IS OVERLAP COMMON?
Yes. You will find overlap on many well designed road bicycles in smaller sizes. Speak to your retailer or to short friends who are
experienced cyclists.
WHAT FACTORS AFFECTING OVERLAP MUST A DESIGNER BALANCE?
Road frames in small sizes have relatively short top tubes compared to hybrid or mountain frames. Whereas a mountain frame must
have a generous front center distance for singletrack maneuverability without overlap at 2-3 mph, a road frame is must perform well at
more than 10 mph and if you turned the wheel enough to get overlap you would go flying over the bars due to the steering input.
The challenge that our frame designers face is to design a frame that has minimal toe clip overlap, while ensuring that the top tube is
not so long that the frame does not properly fit the customer. On a smaller road frame from any manufacturer, it will be possible to hit
your feet on the front wheel if you ride around in circles in the parking lot at 4 mph.
For hybrid and mountain frames that are used with flat bars, frame designers lengthen the top tube and slacken the head tube to give
more clearance. If we followed strategy with road frames, the top tubes would be too long especially considering that road
handlebars require another few inches of reach to get to the brake levers compared to flat bars. Such a long top tube would not allow
the shorter rider to fit properly, causing well known upper body discomfort.
Pure high performance road frames are designed to place the rider in an efficient, powerful and aerodynamic position. Ask a racer,
overlap in small frame sizes is common.
Some road bikes, such as our Road Warriors are designed to be a performance road bike for the customer that needs more relaxed
geometry than a pure racing bike. This relaxed geometry includes longer head tubes and shorter top tubes so that the rider is more
upright and not stretched out. The shorter top tube on these bikes does not help clearance.
For the dealer or customer that is interested in 700c wheels and the maximum amount of clearance between the pedals and front
wheels, we suggest they look at our Adventure bikes or Bad Boy bikes. Our geometry chart shows that the top tube length on the
size small Adventure 1000 is 57.7 cm compared to 52.5 on the small 2003 Road Warrior 600. This difference in top tube length
improves clearance.
WHAT IS FRONT CENTER DISTANCE?
The dimension between the center of the bottom bracket and the
center of the front hub is called front center (FC). See right. It is
increased by longer top tubes (TT), slacker head tube angles (HA)
and more fork rake (FR) (offset). It is decreased by shorter top tubes,
steeper head tube angles and less fork rake (offset).
ARE YOU DISCOURAGING THE USE OF FENDERS?
No. In addition to their other benefits fenders can be a set of
"whiskers", giving a rider who fails to properly position his feet a
gentle reminder that his or her shoe is about to contact the tire.
IS OVERLAP LEGAL?
Yes. U.S. Consumer Product Safety Commission (CPSC) bicycle
regulations call out a specific clearance for pedal to tire on bicycles that do not have a foot retaining device such as a toe clip (or
clipless pedal). This requirement was intended to protect barefoot kids on juvenile bikes. The existence of a CPSC requirement
related to this clearance has occasionally led some to believe that the CPSC does not allow toe clip overlap.
Factors that tend to
increase overlap:
Factors that tend to
decrease or eliminate overlap:
Large shoe size
Smaller shoe size
Toe clips
Shorter toe clips
Longer toe clips
No toe clips, use of clipless pedals
Longer crank arm length
Shorter crank arm length
Clipless pedal cleat positioned tow ards rear of shoe
Clipless pedal cleat positioned tow ards front of shoe
Addition of fenders
No fenders
Larger tire size
Smaller tire size
Shorter top tube length
Longer top tube length
Frame geometry w ith a shorter front center distance
Frame geometry w ith a longer front center distance
2
HA
FC
FR
TT
