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Sloping Geometry – How to Determine or Measure
the Frame Size
The geometry of some STEVENS frames is referred to as “sloping geometry”.
This means that the top tube inclines towards the seat tube and is not in parallel
to the ground. Other STEVENS frames have a horizontal top tube.
This gives the frame a more compact appearance and more stiffness in the
area of the bottom bracket. For this reason sloping frames can also be used under
certain circumstances by riders who have problems getting on and off their bicycle
with a level top tube due to a bigger standover height (standover clearance when
standing over the bicycle). Even though the optical proportions of the bicycle may
appear mismatching due to the deeply inserted seat post, the selection of a slop-
ing frame is a reasonable alternative.
The sloping design requires a modified formula to determine the frame size. In
the case of STEVENS road bike frames the frame size is normally measured from
the centre of the bottom bracket to the top edge of the top tube.
The size of today’s “sloping top tube“ frames is measured in a different way
than a few years ago when the seat tube length was the decisive measure. The
seat tubes are now shorter in general; the “nominal measure” of seat tube and
top tube are therefore considered to determine the optimal frame size. These are
quasi theoretical dimensions with an imaginary straight top tube.
In the case of the sloping top tube frames, the frame size (nominal seat tube
length) is measured from the centre of the bottom bracket to the top edge of the
nominal top tube. This may be the same as the length to the top edge of the seat
tube, but it does not have to.
On our website www.stevensbikes.de there is now a guide for each bike that
helps you find the proper frame size (“What size fits me?”).
STEVENS road frames sized 56 cm have a 56-cm-long seat tube (measured
from the bottom bracket to the top edge of the top tube), if the top tube were in
parallel to the ground. The seat tube is now a little shorter; this does however not
affect the seating position and the length of the frame. These measures can hardly
be measured; in our geometry tables on the internet you find the values for the
nominal top tube as well as for the real seat tube measures.
As a general rule, if you had a 56-cm-frame (centre of bottom bracket – top
edge of top tube) of a traditional design with horizontal top tube before, you now
need a sloping frame at STEVENS size 56 cm, as well. Because the frame propor-
tions, such as the nominal top tube length, remained the same. The only difference
is the junction between top tube and seat tube which was lowered a little. If you
have determined your frame size at 56 cm (centre of bottom bracket – top edge of
top tube), you should choose a road bike frame sized 56 cm and not a larger one.
Stack-to-Reach
Apart from the freight height, the stack-to-reach measure is another meas-
ure to determine the frame size. The stack-to-reach measure indicates how spor-
tive the seating position provided by the bike is. Furthermore, stack-to-reach is
designed to compare frame sizes.
Stack
is the vertical distance from the centre of the bottom bracket to the top
edge of the head tube.
Reach
is the horizontal distance from the centre of the bottom bracket to the
top edge of the head tube.
The quotient is usually between 1.35 and 1.65.
The lower the value, the more sportive or extended is the seating position.
reach
stack
Note:
Due to the shorter seat
tube on sloping frames
the seat post must be
pulled out further than
in the case of standard
frames. It is therefore
advisable to use a
longer seat post to
make sure that 100 mm
of the seat post at least
remain in the seat tube.
Note:
Keep in mind that the
length “centre of bottom
bracket to top edge
of seat tube” is never
equal frame size!
Note:
Your STEVENS dealer
will be pleased to help
you find the frame size
that fits you.
Note:
To check the frame size
take the separate
geometry tables as
reference! You find them
on the internet at
www.stevensbikes.de
with each bike.
