Bike Suspension Part IV: Rear Suspension Explained
Rear Suspension Explained
Bike Suspension Part Four
“Shock and Awww Yeah”
The shock allows the rear wheel to soak up impacts, helping to keep the tire in contact with the ground, increasing rider control and decreasing rider fatigue. You’ll be… shocked surprised… at how much wear and tear a good rear suspension setup will save your body over the course of ownership.
The rear frame triangle, which holds the rear wheel, will have one or more pivot points to enable the wheel to travel through a range of motion. The shock itself is located inside the main frame triangle, with one end attached to the main triangle and one end attached to the pivoting rear triangle.
Various pivot designs and configurations are available. Each has its pros and cons on how it affects a bike’s ride quality. Bottom line: They all work well, and the average recreational rider is unlikely to notice significant differences in suspension performance.
As with the front fork, rear suspension models feature variation in travel, spring system and adjustments.
Stroke travel: This is how much a rear shock compresses. It is comparatively short: 1.5” to 3”. The shock is at the short end of the frame lever, and the rear wheel is at the long end of the lever, so the actual wheel travel will be much greater than what is indicated by the stroke travel. #archimedes #forcemultiplier
Wheel travel: In contrast to stroke travel, the actual wheel travel will be similar to that found on the front wheel (the amount depends on the type of bike). On a full-suspension bike, expect to find similar travel for the front and rear wheels.
Spring system: This is either coil or air, as per the front suspension. Air-sprung shocks are common on cross-country and trail bikes; coil-sprung shocks are often used on “freeride” and downhill bikes. “All mountain” bikes are in the middle and may feature either style.
Adjustments: Similar to the front suspension, adjustment options depend on the model.
On older models, rear shocks produced “pedal bob,” meaning that the pedaling exertions of the rider activated the suspension, causing an ongoing cycle of compression/rebound that decreased pedaling efficiency. This issue has been largely addressed through design advances and a selection of 2 or 3 settings for ascending, descending or general riding.
“Pedal Bob” was also the name of my second bluegrass-ska fusion band.