Stack and Reach - How does it help me?

While not all bike sizes are equal or even equally named, certain measurements can be used as a constant.

In the two examples below, the size 'M' is a '50' in the upper and '54' in the lower table.

SIZE	HEAD ANGLE	SEAT ANGLE	TOP TUBE	REACH	HEAD TUBE	STACK	CHAIN STAY	WHEEL BASE	STANDOVER HEIGHT
cm	Degrees	Degrees	cm	cm	cm	cm	cm	cm	cm
XS (43.0)	70.5	75.0	51.5	36.6	13.5	53.0	42.0	99.8	67.5
S (46.5)	72.0	74.5	52.5	37.2	15.0	55.0	42.0	99.0	70.2
M (50.0)	72.0	74.0	54.0	37.7	17.0	56.7	42.0	100.0	73.0

SIZE	HEAD ANGLE	SEAT ANGLE	TOP TUBE	REACH	HEAD TUBE	STACK	CHAIN STAY	WHEEL BASE	STANDOVER HEIGHT
cm	Degrees	Degrees	cm	cm	cm	cm	cm	cm	cm
S (50.0)	73.0	75.0/78.0	51.3	40.2	11.0	51.0	40.5	98.2	76.2
M (52.0)	73.0	75.0/78.0	52.9	41.7	13.0	53.0	40.5	100.1	78.5
L (54.0)	73.0	75.0/78.0	54.6	43.0	15.0	54.9	40.5	101.9	80.5

While this does not show us much, the more 'eagle eyed' will have perhaps spotted the upper table is road bike geometry and the lower is TT bike, the 'Stack' and 'Reach' columns will help a great deal.

Keeping with the size 'M', the 'Stack' and 'Reach' numbers are;

Top Table 56.7cm Stack and 37.7cm Reach

Lower Table 53.0cm Stack and 41.7cm Reach

Looking at these numbers shows a much more obvious difference.

So where are 'Stack' and 'Reach' measured from?

The frame 'stack' is the vertical distance from the centre of the bottom bracket to the top of the head tube on the bike frame.

The frame 'reach' is the horizontal distance from the centre of the bottom bracket to the top of the head tube on the bike frame (see above image)

With our current example the 'M' size bike from the first table will be taller with a shorter distance to the bars than the second 'M' which will be lower with a greater distance to the bars.

How does this help you?

Well, simply with these numbers and the seat and head tube angles we can use the studio 'Fitmaster' to replicate the geometry of a given bike to check that it will fit you.

The seat tube angle is a key component to this as it will define where the saddle can be placed in space and show the limitations of adjust ability for a given frame size.

The more vertical (closer to 90) angles in the lower table will allow the Hip angle of the Cyclist to open more facilitating an easier TT position than the less vertical Road bike angles.

From another perspective, a 'long and low' bike will not be comfortable or suitable for the Cyclist with flexibility issues...

As all our Bike Fits follow 'The Physio Bike Fit process' we can help you find the right bike and the right size bike for you.

Any further questions please get in touch and ask away.

Stay safe and Happy Miles

fit me up