Knock Block: Frame Defense
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Knock Block: Frame Defense

October 28, 2019


Ever notice how full suspension mountain bikes have a curve in the downtube by the fork? This design is to ensure the fork never impacts the downtube, but it also negatively affects the downtube stiffness. A straight down tube, on the other hand, produces a stiffer frame with the best strength-to-weight ratio. This means you get a better riding bike without any weight penalty. Trek Engineers developed Knock Block to remove the design constraint caused by fork clearance, allowing a straight downtube. Knock Block is an integrated, redundant frame protection system so you never have to worry about self-inflicted scuffs, dents, or cracks from spinning handlebars. It’s a system consisting of a special stem, headset topcap, spacer, and chip in the frame. It starts with a “stop chip” in the frame near the headtube. The stop chip limits the turning range of the custom keyed headset cover. The top of the headset cover has notches that lock into corresponding notches on the headset spacers. These also correspond with notches in the stem, for the strongest connection to the steerer tube. Working together, these parts will prevent the fork crown and handlebar controls from hitting the frame. For additional, fail-safe protection, we’ve also added an impact-absorbing rubber down tube bumper. With Knock Block – you get integrated frame defense, allowing Trek to use a straight down tube for a lighter, stiffer frame. The result is a better riding bike that you can push harder with more peace of mind.

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  1. …and now if the can make MAKE more bikes with a straight top tube i would love it!

    ,im a tall guy and my old school trek antelope has the straight top tube that I can use with my thighs giving me more control when im digging in to climb those tough hills ————> sloping top tube bikes look like old school "girl bike" frames (fact)

  2. way to go guys… another trek specific part…. You guys will never get it. Have the name and the pedigree, but when it comes to trail bikes, can't seem to understand, sorry trek keep trying.

  3. If I understand the design correctly, if ever the forks rotate enough to contact the downtube bumper it means that the top tube pin/keyed headset top cap combo has sheared. Now what if any redundancy has been engineered into that side of the equation? That is, are there AL inserts or some such there or will the toptube/headtube junction wind up a mess of shredded carbon?

  4. my question is why can't you adjust the head tube angle and lower the head tube too, then have a taller fork to accommodate for the lost angle of the bikes geometry so that way you wouldn't have to have a special stem or spacers to have the knock block

  5. Hello Trek, my question to you is that you say that straight tube is stiffer and curved tube compromises strength. So my question to you Trek is that why is there a curve to the seat tube? Doesn't that compromise the strength of the seat tube , especially with the load of the rider and the rear load when the rear suspension moves at the point of intersection at the curve in the seat tube ?
    So do you also say that your previous curved design in the frame was bad idea ? Whatever you say about straight tube , just feels like its marketing strategy. Seriously. I was a Trek fan until now.

  6. I planned to buy a Trek EX Fuel 9.8, but because of knock block, I cancelled this project. At a big crash, the knock block can break and you should replace it. I buy Specialized or Santa Cruz instead. Crazy Trek – do some improvements pls.

  7. I'd like to point out these are frustratingly easy to break, i suppose if you don't crash then its fine but everyone goes down once in a while a friend and i both own remedy 8's and we've both broken our knock block in the 6 months we've owned them.. now i have to replace it and not many shops sell them so i have to wait for one to come by post…

  8. This makes it difficult to put sideways in my pickup truck. I need a little more wheel rotation. Was going to buy a Trek until I found this out.

  9. Really keen of buying the Trek Remedy but this knockblock keeps drawing me back. I wish Knockblock is optional or you got some fillers if you want to use traditional stem. I know this will take some time so Ordered the Canyon Spectral instead.

  10. This is really limiting on the higher end bikes. It may sound silly but some of us actually want to whip and even bar spin our trail and enduro bikes. This thing is just unnecessary. Not to mention the extra expense when I want to swap out the stem. I was about to part with my cash on a Trek until I heard about this.

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