Fox Issues Warning Against Use Of Forks For 650B

Fox Racing Shox has issued a warning to those using or considering using their suspension forks for anything other than the 26 inch wheels they were designed for. (This does not include the F-29, obviously) Here is an excerpt from the story as posted on Bicycle Retailer and Industry News:

Use of Fox forks with any tire larger than 26 inches, such as a 650b tire, will subject the Fox fork to loads and forces it has not been designed or certified to meet.

Go here to read the rest.

The problem is stemming from the popularity of Fox forks primarily with the 650B proponents who have found that the larger wheel size will fit in forks manufactured by Fox for 26 inch wheels. As Fox states, “Unauthorized and unapproved use of these forks with tires larger than 26 inches may result (in) accidents, causing serious bodily injury or death.”

Twenty Nine Inches would like to remind our 650B fans that White Brothers does make a 650B specific fork that is approved for use with this wheel size.


No Responses to “Fox Issues Warning Against Use Of Forks For 650B”

  1. efried Says:

    What is their argument for doing so?
    The rim-brakes create less moment on the fork with bigger rims- the rest (higher tire weight) is negligible.

  2. Guitar Ted Says:

    efried: You’ll have to ask Fox for specifics, but since they have not tested the fork with a 650B wheel, the knowledge isn’t there for approval of use with a 650B wheel/tire combination off road.

    Additionally, Fox was warning companies playing with the idea out at Interbike as well.

  3. matt Says:

    I assume the main issue is that the tyre can jam against the bottom of the crown on hard compression, which no one wants.

    I doubt the forces on the fork legs would be the over-riding issue as these things are designed with a good deal of tolerance for extra forces applied on them (crashes, heavy users, hard braking, riding style etc).

  4. BunE Says:

    This is a question of liability. Because FOX could reasonbly be considered aware that their forks maybe used in an un-tested manner, I am sure that counsel suggested this release in order to cover their a$$es.

  5. AC Says:

    I’m sure the bottom line is they haven’t done any QA testing with anything other than a 26″ wheel.

  6. AC Says:

    …after submitting my post, I noticed BunE’s post.

    Yup, I total agree that’s the deal.

  7. Tim Grahl Says:

    I would like to know if they had any particular problems, whether in the real world or in the lab, that caused this release. Seems to me they are covered under the normal “don’t use this in any way other than intended” disclaimer that comes with every mtb product. So I wonder if they’ve seen something actually break under the 27.5 condition.

  8. BunE Says:

    Really, it does not matter whether or not there was a break or an accident. The bottom line is the “reasonable person standard”. It is reasonble that an individual would not see a problem with using a FOX fork, if the wheel in question fit on the fork, spun freely and rolled. Further, a fork is intended for use as a front wheel/tire holder. A jury (remember, of your peers) could reasonably find that the use of 650c size tire/wheel is a perfectly reasonable use of the FOX product.

    By specifically stating that the FOX 26″ forks do not work for 650c sized wheels, they are creating a baseline standard putting the public on notice of what is not reasoable in their opinion. The question will then be, was it enough? Was the release widely dissemnated, Did the manufacturer have some sort of device to protect the user from making the mistake of using a 650c, etc. These are all questions of interpretation.

    The Flip side of this action is now, FOX has acknowledged that some people may be using the fork for 650cs. Will this action be enough to protect them from lawsuits and liability for a product that may not be designed well enough to account for the safety issues that come across from misuse?

    Ahhhhh the law.

  9. Tim Grahl Says:

    BunE, I agree it doesn’t matter from a legal standpoint, but I think it absolutely matters from a “real world” standpoint.

    People do things all the time even though they know it “could” be dangerous and I highly doubt that a press release from Fox saying as much will curtail anyone from actually trying it that was going to anyway.

    But if they do have specific information on 27.5 causing breaks in lab tests or real world incidents then I think it’s important they share that information as well because THAT could stop people from doing it way more than just a cover-your-ass press release.

  10. BunE Says:


    You are absolutely right, but releasing negative results of tests is a strategic issue that many manufacturers struggle with. They are conditioned to worry about profits first, safety later. I think that if there are negative results or examples of real world failure that are out there, FOX could go a long way towards reinforcing their crediblity and creating a marketing opportunity by publicizing things.

    IF there are more nefarious thoughts out at FOX, they could also kill the 27.5er movement with bad press too.

    The press release is not about deterring anyone, its about CYA.

    Who the hell knows. I have multiple 29ers and that is the way I likes it.

  11. Desert9r Says:

    To me, though I am not interested 27.5, its just another reason not to like Fox.

    Here is my take on it-

    Fox issued the statement due to there design, and how it uses the max amount of the stauntion, and how a larger wheel/tire would effect that, I.e. lowering their service from having to rebuild yearly, even lower.
    In turn not loosing future sales

  12. Oderus Says:

    It’s nothing more than a CYA statement. Hell, if anyone read and followed the owners manual that came with their bikes, no of us would ride off road for fear of voiding our warranty.

  13. martini Says:

    One thing not mentioned here, and I would suspect that not very many of us would actually DO it, is the experiement from BRAY on mtbeer. bcd cut out some of the arch so BRAY could run a 36 on his Spyder. A questionable move for sure – but this is mountain biking, and we DO take the risk that comes with the sport. I think FOX saw this a kinda shit thier pants too. If they pay attention to the interweb chatter – they probably know that there are fools out there clamoring for big hit stuff on thier 29″s. Both BRAY and bcd fully acknowledge that as soon as material was cut away, any kind of involvment form FOX is off the books, so to speak. Hell bcd ran his 40 in last season’s DH campaign. Said it held up fine. I’m sure FOX is worried they may see more of these modifications too.

  14. Dirt McGirt Says:

    BRAY sounds like a genius. I always cut integral parts of my bike’s front end out. no matter what. It’s actually become something of principal to me. The best part? You don’t have to brush dentures every day like the real teeth i used to have…. pesky teeth. I’m glad I cut my arch, glad I say!

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