The Daylight Difference

A discussion on BMX frame geometry by former AA Pro, Vet Pro, Hall Of Fame BMX racer, USA BMX Certified Coach, Team Manager, and BMX Industry Icon Turnell Henry of Custom Ops Bicycles. 

Frame geometry.  When choosing a frame, It's one of the most important features to consider. I've been racing BMX for 40 years now and I know what I need to compete in this sport and what works more and more for the many racers that I coach. I've witnessed BMX frame geometry evolve from the classic Stingray frame geometry with lower BB's, to today's diamond frame geometry with higher BB's. When the Stingray geometry evolved into the diamond frame geometry, BB heights were moved up to as high as 12+ inches to accommodate the use of longer cranks. 

Of course, BMX tracks have changed tremendously over the years and so to have the many race/riding techniques and styles. Along the way, many of us who have been in this industry since it's beginning realized the center of gravity on some frames went too high and the BB's needed to be lowered to make bike handling more stable. 

The reason cruisers ride so easily is because most of them have BB heights that are perpendicular to or lower than their rear wheel axle height. It's not simply because their wheels are larger. In the case of the cruiser, it's this relationship between axle and BB height geometry that is mostly responsible for how easily they handle. The so called industry standard for 20" pro frames has settled into an accepted "sweet spot" of 11.5 inches and hasn't changed in many years - above the axle. As well, many of the smaller frames - like minis, juniors and experts - that are always built with smaller cranks, should have never had BB heights higher than their pro frame counterparts - but many did and still do. Over the past decade, a few companies brought their BB's down to 11.25 inches, some even down to 11 inches, but most simply left the BB at that old standard. 

It wasn't enough for me. And I don't think it has been enough for most riders. They just don't know it - until they ride the difference. Over the years, I worked closely with many frame builders to get my BB lower. By lowering the bottom bracket just 1/2" - 3/4"- inches - under 11 inches - the BMX race bike becomes more stable, easier to corner, and faster to accelerate. I've seen this transformation in my own riding and in the performance of every rider I have trained who has moved to a lower BB frame. I've ridden race frames with BB's as low as 10.5 inches, with 180 mm cranks, and have never hit my cranks over jumps or in corners.  I realize we all have different sweet spots, but for me the lower BB is mine and I firmly believe it's likely yours. Again, the lower center of gravity gives me more control of my bike in the air and over jumps, allows me to have a more stable manual, and enhances my abilities to carve turns and pass more comfortably, and gives me better leverage on my drivetrain to achieve a faster sprint.  I'm 58 years old riding, racing and pulling on a 20" BMX frame that enhanced my sweet spots. That frame now is the Daylight ARC c1. Thank you Daylight Cycle Co. for your enhanced geometry, furthering the advancement of the BMX race frame and our sport. 

Turnell Henry
Custom Ops Bicycles