Hi Durham -

I did the design work on FR's rack. The important thing to keep in mind is that there is going to be a LOT of tension on those cables. The longer the span between your anchors the larger the tension is going to be. In our system I calculated the anchor hardware and cable ratings, but forgot about the steel frame we were bolting into. The cables have actually deformed that frame in places because of the load from the cables. If you can find a mechanical engineer(ing undergrad) they can figure out the loads and appropriate cable/hardware better than I, but roughly:

• Figure out how much weight you'll but putting on each section of

cable (ie, # of wheels times weight of each wheel)

• Choose a 'maximum drop' that you will allow the cable to hang

downwards in the center of the span (the more this is the lower the tension, but the more space each row takes up)

• Divide span by twice the drop (make sure to use the same units for

the drop and the span, e.g. 6" drop, 48" span = 4), call this value X

• F = SQRT( 1 + X^2 ), where F is your 'force multiplier' - you can

just use F = X if the span is large relative to the drop

• Multiple your total wheel weight by F and divide by 2, this is your

working tension on the cable.

For eg, for 80lbs of wheels on an 8 foot span with 4 inches of drop: X = 80/(2*4) = 10, F ~= 10, Tension = 10 * 80/2 = 400 lbs

So for that setup I'd buy cable and hardware rated at 800lbs or more working tension.

The cable and hardware we used were - you can search for these on mcmaster.com for illustrations or more information:

• wire rope
• eye-bolts (with shoulder)
• wire rope clips and thimbles (the thimbles are VERY IMPORTANT to the

integrity of the system, kinked rope breaks easily)

That's it for the wires and the hardware to hold them in place. We used PVC tube just slightly larger than the cable diameter cut to appropriate lengths as spacers. To hold the wheels we used suicide levers (bend into hooks in a vice).

Hope that helps, I think there are photos on SLC's Wiki.

Stuart

On Nov 9, 2007 10:56 AM, Durham Bike Co-op durhambikecoop@gmail.com wrote:

Hey Free Ride + anyone else who has done something like this: we're also thinking about installing a cable (+ hooks + spacers) kinda thing for wheel storage, as on the "shop organization" part of the wiki. So: I was wondering if there were any suggestions out there about what type of wire is appropriate; what hardware (ends, anchors, assemblies etc.) to use and how to use them. We'll be going into either brick or wood joists to anchor it, depending on how we lay it out. Thanks.

peace, Colin.

-- Durham Bike Co-op 723 N. Mangum St. Durham, NC 27701 www.durhambikecoop.org _______________________________________________ Thethinktank mailing list Thethinktank@lists.bikecollectives.org http://lists.bikecollectives.org/listinfo.cgi/thethinktank-bikecollectives.o...