Clothesline Review: Specialized Pro SL and Pro RBX bibs

Editor’s note: The Clothesline is new column about clothing, shoes, helmets and other cycling accessories. Perhaps the most personal of gear choices, clothing testing is subjective. Two riders can try the same jersey or helmet and come back with completely different opinions. With that in mind, we will try to get at least two editors sampling a product for a few weeks before reporting back on the fit and features. We hope you find it helpful. If it’s true that no two fingerprints are the same, is it fair to say that no two, um, butts are the same?

By Zack Vestal

Clothesline:  Mesh side panels on the Specialized Pro SL shorts add ventilation.

Clothesline: Mesh side panels on the Specialized Pro SL shorts add ventilation.

Photo: Robbie Stout

Editor’s note: The Clothesline is new column about clothing, shoes, helmets and other cycling accessories. Perhaps the most personal of gear choices, clothing testing is subjective. Two riders can try the same jersey or helmet and come back with completely different opinions. With that in mind, we will try to get at least two editors sampling a product for a few weeks before reporting back on the fit and features. We hope you find it helpful.

If it’s true that no two fingerprints are the same, is it fair to say that no two, um, butts are the same?

To suit a broad range of riders, Specialized offers two top-of-the-line bib shorts, each with a distinct personality. The BG Pro SL ($165) and Pro RBX ($170) each feature Body Geometry chamois pads, designed with help from Dr. Roger Minkow. However, the SL and RBX pads are different, as is the construction of each bib.

Clothesline: The RBX short is built to be more substantial, with more padding in the chamois and more traditional construction.

Clothesline: The RBX short is built to be more substantial, with more padding in the chamois and more traditional construction.

Photo: courtesy

On the shelf

The RBX pad and short are more substantial, with a thicker pad than the SL. Features on the BG Pro RBX bib short include:

  • Robust, slightly compressive construction for support and durability
  • Waffle-patterned Fieldsensor fabric for moisture transport and breathability
  • Stretch mesh upper material with narrow bib straps
  • The BG Pro RBX chamois, a seamless, triple-density pad with maximum padding under the sit bones, a center channel, and perforations for flexibility
  • Silicone leg gripper

The SL pad and short are lighter and sleeker; differences include:

Construction is minimalist and sculpted

  • A revised, lighter Fieldsensor material is thinner and more hydrophobic yarn for faster wicking
  • Stretch mesh material in upper is used extensively, no binding at the edges, and is added to leg panels for ventilation and a lighter feel
  • The BG Pro SL dual-density chamois is smaller and more pliable
  • External elastic on leg gripper reduces feel on the body
  • While distinctly different, the shorts share some common elements.

    Clothesline: Overall, the construction on the SL short is more minimalist, with lighter material.

    Clothesline: Overall, the construction on the SL short is more minimalist, with lighter material.

    Photo: Robbie Stout

    Key padding on both chamois pads is put where it’s needed — under the sit bones, instead of farther back like on some other shorts, where it’s often not even in saddle contact.
    Fieldsensor material is used for moisture transport, but in different grades/weights.
    Rather than multiple, small panels sewn together, both use fewer, larger panels of material for fewer seams overall.

    I like the concept of a lighter, more minimalist bib short, especially for short rides on hot days. But I’m also a traditionalist who prefers good support and a substantial feel. So, I was interested in giving both pairs a few months of saddle time and see which won me over.

    In action

    Both bib shorts are very comfortable. If I had to pick one, it would be the RBX, because I like the more robust, compressive fit. Also, the straps on the SL don’t seem to hug my shoulders quite like I am accustomed to. I don’t need a big, thick pad, and the RBX pad feels good without being obtrusive. The legs and butt feel a little more snug, and the straps feel a little more substantial than on the SL.

    But both shorts have worked very well in the month or so that I’ve swapped between them. The Body Geometry chamois pads work well, and the repositioning of the padding is smart. The “diaper” feeling of an oversized, misplaced pad is no fun, and neither short suffered from that syndrome. In the pads, I prefer the SL chamois for its smaller size and more minimalist shaping.

    Generally the shared aspects of the shorts’ construction work well. The yoke at top of the bib straps is positioned well, such that it keeps the straps comfortable. I am used to bibs with more panels of material, and I notice a different feel in the Specialized shorts. The reduction in seams and stitching is nice, but more panels would give a more tailored feel.

    A second opinion

    VeloNews editor in chief Ben Delaney also put in some miles on both pairs of shorts. He found them distinctly different in feel on the body, but similar in performance on the bike. He was most impressed with chamois placement.

    “A few years ago, Matt Pacocha and I did a high-end bib short test in the magazine. I was annoyed at how the chamois in a few pairs was further back than it should have been; the thick part of the pad was not under the sit bones,” Delaney said. “With the design for the RBX and the SL, Specialized has nailed it. The chamois is exactly where it needs to be, and nowhere it doesn’t.”

    Clothesline: Mesh material on the Pro SL shorts extends up from the waist, and is not fabric bound at the edges for a light feel

    Clothesline: Mesh material on the Pro SL shorts extends up from the waist, and is not fabric bound at the edges for a light feel

    Photo: Robbie Stout

    Like me, Delaney also preferred the compressive fit of the RBX material, and the thinner pad of the SL. He commented that when riding he sometimes noticed the bib straps’ yoke moving between the shoulder blades.

    At the end of the day, both of these shorts are quite nice. Pick the RBX for long rides and a more traditional feel. Choose the SL for hot days and short rides, or simply if you like the lighter, sleeker sensation. Or, keep one of each at the ready, to suit the needs of the day.