Fox Racing Shox, based in Watsonville, California, has issued a notice regarding DIY modifications to its suspension forks:
"It has come to the attention of Fox Racing Shox that certain individuals and/or entities are modifying Fox forks to accommodate mountain bike wheel sizes other than those having a 26-inch nominal diameter. One such modification includes removing material from the lower leg cross bridge in order to fit a 29-inch tyre in the fork. Such modification will ultimately separate the lower fork legs at the cross bridge (i.e. the weakened cross bridge will fracture) and may cause bicycle instability and crash that results in SERIOUS INJURY OR DEATH.
Do not modify or misapply Fox forks
NEVER REMOVE MATERIAL from any portion of a Fox fork. USE ONLY 26-INCH WHEELS with Fox 32*, 36 and 40 bicycle suspension forks. Those Fox forks are designed and tested for use ONLY with 26-inch mountain bike wheels/tyres. Use of Fox forks with any wheel other than 26 inches and/or alteration or modification of any Fox fork will subject the Fox fork to loads and forces it has not been designed or certified to meet and will void all warranties. The Fox 32*, 36 and 40 models meet CEN and ASTM testing standards ONLY when used with 26-inch wheels/tyres and are not recommended or approved by Fox Factory, Inc. for use with wheels larger or smaller than 26 inches, either as original equipment or aftermarket.
Do not ride modified or misapplied Fox forks
Proper forks are critical to proper bicycle handling and stability. Improper function or failure of a bicycle fork while riding can cause a bicycle to become uncontrollable and result in a crash. Use of Fox 32*, 36 or 40 forks with wheels larger or smaller than 26 inches, or any other modification, may cause crashes that result in SERIOUS INJURY OR DEATH. Never ride a bicycle that is, or appears to be, fitted with a Fox 32*, 36 or 40 fork that has been modified and/or fitted with any wheel larger or smaller in nominal diameter than 26 inches.
Use the right fork for the job
For those of you who want to ride on 29-inch front wheels with suspension, Fox offers the 32 F29 fork designed specifically for 29-inch wheels. The F29 is available in 80mm, 100mm or 120mm travel configurations and is ideal for tall wheel applications. The F29 is the only Fox fork available for use with 29 inch wheels and is clearly labeled “F29” on the right leg. The F29 should be used only with 29 inch wheels. As with all Fox forks, do not modify or misapply, or ride on improperly applied or modified Fox F29 forks.
Do not modify any portion of a Fox fork and do not purchase or use any fork that appears to have been modified. Any Fox 32*, 36 or 40 model fork that appears to accommodate a tyre larger than 26 inches in nominal diameter, such as 650B or 29 inch, should be avoided. If any doubt exists as to the originality or proper application of a Fox fork, please contact a Fox representative at www.foxracingshox.com."