The Strida Sx is a single speed folding bike with 18 inch wheels. The SX includes upgrades from the Strida Lt single speed model. The upgrades include a Quick Release seat mount that makes adjusting the seat height easier. Also included is the Strida alloy rear rack with an added weight carrying capacity of 10 kg. This Strida model is equipped with alloy spoke 18 inch wheels.
A Strida with 18 inch wheels provides a smoother ride than 16 inch wheels. The larger 18 inch wheels also provides a higher gear ratio and is faster but the 18 inch wheels do make it harder to climb hills.
For an explanation of the different Strida models visit this page.
Upgrade your Strida bike,
TriLock Rear Hinge System, 35.00, designed by Mark Sanders, improves the durability of the Strida rear hinge joint.
Here is a link to the Strida site for more information.