Rack upright size
True 3x3 in rack uprights: size, holes and pulley mounts
What a true 3x3 in upright measures, how it differs from metric 75 mm "3x3", the hole sizes makers name, and which pulley mounts list or exclude it.
Also listed as true 3x3, 3x3 rack, 3 x 3 in tubing
Short answer
A true 3x3 in upright is 3 in per side, or 76.2 mm calculated from 25.4 mm per inch. Valor's RG-26 and Surplus Strength's UPS Low list 3x3 fits with stated hole sizes, while Fringe's Sidewing Bottom Pulley does not fit true 3x3. Fit depends on the maker's named racks and hole size, not the 3x3 label alone.
Key facts
- Nominal size
- 3 x 3 in (true 3x3)[1]
- Calculated metric size
- 76.2 mm per side, calculated from 25.4 mm per inch[2]
- Often confused with
- Metric "3x3" tubing of about 75 mm (2.95 in) per side[1]
- Hole sizes makers list
- 1/2 in (Valor's 3x3 rigs, per the RG-26 hardware); 1 in or 5/8 in (Surplus Strength UPS Low)[3][4]
- Pulley mounts listing this size
- Valor RG-26 (Valor 3x3 rigs, BD-58, BD-57); Surplus Strength UPS Low (3x3 or 2x3 lower crossmembers at least 6.75 in tall)[3][4]
- Mounts that exclude it
- Fringe Sport Sidewing Bottom Pulley (does not fit true 3x3)[1]
- How to check yours
- Measure the outside width of one upright; Fringe gives true 3x3 as 3 in and metric 3x3 as about 75 mm (2.95 in)[1]
- Not confirmed
- REP's 4000 vs 5000 guide gives hole sizes but not the uprights' metric size; Rogue and REP list named racks for their mounts rather than an upright size[5]
Watch out for
- A metric "3x3" of about 75 mm is roughly 1.2 mm smaller per side than a true 3 in upright, and Fringe's Sidewing fits only the metric size.
- Valor's RG-26 bolts are designed for 1/2 in holes; Valor publishes no fit for 5/8 in or 1 in holes.
- Hole size decides fit as much as the label: REP says its 4000 Series uses 5/8 in pinholes and its 5000 Series 1 in.
Some mounts list named racks instead of an upright size. Rogue lists the Monster Slinger for Monster Rack 2.0 models with two 1 in bolt assemblies, and the Monster Lite Slinger for named Monster Lite racks with two 5/8 in bolt assemblies. REP lists the Ares 2.0 for the PR-4000 and PR-5000 only. Check those pages for the exact racks.
Questions
Will a pulley sold for 3x3 fit my 75 mm rack?
Only if its maker says so. Fringe Sport gives metric 3x3 as about 75 mm (2.95 in) and true 3x3 as 3 in, and its Sidewing fits only the metric size; see 75 mm uprights.[1]
Which hole sizes do 3x3 pulley mounts list?
Valor designs the RG-26 bolts for 1/2 in holes on its 3x3 rigs, and Surplus Strength lists 1 in or 5/8 in holes for the UPS Low. REP says its 4000 Series racks use 5/8 in pinholes and its 5000 Series 1 in.[3][4][5]
Does Fringe's Sidewing Bottom Pulley fit true 3x3?
No. Fringe Sport says it fits metric 75 x 75 mm tubing sold as 3x3 but will not fit true 3x3 racks.[1]