Description

Bolt Kit – No 29: Complete Guide to BMC Fourstroke Suspension Maintenance, Replacement, and Performance Restoration

If you own a BMC Fourstroke mountain bike and notice your rear suspension feeling notchy, creaky, or less responsive after hundreds of trail miles, it might be time for a full pivot refresh. The Bolt Kit – No 29 is the official OEM solution designed specifically for short-travel Fourstroke models, delivering everything needed to bring your bike’s linkage back to factory-fresh condition.

This comprehensive guide covers everything you need to know about the Bolt Kit – No 29 — from exact compatibility and contents to step-by-step installation tips, maintenance advice, and why genuine BMC parts matter for long-term performance. Whether you’re a weekend XC racer or an aggressive trail rider, keeping your suspension pivots in top shape is essential for smooth, efficient, and reliable riding.

BMC FOURSTROKE CROSS COUNTRY RACE BIKE REVIEW – Mountain Bike Action Magazine

What Is the Bolt Kit – No 29 and Why Does It Matter?

The Bolt Kit – No 29 is a complete spare-parts package from BMC Switzerland engineered for the short-travel (100 mm rear travel) version of their popular Fourstroke platform. It includes every axle, bolt, bearing, washer, and spacer required to completely rebuild the rear suspension linkage internals.

Unlike generic hardware store bolts or third-party bearings that may not match tolerances or materials, this kit uses premium Enduro MAX bearings with black oxide treatment for superior corrosion resistance and longevity. At just 140 grams total weight, it won’t add unnecessary grams to your lightweight XC or trail rig.

Proper suspension pivot maintenance directly impacts bike handling, pedaling efficiency, and frame longevity. Worn bearings introduce play, which stresses the carbon frame over time and reduces small-bump sensitivity — the very thing that makes the Fourstroke such a capable climber and descender.

Compatible Models: Which BMC Fourstroke Bikes Use Bolt Kit – No 29?

This kit is purpose-built for Gen 6 and current-generation short-travel Fourstroke models:

• Fourstroke 01 Gen 6
• Fourstroke R 01 Gen 6
• Fourstroke (standard)
• Fourstroke LT Gen 6 (short-travel configuration)

It is not compatible with older APS suspension designs or long-travel-only variants that use different pivot hardware. Always double-check your frame’s year and travel spec against BMC’s official parts finder before ordering.

The dual-link suspension on these bikes is compact, stiff, and highly tunable — but that precision comes at the cost of needing periodic bearing and bolt service every 500–1000 km depending on riding conditions (mud, sand, and frequent wet rides accelerate wear).

What’s Actually Included in the Bolt Kit – No 29?

BMC doesn’t leave anything to chance. Here’s the exact contents:

• 2 × LL axle spacers
• 4 × Bearing 6900 (Enduro MAX Black Oxide)
• 4 × 21.5 mm washers
• 2 × LL axles
• 2 × 17.5 mm washers
• 3 × M6xP1.0×15 mm screws
• 4 × Bearing F6800
• 2 × Bearing 6800
• 2 × SS screws
• 2 × SS washers
• 1 × UL axle
• 1 × UL axle screw
• 2 × UL washers

Everything is pre-selected for perfect fitment, with torque values often etched directly onto the bolts for easy reference during reassembly.

Signs Your Suspension Needs the Bolt Kit – No 29

Listen and feel for these common symptoms:

• Creaking or clicking from the rear triangle
• Reduced small-bump sensitivity
• Side-to-side play when rocking the bike in the stand
• Notchy or sticky shock movement
• Visible rust or dried grease around pivot points

If you notice any of these after a wet season or heavy use, replacing the entire linkage hardware at once (rather than piecemeal) prevents uneven wear and future headaches.

Benefits of Using the Genuine Bolt Kit – No 29

• Restored plushness: Fresh bearings eliminate stiction for buttery-smooth travel.
• Improved pedaling efficiency: No more power-robbing flex in the linkage.
• Longer frame life: Proper hardware prevents ovalizing of carbon pivot bores.
• Peace of mind: OEM tolerances and materials match the original design exactly.
• Value: At around $149, the kit is far cheaper than a new shock or frame repair down the line.

Step-by-Step Installation Guide for Bolt Kit – No 29

Important disclaimer: Suspension service involves pressing bearings and precise torque settings. If you’re not confident with bike tools, take it to a professional BMC dealer.

Tools you’ll need:

• Torque wrench (accurate to 8 Nm)
• Bearing press or drift set (or a bike-specific pivot tool)
• Rubber mallet
• Degreaser and isopropyl alcohol
• High-quality grease (Enduro or similar)
• Allen keys and sockets matching the bolts

Basic process overview (always refer to your bike’s manual for exact order):

1. Remove rear wheel and shock for access.
2. Loosen and remove old linkage bolts in the correct sequence (usually starting from the main pivot).
3. Carefully press out old bearings (avoid hammering directly on carbon).
4. Clean all bores thoroughly.
5. Press in new bearings from the Bolt Kit – No 29 using proper alignment.
6. Reinstall axles, spacers, and washers exactly as shown in the exploded diagram.
7. Torque everything to spec (typically 8 Nm on most pivots — check etched values).
8. Reinstall shock and wheel, then check for smooth movement with no play.

Pro tip: Take photos before disassembly and label bags for each pivot group. Many riders service their Bolt Kit – No 29 every 12–18 months for race-prep reliability.

Maintenance Tips to Extend the Life of Your New Hardware

• Rinse the bike after every wet or muddy ride.
• Apply light chain lube or suspension grease to exposed pivots monthly.
• Avoid pressure-washing directly into bearing seals.
• Check torque after the first 50 km of riding post-install.
• Store the bike indoors to minimize corrosion.

Where to Buy the Bolt Kit – No 29

The safest place is through authorized BMC dealers or the official BMC website (us.bmc-switzerland.com or regional stores). Genuine kits come with proper packaging and traceability. Avoid unverified third-party sellers offering suspiciously low prices — counterfeit bearings can destroy your frame.

Frequently Asked Questions About Bolt Kit – No 29

Q: How often should I replace the pivots? A: Every 500–1000 km or annually, whichever comes first, for aggressive riders.

Q: Can I mix old and new bearings? A: No — replace the entire set for even performance and to avoid accelerated wear.

Q: Does this kit work on the Fourstroke LT? A: Yes, but only the 100 mm short-travel configuration. Confirm your exact model year.

Q: Is professional installation required? A: Strongly recommended for first-timers to avoid damaging carbon fiber.

Final Thoughts: Keep Your BMC Fourstroke Feeling New

The Bolt Kit – No 29 is more than just a bag of parts — it’s insurance for your investment in one of the best-handling XC/trail bikes on the market. A fresh set of pivots transforms a tired bike into a responsive, efficient machine ready for new adventures.

Whether you’re chasing KOMs, ripping singletrack, or simply enjoying smoother rides, regular use of genuine BMC maintenance kits like this one keeps your Fourstroke performing at its absolute best.

Ready to refresh your suspension? Grab the Bolt Kit – No 29 from an authorized dealer today and enjoy that factory-fresh feel again. Happy riding!