Suspension on bikes has been around probably as long as the bike itself. And suspension stems have certainly been around since the start of the mountain bike era, with designs such as the Girvin Flexstem and the Softride Suspension Stem, although these didn’t meet with total success. With the surge in gravel biking in the past few years, interest has been rekindled with models such as the XLC Anti-Shock stem and the Redshift ShockStop.
Looking to smooth the ride on my gravel bike a bit, I investigated the Redshift ShockStop. Despite some initial trepidations, I whipped out my credit card and ordered one.
My initial impression was “wow, this is heavy”. Popping it on the scales, it came in at 280 grammes, exactly twice the weight of the stem it replaced. Not a big deal on a gravel bike weighing 10 kg, but something to bear in mind if you’re weight conscious.
The ShockStop looks pretty much like a normal stem, just a little chunkier with a squarer cross-section. The steerer clamp and the actual stem part are joined with a pivot bolt at the steerer end, with sealed cartridge bearings. It’s constructed from 6016 aluminium, and comes with some elastomer inserts, which look a lot like Opal Fruit sweets (or Starburst for the younger amongst you). A table in the instruction sheet details the combination of inserts used, depending on the rider’s weight.
Fitting the ShockStop was fairly straightforward – remove the existing stem and fit new. Once the stem was fitting to the steerer, it was time to fit the elastomer inserts – there are a few dire warnings in the instructions about not doing this before fitting the stem. The elastomers provide the cushioning. The number & type are adjusted for the rider’s weight and for the ride quality. I fitted the inserts for the 70-84kg category, figuring that I could change these later if the ride quality wasn’t what I wanted (I’m towards the top end of that range). Changing the elastomers is pretty easy, although it’s not something you’d want to do on the trail or at the roadside. Fitting the preload wedge was a little tricky, with slight pressure required on the stem to align the bolt with the threads. After that, it’s a case of refitting the handlebars and the faceplate.
I fitted the stem to my Planet-X Tempest Gravel Bike. Since the tyre choice and pressure can have a significant effect on ride quality, I kept the same setup through the test. The bike had Fulcrum Racing 700 wheels with Vittoria Revolution 35 mm tyres, inflated to 4 bar with conventional inner tubes.
After fitting, the stem had a small amount of movement when applying weight to the bars. Redshift reckon there should be 20 mm of movement and this seems pretty much spot-on.
I tested the stem on a variety of roads in my local area – smooth tarmac, rougher tarmac with shallow potholes, rough landrover trails and some single track through the local woods.
Initial impressions were that, although there was some vertical movement, the stem didn’t feel very different to a normal rigid one. The was a bit of rotation on the hoods when braking hard, but little movement when spiriting out of the saddle.
On the tarmac, the stem absorbed the road buzz and took the edge off the shallow potholes.
Once I’d moved onto the landrover tracks, which were considerably more pitted & rutted, the effect of the stem seemed less. I suspect that these were at the limit of the benefits the stem can bring.
I’d chosen a single-track test route through the local woods. It’s fairly flat and sinuous with several narrow sections between trees. The surface is bare ground with loads of tree roots and small fallen branches. Over these conditions, the stem performed well, soaking up the smaller roots and the bumps for the forest floor debris.
Overall, I’m happy with the ShockStop on my gravel bike. It does a good job of damping the majority of the road vibrations on tarmac and the most common gravel conditions, although it’s not so pronounced on the bumpier bits of rougher off-road.
In the long term, I’d have some slight concerns about the durability of the elastomers, and the change in their characteristics over time and environmental conditions. Some will remember the Onza HO pedals that used elastomers instead of springs. These were a nightmare to unclip from in cold weather when the elastomers were cold or once they had aged.