Initiative Customcranks
was created at the initiative of cyclists who found their ideas
regarding ergonomics, biomechanics, and drive train efficiency not
fully satisfied in the marketplace. There are some aspects of several relevant requirements that the big brands in the bicycle industrie so far have not met. (There may be reasons for this or not.) In order to better
serve these specific requirements we manufacture some products that
fall outside what is available in the general marketplace; and also
strive to meet some individual customers specific needs and/or wishes.
Biomechanics & Ergonomics Although
crank length is a major ergonomic variable on all bicycles, petite
150cm ladies (4'11'') and 200cm tall giants (6'7'') all too often have
the same crank length. Only rarely do you find crank length differences
of more than 10%, even though the body and leg lengths vary by more
than 20%.
With relatively longer crank arms, more of the
available muscles in a rider's leg are used to produce power;
consequently, throughout a normal pedaling circle with relatively short
crank arms, some of the available leg muscles remain unused. Short
riders will therefore experience the cycling more like mountain
climbing instead spinning with higher frequencys (what smaller people
usually can better do than the large). Taller riders who cycle
with relatively short crank arms limit their potential power during long or
fast rides by not using all the available leg muscles. The problem
would be alleviated by the use of crank arms proportionate to the
length of the relevant bodyparts (leg, femur or inseam).
Drive Train and Economy There
is a continuing trend in the bicycle industry toward reduction in size
of the drive train used for MTB / ATB. Smaller sized chain rings
increase forces on all sprockets, especially the smallest ones. The
small chain link contact areas on a 10 or 11 tooth sprocket - combined
with the raised chain tension on comparatively smaller chain rings -
result in increased stress and wear on the drive train. Increasingly
durable (and often more expensive) drive train materials are necessary
to even hold the drive trains life time on smaller
chainrings/spockets. This is not to everybody's advantage,
since most cyclists are not involved in winning the Tour de France.
Many cyclists will therefore value longevity of the drive train higher
than small weight savings. For touring cyclists, who commonly use
cross- or mtb-type bicycles laden with packing, this context becomes
even more obvious. Avoidance the use of very small sprockets in
combination with very small chainrings will increase the life of the
drive train. Heavier and/or stronger cyclists need larger chain rings
to overcome the problem of increased drive train wear.
We are
making a selection of five-arm crank sets with 110/74mm Bolt Circle
Diameter (often called 'Standard' bolt circle). The chain ring bolt
angle of 72° on five-arm cranks, compared to 90° on four-arm
cranks, allow for improved lateral stiffness with the largest selection
of competitively priced chain rings from most manufacturers and fitting
for different types of chains (for single speed or for 6,7,8,9.10 and
11 fold spockets).
Smallest chainrings on BCD 110mm have 34
(or even 33) teeth . The largest ring we have mounted on BCD110 so far
is 70teeth. Smallest chainrings for the BCD74mm have 24teeth
(there *are* smaller chainrings [down to 20teeth] for other bolt circle
patterns in the market - but with the mentioned disadvantages on drive
wear - especially for heavier/stronger bikers).
Location Customcranks are made according to customers wishes (and within our existing limitations) in the "United Crank Factories of Rennersdorf" in Stolpen, 30km in the East of Dresden.
Together
with the cranks we can also deliver on wish: fitting chainrings,
bottom brackets, crank bolts, chainring bolts and very precise spacers
for the best chainring adjustment.
