Suspension manufacturers introduce metric shock sizing

We received a somewhat strange press release today (March 31) from SRAM and are just going to let it do the talking. Below it is our attempt at an explanation.

“Six of the bicycle industry’s main suspension manufacturers announced today that, beginning with model year 2017 bicycles, consumers will see several new shock lengths and fitment options. The new lengths are based on metric dimensions instead of the imperial-based dimensions of most current shock offerings.

Cane Creek, DVO Suspension, Manitou, RockShox, SR Suntour, and X-Fusion are each working independently to develop shock options within their own product lines, and each brand will announce its metric sizing offerings separately. The group of suspension manufacturers says that metric sizing allows both suspension and frame manufacturers to significantly simplify rear shock sizing and fitment, while also providing performance benefits to both suspension and frame designs.

A significant number of major bicycle manufacturers have recognized the advantages metric sizing offers frame design, and will be introducing new bikes equipped with metric rear shocks in the near future. Though the group is enthusiastic about the future of metric sizing in suspension, each company says it will remain committed to supporting its imperial shock sizes as long as market demand is relevant.”

In which we try to explain

What does all this really mean? Surprisingly, this has little to do with metric vs. imperial measurements and more to do with the ratio of shock travel to eye-to-eye length. By pumping up the shock length for a given travel, there will be more internal space for ever-more-involved damping mechanisms and an increase in busing overlap.

Expect to see more trunnion mounts, which can keep the eye-to-eye measurement in check while lengthening the shock. Bike such as the Trek Fuel EX and (to date myself) the Schwinn 4-Banger are good examples of the trunion mount shock in use.

The idea these are “metric” vs “imperial” seems confusing to me. Current shocks are often listed in metric sizes already. What is really happening here is the same thing that has happened to pretty much every other part of the bike. Oversize! Headtube, bottom brackets, crank spindles, axle width, axle diameter, wheel size, rim width, tire width, bar width, bar clamp diameter, rotor size, etc……

Save for a few exceptions, the oversize-ification of mountain bike components has been hugely successful in improving performance. Let’s hope this latest round of standard switching continues that tradition.



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