31.8 mm Front Derailleur Style Chain Keeper

prusaprinters

<p>This keeps your chain from falling off a single ring setup.</p> <p>There are various STLs which documented the cage profile before I trimmed off the extraneous lines, which I kept in case I want to tweak the profile later.</p> <p>I never use the 52/53 tooth ring for standard road doubles, &amp; I can't fit a 28 mm rear tire in my road bike because of the front derailleur clamp, so I thought I'd go to 1x &amp; get rid of the front derailleur. I don't have a narrow-wide chainring or a clutch rear derailleur, so I'll need one of these to prevent the chain from falling off.</p> <p>There's a Driveside SLDPRT/STL which is literally just a pole. Hopefully with this close enough of the top, the chain can't even achieve the height necessary to fall off.</p> <h3>How I Designed This</h3> <p>Designed for a 38 tooth SRAM Apex 10 speed ring, which is approximately 160 mm in diameter.</p> <p>Measuring from the center of my seat tube to the middle of the largest ring (double crankset, so the 1x ring will default to the furthest outboard position), I got 49.50 mm.</p> <p>I measured the distance between the plates on a Shimano Claris FD-2400 to be 13.44 mm, then I scaled that by 1.25 to get a wide width that could accommodate cross chaining to the big cog.</p> <p>Designed around a 1.2 mm high, 4.85 mm wide zip tie.</p> <p>For 31.8 mm seat tubes.</p> <p>These measurements might make the STL useless to you, but you could always just edit the STLs if you want.</p> <h3>Assembly &amp; Materials</h3> <p>Print a non-driveside piece &amp; the driveside variation of your choice. Clamp around your seat tube &amp; zip tie them together.</p> <h3>Updates</h3> <p>Never tested yet. Hopefully it's stiff/strong enough to resist deflection from the chain. I didn't close the rear end of the cage because I thought I'd be unnecessary.</p> Category: Replacement Parts