May 09, 2017 3 min read
A better kids’ bike geometry – confidence inspiring lowered geometry (LG), lowered seat height (LSH) and perfect sizing (PS).
For over 40 years I have been designing and developing bikes, including hundreds of kids bikes, within “accepted bicycle geometry standards.” Lots of ground clearance, extended top tubes and cranks that are way too long. The results is what I call “tippy-toe” geometry. The only way to reach the ground was to fall-over or stand on your tippy-toes and then fall over.
For confident adult riders we design bikes so that the rider’s leg will be well extended at the bottom of the pedal stroke. This provides an efficient pedaling position. But when I started taking a really hard look at how kids ride, I realized that when it comes to kids bikes that geometry is all wrong! If a bike is sized to provide full leg extension at the bottom of the pedal stroke then either (1) the bike will need to employ some form of bottom bracket forward geometry or (2) the rider will be physically unable to get both feet on the ground. Neither of these options are appropriate for young riders. Bikes for kids, particularly young kids who are just learning or still gaining confidence, need to be designed so that the rider can get both feet comfortably on the ground while seated in the saddle.
But lowering a bike isn’t as simple as just shortening the seat tube. To maintain ergonomics and rider performance with a low saddle height we increased the bottom bracket drop (which lowered the bottom bracket closer to the ground), sloped the top tube to improve the stand-over height, resized the cranks to keep the rider’s knees from being forced into their chests at the top of the pedal stroke and to provide ground clearance at the bottom of the pedal stroke. We narrowed the bottom bracket axle and employed low profile cranks to minimize the Q factor (the horizontal distance between the pedals). We extended the wheelbase and the effective top tube length. The stem and handlebar rise to put the rider in a confident comfortable position. We also get away from short bicycle cockpits that make the rider’s knees bang against the handlebars (whoever designs bikes like that should be forced to ride 10 miles on his own creation!)
This is the end of “tippy-toe” kids’ bike geometry and the creation of confidence inspiring lowered geometry (LG), lowered seat height (LSH) and perfect sizing (PS) for kids bikes. This geometry makes the bike less intimidating, safer and easier to ride. It puts kids in control.
After 40+ years of designing bikes, including countless bikes for kids, I now know that we have discovered a better design for bikes for kids. I’m calling it. We are entering a new era of kids’ bike geometry. An era where kids can learn to ride two wheel pedal bikes before age 3! No training wheels. No tricycles. Just kids riding confidently.
This is a post from Brad Hughes, an important member of our team both in product development and at Prevelo Bikes HQ in California. Brad has worked in the bicycle industry for over four decades and has managed the development of thousands of products. At Prevelo Bikes Brad harnessed all of that expertise and focused it just on kids bikes. Kind of like a laser. A Brad Laser.