Ben's Burly 3-Bolt Cage Mount For MTB Suspension Forks

Add a bottle cage or bikepacking bag cage mount to your 43mm diameter suspension fork leg; attach using pipe clamps
5h 28m
2× print file
0.20 mm
0.40 mm
62.00 g
15
62
0
1232
updated January 30, 2022

Description

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The goal of this design was to make a 3-bolt water bottle/bikepacking cage mount that could be secured to the 43mm diameter lower tubes of my mountain bikes' suspension forks. I wanted it to be a very secure fit, strong, lightweight, low-profile, inexpensive, easy to print, and to also not damage the surface of the fork. I managed to achieve those goals. 

I got the idea for this project from k-Lite's design, which I spotted on a compilation page on Bikepacking.com (maybe mine will be there as well some day). I removed a bunch of material to make it easier to route the brake cable through it, and to contour it to the curve of the clamp. I like the strength and height of heat-set threaded inserts over simple hex nuts, so I went with that option. I went with the screw clamps instead of zip ties for a more secure fit.

A big part of my design is the leg guard rings which sit flush under the main piece to provide a better, more stable fit. They have a small lip on them to help make installation easier, since they will hold it in place on the clamp band. There is a small gap between the parts which gets taken up when everything is tightened down fully, when the plastic gets stretched and bent into place by the clamping force. That took several iterations to get just right. Installation is pretty quick with an electric driver and a hex socket. 

If there's enough interest I may make a lighter two bolt, two clamp option, but of course this one works great with just a water bottle cage, which I tested. It's fairly convenient to grab it down there as well. I recently got the titanium King cages and some bikepacking bags, but I haven't had a chance to test them yet (it's mid-winter here in Minnesota). I'll update this page when I do some more extensive testing with full loads and have some more pictures, but I'm confident the design is strong enough to handle it. Honestly it's probably overkill, based on my yarding on it with some leverage.

 

Parts List:

  • qty. 3 - M5 x 9.5 mm long brass heat-set threaded insert for plastic (https://www.mcmaster.com/94459A180/ or equivalent)
  • qty. 3 - M5 socket head cap screws and washers (length will vary based on what is being mounted. I use 12mm long screws with a couple of washers to mount king cages. You just need to make sure they won't go in too far and push into your fork.)
  • qty. 4 - Ideal Tridon size 28 Stainless Steel Worm Drive Clamp, ½" (12.6mm) band width (I used size 36 and cut them down using tin-snips and a file to fit, to make a 180mm long band. The size 28 would have been ideal, but they weren't available at Home Depot)
  • Black PETG or ASA filament (other colors will work, but black is the most UV resistant)

The soldering iron tip for the threaded inserts is available in a nice set on Amazon, but you should be able to get away with a standard conical soldering iron tip of the right proportions. There are plenty of tutorials out there if you need help with that process, such as this one. I included several images of insertion procedure.

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