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RockShoxSID SL Ultimate TwistLoc 29in Boost Fork


Item # RSXB04X

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  • Gloss Black, 100mm, 44 Offset ($886.00)
  • Gloss Blue, 100mm, 44 Offset ($886.00)
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Item # RSXB04X

Why We Like The SID SL Ultimate TwistLoc 29in Boost Fork

When all that matters is getting to the finish line as quickly and efficiently as possible we ride with the RockShox SID SL Ultimate TwistLoc 29in Boost Fork. This ultra-light cross-country-specific fork can mount a TwistLock system that quickly locks and unlocks our suspension on race day. The ultralight package comes with 100mm of travel supported by the proven Charger Race Day damper and DebonAir air spring.

  • RockShox's cross-country specific fork for performance during 90min races
  • Aluminum uppers resist flex while magnesium lowers shave weight
  • Superlight design sheds grams by only being offered in 100mm
  • Charger Race Day damper is race proven and ready for big hits
  • 32mm stanchions shed grams all while staying composed
  • 110mm boost axle spacing fits most modern mountain bike wheels

Tech Specs
Stanchion MaterialFast Black-coated straight wall aluminum
Lower Materialmagnesium
Crown Materialforged, hollow 7050 aluminum
Wheel Size29in
Steer Tube Diameter1-1/8 - 1-1/2in tapered
Stanchion Diameter32mm
Axle To Crown506mm
Spring TypeDebonAir
DamperCharger Race Day
Adjustabilityexternal rebound, 2-position remote compression (Open/Lock)
Axle15 x 110mm Boost
Brake Compatibilitypost-mount disc
Rotor Compatibility160 - 200mm
Manufacturer Warranty2 years
Activitymountain biking, cross-country

What do you think about this product?


>Rating: 5


I've put it through the wringer
True to size
Size Bought
120MM Blue

I had the opportunity to swap out my Fox 34SC for the SID Ultimate for about 2 months, and about 300 miles later I can confirm that the SID Ultimate takes the title as the best fork for Down Country, or Even XC Racing if you want a little extra cushion and a stiffer feel. The fork climbs well unlocked, which is something I had to force myself to try climbing with the fork opened up, as I usually lock my fork out on the slightest climbs. I didn't really notice any bouncing when climbing which is what I find on the Fox 34. I did lockout the fork on some steeper climbs which required out of the saddle efforts, (even taking a PR on a climb in Park City, I cant 100% say it was the fork. But i like to think it was) The SID Ultimate Handles small bumps better than the Fox 34SC, The SID also comes in at a lighter weight by about 120 grams and packs a bigger punch. The fork Locks out stiff and climbs like a beast. I Rode everything from Park City Loam, to St George Rocks and Sand. To Desert Torrential downpour rain/snow. This fork performs in all conditions, and I found was able to handle lower temperatures better than my Fox 34 I have also taken some serious hits on the fork, Not once bottoming out the fork, it's very progressive in its travel, while still feeling smooth and grounded. My front wheel would hold hardpack berms, and loose washed-out corners better than the fox 34. I Plan on swapping my forks for the near and immediate future over to the SID Ultimate. I am 100% sold. ---SHORT SUMMARY-- Stiff, Fast, Light, Reliable, Fun, Confident. The photo below sums up this fork perfectly, It's a Riot.