[Jeff in Kentucky]

Since I know very little about suspensions, my post will be fairly short.

Almost all bikes come with a back shock adjustable for preload- how stiff the spring is when you are sitting on the bike. Adjust it stiffer for more weight on the bike or for faster cornering, but the bike will be bouncier on bumps and less comfortable for smooth straight pavement. If the preload is set too low, the back shock will bottom out sooner on big bumps, and the bike will wallow through turns and feel less stable. I experimented with my back shock preload, and a middle setting was best for my 200 pounds, and a higher setting would be best for a big passenger added for a long trip. A 100 pound rider would probably be best off with one of the lower settings for normal street use. My back shock came from the dealership set at 2, with 1 the lowest and 7 the highest- this setting is probably best for a person weighing about 150 pounds. I moved it to 4, a compromise between comfort and better cornering.

Most bikes are greatly improved by having an expert rebuild the back shock or shocks, or getting a newer used shock from someone with a sportier bike, when they replaced their stock back shock before it wore out for track days. Here is one company that rebuilds back shocks:

http://www.cyclepathic.com/ninja1000/ninja1000suspension.htm

The front forks on a cheap bike have no adjustments. For more weight on the bike, you can buy stiffer springs, add spacers to compress the stock springs more, or add heavier and more fork oil. I used the cheapest and easiest method, more and heavier fork oil, after my bike had 2,000 miles on it and the new springs started to sag more. A bike with preload adjustment for the front forks can have the sag set, but all of the sag and damping adjustments will vary depending on a rider’s style- pros have a range of settings that are typical, and it is up to the individual to do any fine tuning for more comfort or more speed in corners.