The history of elastomer-based suspension systems on bikes isn’t littered with success. The Proflex Flex Stem from 1991 was a sound idea that didn’t perform well in the real world. Redshift’s Shockstop stem also uses elastomers, but this one does work!
Consisting of two 6061 T6 aluminium sections pivoting on two cartridge bearings, the Shockstop’s steerer clamp extends within the handlebar-holding stem-tube, ending in a cross-shaped elastomer support with central bolt hole for the stepped plastic preload wedge.
One or two of the five supplied elastomers are placed within the upper quarters of the support, and the preload wedge is tightened to lock them in place above it. The handlebar can then be fitted with the four-bolt faceplate.
Shockstop comes in lengths from 90 to 120mm with +/- 6-degree rise, or 100mm in +30 degrees. My 110mm example with two elastomers weighed 294g. A table gives the recommended combinations of elastomers for different rider weight and handlebar type. I fell near the middle of the 70 to 84kg range.
When holding the hoods, it’s obvious that the stem isn’t vertically rigid, but it doesn’t bob and there’s little noticeable dive when out of the saddle or braking hard. Torsional stiffness is very good and sprinting with the Shockstop fitted felt much like normal.
It works in a subtle way, squashing sudden bumps and effectively smoothing incessantly rough surfaces. I found the recommended set-up ideal, but you can tune it to suit your preference.
On tarmac it was good, so I headed to a potholed dirt track, then some gravel on a titanium bike with 40mm tyres at a firm 50psi.
Tearing along hardpacked gravel at 26mph holding the hoods, my forearms wobbled rhythmically, but placing hands on the tops instead saw them vibrate violently. Staying on the hoods or drops was much more comfortable.
This confirms the difference in effective travel, which is claimed to be 20mm on drop bars when holding the hoods and 10mm on flat bars.
The Shockstop’s styling is a little clumsy but its looks and mass are easily outweighed by superb performance.
Redshift Shockstop Stem details
- The five supplied elastomers are coloured and marked 50, 60, 70, 80 and 90 in relation to their durometer values.
- The Shockstop fits 1 1/8-inch steerers and 31.8mm handlebars, but shims are available for 25.4mm or 26mm bars, too.
- The max rider weight is 135kg / 300lb. A table gives combinations of elastomers for different rider weight and handlebar type.