Fox 2013 Float CTD BoostValve shock 3After a couple of warranty visits for our 2012 BMC Trailfox test bike’s stock shock, we and Fox came to the realization that the unit on that ex-demo bike was just bad egg that needed replacing.  After talking with the pros at Fox and BMC, we decided to bring the bike up to date with an upgraded Factory series Float CTD model.  Even though clearance issues on the ’12 linkage forced the change to a small-can model, we weren’t expecting big performance improvements from the updated shock.  We were wrong.  Hit the jump to find out more…

Fox 2013 Float CTD BoostValve shock 1For 2013, Fox introduced their Climb-Trail-Descend damping scheme.  Providing largely locked, active-but-firm, and fully open settings, Fox have aligned the distinct compression damping settings with their intended uses.  From the first ride, it was clear that Fox’s latest damper compliments BMC’s Advanced Pivot System well.  To our shorts, it feels as though Fox have managed to do a better job than ever before at separating low- and high-speed compression damping.  This means that any of the three Trail settings can be engaged to control bobbing and limit dive and overtravel without sacrificing high-speed or small-bump compliance.

Further aiding in small-bump activity is Fox’s exclusive use of Kashima Coat.  At the “Factory” level, Float rear shocks get the slick (and sexy) gold coating inside and out.  While bog standard hard anodizing is very durable, creating a ceramic layer on top of the base aluminum, that layer is porous and can actually be rough pretty rough.  In the case of some cookware a hard anodized surface is actually impregnated with Teflon for a combination of durability and easy cleaning.  Taking this concept one step further, Kashima developers Miyaki impregnate the Fox shock’s hard anodized surfaces with lubricating molybdenum disulfide for tough and slick shock surfaces- in this case improving wear while reducing stiction.Fox 2013 Float CTD BoostValve shock 2

Even though it was driven by clearance issues with the ’12 Trailfox linkage, the change for this 140lb rider to a small-can shock was an easy sell.  When considering shock replacement, other small riders should consider the same:  a smaller air chamber at little guys’ and gals’ air pressures makes for a spring curve that is somewhat more progressive than it would be at the same pressures in a larger shock.  This allows for good performance early in the stroke without resulting in excessive bottoming.  As you can see from the photos, every bit of the Trailfox’s 150mm travel is used regularly: the CTD damper and somewhat steeper spring curve just ensure that it’s used when–and only when–it’s needed.

The net result of the change from a ’12 Fox RP23 is a bike that sits a bit higher in its travel when pedaling, better maintains traction while climbing, and is even smoother on descents than the ProPedal shock it replaced.  Big hits are every bit as controlled as before and, as much fun as the descend setting is, the first Trail setting is good enough that the shock stays in a single setting more than ever before.  While the $440 price tag keeps the upgrade from being a no-brainer, it doesn’t seem unfair for a complex product that is made right here in the USA (with parts Kashima Coat-ed in Japan).  Forgoing the slick coating and replacing three Trail setting with one will save nearly a third- making the US-built Evolution Float CTD look like a steal at $310.

If faced with an older or ailing shock, the upgrade to a CTD Float will be noticeable a step forward.  In this case, it has taken everything good about the BMC Trailfox and turned it up a notch.  And that’s an upgrade that’s hard to argue with.



  1. Tim A on


    Care to back that with… anything? Any saddle time on this or other APS bikes? On Giant’s Maestro? It could suck, but your link doesn’t prove anything. A chart without attribution says more about your analysis than the bike.

  2. Dave on


    the article contains all the clues you need:

    “…a couple of warranty visits for our 2012 BMC Trailfox test bike’s stock shock”

    “…we weren’t expecting big performance improvements from the updated shock. We were wrong.”

    “As you can see from the photos, every bit of the Trailfox’s 150mm travel is used regularly.”

    after a shock swap (to a smaller can mind you) the asinine progressive-regressive leverage curve is still blowing through travel regularly, and the author indicates it was worse before (likely the true cause of his warranty needs).

    maestro designs aren’t nearly as regressive at the end of stroke.

  3. Marc Basiliere on

    Dave & Tim,

    We’ve seen these charts (from a Spanish blogger?) for a few review bikes and, based on the Google translations, the author’s ‘analyses’ don’t tend to reflect the reality of the bikes’ rides on the trail. It could be because the charts are based on linkage points traced from images or because the analysis is flawed in some other way- at the very least they fail to take into account the shock tune and haven’t been a particularly good predictor of on-trail performance. In any case, the author seems far too eager to deem bikes unworthy if they don’t fit his/her predetermined notions about what should work- without ever having to go for a ride. It may be a good way to whittle down the number of bikes you’re considering- but using this tool will cause the reader to miss out on some truly great options. Which would be a shame. If at all possible, it really is best to get out on as many demo bikes as possible- or at least to speak with someone who’s ridden the bikes you’re considering.


    I’m afraid that your comment reflects misreading of my writing (which may well be my fault- so I’ll clarify).
    * The warranty visits had to do with actual shock failures- when working properly, the RP23 rode well (which would not be the case were the design inherently flawed).
    * The bike was a favorite before the shock swap- now it’s better. Please see the early review to find my opinion of the stock setup. The BMC Fourstroke FS01, which shares the same basic design is also a fantastic bike (reviews available from myself and numerous other outlets).
    * The shock is using every bit of its travel- not “blowing through” it or bottoming hard. If you’re not using full travel with some regularity, there may be a setup, ‘too much bike,’ or design issue. Using full travel is not a problem- using it unnecessarily is.

    At my weight, most bikes benefit from a smaller can shock. Because air shocks are inherently progressive, a smaller rider going to a smaller can gives them a similar experience to that which a larger rider gets with a larger can. Assuming that a 110lb or 120lb rider would get the intended performance from the same shock as the 160-180lb rider is simply incorrect. There’s a target rider weight for which a bike is designed- other rider sizes will need adjustment to work as intended.


  4. bin judgin on

    I’ve always been of the opinion big riders should ride small air cans to avoid bottoming out easily. The bigger can will allow a smoother spring rate for a lighter rider since the damper won’t be as overwhelmed at a specific tune with a non variable oil weight.

  5. bin judgin on

    I shouldn’t say words in the AM. That reads like s**t. I mean essentially keeping the damper static, it would be overwhelmed by a heavier rider easier, so the small air can allows spring ramp for a heavy rider. Nahimsayin? Tuning is tuning though. People like different feels for their shoxxxxxx


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