Custom front rack, Surly Cross Check

December 6, 2010

A few months back, before le Distraction Majeure (my wedding), and the subsequent trip out to Montreal, and the subsequent cold snap, I was spending a veritable heap of time in the workshop getting things outfitted, working on some prototype clamp designs for a handlebar support for Tom’s awesome Tauro-brand bike luggage, and generally getting acquainted with my torch setup, trying different brass fillers, and experimenting with different fluxes.

I was also building a custom front rack for Ariella’s Cross-Check. It’s a small-ish rack, measuring approximately 12cm wide x 23cm long across the top deck, and features a mildly ornamental backstay, as well as some pseudo-lugs (externally-sleeved construction joining the left & right halves of the top deck—necessary due to the limitations of my current crappy 5/16″ tubing bender).  It’s designed to sit nice and low to the front tire, both for a clean look and to minimize flex, and attaches to both the mid-fork lowrider mounts, and the fork crown, the latter by way of a stainless flat-tang.

The design of the rack was loosely based on the Nitto Mark’s Rack, but with a larger deck profile, and without the adjustable stays.  The nice thing about a custom rack design, is that it allows you to minimize the extraneous hardware needed to attach the rack to the bike, since the possible mounting scenarios are reduced.  The flip-side of this benefit is that the rack is primarily valuable on the bike it’s designed for, and its utility on other bikes may be somewhat reduced.  This rack splits the difference: the stays are a fixed-length which should work reasonably well on most 700-C wheeled bikes with mid-fork lowrider mounts, since the adjustable upper-tang is bendable to accommodate differences in the distance between the rack’s deck and the fork-crown of the bike.

The backstay of the rack was originally bent-up as a simple inverted ‘U’, but between a brazing error, and the legs of the backstay sitting wider than I liked relative to the rear sleeve, I decided to chop the ‘U’ in half, which brought the legs inwards, and straddle them with a brass-capped cross-piece. The fringe benefit is that you can wrap a bungee around the resultant ‘ears’ of the backstay.

Detail of the front sleeve.  This construction was necessary, since the discount 5/16″ outer-diameter tubing bender that I own is incapable of doing more than 180° of bending in one-direction, due to the fact that the bender’s arms are not offset, and consequently gets in the way of the workpiece.  The bender also has a bit of slip to it, and has no calibration marks on the mandrel, which makes it very difficult to accurately plan and measure compound bends. Watch out for a post looking more closely at the different benders I’ve got in the shop, and what differentiates a decent one from a poor one.

The sleeve was filed to resemble a pointed ‘lug’—I could have internally-sleeved the tubing for a clean, flush look that would be invisible after painting, but I didn’t have any 1/4″ tubing on-hand, and thought that this would make for a nice detail.

If you look closely at the front sleeve, you can see that the leftover brass on the outside of the sleeve is a different colour than the other braze joints in the rack. This is due to some confusion at the welding supplier; as it turns out, most local welding suppliers don’t deal with a lot of brazing supplies, and those that do are relatively unfamiliar with their stock.  Consequently I ended up with a pound of silicon bronze, rather than low-fuming bronze, the former of which has a liquidus (melting point) about 200° hotter than the latter, which was resulting in all kinds of charred flux and general brazing grief.  Luckily, they took it back and replaced it with the correct filler, which, in conjunction with some flux that the great folks at Gasflux mailed me, is resulting in way cleaner, more controllable joints.  I’ll be writing another post soon comparing a few different fluxes I’ve tried.

One Response to “Custom front rack, Surly Cross Check”

  1. Kilpatrick Says:

    You wouldn’t want to sell this would you? email me if you want to make a deal… Love the blog, btw

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