Monday, September 19, 2016

Custom mounts for Topeak Explorer rack

I have the Topeak Explorer rack on two of my bikes, the Raleigh Olympian and the X-Peria tandem. This rack comes with adjustable steel rails that attach to the upper part of the rack.

These rails are designed to be bent to fit the particular frame on which they are mounted, and can fit nearly any frame, provided there is a set of mount points to attach to. In the case of both the Raleigh and X-Peria tandem, there are no upper eyelets, so in both cases I made my own mounts to attach to other available mount points.

In the case of the Raleigh frame, I used the rear brake mount. The custom mount was made from 1/8" (3.175 mm) aluminum sheet. Because I intended for the mount to be specific to this bike and therefore not adjustable, I cut out the shape I had in mind in paper first to ensure that all of the holes were in the right place. I cut the aluminum to the shape I wanted with a circular saw (a fairly crude tool for this sort of job, but it's what I had available and it cuts the aluminum of that thickness relatively easily). I drilled the holes, and used a sander to smooth all of the edges. Bending the aluminum sheet to the desired shape takes a lot of leverage, so I used the holes to attach the ends of the cut out piece to some long pieces of scrap wood. I was eventually able to get the mount into the shape I wanted, but the aluminum got pretty scratched up in the process, so I did some more sanding on the finished product to remove all of the scratches, leaving it with a brushed look.

Here's the whole rack, held perfectly level by the custom mount.

The X-Peria tandem does not have dedicated upper rack mounts, nor does it have a caliper brake mount in the rear, since it is a disc brake frame. As I noted in my original blog about the tandem, there is a seatstay bridge where one would expect a caliper brake mount, which has a threaded hole underneath, possibly for mounting a fender. I used the same method and gauge of sheet aluminum to create the fender mount for the X-Peria. Since I happened to have some white paint close to the color of the bike, I painted this one.

The threaded hole on the frame is for an M4 screw (similar to what is used on water bottle mounts), but there is not a lot of clearance, so instead of a standard water bottle bolt (below left), I used an angle head screw (right).

Combined with a hole to match the shape, the screw protrudes only a minimal amount, leaving more tire clearance.

This is what the finished product looks like, installed.

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