply dialectic grease on contacts occasionally to prevent corrosion from wet, muddy conditions.
  • Check that cooling vents or fins are unobstructed to prevent overheating.

Motors are designed to be water resistant but not waterproof. Reasonable care and prompt addressing of any abnormal noises or play will ensure a long service life.

eMTB Battery Maintenance and Care

Batteries perform best when:

  • Charged fully after each ride no matter how short. Lithium batteries dislike partial charges.
  • Stored around 60% charge rather than fully charged or empty during off seasons. Removes stress.
  • Kept away from temperature extremes. Don’t leave batteries baking in a hot garage or freezing in the cold.
  • Housed inside a protective case or bag during transport and storage. Prevents punctures.
  • Inspected for any swollen, misshapen cells or damaged connectors and wiring. Immediately discontinue use if issues found.
  • Periodically balance charged to calibrate and equalize individual cell voltages.
  • Allowed to reach room temperature before charging if exposed to extremes. Avoid charging outside manufacturer’s temp limits.

Proper battery care does require some diligence but dramatically extends their lifespan. Adhere to the included guidelines.

eMTB Drivetrain Maintenance

The high torque output of electric motors accelerates wear on drivetrain components:

  • Chains – Monitor with a checker tool regularly. Expect increased stretch from motor force necessitating more frequent replacement. Clean and lube chains very regularly.
  • Cassettes – The added power wears the sprocket teeth faster over time. Replace once hooked shaping is evident.
  • Chainrings – Check for shark fin type shaping on outer chainring teeth indicating replacement time.
  • Derailleurs – Ensure clutches feel crisp and wire tension is properly set as motor forces can knock things out of adjustment over time.

Closely monitoring chain stretch and wearing is key to maximizing drivetrain lifespan. Prompt replacement when worn prevents accelerated cassette and chainring damage.

eMTB Brake Maintenance

Electric bikes allow riding faster and harder. This punishes brakes:

  • Pads – Aggressive eMTB-specific pads better withstand repeated heavy braking. Swap when worn.
  • Rotors – Larger diameters shed heat better. Straighten or replace warped rotors promptly.
  • Fluids – High quality DOT fluid resists overheating fade. Change fluid regularly.
  • Bleeding – Flush old fluid and bleed brakes annually prior to wet months when pad friction falls off. Prevents mushy levers.
  • Cleaning – Brush away external grit around calipers. Don’t blast water directly into calipers.

The sustained speeds and repetition of braking on descents requires keeping eMTB brakes tuned for optimal power and feel. Don’t cut corners.

eMTB Suspension Maintenance

Suspension sees considerable forces from motor output and descending speeds:

  • Seals – Replace dust seals yearly before wet winter riding to prevent dirt ingress leading to damage.
  • Lower legs – Change oil baths in forks and rear shocks more frequently, around every 50 hours, as eMTBs experience more wear.
  • Air springs – Expect reduced air spring lifespan from heavier rider weights and bigger impacts. Rebuild or replace once declining performance noted.
  • Bearings and bushings – The play checks required more frequently, around every 20 hours. Replace worn parts leading to looseness or binding.
  • Fasteners – Don’t overlook basic bolt checks. Loose shock mounts or brake caliper bolts can occur over time.

While robust, suspension needs closer monitoring and servicing intervals halved compared to standard mountain bikes. Keep your fork and shock riding plush.

eMTB Bearing Maintenance

Expect accelerated wear on bearings from the sheer forces of electric assist:

  • Wheel bearings see higher loads, especially the rear hub motor or drive side. Listen for grinding noises indicating imminent failure. Replace annually or sooner if worn.
  • Bottom bracket and pivot bearings experience severe loads from pedaling forces and torque reaction forces. Clean and lube regularly.
  • Headset bearings endure larger compression and tensile forces on head tube area. Loosen and lubricate bearings seasonally.
  • Shock and linkage bearings fail more rapidly from continuous extreme loads. Swap bearings at lower hour thresholds if slop is felt.

Monitoring for play, listening for sounds and proactively replacing high wear bearings prevents major damage to hubs and frame areas over time.

eMTB Troubleshooting Guide

Issues arise. Here are tips on diagnosing common eMTB problems:

Motor cuts out under load – Check connections. With mid-drives, lubricate chain and re-tension optimally. Ensure sensors are tight and free of debris.

Reduced range – If range rapidly diminishes, the battery may be wearing out. Try an external charger to confirm. Replace if <70% of original range.

Display or shifting errors – Rule out connections by unplugging/reconnecting motor, display, and battery to reset system. Check for loose or corroded connectors.

Suspension feels harsh – Replace wiper seals if excess stiction felt. Bleed and lower legs service can restore function. Check air pressures.

Brake squealing and chatter – Equalize pad contact across rotor face. Check rotor true. Lubricate pad backing plates and caliper guides. Consider sintered pads.

Knocking noises – Isolate and identify source. Could be loose motor mount, worn bottom bracket or pivot bearings, damaged rotor, or suspension issue. Inspect systematically.

Pinpointing unusual symptom causes takes patience but pays off. Seek professional assistance whenever needed.

eMTB Winter Riding Precautions

Riding in cold and wet conditions requires additional maintenance vigilance:

  • Clean bike promptly after wet rides to prevent corrosion. Hose salt and grime off.
  • Apply anti-fog treatment to goggles and face shields to maintain visibility.
  • Warm components to room temperature before washing to prevent cracking carbon fiber or composite parts.
  • Thoroughly dry frame, pivots, motor and battery after washing. Moisture causes electrical issues over time.
  • Avoid storing in cold garages or temperatures below freezing – electronics and batteries prefer moderate temps.
  • Lubricate pivot points and derailleur jockey wheels more frequently as wetness washes away grease.
  • Check tire pressures closely. Cold temperatures cause inflation to drop.

While very capable in foul conditions, protecting eMTB components from moisture, salt and temperature swings requires diligence when riding year-round.

eMTB Storage Best Practices

Use care when storing your eMTB long term during an off season:

  • Fully charge battery to optimal voltage for storage as specified by manufacturer. Usually around 60%. Remove from bike and store separately in a protected area if possible.
  • Clean bike thoroughly and lubricate chain to inhibit corrosion during storage downtime.
  • Inflate tires to maximum pressure listed on sidewall to prevent flat spots from sitting.
  • Consider removing and storing high-end seat posts upside down to prevent seizure. Grease exposed dropper post shafts.
  • Spray exposed metal surfaces like rotors with a corrosion inhibitor or light oil to repel moisture.
  • Store indoors in a moderately warm, dry area out of temperature extremes and away from direct sunlight which can fade finishes.

Proper storage practices greatly reduce the refresh service needed before getting your eMTB trail ready at season start.

eMTB Deep Cleaning Guide

Over time, deep grime buildup warrants intensive cleaning:

  • Remove chain, cassette, crankarms, pedals, and other components to access every surface.
  • Use a degreasing agent and stiff brushes to scrub every inch of frame, pivots, chainstays and other regions housing cables.
  • For carbon fiber frames, use dedicated carbon cleaners and gentle scrub brushes to prevent abrasion or damage to the resin.
  • Rinse with water, using a light spray only around bearings and electrical components.
  • Fully dry frame before lubricating pivots, bolts, and reinstalling components.
  • Avoid immersing or pressure washing motors. Clean externally with a damp rag only.

Thorough deep cleaning allows addressing every contaminated region to restore performance and keep your eMTB looking like new for years.

Conclusion

Like any complex vehicle, electric mountain bikes rely on proper routine maintenance to deliver reliable performance and reach their long lifespan potential. Monitor wear on eMTB-specific areas like motors, batteries, drivetrains and brake systems especially closely. Implementing systematic upkeep prevents avoidable breakdowns, extending the enjoyment and lifetime of your e-bike investment. Don’t cut corners.

eMTB Maintenance FAQs

How often should eMTB suspension be serviced?

Every 50 hours ridden or at least annually as the added forces accelerate wear dramatically.

What cleaning agents are safe for eMTB carbon frames?

Dedicated carbon cleaners with ingredients like denatured alcohol, dish soap or citrus degreasers are recommended. Avoid harsh chemicals.

Should an eMTB be lubricated after every ride?

Not comprehensively but do clean and lube the chain after muddy outings to prevent premature wear and corrosion.

Can I high pressure wash an eMTB?

Yes but avoid aiming directly at bearings, motors, electronics or suspension shafts/seals. Use common sense.

How do I know if my eMTB chain needs replacing?

Inspect with a checker tool regularly. Replace once 12+ links measure worn and new chains skip over worn cassette sprockets.

Cleaning eMTB Motors and Electronics

While resilient, motors and electronics still warrant careful cleaning:

  • Use a damp towel to wipe exterior motor surfaces after wet rides. Avoid direct high pressure hose blasts on motor.
  • Periodically remove the battery and blow out the compartment with compressed air to clear any accumulated debris.
  • Inspect wires entering the motor housing for signs of corrosion or cracked insulation. Protect any exposed copper strands.
  • For the controller, gently clean any dirty connectors with isopropyl alcohol and a toothbrush. Prevent moisture ingress.
  • After washing bike, let components fully dry before reconnecting battery and electrical accessories. Residual water leads to gradual damage.
  • Cover external terminals and contacts with dielectric grease annually to prevent moisture corrosion.

Regular inspection and gentle cleaning reduces problems over time. But avoid overzealous pressure washing or immersion. Electronics and motors are water resistant, not waterproof.

Adjusting eMTB Brake Lever Reach

Brake lever reach adjustment accommodates varying hand sizes:

  • Use a 2mm hex key to loosen the reach adjustment screw found by the lever pivot. Not all brake models include reach adjustment.
  • While pulling the brake lever, slide the actuator blade in or out as needed.
  • Tighten lever pivot bolt to 7-9 Nm while holding lever in desired position.
  • Confirm lever does not contact the handlebar when fully pulled. Some clearance should remain.
  • Reach adjustment range is typically 20-30mm. Adjust in small increments for optimum feel.

Properly positioning brake levers reduces hand fatigue and allows covering the levers without overextending your fingers.

Bleeding eMTB Brakes

Brake bleeding removes air bubbles and old fluid:

  • Shimano uses a pressurized bleed method. SRAM and others use a syringe and cup vacuum method. Follow manufacturer procedure.
  • Change pads first if significantly worn. Pistons must fully retract when bleeding.
  • Use fresh DOT fluid only from a sealed container. Don’t remix old fluid.
  • Ensure bleed kit fittings form secure seals. Double check banjo bolt tightness.
  • Take care not to spill fluid on painted surfaces as it will damage finishes.
  • Dispose of old fluid properly. Do not pour down drains.

Bleeding restores power, eliminates spongy feel, and swaps out moisture-contaminated brake fluid. Most systems require annual bleeds.

Removing eMTB Fork Lowers

Removing fork lowers allows servicing oil baths:

  • Secure front wheel off the ground. Release pinch bolts and detach brake caliper.
  • Loosen top caps. Holding legs firmly, loosen bottom bolts gradually to allow controlled spring release as compression dampers decompress.
  • Slide lowers downward, draining old oil/emulsion fluid. Inspect bushings, scrapers and foam rings. Replace as needed.
  • Thoroughly clean lowers internals with suspension cleaner spray and rag. Avoid contamination entering damper tubes.
  • Reinstall new wiper seals dry on upper tubes. Lubricate bushings and foam rings lightly with suspension oil.

Periodic lower service reduces binding and restores plushness as old fluid breaks down. Follow manufacturer service intervals, around every 50 hours on eMTBs.

Applying Frame Protection Film

Frame protection film guards against rock chips and trail damage:

  • Thoroughly clean frame with isopropyl alcohol where film will be applied. Any remaining grease or grime prevents adhesion.
  • For precut kits, check fitment and alignment before removing backing. Realign as needed.
  • Use a squeegee, plastic card or your fingers to remove bubbles and ensure film adheres fully, especially at edges. Take care around contours.
  • Use a hair dryer on low setting to heat film and further conform it around complex shapes. Be cautious with carbon frames.
  • Avoid overstretching or creasing protection film. Small folds lead to premature peeling and require reapplication.
  • Trim any excess using a sharp razor blade. Don’t stretch film tighter than necessary.

Patience during install prevents bubbles, lifts and creases that lead to premature film failure. Maintenance will still be required as chips penetrate.

eMTB Tire Insert Installation

Tire inserts provide added puncture protection:

  • Ensure your rim and tire combination provides adequate clearance for insert width. Inserts add volume.
  • Deflate tire fully. Break the bead seal on one side. Remove tube or sealant if tubeless. Use tire levers carefully.
  • Insert the liner working it around the rim bead and into the tire cavity. Feed the liner’s stem through rim valve hole.
  • Reseal tire bead. Inflate slowly while pushing liner into tire center until it seats. Add sealant if tubeless.
  • The liner may make noise while seating. Roll bike forward while gently lifting wheel to help it center correctly.
  • Retest insert for proper fit after several rides. Air pressure and use can allow it to shift. Realign if required.

Inserts require matching your rim and tire carefully. But they can nearly eliminate flats from punctures and pinches when sized right.

Boost Hub Spacing Overview

Boost hub spacing widens rear and front hub spacing for eMTB benefits:

Rear – Increases from 135mm to 148mm. Enables stiffer wheel builds to handle torque. Provides more tire clearance.

Front – Widens from 100 to 110mm. Permits use of shorter, stiffer fork offset. Also allows more mud room.

Chainline – Wider hubs move cassette outboard, centered better with chainrings to reduce interference.

Compatibility – Boost bikes still accept standard 135/100mm wheelsets. But some wider hub frames won’t take non-Boost wheels.

While not universally adopted, Boost continues gaining support from manufacturers. The stiffness and spacing advantages optimize eMTB handling and power transfer.

Bottom Bracket Standards

Several bottom bracket types see use on eMTBs:

Threaded – Traditional screw-in BSA threaded shells remain common. Simple, widely compatible, and durable.

Press-Fit – Pressed into frame rather than threaded. Can creak if tolerances loose over time.

BB30 – Larger diameter 30mm spindle provides more direct crank arm fit. Reduces weight.

PF30 – Combination of press-fit and wider BB30 standard. Used on many full suspension eMTBs.

Dub – SRAM’s wider press-fit design allows bigger spindle bearings. Increased stiffness.

No standard eliminates creaking entirely. Threaded remains simplest. Press-fit offers a compromise between stiffness and installation ease.

Wheel Truing and Tensioning

A truing stand lets you address wheel wobbles and get wheels perfectly round:

  • Mount wheel and give it a spin, using a zip tie on the fork to check for rubs. Mark high spots with a marker.
  • Tighten spokes on the same side as rub marks in small increments using a spoke wrench. This pulls that section of the rim into alignment.
  • Always turn nipples equally on both sides to retain rim centering while eliminating wobbles.
  • Pluck spokes. A musical note indicates proper tension. Dead thuds mean overly loose spokes requiring tightening.
  • Check dish and roundness periodically as you make adjustments. Minor tweaks restore straightness without overtensioning.

Perfectly round, tensioned wheels roll faster and withstand eMTB forces without failing. Truing is a learnable skill. Invest in a spoke tension meter for precise builds.

Torque Wrench Use Essentials

Properly torquing fasteners prevents component damage:

  • Use manufacturer’s recommended torque specs for each fastener. Do not guess.
  • Ensure you are using a Newton meter (Nm) torque wrench suited to the specified range. Do not substitute other units.
  • Choose appropriate bit size for maximum engagement in fastener heads. Avoid worn Allen keys.
  • Keep wrench properly calibrated. Test periodically against verification beams.
  • Let electric wrenches come to complete stop before reading torque value. Don’t round up.
  • For carbon parts, use lower torque limits specified and tighten gradually. Prevent crushing.

Incorrect torque leads to loose parts or stripped threads. But over-tightening can crack frames or break bolts. Confirm specs and tool calibration.

Shimano Di2 eMTB Drivetrain Overview

Di2 uses electronic actuation shifting without cables:

  • Wires connect switches, derailleurs and battery for instant precision shifts.
  • Multiple auto trim positions adjust chain gap as you shift. Reduces rub.
  • Programmable multi-shift enables shifting across entire cassette in one press.
  • Extremely low maintenance and adjustment over time compared to cables.
  • Higher purchase cost but with long-term reliability benefits for frequent muddy eMTB use.
  • Requires keeping internal battery charged but lasts several hundred hours before needing a recharge.

If eMTB budget allows, Di2 shifting provides incredible speed, precision and durability. The long-term reliability offsets initial cost over time.

Headset Overhaul

A loose or damaged headset impedes handling:

  • Fully loosen stem to remove fork. Slide off frame. Clean thoroughly.
  • Use headset wrench to unthread locknut and loosen top cap. Slide cups out checking for pitting or cracks.
  • Apply fresh grease to cup interfaces. Do not grease bearing/race interfaces.
  • Reinstall cups gently tapping any that fit tightly. Confirm no binding turning fork.
  • Adjust crown race gap per manufacturer spec. Snug locknut. Tighten top cap to settle bearings. Reinstall stem and align bars.

Annual cleaning, inspection and adjustment of headset bearings ensures optimal steering precision and safe handling. Loose headsets wear quickly.

Stripped Suspension Bolt Removal

Rusted or overtightened suspension bolts can be extracted:

  • For steel bolts, apply penetrating oil and heat the area with a torch to expand the metal. Attempt to turn with a correct-size wrench.
  • Use a Dremel to cut a notch across the bolt head and use a large flathead screwdriver to back it out.
  • Drill into the center of the fastener with a bit sized slightly smaller than the core diameter. The bit will grab as you reverse direction, backing the bolt out.
  • As a last resort, a bolt extractor set uses left-hand threads to bite and back out even deeply stuck bolts.

With heat, lubrication, notching and drilling, badly mangled fasteners can be removed to avoid further damage to threads.

Derailleur Hanger Straightening

A bent hanger alters shifting:

  • Remove rear wheel and derailleur. Clamp hanger lightly in a vise wrapped in thick leather or wood.
  • Use calipers to measure deviation from flat on the sides of knuckle. Gently tweak with controlled force to realign.
  • Test by installing derailleur and shifting through all gears. Bend slightly to fine tune if needed.
  • Consider replacing hangers showing cracks or threads damage from repeated bending rather than re-straightening again.

A precision hanger gauge tool can also quantify misalignment numerically to adjust back to spec. But use care – hangers fatigue with repeated bends.

Bleeding eMTB Brakes

Brake bleeding removes air bubbles and old fluid:

  • Shimano uses a pressurized bleed method. SRAM and others use a syringe and cup vacuum method. Follow manufacturer procedure.
  • Change pads first if significantly worn. Pistons must fully retract when bleeding.
  • Use fresh DOT fluid only from a sealed container. Don’t remix old fluid.
  • Ensure bleed kit fittings form secure seals. Double check banjo bolt tightness.
  • Take care not to spill fluid on painted surfaces as it will damage finishes.
  • Dispose of old fluid properly. Do not pour down drains.

Bleeding restores power, eliminates spongy feel, and swaps out moisture-contaminated brake fluid. Most systems require annual bleeds.

Conclusion

Proper eMTB maintenance requires close monitoring of components like motors, batteries, suspension and brakes that experience considerable stress from the forces involved. But basic mechanical competency and following prescribed service intervals will keep your electric mountain bike running reliably for years. Take care of your bike and it will take care of you when riding remote backcountry!