Review on 🚲 DNM Preload MTB Mountain Wheelchair Bike Rear Suspension Shock Absorber AL 6061 Coil Spring 750 Lbs 150mm (5.9") x 30mm 160mm (6.23") x 35mm 165mm (6.5") x 35mm + Additional Bushing by Matthew Watkins

This is a basic spring damper with only adjustable preload, but it could be a good choice for the application you need it for. I recently bought an Aostirmotor S18 e-bike (known by other names and manufacturers) with a very stiff rear suspension. The stock shock is rated at 1,500 pounds and is only 5 inches long. I wanted a softer ride, so I replaced that 6-inch shock with a 750-pound spring. The ride is smoother and there is a little more travel. For only $40, I'm happy with the improved ride. A heavier rider can simply increase the spring preload if it is too soft. Installing a shock that is an inch longer than stock increases the seat and rack height. So this is something to consider if you are under 5'10". A bike company or an experienced welder can easily move the shock. Install the front shock an additional 0.5-0.75" lower on the frame to provide a 6"/150mm shock that lowers the seat height. To get the best performance out of a cheap shock, a longer shock must be used. You have more adjustability (air/damping/preload/valving), but you may be not suitable for your project. If doing this with the same bike, loosen/adjust the rear brake cable to provide additional extension.