It is easy to buy a bike  because your salesperson says it is “right for you”, but what does that really mean?

What it means to me, is that your bike can be positioned to provide a comfortable, fast ride for YOUR body.

Every Triathlon Bike Manufacturer provides geometry specifics via the web, which vary between makers/models.

Stack and Reach

The term “Stack” referrs to the distance above the Bottom Bracket

The term “Reach” refers to the distance forward of the Bottom Bracket

The Bottom Bracket is measured from the center of the Crankset Bolt

Morphology

In General:

1. “C” impacts Stack.  Longer legs tend towards a “taller” bike, and vice-versa.

2. The measure “D” is more vertical on a bike than the measure “A”, and is therefore more important for determining Stack.

3. “E-F” aids to determine arm-pad Stack. Longer or short upper-arm = taller/lower pad position.

4. “B” impacts Reach, primarily, with “A” acting as a constraint with regard to knee/elbow clearance.

In Complex Terms:

Arm Pad “Stack” and “Reach” should match Torso Length and Effective Trunk Angle.  Effective Trunk Angle accounts for Anatomical Variability (Upper/Lower Arm Length, Kyphosis, Lordosis, Scoliosis, Shoulder Roll, Injury, Prosthetic(s), etc.), betwen Hip Angle and Arm/Pad Contact.